Link:  Pharm/Biotech Resources

Title:  Serine protease BSSP6

United States Patent:  6,921,658

Issued:  July 26, 2005

Inventors:  Uemura; Hidetoshi (Hyogo, JP); Okui; Akira (Nara, JP); Kominami; Katsuya (Osaka, JP); Yamaguchi; Nozomi (Kyoto, JP); Mitsui; Shinichi (Kyoto, JP)

Assignee:  Fuso Pharmacutical Industries, Ltd. (Osaka, JP)

Appl. No.:  856320

Filed:  November 19, 1999

PCT Filed:  November 19, 1999

PCT NO:  PCT/JP99/06476

371 Date:  May 21, 2001

102(e) Date:  May 21, 2001

PCT PUB.NO.:  WO00/31257

PCT PUB. Date:  June 2, 2000

There are provided a human BSSP6 serine protease and a pharmaceutical composition containing this serine protease. Also provided is an antibody to this serine protease or to a fragment thereof.

SUMMARY OF THE INVENTION

Under these circumstances, the present inventors have succeeded in cloning of cDNA encoding novel human and mouse serine proteases. The present inventors have shown that the mature type of the novel human serine protease (hBSSP6) is composed of 229 amino acids, the prostate type thereof is composed of 282 amino acids (the -;53rd to 229th amino acids of SEQ ID NO: 2) and the brain type thereof is composed of 250 amino acids (the -;21st to 229th amino acids of SEQ ID NO: 2). The placenta type thereof is considered to be a larger protein started from methionine located at a more upstream region. Further, the present inventors have shown that the mature type of mutant type of hBSSP6 (hereinafter referred to as mutant hBSSP6) is composed of 254 amino acids (the 1st to 254 amino acids of SEQ ID NO: 6). The present inventors have shown that the mature type of the novel mouse serine protease (mBSSP6) is composed of 229 amino acids (the 1st to 229th amino acids of SEQ ID NO: 4), the brain type thereof is composed of 249 amino acids (the -;20th to 229th amino acids of SEQ ID NO: 4) and the prostate type thereof is composed of 276 amino acids (the -;47th to 229th amino acids of SEQ ID NO: 4). In addition, 110 amino acid sequences of the mature type serine proteases contain consensus sequences having serine protease activity.

In summary, the 1st feature of the present invention is amino acid sequences of biological active mature serine proteases hBSSP6 and mBSSP6 and nucleotide sequences encoding the amino acid sequences.

That is, they are the amino acid sequence composed of 229 amino acids (the 1st to 229th amino acids) represented by SEQ ID NO: 2 (the mature type hBSSP6 (SEQ ID NO: 6)) and a nucleotide sequence encoding the amino acid sequence (the 272nd to 958th bases of SEQ ID NO: 1). Further, they are the amino acid sequence composed of 254 amino acids (the 1st to 254 amino acids) represented by SEQ ID NO: 6 (the mutant hBSSP6 (SEQ ID NO: 6)) and a nucleotide sequence encoding the amino acid sequence (the 114th to 875th bases of SEQ ID NO: 5). In addition, they include amino acid sequences substantially similar to SEQ ID NOS: 2 and 6 and nucleotide sequences encoding such similar amino acid sequences. Further, they include modified derivatives of proteins having these amino acid sequences. An amino acid sequence substantially similar to a given amino acid sequence used herein means an amino acid sequence derived from the given amino acid sequence by modification such as substitution, deletion, addition and/or insertion of one to several amino acids with maintaining the same property as that of the protein having the given amino acid sequence. The modified derivative of the proteins includes, for example., phosphate adduct, sugar chain adduct, metal adduct (e.g., calcium adduct), the protein fused to another protein such as albumin etc., dimer of the protein, and the like.

Further, they are the amino acid sequence composed of 229 amino acids (the 1st to 229th amino acids) or SEQ ID NO: 4 (the mature type mBSSP6 (SEQ ID NO: 4)) and a nucleotide sequence encoding the amino acid sequence (the 224th to 930th bases of SEQ ID NO: 3). In addition, they include amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding such similar amino acid sequences. Further, they include modified derivatives of proteins having these amino acid sequences.

The 2nd feature of the present invention is an amino acid sequence composed of 282 amino acids (prostate type hBSSP6 (the -;53rd to 229th amino acids of SEQ ID NO: 2)) wherein 53 amino acids represented by the -;53rd to -;1st amino acids of SEQ ID NO: 2 is added to the N-terminus side of the mature type hBSSP6 amino acid sequence (SEQ ID NO: 2) and a nucleotide sequence encoding the amino acid sequence (the 113th to 958th bases of SEQ ID NO: 1). In addition, this feature includes amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding these substantially similar amino acid sequences. Further, this feature includes modified derivatives of proteins having these amino acid sequences.

The 3rd feature of the present invention is an amino acid sequence composed of 250 amino acids (the brain type hBSSP6 (the -;21st to 229th amino acids of SEQ ID NO: 2)) wherein 21 amino acids represented by the -;21st to -;1st amino acids of SEQ ID NO: 2 is added to the N-terminus side of the mature type hBSSP6 amino acid sequence (SEQ ID NO: 2) and a nucleotide sequence encoding the amino acid sequence (the 209th to 958th bases of SEQ ID NO: 1). In addition, this feature includes amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding these substantially similar amino acid sequences. Further, this feature includes modified derivatives of proteins having these amino acid sequences.

The 4th feature of the present invention is an amino acid sequence composed of 249 amino acids (the brain type mBSSP6 (the -;20th to 229th amino acids of SEQ ID NO: 4)) wherein 20 amino acids represented by the -;21st to -;1st amino acids of SEQ ID NO: 4 is added to the N-terminus side of the mature type mBSSP6 amino acid sequence (SEQ ID NO: 4) and a nucleotide sequence encoding the amino acid sequence (the 184th to 930th bases of SEQ ID NO: 1). In addition, this feature includes amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding these substantially similar amino acid sequences. Further, this feature includes modified derivatives of proteins having these amino acid sequences.

The 5th feature of the present invention is an amino acid sequence composed of 276 amino acids (the prostate type mBSSP6 (the -;47th to 229th amino acids of SEQ ID NO: 4)) wherein 47 amino acids represented by the -;47th to -;1st amino acids of SEQ ID NO: 4 is added to the N-terminus side of the mature type mBSSP6 amino acid sequence (SEQ ID NO: 4) and a nucleotide sequence encoding the amino acid sequence (the 103rd to 930th bases of SEQ ID NO: 3). In addition, this feature includes amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding these substantially similar amino acid sequences. Further, this feature includes modified derivatives of proteins having these amino acid sequences.

The 6th feature of the present invention is an amino acid sequence composed of 275 amino acids (the mutant hBSSP6 (the -;21st to 254th amino acids of SEQ ID NO: 6)) wherein 21 amino acids represented by the -;21st to -;1st amino acids of SEQ ID NO: 6 is added to the N-terminus side of the mature type of mutant hBSSP6 amino acid sequence (the 1st to 254th amino acids of SEQ ID NO: 6) and a nucleotide sequence encoding the amino acid sequence (the 51st to 875th of SEQ ID NO: 5). In addition, this feature includes amino acid sequences substantially similar to the amino acid sequence and nucleotide sequences encoding these substantially similar amino acid sequences. Further, this feature includes modified derivatives of proteins having these amino acid sequences.

The 7th feature of the present invention is a vector comprising the nucleotide sequence according to any of the above 1st to the 6th features, and transformant cells transformed with the vector.

The 8th feature of the present invention is a process for producing BSSP6 protein from the transformed cells of the 7th feature.

The 9th feature of the present invention is a transgenic non-human animal, wherein the expression level of BSSP6 gene has been altered.

The 10th feature of the present invention is an antibody against BSSP6 protein or its fragment and a process for producing thereof.

The 11th feature of the present invention is a method for determining BSSP6 protein or its fragment in a specimen using the antibody of the 9th feature.

The 12th feature of the present invention is a diagnostic marker of diseases comprising BSSP6 protein.

Hereinafter, unless otherwise stated, the nucleotide sequence represented by each SEQ ID NO: includes the above-described various fragments thereof, and similar nucleotide sequences and their fragments. Likewise, the amino acid sequence represented by each SEQ ID NO: includes the above-described various fragments thereof, similar amino acid sequences and their fragments, and modified derivatives thereof. In addition, unless otherwise stated, BSSP6, hBSSP6 (including the mutant hBSSP6), and mBSSP6 include proteins having the above-described respective amino acid sequences.

DETAILED DESCRIPTION OF THE INVENTION

The term "pro part" used herein means a part of a pro-form, i.e., the pro-form from which the corresponding active type protein part is removed. The term "pre part" used herein means a part of a prepro-form, i.e., the prepro-form from which the corresponding pro-form is removed. The term "prepro part" used herein means a part of a prepro-form, i.e., the prepro-form from which the corresponding active type protein part is removed.

The amino acid sequence represented by SEQ ID NO: 2 (the 1st to 229th amino acids) is the hBSSP6 mature or active type protein composed of 229 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 687 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the mature type protein of the present invention is deleted or added, while the above amino acid sequence is preferred.

The amino acid sequence represented by SEQ ID NO: 2 (the -;70th to 229th amino acids) is the hBSSP6 prostate type protein composed of 299 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 897 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the prostate type protein is deleted or added, while the above amino acid sequence is preferred. The -;70th to -;1st amino acids is the prepro or pro part and this is considered to be a precursor type of hBSSP6 protein.

The amino acid sequence represented by SEQ ID NO: 2 (the -;21st to 229th amino acids) is the hBSSP6 brain type protein composed of 250 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 750 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the brain type protein is deleted or added, while the above amino acid sequence is preferred. The -;21st to -;1st amino acids is the prepro or pro part and this is considered to be a precursor type of hBSSF6 protein.

The amino acid sequence represented by SEQ ID NO: 4 (the 1st to 229th amino acids) is the mBSSP6 mature or active type protein composed of 229 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 687 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the mature type protein is deleted or added, while the above amino acid sequence is preferred.

The amino acid sequence represented by SEQ ID NO: 4 (the -;20th to 229th amino acids) is the mBSSP6 brain type protein composed of 249 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 747 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the brain type protein is deleted or added, while the above amino acid sequence is preferred. The -;20th to -;1st amino acids is the prepro or pro part and this is considered to be a precursor type of mBSSP6 protein.

The amino acid sequence represented by SEQ ID NO: 4 (the -;47th to 229th amino acids) is the mBSSP6 prostate type protein composed of 276 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 828 bases. The present inventors have shown that the serine protease activity is maintained even when one to several amino acids of the N-terminus in the amino acid sequence of the prostate type protein is deleted or added, while the above amino acid sequence is preferred. The -;47th to -;1st amino acids is the prepro or pro part and this is considered to be a precursor type of mBSSP6 protein.

The amino acid sequence represented by SEQ ID NO: 6 (the 1st to 254th amino acids) is the mutant hBSSP6 mature or active type protein composed of 254 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 762 bases. The amino acid sequence of the mutant hBSSP6 differs from that of hBSSP6 in that the amino acid sequence of hBSSP6 (SEQ ID NO: 2) corresponds to that of mutant hBSSP6 (SEQ ID NO: 6) from which the 46th to 70th amino acids thereof is removed. The term "mutant" of mutant hBSSP6 is used to merely differentiate it from hBSSP6.

The amino acid sequence represented by SEQ ID NO: 6 (the -;21st to 254th amino acids) is a precursor protein of the mutant hBSSP6 composed of 275 amino acids, and the nucleotide sequence encoding the amino acid sequence is composed of 825 bases. The -;21st to -;1st amino acids is the prepro or pro part.

The nucleotide sequences encoding hBSSP6 (including mutant hBSSP6, hereinafter simply referred to as hBSSP6) or mBSSP6 of the present invention can be obtained by preparing mRNAs from cells expressing the protein and converting it into double stranded DNAs according to a conventional manner. For preparing mRNA, guanidine isothiocyanate-calcium chloride method (Chirwin, et al., Biochemistry, 18, 5294, 1979) or the like can be used. For preparing poly (A)+RNA from total RNAs, there can be used affinity chromatography using a carrier, for example, Sepharose, latex particles, etc., to which oligo (dT) is attached, and the like. The above-obtained RNA can be used as a template and treated with reverse transcriptase by using, as a primer, oligo (dT) which is complementary to the poly (A) strand at the 3′-terminus, or a random primer, or a synthesized oligonucleotide corresponding to a part of the amino acid sequence of hBSSP6 or mBSSP6 to obtain a hybrid mRNA strand comprising DNA complementary to the mRNA or cDNA. The double stranded DNA can be obtained by treating the above-obtained hybrid mRNA strand with E. coli RNase, E. coli DNA polymerase and E. coli DNA ligase to convert into a DNA strand.

It is also possible to carry out cloning by RT-PCR method using primers synthesized on the basis of the nucleotide sequence of hBSSP6 or mBSSP6 gene and using hBSSP6 or mBSSP6 expressing cell poly (A)+RNA as a template. Alternatively, the desired cDNA can be obtained without using PCR by preparing or synthesizing a probe on the basis of the nucleotide sequence of hBSSP6 or mBSSP6 gene and screening a cDNA library directly. Among genes obtained by these methods, the gene of the present invention can be selected by confirming a nucleotide sequence thereof. The gene of the present invention can also be prepared according to a conventional method using chemical syntheses of nucleic acids, for example, phosphoamidite method (Mattencci, M. D. et al., J. Am. Chem. Soc., 130, 3185, 1981) and the like.

By using the thus-obtained hBSSP6 or mBSSP6 gene, their expression in various tissues can be examined.

In case of northern blotting analysis, the expression of hBSSP6 is observed in each part of brain, medulla, placenta, lung, heart, prostate, testicle, mucous membrane gland, etc., and the expression of mBSSP6 is observed in brain of 15-day fetus and testicle and prostate of 3-month-old mouse. In case of RT-PCR analysis, the expression of hBSSP6 is observed in hippocampus and prostate of the adults, and the expression of mBSSP6 is observed in brain of newborn to 12-day-old mice and in prostate of 4-month-old mouse. mRNA of the mutant hBSSP6 is expressed in prostatic cancer cell strains, PC3, DU145 and LNCaP. As for tissues, it is expressed in testicle, lung, fetus brain, and adult hippocampus. Then, the novel proteases of the present invention are presumed to play various roles in brain, prostate, medulla, lung, placenta, heart, testicle and mucous membrane gland. For example, in brain, there is a possibility that they can be used for treatment and diagnosis of brain diseases such as Alzheimer's disease (AD), epilepsy, brain tumor and the like. Further, in other tissues, there is a possibility that they can be used for treatment and diagnosis of various diseases such as cancer, in particular, prostatic cancer, inflammation, sterility, prostate hypertrophy and the like. Further, it is presumed they may have a certain influence on blood coagulation, fibrinolysis and complement systems.

In general, many genes of eucaryote exhibit polymorphism and, sometimes, one or more amino acids are substituted by this phenomenon. Further, even in such case, sometimes, a protein maintains its activity. Then, the present invention includes a gene encoding a protein obtained by modifying a gene encoding the amino acid sequence represented by SEQ ID NO: 2, 4 or 6, artificially, in so far as the protein has the characteristic function of the gene of the present invention. Further, the present invention includes a protein which is a modification of the amino acid sequence represented by SEQ ID NO: 2, 4 or 6 in so far as the protein has the characteristics of the present invention. Modification is understood to include substitution, deletion, addition and/or insertion. In particular, the present inventors have shown that, even when several amino acids are added to or deleted from the N-terminus amino acid of hBSSP6 or mBSSP6 mature protein represented by SEQ ID NO: 2 or 4, the resultant sequence maintains its activity.

That is, the present invention includes a protein comprising either amino acid sequence described in SEQ ID NOS: 2. 4 and 6; or one of these amino acid sequences wherein one to several amino acids have been substituted, deleted, added and/or inserted, and being belonging to serine protease family.

Each codon for the desired amino acid itself has been known and it can be selected freely. For example, codons can be determined according to a conventional manner by taking into consideration of frequency of use of codons in a host to be utilized (Grantham, R. et al., Nucleic Acids Res., 9, r43, 1989). Therefore, the present invention also includes a nucleotide sequence appropriately modified by taking into consideration of degeneracy of a codon. Further, these nucleotide sequences can be modified by a site directed mutagenesis using a primer composed of a synthetic oligonucleotide encoding the desired modification (Mark, D. F. et al., Proc. Natl. Acad. Sci. USA., 81, 5662, 1984), or the like.

Furthermore, the DNA of the present invention includes DNA which is hybridizable to either of nucleotide sequences described in SEQ ID NOS: 1, 3 and 5, or nucleotide sequences complementary to these nucleotide sequences in so far as the protein encoded by the nucleotide sequence has the same properties as those of hBSSP6 or mBSSP6 of the present invention. It is considered that many of sequences which are hybridizable to a given sequence under stringent conditions have a similar activity to that of a protein encoded by the given sequence. The stringent conditions according to the present invention includes, for example, incubation in a solution containing 5×SSC, 5% Denhardt's solution (0.1% BSA, 0.1% Ficol 1400, 0.1% PVP), 0.5% SDS and 20 μg/ml denatured salmon sperm DNA at 37° C. overnight, followed by washing with 2×SSC containing 0.1% SDS at room temperature. Instead of SSC, SSPE can be appropriately used.

Probes for detecting a hBSSP6 or mBSSP6 gene can be designed based on either of nucleotide sequences described in SEQ ID NOS: 1, 3 and 5. Or, primers can be designed for amplifying DNA or RNA containing the nucleotide sequence. To design probes or primers is carried out routinely by a person skilled in the art. An oligonucleotide having a designed nucleotide sequence can be synthesized chemically. And, when a suitable label is added to the oligonucleotide, the resultant oligonucleotide can be utilized in various hybridization assays. Or, it can be utilized in nucleic acid synthesis reactions such as PCR. An oligonucleotide to be utilized as a primer has, preferably, at least 10 bases, more preferably 15 to 50 bases in length. An oligonucleotide to be utilized as a probe has, preferably, 100 bases to full length.

Moreover, it is possible to obtain a promoter region and an enhancer region of a hBSSP6 or mBSSP6 gene present in the genome based on the cDNA nucleotide sequence of hBSSP6 or mBSSP6 provided by the present invention. Specifically, these control regions can be obtained according to the same manner as described in JP 6-181767 A; J. Immunol., 155, 2477, 1995; Proc. Natl. Acad. Sci., USA, 92, 3561, 1995 and the like. The promoter region used herein means a DNA region which is present upstream from a transcription initiation site and controls expression of a gene. The enhancer region used herein means a DNA region which is present in an intron, a 5′-non-translated region or a 3¹-non-translated region and enhances expression of a gene.

The present invention also relates to a vector comprising the nucleotide sequence represented by SEQ ID NO: 1 or a nucleotide sequence encoding the amino acid sequence represented by SEQ ID NO: 2; the nucleotide sequence represented by SEQ ID NO: 3 or a nucleotide sequence encoding the amino acid sequence represented by SEQ ID NO: 4; the nucleotide sequence represented by SEQ ID NO: 5 or a nucleotide sequence encoding the amino acid sequence represented by SEQ ID NO: 6; or a nucleotide sequence similar to them. A nucleotide sequence similar to a give nucleotide sequence used herein means a nucleotide sequence which is hybridizable to the given nucleotide sequence or its complementary nucleotide sequence under the above-described stringent conditions and encodes a protein having the same properties as those of the protein encoded by the nucleotide sequence.

The vector is not specifically limited in so far as it can express the protein of the present invention. Examples thereof include pBAD/His, pRSETA, pcDNA2.1, pTrcHis2A, pYES2, pBlueBac4.5, pcDNA3.1 and pSecTag2 manufacture by Invitrogen, pET and pBAC manufactured by Novagen, pGEM manufactured by Promega, pBluescriptII manufactured by Stratagene, pGEX and pUC18/19 manufactured by Pharmacia, PfastBAC1 manufactured by GIBCO and the like. Preferably, a protein expression vector (described in the specification of a patent application entitled "Protein expression vector and its use" and filed by the same applicant on the same day) is used. This expression vector is constructed by using pCR11-TOPO vector described in the Examples hereinafter, or a commercially available expression vector, for example pSecTag2A vector or pSecTag2B vector (Invitrogen) and integrating a secretory signal nucleotide sequence suitable for expression of the protein of the present invention, in the 3′ downstream side thereof, a Tag nucleotide sequence, a cleavable nucleotide sequence and a cloning site, into which a nucleotide sequence encoding a target protein can be inserted, in this order. More specifically, it is preferred to use trypsin signal as the secretory signal, a nucleotide sequence encoding polyhistidine as the Tag nucleotide sequence, and a nucleotide sequence encoding an amino acid sequence which is susceptible to enzyme-specific cleavage, i.e., a nucleotide sequence encoding the amino acid sequence of Asp-Asp-Asp-Asp-Lys (SEQ ID NO:40) (said amino acid sequence is recognized by enterokinase, and the recombinant fusion protein is cleaved at the C-terminus part thereof) as the cleavable nucleotide sequence.

Furthermore, the present invention provides transformed cells having the nucleotide sequence of the present invention in an expressible state by means of the above vector. Preferably, host cells to be used for the transformed cells of the present invention are animal cells and insect cells. However, host cells include any cells (including those of microorganisms) which can express a nucleotide sequence encoding the desired protein in the expression vector of the present invention and can secrete extracellularly.

The animal cells and insect cells used herein include cells derived from human being and cells derived from fly or silk worm. For example, there are CHO cell, COS cell, BHK cell, Vero cell, myeloma cell, HEK293 cell, HeLa cell, Jurkat cell, mouse L cell, mouse C127 cell, mouse FM3A cell, mouse fibroblast, osteoblast, cartilage cell, S2, Sf9, Sf21, High Five™ (registered trade mark) cell and the like. The microorganisms used herein include E. coli, yeast or the like.

The protein of the present invention as such can be expressed as a recombinant fused protein so as to facilitate isolation, purification and recognition. The recombinant fused protein used herein means a protein expressed as an adduct wherein a suitable peptide chain are added to the N-terminus and/or C-terminus of the desired protein expressed by a nucleotide sequence encoding the desired protein. The recombinant protein used herein means that obtained by integrating a nucleotide sequence encoding the desired protein in the expression vector of the present invention and cut off an amino acid sequence which derived from nucleic acids other than those encoding the desired protein from the expressed recombinant fused protein, and is substantially the same as the protein of the present invention.

Introduction of the above vector into host cells can be carried out by, for example, transfection according to lipopolyamine method, DEAE-dextran method, Hanahan method, lipofectin method or calcium phosphate method, microinjection, eletroporation and the like.

As described above, the present invention also relates to a process for producing hBSSP6 or mBSSP6 comprising culturing cells transformed with the above nucleotide sequence of the present invention and collecting the produced hBSSP6 or mBSSP6. The culture of cells and separation and purification of the protein can be carried out by a per se known method.

The present invention also relates to an inhibitor of the novel serine protease of the present invention. Screening of the inhibitor can be carried out according to a per se known method such as comparing the enzyme activity upon bringing into contact with a candidate compound with that without contact with the candidate compound, or the like.

The present invention relates to a non-human transgenic animal whose expression level of hBSSP6 or mBSSP6 gene has been altered. The hBSSP6 or mBSSP6 gene used herein includes cDNA, genomic DNA or synthetic DNA encoding hBSSP6 or mBSSP6. In addition, expression of a gene includes any steps of transcription and translation. The non-human transgenic animal of the present invention is useful for studies of functions or expression control of hBSSP6 or mBSSP6, elucidation of mechanisms of diseases in which hBSSP6 or mBSSP6 is presumed to be involved, and development of disease model animals for screening and safety test of medicine.

In the present invention, expression of a gene can be modified artificially by mutagenizing at a part of several important sites which control normal gene expression (enhancer, promoter, intron, etc.) such as deletion, substitution, addition and/or insertion to increase or decrease an expression level of the gene in comparison with its inherent expression level. This mutagenesis can be carried out according to a known method to obtain the transgenic animal.

In a narrow sense, the transgenic animal means an animal wherein a foreign gene is artificially introduced into reproductive cells by gene recombinant techniques. In a broad sense, the transgenic animal includes an antisense transgenic animal the function of whose specific gene is inhibited by using antisense RNA, an animal whose specific gene is knocked out by using embryonic stem cells (ES cells), and an animal into which point mutation DNA is introduced, and the transgenic animal means an animal into which a foreign gene is stably introduced into a chromosome at an initial stage of ontogeny and the genetic character can be transmitted to the progeny.

The transgenic animal used herein should be understood in a broad sense and includes any vertebrates other than a human being. The transgenic animal of the present invention is useful for studies of functions or expression control of hBSSP6 or mBSSP6, elucidation of mechanisms of diseases associated with cells expressing in a human being, and development of disease model animals for screening and safety test of medicine.

As a technique for creating the transgenic animal, a gene is introduced into a nucleus in a pronucleus stage of egg cells with a micropipette directly under a phase-contrast microscope (microinjection, U.S. Pat. No. 4,873,191). Further, there are a method using embryonic stem cell (ES cell), and the like. In addition, there are newly developed methods such as a method wherein a gene is introduced into a retroviral vector or adenoviral vector to infect egg cells, a sperm vector method wherein a gene is introduced into egg cells through sperms, and the like.

A sperm vector method is a gene recombinant technique wherein a foreign gene is incorporated into sperm cells by adhesion, electroporation, etc., followed by fertilization of egg cells to introduce the foreign gene into the egg cells (M. Lavitranoet et al., Cell, 57, 717, 1989). Alternatively, an in vivo site specific gene recombinant technique such as that using cre/loxP recombinase system of bacteriophage P1, FLP recombinase system of Saccharomyces cerevisiae, etc. can be used. Furthermore, introduction of a transgene of the desired protein into a non-human animal using a retroviral vector has been reported.

For example, a method for creating a transgenic animal by microinjection can be carried out as follows.

First, a transgene primarily composed of a promoter responsible for expression control, a gene encoding a specific protein and a poly A signal is required. It is necessary to confirm expression modes and amounts between respective systems because an expression mode and amount of a specific molecule is influenced by a promoter activity, and transgenic animals differ from each other according to a particular system due to the difference in a copy number of an introduced transgene and a introduction site on a chromosome. An intron sequence which is spliced may be previously introduced before the poly A signal because it has been found that an expression amount varies due to a non-translation region and splicing. Purity of a gene to be used for introduction into fertilized egg cells should be as high as possible. This is of importance. Animals to be used include mice for collecting fertilized eggs (5- to 6-week-old), male mice for mating, false pregnancy female mice, seminiferous tubule-ligated mice, and the like.

For obtaining fertilized egg cells efficiently, ovulation may be induced with gonadotropin or the like. Fertilized egg cells are recovered and a gene in an injection pipette is injected into male pronucleus of the egg cells by microinjection. For returning the injected egg cells to a fallopian tube, an animal (false pregnancy female mouse, etc.) is provided and about 10 to 15 eggs/mouse are transplanted. Then, genomic DNA is extracted from the end part of the tail to confirm whether the transgene is introduced into newborn mouse or not. This confirmation can be carried out by detection of the transgene with southern blot technique or PCR technique, or by positive cloning wherein a marker gene, which is activated only when homologous recombination is caused, has been introduced. Further, transcribed products derived from the transgene are detected by northern blot technique or RT-PCR technique to confirm expression of the transgene. Or, western blotting can be carried out with a specific antibody to a protein.

The knockout mouse of the present invention is treated so that the function of mBSSP6 gene is lost. A knockout mouse means a transgenic mouse any of whose gene is destroyed by homologous recombination technique so that its function is deficient. A knockout mouse can be created by carrying out homologous recombination with ES cells and selecting embryonic stem cells wherein either of allele genes are modified or destroyed. For example, embryonic stem cells whose genes are manipulated at blastocyte or morula stage of fertilized eggs are injected to obtain a chimera mouse wherein cells derived from the embryonic stem cells are mixed with those derived from the embryo. The chimera mouse (chimera means a single individual formed by somatic cells based on two or more fertilized eggs) can be mated with a normal mouse to create a heterozygote mouse wherein all of either of the allele genes have been modified or destroyed. Further, a homozygote mouse can be created by mating heterozygote mice.

Homologous recombination means recombination between two genes whose nucleotide sequences are the same or very similar to each other in terms of gene recombination mechanism. PCR can be employed to select homologous recombinant cells. A PCR reaction can be carried out by using a part of a gene to be inserted and a part of a region where the insertion is expected as primers to find out occurrence of homologous recombination in cells which give an amplification product. Further, for causing homologous recombination in a gene expressed in embryonic stem cells, homologous recombinant cells can readily be selected by using a known method or its modification. For example, cells can be selected by joining a neomycin resistant gene to a gene to be introduced to impart neomycin resistance to cells after introduction.

The present invention also provide an antibody recognizing hBSSP6 or mBSSP6 or a fragment thereof. The antibody of the present invention includes an antibody against a protein having the amino acid sequence described in SEQ ID NO: 2, 4 or 6 or its fragment. An antibody against hBSSP6 or mBSSP6 or a fragment thereof (e.g., polyclonal antibody, monoclonal antibody, peptide antibody) or an antiserum can be produced by using hBSSP6 or mBSSP6 or a fragment thereof, etc. as an antigen according to a per se known process for producing an antibody or an antiserum.

The hBSSP6 or mBSSP6 or a fragment thereof is administered to a site of a warm-blooded animal where an antibody can be produced by administration thereof as such or together with a diluent or carrier. For enhancing the antibody production, upon administration, Freund's complete adjuvant or Freund's incomplete adjuvant may be administrated. Normally, the administration is carried out once every 1 to 6 weeks, 2 to 10 times in all. Examples of the warm-blooded to be used include monkey, rabbit, dog, guinea pig, mouse, rat, sheep, goat, chicken and the like with mouse and rat being preferred. As rats, for example, Wistar and SD rats are preferred. As mice, for example, BALB/c, C57BL/6 and ICR mice are preferred.

For producing monoclonal antibody producer cells, individuals whose antibody titer have been recognized are selected from warm-blooded animals, e.g., a mouse immunized with an antigen. Two to 5 days after the last immunization, the spleen or lymph node of the immunized animal is collected and antibody producer cells contained therein are subjected to cell fusion with myeloma cells to prepare a monoclonal antibody producer hybridoma. The antibody titer in an antiserum can be determined by, for example, reacting the antiserum with a labeled hBSSP6 or mBSSP6 as described hereinafter, followed by measurement of the activity bound to the antibody. The cell fusion can be carried out according to a known method, for example, that described by Koehler and Milstein (Nature, 256, 495, 1975) or its modifications (J. Immunol. Method, 39, 285, 1980; Eur. J. biochem, 118, 437, 1981; Nature, 285, 446, 1980). As a fusion promoting agent, there are polyethylene glycol (PEG), Sendai virus and the like. Preferably, PEG is used. Further, for improving fusion efficiency, lectin, poly-L-lysine or DMSO can be appropriately added.

Examples of myeloma cells include X-63Ag8, NS-1, P3U1, SP2/0, AP-1 and the like with SP2/0 being preferred. The preferred ratio of the number of the antibody producer cells (spleen cells): the number of myeloma cells are 1:20 to 20:1. PEG (preferably PEG 1000 to PEG 6000) is added at a concentration of about 10 to 80% and the mixture is incubated at 20 to 40° C., preferably 30 to 37° C. for 1 to 10 minutes to carry out the cell fusion efficiently. Screening of anti-hBSSP6 or mBSSP6 antibody producer hybridomas can be carried out by various methods. For example, a supernatant of a hybridoma culture is added to a solid phase to which hBSSP6 or mBSSP6 antigen is adsorbed directly or together with a carrier (e.g., microplate), followed by addition of an anti-immunoglobulin antibody (in case that the cells used in cell fusion is those of a mouse, anti-mouse immunoglobulin antibody is used) or protein A to detect the anti-hBSSP6 or mBSSP6 monoclonal antibody attached to the solid phase. Or, a supernatant of a hybridoma culture is added to a solid phase to which an anti-immunoglobulin antibody or protein A is adsorbed, followed by addition of hBSSP6 or mBSSP6 labeled with a radioactive substance, an enzyme, etc., to detect the anti-hBSSP6 or mBSSP6 monoclonal antibody attached to the solid phase.

Selection and cloning of the anti-hBSSP6 or mBSSP6 monoclonal antibody can be carried out according to a per se known method or its modification. Normally, a HAT (hypoxanthine, aminopterin, thymidine)-added medium for culturing animal cells is used. Any culture medium can be used for selection, cloning and growing up in so far as the hybridoma can grow. For example, there can be used RPMI culture medium containing 1 to 20%, preferably 10 to 20% fetal bovine serum, or a serum-free medium for culturing hybridomas. Preferably, the culture is carried out at a temperature of about 37° C. Normally, the culture time is 5 days to 3 weeks, preferably 1 weeks to 2 weeks. Normally, the culture is carried out under 5% CO₂. The antibody titer of a supernatant of a hybridoma culture can be measured according to the same manner as that of the above-described measurement of anti-BSSP6 antibody titer in an antiserum. That is, examples of the measurement to be used include radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), FIA (fluorescence immunoassay), plaque assay, agglutination reaction method, and the like. Among them, ELISA as shown blew is preferred.

Screening by ELISA

A protein prepared according to the same operation as that for an immunogen is immobilized on the surface of each well of an ELISA plate. Next, BSA, MSA, OVA, KLH, gelatin, skimmed milk, or the like is immobilized on each well to prevent non-specific adsorption. A supernatant of a hybridoma culture is added to each well and is allowed to stand for a given time so that an immunological reaction proceeds. Each well is washed with a washing solution such as PBS or the like. Preferably, a surfactant is added to this washing solution. An enzyme labeled secondary antibody is added and allowed to stand for a given time. As the enzyme to be used for the label, there can be used β-galactosidase, alkaline phosphatase, peroxidase and the like. After washing each well with the same washing solution, a substrate solution of the labeled enzyme used is added so that an enzymatic reaction proceeds. When the desired antibody is present in the supernatant of a hybridoma culture, the enzymatic reaction proceeds and the color of the substrate solution is changed.

Normally, cloning is carried out by a per se known method such as semi-solid agar method, limiting dilution method and the like. Specifically, after confirming a well in which the desired antibody is produced by the above-described method, cloning is carried out to obtain a single clone. For cloning, it is preferred to employ limiting dilution method wherein hybridoma cells are diluted so that one colony is formed per one well of a culture plate. For cloning by limiting dilution method, feeder cells can be used, or a cell growth factor such as interleukin 6, etc. can be added to improve colony forming capability. In addition, cloning can be carried out by using FACS and single cell manipulation method. The cloned hybridoma is preferably cultured in a serum-free culture medium and an optimal amount of an antibody is added to its supernatant. The single hybridoma thus obtained can be cultured in a large amount by using a flask or a cell culture device, or cultured in the abdominal cavity of an animal (J. Immunol. Meth., 53, 313, 1982) to obtain a monoclonal antibody. When culturing in a flask, there can be used a cell culture medium (e.g., IMDM, DMEM, RPMI1640, etc.) containing 0 to 20% of FCS. When culturing in the abdominal cavity of an animal, the animal to be used is preferably the same species or the same line as that from which the myeloma cells used in the cell fusion are derived, a thymus deficient nude mouse or the like, and the hybridoma is transplanted after administration of a mineral oil such as pristane, etc. After 1 to 2 weeks, myeloma cells are proliferated in the abdominal cavity to obtain ascites containing a monoclonal antibody.

The monoclonal antibody of the present invention which does not cross-react with other proteins can be obtained by selecting a monoclonal antibody which recognizes an epitope specific to hBSSP6 or mBSSP6. In general, an epitope presented by an amino acid sequence composed of at least 3, preferably 7 to 20 successive amino acid residues in an amino acid sequence which constitutes a particular protein is said to be an inherent epitope of the protein. Then, a monoclonal antibody recognizing an epitope constituted by a peptide having an amino acid sequence composed of at least 3 successive amino acid residue selected from the amino acid residues disclosed in either of SEQ ID NOS: 2, 4 and 6 can be said to be the monoclonal antibody specific for hBSSP6 or mBSSP6 of the present invention. An epitope common to BSSP6 family can be selected by selecting an amino acid sequence conservative among the amino acid sequences described in SEQ ID NOS: 2, 4 and 6. Or, in case of a region containing an amino acid sequence specific for each sequence, a monoclonal antibody which can differentiate respective proteins can be selected.

Separation and purification of the anti-hBSSP6 or mBSSP6 monoclonal antibody, like a conventional polyclonal antibody, can be carried out according to the same manner as those of immunoglobulins. As a known purification method, there can be used a technique, for example, salting out, alcohol precipitation, isoelectric precipitation, electrophoresis, ammonium sulfate precipitation, absorption and desorption with an ion exchange material (e.g., DEAE), ultrafiltration, gel filtration, or specific purification by collecting only an antibody with an antibody-binding solid phase or an active adsorber such as protein A or protein G, etc., and dissociating the binding to obtain the antibody. For preventing formation of aggregates during purification or decrease in the antibody titer, for example, human serum albumin is added at a concentration of 0.05 to 2%. Alternatively, amino acids such as glycine, α-alanine, etc., in particular, basic amino acids such as lysine, arginine, histidine, etc., saccharides such as glucose, mannitol, etc., or salts such as sodium chloride, etc. can be added. In case of IgM antibody, since it is very liable to be aggregated, it may be treated with β-propionilactone and acetic anhydride.

The polyclonal antibody of the present invention can be produced according to a per se known method or its modification. For example, an immunogen (protein antigen) per se or a complex thereof with a carrier protein is prepared and, according to the same manner as that in the above monoclonal antibody production, a warm-blooded animal is immunized. A material containing an antibody against the protein of the present invention or its fragment is collected from the immunized animal and the antibody is separated and purified to obtain the desired antibody. As for a complex of an immunogen and a carrier protein for immunizing a warm-blooded animal, the kind of a carrier protein and the mixing ratio of a carrier and a hapten are not specifically limited in so far as an antibody against the hapten immunized by cross-linking with the carrier is efficiently produced. For example, there can be used about 0.1 to 20, preferably about 1 to 5 parts by weight of bovine serum albumin, bovine cycloglobulin, hemocyanin, etc. coupled with one part by weight of a hapten. For coupling a carrier and a hapten, various condensing agents can be used. Examples thereof include glutaraldehyde, carbodiimide or maleimide active ester, active ester agents having thiol group or dithiopyridyl group, and the like. The condensed product is administered as such or together with a carrier or diluent to a site of a warm-blooded animal where an antibody can be produced. For enhancing the antibody production, upon administration, Freund's complete adjuvant or Freund's incomplete adjuvant may be administrated. Normally, the administration is carried out once every 2 to 6 weeks, 3 to 10 times in all. The polyclonal antibody can be collected from blood, ascites, or the like, preferably blood of the immunized animal. The polyclonal antibody titer in an antiserum can be measured according to the same manner as measurement of the above monoclonal antibody titer in the antiserum. Separation and purification of the polyclonal antibody, like the above monoclonal antibody, can be carried out according to the same manner as those of immunoglobulins.

The monoclonal antibody and polyclonal antibody against hBSSP6 or mBSSP6 or a fragment thereof can be utilized for diagnosis and treatment of diseases associated with cells expressing hBSSP6 or mBSSP6. By using these antibodies, hBSSP6 or mBSSP6 or a fragment thereof can be determined based on their immunological binding to hBSSP6 or mBSSP6 or a fragment thereof of the present invention. Specifically, examples of a method for determining hBSSP6 or mBSSP6 or a fragment thereof by using these antibodies include a sandwich method wherein the antibody attached to an insoluble carrier and the labeled antibody are reacted with hBSSP6 or mBSSP6 or a fragment thereof to form a sandwich complex and the sandwich complex is detected, as well as a competitive method wherein labeled hBSSP6 or mBSSP6, and hBSSP6 or mBSSP6 or a fragment thereof in the specimen are competitively reacted with the antibody and hBSSP6 or mBSSP6 or a fragment thereof in the specimen is determined based on the amount of the labeled antigen reacted with the antibody.

As a sandwich method for determining hBSSP6 or mBSSP6 or a fragment thereof, there can be used two step method, one step method and the like. In two step method, first, the immobilized antibody is reacted with hBSSP6 or mBSSP6 or a fragment thereof and then unreacted materials are completely removed by washing, followed by addition of the labeled antibody to form immobilized antibody-hBSSP6 or mBSSP6-labeled antibody. In one step method, the immobilized antibody, labeled antibody and hBSSP6 or mBSSP6 or a fragment thereof are added at the same time.

Examples of an insoluble carrier used for the determination include synthetic resins such as polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyester, polyacrylate, nylon, polyacetal, fluorine plastic, etc.; polysaccharides such as cellulose, agarose, etc.; glass; metal; and the like. An insoluble carrier may be shaped in various forms, for example, tray, sphere, fiber, rod plate, container, cell, test tube, and the like. The antibody adsorbed by a carrier is stored at a cold place in the presence of an appropriate preservative such as sodium azide or the like.

For immobilization of the antibody, a known chemical bonding method or a physical adsorption can be used. Examples of a chemical bonding method include a method using glutaraldehyde; maleimide method using N-succusinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate, N-succusinimidyl-2-maleimide acetate or the like; carbodiimide method using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride; or the like. In addition, there are maleimidobenzoyl-N-hydroxysuccinimide ester method, N-succinimidyl-3-(2-pyridylthio)propionic acid method, bisdiazobenzidine method, and dipalmityllysine method. Or, it is possible to capture a complex formed beforehand by reacting a materiel to be tested with two antibodies, whose epitopes are different, with an immobilized a 3rd antibody against the antibody.

For labeling, it is preferred to use enzyme, fluorescent substance, luminous substance, radioactive substance, metal chelate, or the like. Examples of the enzyme include peroxidase, alkaline phosphatase, β-D-galactosidase, malate dehydrogenase, Staphylococcus nuclease, δ-5-steroidisomerase, α-glycerol phosphate dehydrogenase, triose phosphate isomerase, horseradish peroxidase, asparaginase, glucose oxidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase, acetylcholinesterase and the like. Examples of the fluorescent substance include fluorescein isothiocyanate, phycobiliprotein, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthalaldehyde, and the like. Examples of the luminous substance include isoluminol, lucigenin, luminol, aromatic acridinium ester, imidazole, acrdinium salt and its modified ester, luciferin, luciferase, aequorin and the like. Examples of the radioactive substance include ¹²⁵I, ¹²⁷I, ¹³¹I, ¹⁴C, ³H, ³²P, ³⁵S and the like. The labeling material is not limited to them and any material which can be used for immunological determination can be used. Further, a low molecular weight hapten such as biotin, dinitrophenyl, pyridoxal or fluorescamine may be attached to the antibody. Preferably, horseradish peroxidase is used as a labeling enzyme. This enzyme can be reacted with various substrates and can readily be attached to the antibody by periodate method.

When an enzyme is used as a labeling material, a substrate and, if necessary, a coloring enzyme is used for measuring its activity. In case of using peroxidase as the enzyme, H₂O₂ is used as a substrate and, as a coloring agent, there can be used 2,2′-azino-di-[3-ethylbenzthiazoline sulfonic acid] ammonium salt (ABTS), 5′-aminosalicylic acid, o-phenylenediamine, 4-aminoantipyrine, 3,3′,5,5′-tetramethylbenzidine and the like. In case of using alkaline phosphatase as the enzyme, o-nitorphenylphosphate, p-nitrophenylphosphoric acid, or the like can be used as a substrate. In case of using β-D-galactosidase as the enzyme, fluorescein-d-(β-D-galactopyranoside), 4-methylumbelliphenyl-β-D-galactopyranoside, or the like can be used as a substrate. The present invention also include a kit comprising the above monoclonal antibody, polyclonal antibody and reagents.

As a cross-linking agent, a known cross-linking agent such as N,N′-o-phenylenedimaleimide, 4-(N-maleimidomethyl)cyclohexanoate N-succinimide ester, 6-maleimidohexanoate N-succineimide ester, 4,4′-dithiopyridine or the like can be utilized. The reaction of these cross-linking agents with enzymes and antibodies can be carried out by a known method according to properties of a particular cross-linking agent. Further, as the antibody, a fragment thereof, for example, Fab′, Fab, F(b′2) can be used as the case may be. A labeled enzyme can be obtained by the same treatment regardless of whether the antibody is polyclonal or monoclonal. When the above labeled enzyme obtained by using a cross-linking agent is purified by a known method such as affinity chromatography or the like, a immunoassay system having more higher sensitivity can be obtained. The enzyme labeled and purified antibody is stored at a dark cold place with addition of a stabilizer such as thimerosal, glycerin or after lyophilization.

An objective to be determined is not specifically limited in so far as it is a sample containing hBSSP6 or mBSSP6 or a fragment thereof, or a sample containing a precursor or a fragment thereof and includes body fluids such as plasma, serum, blood, serum, urine, tissue fluid, cerebrospinal fluid and the like.
 

Claim 1 of 2 Claims

1. A protein consisting of amino acid residues 1 to 229 of SEQ ID NO:2.

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