The major androgen-dependent protease in dog prostate belongs to the kallikrein family: confirmation by partial amino acid sequencing

Old genes and new genes: The evolution of the kallikrein locus

The human kallikrein locus consists of KLK1, the gene of major tissue kallikrein, and 14 genes of kallikrein-related peptidases (KLKs) located in tandem on chromosome 19q13.3-13.4. In this review, based on information retrieved from the literature or extracted from genome databases, it is hypothesised that the kallikrein locus is unique to mammals. The majority of genes are highly conserved, as demonstrated by the identification of 11 KLK genes in the opossum, a metatherian species. In contrast, a sublocus, encompassing KLK1-4, has gone through major transformations that have generated new genes, which in most cases are closely related to KLK1. In the primate lineage, this process created KLK3, the gene of the prostate cancer marker, prostate-specific antigen (PSA), whereas in the murine lineage it gave rise to 13 genes unique to the mouse and nine unique to the rat. The KLK proteases are effector molecules that emerged early in mammalian evolution and their importance in skin homeostasis and male reproductive function is undisputed and there are also accumulating evidence for a role of KLK proteases in the development of the brain. It is speculated that the KLK gene family arose as part of the process that generated distinguishing mammalian features, like skin with hair and sweat glands, and specialised anatomical attributes of the brain and the reproductive tract.

Kallikreins on steroids: structure, function, and hormonal regulation of prostate-specific antigen and the extended kallikrein locus

The 15 members of the kallikrein-related serine peptidase (KLK) family have diverse tissue-specific expression profiles and putative proteolytic functions. The kallikrein family is also emerging as a rich source of disease biomarkers with KLK3, commonly known as prostate-specific antigen, being the current serum biomarker for prostate cancer. The kallikrein locus is also notable because it is extraordinarily responsive to steroids and other hormones. Indeed, at least 14 functional hormone response elements have been identified in the kallikrein locus. A more comprehensive understanding of the transcriptional regulation of kallikreins may help the field make more informed hypotheses about the physiological functions of kallikreins and their effectiveness as biomarkers. In this review, we describe the organization of the kallikrein locus and the structure of kallikrein genes and proteins. We also focus on the transcriptional regulation of kallikreins by androgens, progestins, glucocorticoids, mineralocorticoids, estrogens, and other hormones in animal models and human prostate, breast, and reproductive tract tissues. The interaction of the androgen receptor with androgen response elements in the promoter and enhancer of KLK2 and KLK3 is also summarized in detail. There is evidence that all kallikreins are regulated by multiple nuclear receptors. Yet, apart from KLK2 and KLK3, it is not clear whether all kallikreins are direct transcriptional targets. Therefore, we argue that gaining more detailed information about the mechanisms that regulate kallikrein expression should be a priority of future studies and that the kallikrein locus will continue to be an important model in the era of genome-wide analyses.

Prostatic kallikrein: a new major dog allergen

BACKGROUND

Dog dander is an important cause of respiratory allergy, but the spectrum of known dog allergens appears incomplete. Two lipocalins, Can f 1 and Can f 2, and serum albumin, Can f 3, have been characterized in detail but do not fully account for the IgE antibody-binding activity of dog dander extract. Allergen activity has previously been detected in dog urine but not further characterized.

OBJECTIVE

We sought to identify, characterize, and assess the importance of allergen components in dog urine.

METHODS

Dog urine was fractionated by means of size exclusion chromatography and examined for IgE antibody binding. A protein present in one fraction displaying IgE antibody-binding activity was identified by means of N-terminal sequencing and mass spectrometry. A recombinant form of the protein was produced in Pichia pastoris. IgE antibody binding to dog allergen components among sera of 37 subjects with dog allergy was determined by means of ImmunoCAP analysis.

RESULTS

An IgE antibody-binding protein was isolated from dog urine and identified as prostatic kallikrein. A closely related or identical protein was detected in dog dander. The recombinant prostatic kallikrein displayed immunologic and biochemical properties similar to those of the natural protein and bound IgE antibodies from 26 (70%) of 37 sera of subjects with dog allergy, 14 of which reacted to none of Can f 1, Can f 2, or Can f 3. The dog allergen identified here was found to cross-react with human prostate-specific antigen, a key culprit in IgE-mediated vaginal reactions to semen.

CONCLUSION

Prostatic kallikrein is a new major dog allergen.

Separation, characterization and identification of boar seminal plasma proteins

Methods used for the isolation, separation and characterization of boar seminal plasma proteins are discussed, as well as techniques applied to study their binding properties. Attention is paid to interactions of these proteins with different types of saccharides and glycoconjugates, with membrane phospholipids, and to interactions between proteins. Boar seminal plasma contains different types of proteins: spermadhesins of the AQN and AWN families; DQH and PSP proteins belong to the most abundant. Some of these proteins are bound to the sperm surface during ejaculation and thus protein-coating layers of sperm are formed. Sperms coated with proteins participate in different types of interactions occurring in the course of the reproduction process, e.g. formation of the oviductal sperm reservoir, sperm capacitation, oocyte recognition and sperm binding to the oocyte.

Evolution of kallikrein-related peptidases in mammals and identification of a genetic locus encoding potential regulatory inhibitors

The human kallikrein locus on chromosome 19 consists of 15 genes encoding serine proteases. Here we review studies on their evolution, which demonstrate that there are several taxon-unique KLK1 paralogs in mouse, rat and horse, but not in primates and many other mammals. Furthermore, the duplication yielding KLK2 and prostate-specific antigen (KLK3) appears to be specific to primates, but a functional progenitor to KLK2 is expressed in the dog prostate. The linkage to a locus of possible regulatory protease inhibitors on chromosome 20 is discussed, as is the potential role of the kallikrein locus in innate immunity.

A comprehensive nomenclature for serine proteases with homology to tissue kallikreins

The human kallikrein locus on chromosome 19q13.3-13.4 contains kallikrein 1--the tissue kallikrein--and 14 related serine proteases. Recent investigations into their function and evolution have indicated that the present nomenclature for these proteins is inadequate or insufficient. Here we present a new nomenclature in which proteins without proven kininogenase activity are denoted kallikrein-related peptidase. Names are also given to the unique rodent proteins that are closely related to kallikrein 1.

Taxon-specific evolution of glandular kallikrein genes and identification of a progenitor of prostate-specific antigen

In a previous study we demonstrated that repeated duplications of the tissue kallikrein gene (Klk1) had resulted in 24 paralogs in mouse. Here we demonstrate a different evolution of rat glandular kallikrein genes. Repeated duplications of an approximately 30-kb region, encompassing Klk1, Klk15, and Klk2-ps, resulted in 10 copies of each gene, but only the Klk1 paralogs are functional. The number of genes varies also between nonrodent mammals, e.g., there are probably no paralogs to KLK1 in cow and pig, whereas horse could have up to 5. In the dog, the gene encoding the prostatic arginine esterase was identified as an ortholog to the progenitor of the PSA and hK2 genes, and it carries the same conserved androgen-responsive elements directing prostate transcription as these genes. This is highly interesting with respect to animal models of benign prostate hyperplasia and prostate adenocarcinoma--diseases that have been described only in humans and dogs.

Localization of a proteolytic enzyme within the efferent and deferent duct epithelial cells of the turkey (Meleagris gallopavo) using immunohistochemistry

Turkey seminal plasma contains a serine protease found to be distinct from the spermatozoal acrosin. However, the origin and biological roles of this enzyme are unknown. Our experimental objective was to identify the cellular source of this protease within the male reproductive tract. The enzyme was isolated from seminal plasma using benzamidine-Sepharose 6B chromatography. A synthetic substrate, Nalpha-benzoyl-DL-arginine p-nitroanilide, was used to detect fractions containing the enzyme. The affinity chromatography technique yielded a 150-fold increase in amidase activity. Analysis of the protease by SDS-PAGE revealed two protein bands with relative molecular masses of 37 000 and 61 000. Proteolytic activity was detected within the smaller band as evidenced by casein digestion. Further analysis of the purified protein revealed that the smaller protein band was glycosylated. To determine the cellular source of the protease, a panel of mouse monoclonal antibodies was then developed against the purified protease, and used in immunohistochemistry. Frozen tissue sections from the liver, testis, epididymal region, and deferent duct were fixed in 4% (w/v) paraformaldehyde, permeabilized with 0.2% (v/v) (octylphenoxy)polyethoxyethanol followed by routine immunohistochemistry procedures. Monoclonal antibodies did not bind to tissue sections from either the liver or testis, or to blood plasma proteins. Both the distal portion of the efferent duct and the deferent duct were immunoreactive. We concluded that the protease found in turkey seminal plasma is concentrated to the distal efferent duct and the deferent duct epithelial cells.

Pharmacological characterization of rabbit corpus cavernosum relaxation mediated by the tissue kallikrein-kinin system

1. The roles of the tissue kallikrein-kinin system and nitric oxide (NO) release in Phoneutria nigriventer venom-induced relaxations of rabbit corpus cavernosum (RbCC) smooth muscle have been investigated by use of a bioassay cascade. 2. Phoneutria nigriventer venom (10-30 micrograms), porcine pancreatic kallikrein (100 mu), rabbit urinary kallikrein (10 mu), bradykinin (BK, 0.3-3 nmol), acetylcholine (ACh, 0.3-30 nmol) and glyceryl trinitrate (GTN, 0.5-10 nmol) caused relaxations of the RbCC strips. Captopril (1 microM) substantially potentiated Phoneutria nigriventer venom- and BK-induced RbCC relaxations without affecting those elicited by GTN. 3. The bradykinin B2 receptor antagonist, Hoe 140 (D-Arg-[Hyp3,Thi5,D- Tic7,Oic8]-BK, 50 nM), aprotinin (10 micrograms ml-1) and the tissue kallikrein inhibitor, Pro-Phe-Aph-Ser-Val- Gln-NH2 (KIZD-06, 1.3 microM) significantly inhibited Phoneutria nigriventer venom-induced RbCC relaxations, without affecting those provoked by GTN and ACh. The B1 receptor antagonist, [Leu9]des Arg10BK (0.5 microM) and soybean trypsin inhibitor (SBTI, 10 micrograms ml-1) had no effect on Phoneutria nigriventer venom-induced RbCC relaxations. 4. The relaxations induced by Phoneutria nigriventer venom, porcine pancreas kallikrein, BK and ACh were significantly inhibited by N omega-nitro-L-arginine methyl ester (L-NAME, 10 microM) but not by D-NAME (10 microM). L-NAME did not affect GTN-induced relaxations. L-Arginine (300 microM), but not D-arginine (300 microM), significantly reversed the inhibitory effect of L-NAME. 5. Our results indicate that Phoneutria nigriventer venom activates the tissue kallikrein-kininogen-kinin system in RbCC strips leading to NO release and suggest a functional role for this system in penile erection.

Activation of tissue kallikrein-kininogen-kinin system in rabbit skin by a fraction isolated from Phoneutria nigriventer (armed spider) venom

Phoneutria nigriventer venom was fractionated by gel filtration followed by ion-exchange chromatography from which 16 fractions (I-XVI) were obtained and assayed in rabbit skin in order to identify those responsible for the increased vascular permeability observed with the whole venom. The fractions, and control mediators (tissue kallikrein, bradykinin and histamine) were intradermally injected in male New Zealand white rabbits. Local oedema formation was measured as the local accumulation of i.v. injected 125I-human serum albumin into skin sites. Fraction XIII was the only fraction assayed which significantly induced oedema formation. Fraction XIII-induced oedema was greatly reduced by either the protease inhibitor aprotinin or the bradykinin B2 receptor antagonist D-Arg,[Hyp3,Thi5,8D-Phe7]-Bk, whereas the plasma kallikrein inhibitor soybean trypsin inhibitor failed to significantly affect this oedematogenic response. The kininase II inhibitor captopril markedly potentiated fraction XIII-induced oedema. Our results indicate that the increased vascular permeability induced by fraction XIII is due to local generation of kinins in response to tissue (but not plasma) kallikrein-kinin system activation.

Nucleotide sequence of the androgen-dependent arginine esterase mRNA of canine prostate

The nucleotide sequence of canine prostate arginine esterase mRNA was determined using a 400 bp cDNA clone and primer-extended cDNA transcripts for the 5'-coding and noncoding regions. The mRNA contains 864 nucleotides encoding a protein of 236 amino acids preceded by 24 amino acids which constitutes both the signal and the zymogen peptides. The sequence indicates the presence of one potential glycosylation site. A high degree of homology was found between the canine enzyme and other members of the kallikrein family including human prostate specific antigen. The protein appears to be specified by a single gene.

Androgen regulation of canine prostatic arginine esterase mRNA using cloned cDNA

Canine prostatic arginine esterase complementary DNA has been cloned in pPBS27, a new cloning vector. The relative abundance of androgen-regulated mRNA in intact dog prostate was reflected by the finding that a high proportion of the clones in the cDNA library hybridized strongly by plaque or colony hybridization with a poly(A)+ RNA probe from intact dog prostate but not with a poly(A)+ RNA probe from castrated dog prostate. One clone carrying a 400 base pairs cDNA insert was selected for further studies. Translation of the hybrid-selected RNA in a cell-free system resulted in the production of a 31 kDa peptide immunoprecipitable by antibodies against arginine esterase. This identification was confirmed by partial sequence analysis of the cDNA revealing an encoding protein with high homology to known kallikreins. Northern blot analysis of poly(A)+ and total RNA showed that arginine esterase mRNA had an approximate size of 1.0 kb which corresponded to a major androgen-regulated RNA species that could be observed after denaturing agarose gel electrophoresis of prostatic poly(A)+ RNA from intact dogs. Dot-blot analysis showed that dogs which had been castrated 3 weeks before had more than 100-fold lower arginine esterase mRNA level than intact dogs or castrated dogs treated with Depo-testosterone.

Biochemistry of human tissue (urinary) kallikrein

Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. Thus an enzyme preparation with a specific activity of 1100 U/mg protein (substrate: AcPheArgOEt) was obtained. In dodecyl sulfate electrophoresis two protein bands with apparent molecular weights of 41 kDa (form B) and 34 kDa (form A) have been separated. On isoelectric focusing different protein bands with isoelectric points between 3.75 and 4.25 were found. Both forms (form A and B) could be separated by gel filtration on Sephadex G-100 and characterized by dodecyl-sulfate electrophoresis and isoelectric focusing. The kinetic constants for the kallikrein-catalyzed hydrolysis of AcPheArgOEt and DValLeuArgNan were determined. The Ki value for the tissue kallikrein aprotinin complex was measured as well as the bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9 +/- 2 1 x mol-1 x min-1). The amino acid composition and the amino acid sequence of active human tissue (urinary) kallikrein is presented.

The major 40-kDa glycoprotein in human prostatic fluid is identical to Zn-alpha 2-glycoprotein

A major 40-KDA protein secreted by human prostate was isolated from whole seminal plasma by sequential column chromatography on DEAE-Sepharose CL-6B, concanavalin A(Con A)-Sepharose, and Sephadex G-100. Although the purified preparation still contained minor contaminants, its amino acid composition was found to be identical to the one of a glycoprotein isolated previously from seminal plasma by Lin et al (1983). Antibodies against this protein were produced in rabbits and their use in immunoblotting experiments revealed the presence of the antigen in several tissues including the prostate, the liver, the heart, the kidney, the epididymis, and the testis. A radioimmunoassay confirmed these results and showed that blood serum concentrations of this protein were relatively high in men (81 +/- 3 micrograms/ml), women (68 +/- 3 micrograms/ml), and cord blood of newborns (32 +/- 1 micrograms/ml). The serum concentrations of this protein along with its physicochemical characteristics suggested that it could be identical to Zn-alpha 2-glycoprotein, a human serum protein previously isolated by Burgi and Schmid (1961). This hypothesis was confirmed by a double immunodiffusion analysis using a commercial anti-Zn-alpha 2-glycoprotein antiserum. Finally, in vitro translation of prostatic poly(A) + RNA in rabbit reticulocyte lysate in the presence of canine pancreatic microsomal membranes resulted in the formation of an immunoprecipitable 42-kDa band. These results show that Zn-alpha 2-glycoprotein can be synthesized in the prostate itself. The demonstration of high concentrations of this protein in prostatic tissue and prostatic secretion should facilitate the elucidation of its role in the prostate and in other tissues.

Radioimmunoassay in blood plasma of arginine esterase: the major secretory product of dog prostate

We have developed a radioimmunoassay to determine serum levels of arginine esterase, the major secretory product of the canine prostate. Although the antibodies recognized other related proteins in immunoblotting conditions, particularly in the pancreas, the radioimmunoassay appeared specific for arginine esterase of prostatic origin and reacted only slightly or not at all with cytosolic proteins from salivary glands, liver, skeletal muscles, and kidney. In serum samples, the sensitivity limit of the assay was about 2.5 ng per ml. The interassay and intraassay variations for serum samples that contained concentrations of arginine esterase ranging from 6 to 21 ng per ml were, respectively, 14% and 24%. Sera from 30 adult males and 14 adult females contained, respectively, 71 +/- 9 and 5.3 +/- 0.4 ng per ml. In a group of 12 dogs treated daily for 36-39 days with 50 micrograms of D-Trp6-luteinizing hormone-releasing hormone ethylamide, the concentrations of arginine esterase in the serum decreased progressively and became identical with those observed in the females. These results constitute the first evidence for the presence of a serum marker of the normal prostate in an experimental model. It should be particularly useful to test the effects of various agents on the prostate.

Adenocarcinoma of the canine prostate: immunohistochemical examination for secretory antigens

Thirty-one canine adenocarcinomas of prostatic origin were examined immunohistochemically with antibodies generated against three prostate-specific antigens by using a peroxidase-antiperoxidase technique. Primary antibodies included two generated with human prostatic antigens (PSA, PSAP) and one generated with a canine prostatic antigen (CPSP). Eight of 31 adenocarcinomas were positive with CPSP, two were positive with PSA, and three were PSAP positive. Normal and hyperplastic canine prostatic epithelium was strongly positive with all three markers. These results contrast with those in human studies in which PSA and PSAP stain normal and neoplastic epithelium with comparable intensity in all but the most anaplastic tumors.

Proteolytic activity of arginine esterase from dog seminal plasma towards actin and other structural proteins. Comparison with trypsin and kallikrein

At equimolar ratio of enzyme/substrate, actin, tropomyosin, fibronectin and myosin were extensively hydrolyzed during an incubation of one hour at 37 degrees C. Dog serum albumin, ovalbumin, bovine gamma-globulin and human prostatic acid phosphatase were not hydrolyzed. The activity of arginine esterase towards actin at pHs 6.5, 7.1 and 7.6 was respectively 60, 74 and 84% of the one found at optimum pH 8.2. The cleavage products of actin by arginine esterase and trypsin were similar although trypsin activity was 5000-fold higher. Kallikrein produced a major fragment of actin not observed with arginine esterase and trypsin. It is concluded that arginine esterase has a low trypsin-like activity towards structural proteins and that this activity may have a physiological significance.

The tissue kallikrein-kinin system in human seminal plasma--biochemical and functional aspects

At least three species of tissue kallikrein-like antigens are present in human seminal plasma which differ in their molecular masses and enzymatic activities. At least one of these species is a genuine tissue kallikrein as judged by the criteria of molecular mass, immunoreactivity, inhibition by aprotinin and non-inhibition by soybean trypsin inhibitor, and the ability to release kallidin from kininogen. The prostatic gland was identified as the origin of the seminal fluid tissue kallikrein first by indirect studies and then by demonstrating the presence of immunoreactive tissue kallikrein both in prostatic tissue and secretion.

The predominant protein in human seminal coagulate

The predominant protein in human seminal vesicle secretion constitutes the structural protein of coagulated semen. This high molecular weight protein (HMW-SV-protein) is stable in seminal vesicle secretion during in vitro storage at 37 degrees C for at least 20 h, but is rapidly cleaved on mixing with prostatic proteases. Seminal coagulate, washed free of soluble components, is dissoluble by 2 to 3 mol/l of guanidine-HCl. Although dithiothreitol added to seminal coagulate does not liquefy the clot, complexes between HMW-SV-proteins are broken up by reduction under denaturing conditions, which suggests that the non-covalent linkages of HMW-SV-proteins are essential in the clot. Prostatic proteases cleave the HMW-SV-protein during liquefaction of ejaculated semen to a series of labile proteins. These proteins are further cleaved to peptides of successively decreasing size after completed liquefaction. The cleavage of the HMW-SV-protein is the major cause of the fast shift of the electrophoretic pattern of seminal proteins if semen is stored without protease inhibitors.

Enzymatic characterization of arginine esterase from dog seminal plasma

Previously purified arginine esterase from dog seminal plasma was characterized enzymatically. The enzyme was found to have a rather narrow specificity for arginine esters, much less for lysine esters and was practically devoid of activity towards tyrosine esters, casein, albumin and azocoll. It had a broad optimum pH between 8 and 9. It presented no kallikrein-like activities either in the blood pressure test in dog or in the rat uterus contraction test. It was inhibited by bovine pancreas trypsin inhibitor, aprotinin, phenylalanylprolyl arginine chloromethyl ketone, diisopropylfluorophosphate, phenylmethylsulfonyl fluoride, sodium dodecyl sulfate and leupeptin, but not by soybean trypsin inhibitor, tosyllysine chloromethyl ketone, tosylamide-2-phenylethyl chloromethyl ketone, iodoacetamide, Triton X-100 and EDTA. Experiments involving incubation of prostatic cytosol with purified arginine esterase showed that actin was the only important prostatic protein that was extensively hydrolyzed by this enzyme. It is not known presently whether the hydrolysis of actin is related to a true physiological function of the enzyme and whether actin and arginine esterase ever come into contact with each other in vivo. These properties indicate that arginine esterase from dog seminal plasma is different from other known proteinases including classical kallikreins, although it presents many similarities with this class of enzyme.