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K X Chai

Publications and source records attributed to K X Chai.

17 recordsLinked to original sources
PubMed2001

Down-regulation of prostasin serine protease: a potential invasion suppressor in prostate cancer.

BACKGROUND: Prostasin is a serine protease predominantly expressed in normal prostate epithelial cells. The biological function of prostasin has not been determined. METHODS: Western blot and RT-PCR analyses were used to examine the expression of prostasin in prostate cancer cell lines. Immunohistochemistry was used to evaluate prostasin protein expression in human prostate cancer. An in vitro Matrigel invasion assay was used to test the invasiveness of prostate cancer cell lines forced to express recombinant prostasin. RESULTS: Both prostasin protein and mRNA were found to be expressed in normal human prostate epithelial cells and a non-invasive human prostate cancer cell line, the LNCaP, but neither was found in invasive human prostate cancer cell lines DU-145 and PC-3. Prostasin mRNA expression was absent in invasive prostate cancer cell lines of a transgenic mouse model. Immunohistochemistry analysis showed that prostasin protein expression is down-regulated in high-grade prostate cancer. Transfection of DU-145 and PC-3 cells with a full-length human prostasin cDNA restored prostasin expression and reduced the in vitro invasiveness by 68 and 42%, respectively. CONCLUSIONS: Our data indicate that prostasin may be implicated in normal prostate biology and is able to suppress prostate cancer invasion in vitro.

Blotting, Western↗
PubMed2001

Prostasin is a glycosylphosphatidylinositol-anchored active serine protease.

A recombinant human prostasin serine protease was expressed in several human cell lines. Subcellular fractionation showed that this serine protease is synthesized as a membrane-bound protein while a free-form prostasin is secreted into the culture medium. Prostasin was identified in nuclear and membrane fractions. Membrane-bound prostasin can be released by phosphatidylinositol-specific phospholipase C treatment, or labeled by [(3)H]ethanolamine, indicating a glycosylphosphatidylinositol anchorage. A prostasin-binding protein was identified in mouse and human seminal vesicle fluid. Both the secreted and the membrane-bound prostasin were able to form a covalently linked 82-kDa complex when incubated with seminal vesicle fluid. The complex formation between prostasin and the prostasin-binding protein was inhibited by a prostasin antibody, heparin, and serine protease inhibitors. Prostasin's serine protease activity was inhibited when bound to the prostasin-binding protein in mouse seminal vesicle fluid. This study indicates that prostasin is an active serine protease in its membrane-bound form.

Animals↗
PubMed2000

Reduced cardiac hypertrophy and altered blood pressure control in transgenic rats with the human tissue kallikrein gene.

To evaluate the cardiovascular actions of kinins, we established a transgenic rat line harboring the human tissue kallikrein gene, TGR(hKLK1). Under the control of the zinc-inducible metallothionein promoter, the transgene was expressed in most tissues including the heart, kidney, lung, and brain, and human kallikrein was detected in the urine of transgenic animals. Transgenic rats had a lower 24-h mean arterial pressure in comparison with control rats, which was further decreased when their diet was supplemented with zinc. The day/night rhythm of blood pressure was significantly diminished in TGR(hKLK1) animals, whereas the circadian rhythms of heart rate and locomotor activity were unaffected. Induction of cardiac hypertrophy by isoproterenol treatment revealed a marked protective effect of the kallikrein transgene because the cardiac weight of TGR(hKLK1) increased significantly less, and the expression of atrial natriuretic peptide and collagen III as markers for hypertrophy and fibrosis, respectively, were less enhanced. The specific kinin-B2 receptor antagonist, icatibant, abolished this cardioprotective effect. In conclusion, the kallikrein-kinin system is an important determinant in the regulation of blood pressure and its circadian rhythmicity. It also exerts antihypertrophic and antifibrotic actions in the heart.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Molecular cloning and expression of rat bradykinin B1 receptor.

The gene encoding rat bradykinin B1 receptor has been cloned by using a partial rat B1 cDNA probe. The rat B1 receptor gene contains two exons and the entire coding region is within the second exon. The 5'-flanking region of the rat B1 receptor gene contains several putative transcriptional regulatory sites including TATA box, cAMP response element, NF-kappaB and AP-1. It showed promoter activity inducible by lipopolysaccharide in vascular smooth muscle cells. Rat B1 receptor mRNA was found to be alternatively spliced and induced by lipopolysaccharide treatment in a wide range of tissues, such as the salivary gland, testis, kidney, lung, heart, prostate and aorta. The deduced rat B1 receptor amino acid sequence is 71% homologous to human and rabbit counterparts, and 89% homologous to the mouse counterpart. The expressed B1 receptor in HEK293 cells displayed a rank order of affinity for the kinin peptides: des-Arg9-BK>Lys-des-Arg9-BK approximately des-Arg9, Leu8-BK>Sar-Tyr-epsilonAhx-Lys-[D-betaNal7, Ile8]-des-Arg9-BK>Sar-Tyr-epsilonAhx-Lys-des-Arg9-BK>>BK>> Hoe140. These results indicate that the cloned gene encodes a functional rat B1 receptor.

Amino Acid Sequence↗
PubMed1997

Molecular cloning and expression of rat kallistatin gene.

We have previously purified and cloned human kallistatin and rat kallikrein-binding protein (RKBP), which are tissue kallikrein inhibitors belonging to the serine proteinase inhibitor superfamily. In this study, we have cloned and sequenced the gene encoding rat kallistatin with Phe-Phe-Ser-Ala-Gln at positions P2-P3', which is identical to the reactive center of human kallistatin. Rat kallistatin is highly similar to human kallistatin, sharing 68% and 57% sequence identity at the cDNA and the amino acid levels. The rat kallistatin gene exists in a single copy and is located on chromosome 6. An SphI RFLP is found between SHR and WKY rats at or near the rat kallistatin gene locus. Two amino acid polymorphisms of the rat kallistatin gene between these two strains were found by sequence analysis. A candidate promoter in the 5'-flanking region (109 bp) of the rat kallistatin gene has been identified by reporter assays. The expression of rat kallistatin in the liver is growth-dependent and down-regulated during acute phase inflammation. Recombinant rat kallistatin produced in E. coli is able to bind to tissue kallikrein, and the interaction is inhibited by heparin. These characteristics define rat kallistatin as the counterpart of human kallistatin.

Amino Acid Sequence↗
PubMed1996

Genomic DNA sequence, expression, and chromosomal localization of the human B1 bradykinin receptor gene BDKRB1.

We have cloned and sequenced the human B1 bradykinin receptor gene (BDKRB1), which contains an uninterrupted coding exon. A putative promoter was identified by linking various lengths of the 5'-flanking region of the B1 receptor gene coding sequence to a CAT reporter and assaying for CAT activity. Deletion analysis showed that a 300-bp fragment in the promoter region is sufficient to direct the synthesis of the reporter and that an enhancer-like element is present between -1842 and -812. A genomic Southern blot using the B1 cDNA revealed that the receptor is encoded by a single-copy gene. The gene is located on chromosome 14q32.1-q32.2, in close proximity to the B2 receptor gene. Northern blot analysis identified a 1.7- to 1.8-kb mature mRNA transcript of the B1 receptor gene in the kidney and pancreas. A widespread tissue distribution of the B1 gene expression was identified by RT-PCR-Southern blot analysis using specific oligonucleotide probes.

Chloramphenicol O-Acetyltransferase↗
PubMed1996

Tissue kallikrein inhibitors in mammals.

We have discovered, purified and cloned a new kallikrein-binding protein (KBP or kallistatin) from humans and rodents. Kallistatins are members of the serine proteinase inhibitor (serpin) superfamily. They are acidic glycoproteins with molecular masses of 58-62 kDa and pI values of 4.6-5.2. Kallistatin forms a SDS-stable complex with tissue kallikrein and inhibits kallikrein's activities. Human kallistatin has a unique cleavage site with Phe-Phe-Ser at the P2-P1-P1' positions. The protein sequence of mature human kallistatin shares 44-46% identity with other serpins such as human alpha 1-antitrypsin, protein C inhibitor and rat kallikrein-binding protein. The kallistatin genes display the typical five exon-four intron serpin gene structure. The human kallistatin gene is localized on chromosome 14q31-32.1 and the RKBP gene is on chromosome 6. Kallistatin is evolutionarily diverse but functionally conserved in mammalian species. This overview summarizes the biochemistry, molecular biology and potential physiology and/or pathophysiology of this new tissue kallikrein inhibitor.

Animals↗
PubMed1994

Molecular cloning, sequence analysis, and chromosomal localization of the human protease inhibitor 4 (kallistatin) gene (PI4).

The gene encoding human protease inhibitor 4 (kallistatin; gene symbol PI4), a novel serine proteinase inhibitor (serpin), has been isolated and completely sequenced. The kallistatin gene is 9618 bp in length and contains five exons and four introns. The structure and organization of the kallistatin gene are similar to those of the genes encoding alpha 1-antichymotrypsin, protein C inhibitor, and alpha 1-antitrypsin. The kallistatin gene is also similar to the genes encoding rat and mouse kallikrein-binding proteins. The first exon of the kallistatin gene is a noncoding 89-bp fragment, as determined by primer extension. The fifth exon, which contains 308 bp of noncoding sequence, encodes the reactive center of kallistatin. In the 5'-flanking region of the kallistatin gene, 1125 bp have been sequenced and a consensus promoter segment with potential transcription regulatory sites, including CAAT and TATA boxes, an AP-2 binding site, a GC-rich region, a cAMP response element, and an AP-1 binding site, has been identified within this region. The kallistatin gene was localized by in situ hybridization to human chromosome 14q31-q32.1, close to the serpin genes encoding alpha 1-antichymotrypsin, protein C inhibitor, alpha 1-antitrypsin, and corticosteroid-binding globulin. In a genomic DNA Southern blot, kallistatin-related genes were identified in monkey, mouse, rat, bovine, dog, cat, and a ground mole. The patterns of hybridization revealed clues of human serpin evolution.

Amino Acid Sequence↗
PubMed1994

Molecular cloning and characterization of a novel kallikrein transcript in colon and its distribution in human tissues.

1. We have cloned and characterized a new species of kallikrein cDNA from a human colon cDNA library. The new kallikrein cDNA clone contains a part of intron 2 of the tissue kallikrein gene which is spliced to the remaining exon sequences. It does not contain exons 1 and 2. 2. An in-frame open reading frame is present in the new kallikrein cDNA allowing translation of a 216-amino acid product. The intron-containing kallikrein transcript was detected in salivary glands, pancreas, kidney, colon, prostate gland, testis, spleen, and lung by reverse-transcription/polymerase chain reaction followed by Southern blot analysis using an intron-containing kallikrein-specific oligonucleotide probe. 3. The results indicate that the new species of kallikrein may be processed by alternative splicing or arises from a different transcription initiation site.

Amino Acid Sequence↗
PubMed1993

Kallistatin: a novel human serine proteinase inhibitor. Molecular cloning, tissue distribution, and expression in Escherichia coli.

We have recently purified a novel human serine proteinase inhibitor (serpin), designated as kallistatin, which binds to tissue kallikrein and inhibits kallikrein's kininogenase and amidolytic activities. In the present studies, we have cloned a full-length cDNA encoding kallistatin from human liver RNA by the polymerase chain reaction. The cDNA is 1284 base pairs in length and encodes 427 amino acid residues, including a 26-residue signal peptide and a 401-residue mature peptide. The translated amino acid sequence of kallistatin matches with the protein sequence and shares 44-46% sequence identity with human alpha 1-antichymotrypsin, protein C inhibitor, corticosteroid-binding globulin, alpha 1-antitrypsin, thyroxin-binding globulin, and rat kallikrein-binding protein. Kallistatin is a new member of the serpin superfamily with a unique reactive site P1-P1' of Phe-Ser. Four potential glycosylation sites are found in the translated amino acid sequence of kallistatin. In a Southern blot analysis following reverse transcription and polymerase chain reaction, kallistatin was found to be expressed in human liver, stomach, pancreas, kidney, aorta, testes, prostate, artery, atrium, ventricle, lung, renal proximal tubular cell, and a colonic carcinoma cell line T84. A genomic Southern blot using the full-length kallistatin cDNA probe revealed simple banding patterns suggesting the gene encoding kallistatin is single-copied. The kallistatin cDNA encoding the mature peptide was expressed in Escherichia coli. The recombinant kallistatin forms an SDS-stable complex with 125I-human tissue kallikrein and has a molecular mass of 40 kDa. The cloning of human kallistatin cDNA established the identity of the novel kallikrein inhibitor and its expression in a functional form in E. coli provides means for studying its structure-function relationship through protein engineering.

Amino Acid Sequence↗
PubMed1992

Expression of kallikrein-binding protein and alpha 1-antitrypsin genes in response to sex hormones, growth, inflammation and hypertension.

We have recently purified rat kallikrein-binding protein (RKBP) and alpha 1-antitrypsin (alpha 1-AT) to homogeneity and isolated, sequenced cDNAs encoding these potential regulators of tissue kallikreins. Characterization of the cDNA and the gene has established the identity of the kallikrein-binding protein as a new member of the serpin (serine proteinase inhibitor) superfamily. Using the cDNA probes in Northern blot hybridization, we found a differential regulation of RKBP and alpha 1-AT gene expression in the liver. Ovariectomy results in a 67% reduction of RKBP mRNA levels but a 30% increase of alpha 1-AT mRNA levels. Estradiol or progesterone treatment of the ovariectomized rats increases RKBP transcripts by 2.5- and 6.5-fold, respectively, but reduces alpha 1-AT mRNA level by 30% and 45%, respectively. In contrast to kininogen expression, both RKBP and alpha 1-AT mRNA levels in the liver are at the lowest at birth and rapidly increase during growth and development. Rats injected with endotoxin from 4 to 24 h show a time-dependent decrease of RKBP mRNA levels while the same treatment induces alpha 1-AT gene expression. RKBP mRNA levels in the normotensive Wistar Kyoto (WKY) rats are higher than those in the spontaneously hypertensive rats (SHR) while there are no differences of alpha 1-AT mRNA levels between SHR and WKY.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗
PubMed1992

Effects of diabetes and insulin on expression of kallikrein and renin genes in the kidney.

We previously showed that renal prokallikrein synthesis is reduced in streptozotocin (STZ)-diabetic rats. Plasma renin activity is also reduced in diabetic rats. To investigate the molecular mechanisms underlying these changes, we examined the effects of diabetes and insulin treatment on renal kallikrein and renal renin mRNA levels and the activities of these enzymes. Rats made diabetic by STZ were either treated with 1.5 to 1.75 U PZI insulin daily to maintain moderate hyperglycemia (plasma glucose 200 to 300 mg/dl, D + I) or left untreated to produce severe hyperglycemia (plasma glucose greater than 400 mg/dl, D). Control (C) rats were also studied. After three weeks, renal kallikrein mRNA was reduced 50% in D rats. A proportional reduction in immunoreactive kallikrein was also observed (37.8 +/- 2.5 vs. 55.8 +/- 6.8 ng/mg protein, D vs. C, P less than 0.001). Kallikrein mRNA and immunoreactive kallikrein levels in D + I rats were not different from C rats. Renin mRNA level was also markedly reduced in D rats, compared to C rats. This was associated with reduced plasma renin concentration (4.5 +/- 0.2 vs. 10.5 +/- 1.6 ng Ang I/ml/hr, D vs. C, P less than 0.01). However, renal renin concentration was unchanged (0.84 +/- 0.17 vs. 0.84 +/- 1.3 micrograms Ang I/mg protein/hr, D vs. C). In D + I rats, renin mRNA level and plasma renin concentration were not different from C levels. However, renal renin concentration was increased (1.49 +/- 0.27 micrograms Ang I/mg protein/hr) compared to C rats (P less than 0.05). beta-actin mRNA levels were unchanged in either diabetic rat group.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1991

Molecular cloning and sequence analysis of the mouse kallikrein-binding protein gene.

A genomic clone (MKBP-10) encoding the mouse kallikrein-binding protein (MKBP) was isolated from a mouse genomic DNA library by screening with a rat kallikrein-binding protein (RKBP) cDNA probe. The total sequenced region of the MKBP gene spans 8615 base pairs. The exon and intron locations of the RKBP gene were identified by similarity with the RKBP gene. The MKBP gene encodes a prepeptide of 417 amino acid residues which exhibits 71% homology with RKBP. A TATA box sequence was located in the 5' flanking region of the MKBP gene by similarity with the consensus sequence TATAAAA.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and analysis of the rat kallikrein-binding protein gene.

The gene encoding rat kallikrein-binding protein (RKBP), a serine protease inhibitor, has been isolated and analyzed with the aid of the polymerase chain reaction. The gene is approximately 10 kilobases in length with four introns of approximately 2.2, 1.8, 0.9, and 0.84 kilobases. This gene is composed of five exons and encodes a polypeptide of 416 amino acid residues. The reactive center region of RKBP is encoded by the fifth exon with the putative P1-P1' residues being Lys-Ser. The organization of the RKBP gene is homologous to those of human alpha 1-antitrypsin and alpha 1-antichymotrypsin in size and arrangement of exons and introns, suggesting that they belong to the same subgroup of serpins. In the 5'-flanking region of the RKBP gene, a variant TATA box sequence, ATAAATA, is found 20 base pairs upstream from the transcription initiation site. The 5'-flanking region of the RKBP gene was able to direct transcription of the reporter gene chloramphenicol acetyltransferase when transfected into a rat hepatoma cell line. An internal promoter-like region was found in the first intron of the RKBP gene, downstream from the transcription initiation site and upstream from the translation initiation codon, however, it was unable to direct expression of the chloramphenicol acetyltransferase reporter gene in our experiments. The expression of RKBP in rat liver was induced by sex hormone treatment as indicated by dot-blot analysis. A genomic Southern blot using an RKBP cDNA probe revealed multiple bands suggesting that the RKBP gene belongs to a family of highly conserved genes.

Amino Acid Sequence↗
PubMed1990

Tissue kallikrein-binding protein is a serpin. I. Purification, characterization, and distribution in normotensive and spontaneously hypertensive rats.

Kallikrein-binding protein was purified to apparent homogeneity from rat serum by Affi-Gel Blue, DEAE-Sepharose CL-6B, Sephacryl S-200 chromatography, and preparative gel electrophoresis or high performance liquid chromatography. The purified protein migrates as a single band of 60 kDa in a sodium dodecyl sulfate-polyacrylamide gel under reducing conditions. It is an acidic protein with isoelectric points ranging from 4.2 to 4.6. The amino terminus of the binding protein is an Asp residue as determined by sequence analysis. It forms a 92-kDa sodium dodecyl sulfatestable complex with kallikrein with a t1/2 of 18 min. Western blot and radioimmunoassay showed a distribution of the kallikrein-binding protein in serum, urine, and various tissues with a 5-10-fold lower amount in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto rats (WKY). A full length cDNA clone encoding the kallikrein-binding protein was isolated from a rat liver cDNA library by immunoscreening and the translated amino acid sequence matches the amino-terminal 29-amino acid sequence of the binding protein. The cDNA sequence shares 68.8% identity with human alpha 1-antichymotrypsin and is identical to that of a rat hepatic protein. Dot blot analysis shows that kallikrein-binding protein is expressed at high levels in the liver and at low levels in the lung, salivary gland, and kidney. Its mRNA level in the liver decreases by 2-fold after acute phase inflammation and is higher in male than in female rats. Genomic Southern blot analyses reveal restriction fragment length polymorphisms between SHR and WKY rats in the binding protein locus. The results indicate that rat kallikrein-binding protein belongs to the serpin superfamily and its level is significantly reduced in the spontaneously hypertensive rats.

Amino Acid Sequence↗
PubMed1990

Molecular cloning and primary structure of rat alpha 1-antitrypsin.

A cDNA clone encoding rat alpha 1-antitrypsin has been isolated from a lambda gt-11 rat liver cDNA library using an antigen-overlay immunoscreening method. The nucleotide sequence of this cDNA clone is 1306 base pairs in length and has a coding region of 1224 base pairs which can be translated into an alpha 1-antitrypsin precursor protein consisting of 408 amino acid residues. The cDNA sequence contains a termination codon, TAA, at position 1162 and a polyadenylation signal sequence, AATAAT, at position 1212. The calculated molecular weight of the translated mature protein is 43,700 with 387 amino acid residues; this differs from purified rat alpha 1-antitrypsin's apparent molecular weight of 54,000 because of glycosylation. Five potential glycosylation sites were identified on the basis of the cDNA sequence. The translated mature protein sequence from the cDNA clone matches completely with the N-terminal 33 amino acids of purified rat alpha 1-antitrypsin, which has an N-terminal Glu. The cDNA encoding rat alpha 1-antitrypsin shares 70% and 80% sequence identity with its human and mouse counterparts, respectively. The reactive center sequence of rat alpha 1-antitrypsin is highly conserved with respect to human alpha 1-antitrypsin, both having Met-Ser at the P1 and P1' residues. Genomic Southern blot analysis yielded a simple banding pattern, suggesting that the rat alpha 1-antitrypsin gene is single-copy. Northern blot analysis using the cDNA probe showed that rat alpha 1-antitrypsin is expressed at high levels in the liver and at low levels in the submandibular gland and the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗