The relationship between glandular kallikrein and growth factor-processing proteases of mouse submaxillary gland

Endoplasmic reticulum stress affects mouse salivary protein secretion induced by chronic administration of an α1-adrenergic agonist

Stress stimulates both the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal axes. Activation of these axes results in the release of catecholamines, which in turn affects salivary secretion. Thus, repetitive stimulation of the α₁-adrenergic receptor could be useful for studying the effects of chronic stress on the salivary gland. Salivary protein concentration and kallikrein activity were significantly lower in mice following chronic phenylephrine (PHE) administration. Chronic PHE administration led to significantly increased expression of the 78-kDa glucose-regulated protein, activating transcription factor 4, and activating transcription factor 6. Histological analyses revealed a decrease in the size of the serous cell and apical cytoplasm. These results suggest that repetitive pharmacological stimulation of the sympathetic nervous system elicits ER stress and translational suppression. In addition, PHE-treated mice exhibited a decrease in intracellular Ca²⁺ influx elicited by carbachol, a muscarine receptor agonist in the submandibular gland. The present findings suggest that chronic psychological, social, and physical stress could adversely affect Ca²⁺ regulation.

Mastication as a tool to prevent cognitive dysfunctions

Mastication as we all know has always been related to its primary function of digestion, but little do we know that it produces an enhancing effect on general health, especially the cognitive performance related aspects of memory. Recent studies have shown its association with activation of various brain regions, however little is known about its effects on neuronal activity in these specified regions. According to the enormous evidences collected so far, mastication has proved to be effective in conducting huge amount of sensory information to the brain, and maintaining learning and memory functions of hippocampus. Therefore it is essential that we maintain normal occlusion and preserve the masticatory function as long as possible to prevent the attenuation of hippocampus, caused by occlusal disharmony and reduced mastication. We provide an overview on how mastication activates various cortical areas of the brain and how an increase in the cerebral blood oxygen level of hippocampus and prefrontal cortex (PFC) accentuates the learning and memory process. We also justify why maintaining and establishing a normal occlusion is important from neurological point of view.

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.

NGF, BDNF, NT3, and NT4

The discovery of nerve growth factor (NGF) was a seminal event in history of research in developmental neurobiology. The further discovery that NGF was just one of a family of structurally similar growth factors, neurotrophins, provided important insights into the way nerve cells communicate, during development of the nervous system, and in neuroplasticity, memory, and learning in the adult nervous system. Four neurotrophins, NGF, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3), and neurotrophin-4 (NT4), regulate a wide variety of neural functions, acting upon p75NTR, TrkA, TrkB, and TrkC receptors.

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.

Occlusion and brain function: mastication as a prevention of cognitive dysfunction

Research in animals and humans has shown that mastication maintains cognitive function in the hippocampus, a brain area important for learning and memory. Reduced mastication, an epidemiological risk factor for the development of dementia in humans, attenuates spatial memory and causes hippocampal neurons to deteriorate morphologically and functionally, especially in aged animals. Active mastication rescues the stress-attenuated hippocampal memory process in animals and attenuates the perception of stress in humans by suppressing endocrinological and autonomic stress responses. Active mastication further improves the performance of sustained cognitive tasks by increasing the activation of the hippocampus and the prefrontal cortex, the brain regions that are essential for cognitive processing. Abnormal mastication caused by experimental occlusal disharmony in animals produces chronic stress, which in turn suppresses spatial learning ability. The negative correlation between mastication and corticosteroids has raised the hypothesis that the suppression of the hypothalamic-pituitary-adrenal (HPA) axis by masticatory stimulation contributes, in part, to preserving cognitive functions associated with mastication. In the present review, we examine research pertaining to the mastication-induced amelioration of deficits in cognitive function, its possible relationship with the HPA axis, and the neuronal mechanisms that may be involved in this process in the hippocampus.

Substrate specificity of human kallikrein 6: salt and glycosaminoglycan activation effects

Human kallikrein 6 (hK6) is abundantly expressed in the central nervous system and is implicated in demyelinating disease. This study provided biochemical data about the substrate specificity and activation of hK6 by glycosaminoglycans and by kosmotropic salts, which followed the Hofmeister series. The screening of fluorescence resonance energy transfer (FRET) peptide families derived from Abz-KLRSSKQ-EDDnp resulted in the finding that Abz-AFRFSQ-EDDnp (where Abz is ortho-aminobenzoic acid and EDDnp is N-[2,4-dinitrophenyl]ethylenediamine)) is the best synthetic substrate described so far for hK6 (kcat/Km 38,667 s(-1) mm(-1)). It is noteworthy that the AFRFS sequence was found as a motif in the amino-terminal domain of seven human ionotropic glutamate receptor subunits. We also examined the hK6 hydrolytic activity on FRET peptides derived from human myelin basic protein, precursor of the Abeta amyloid peptide, reactive center loop of alpha1-antichymotrypsin, plasminogen, and maturation and inactivation cleavage sites of hK6, which were described earlier as natural substrates for hK6. The best substrates were derived from myelin basic protein. The hK6 maturation cleavage site was poorly hydrolyzed, and no evidence was found to support a two-step self-activation process reported previously. Finally, we assayed FRET peptides derived from sequences that span the cleavage sites for activation of protease-activated receptors (PAR) 1-4, and only the substrate with the PAR 2 sequence was hydrolyzed. These results further supported the hypothesis that hK6 expressed in the central nervous system is involved in normal myelin turnover/demyelination processes, but it is unlikely to self-activate. This report also suggested the possible modulation of ionotropic glutamate receptors and activation of PAR 2 by hK6.

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.

Human Tissue Kallikreins: Physiologic Roles and Applications in Cancer

Tissue kallikreins are members of the S1 family (clan SA) of trypsin-like serine proteases and are present in at least six mammalian orders. In humans, tissue kallikreins (hK) are encoded by 15 structurally similar, steroid hormone–regulated genes (KLK) that colocalize to chromosome 19q13.4, representing the largest cluster of contiguous protease genes in the entire genome. hKs are widely expressed in diverse tissues and implicated in a range of normal physiologic functions from the regulation of blood pressure and electrolyte balance to tissue remodeling, prohormone processing, neural plasticity, and skin desquamation. Several lines of evidence suggest that hKs may be involved in cascade reactions and that cross-talk may exist with proteases of other catalytic classes. The proteolytic activity of hKs is regulated in several ways including zymogen activation, endogenous inhibitors, such as serpins, and via internal (auto)cleavage leading to inactivation. Dysregulated hK expression is associated with multiple diseases, primarily cancer. As a consequence, many kallikreins, in addition to hK3/PSA, have been identified as promising diagnostic and/or prognostic biomarkers for several cancer types, including ovarian, breast, and prostate. Recent data also suggest that hKs may be causally involved in carcinogenesis, particularly in tumor metastasis and invasion, and, thus, may represent attractive drug targets to consider for therapeutic intervention.

Structure and function of human sweat glands studied with histochemistry and cytochemistry

The basic structure and the physiological function of human sweat glands were reviewed. Histochemical and cytochemical techniques greatly contributed the elucidation of the ionic mechanism of sweat secretion. X-ray microanalysis using freeze-dried cryosections clarified the level of Na, K, and Cl in each secretory cell of the human sweat gland. Enzyme cytochemistry, immunohistochemistry and autoradiography elucidated the localization of Na,K-ATPase. These data supported the idea that human eccrine sweat is produced by the model of N-K-2Cl cotransport. Cationic colloidal gold localizes anionic sites on histological sections. Human eccrine and apocrine sweat glands showed completely different localization and enzyme sensitivity of anionic sites studied with cationic gold. Human sweat glands have many immunohistochemical markers. Some of them are specific to apocrine sweat glands, although many of them stain both eccrine and apocrine sweat glands. Histochemical techniques, especially immunohistochemistry using a confocal laser scanning microscope and in situ hybridization, will further clarify the relationship of the structure and function in human sweat glands.

Early days of the nerve growth factor proteins

Adult male mouse submaxillary glands served as the preferred starting material for the isolation of the nerve growth factor (NGF) proteins in most of the isolation studies done. Two types of NGF proteins were isolated from extracts of the gland, a high-molecular-weight 7S NGF complex and a low-molecular-weight protein variously called NGF, betaNGF, or 2.5S NGF. The latter, which mediated all known biological functions of NGF, were closely related forms of a basic NGF dimer in which the N and C termini of two monomers (chains) were modified by proteolytic enzymes to different extents with no effect on biological activity. The betaNGF dimer showed a novel protein structure in which the two chains interacted non-covalently over a wide surface. Correspondingly, the betaNGF dimer was found to be unusually stable and the form through which NGFs actions were mediated at physiological concentrations. The betaNGF dimer was one of three subunits in 7S NGF; the other two were the gamma subunit, an arginine esteropeptidase or kallikrein, and the alpha subunit, an inactive kallikrein. Two zinc ions were also present in the complex and contributed greatly to its stability. There was much debate about whether 7S NGF was a specific protein complex of interacting subunits and, if so, what functions it might play in the biology of NGF. Observations of the inhibition of the enzyme activity of the gamma subunit and of the biological activity of betaNGF in 7S NGF were important in determining that 7S NGF was a naturally occurring complex and the sole source of NGF in the gland extract or in saliva. Specific interactions between the active site of the gamma subunit and the C-terminal arginine residues of the NGF chains, confirmed in the three-dimensional structure of 7S NGF, suggested a role for the gamma subunit in pro-NGF processing during the assembly of 7S NGF. In spite of the detailed knowledge of 7S NGF structure, no information on the role of this complex in the neurobiology of NGF has emerged. With the exception of the submaxillary gland of an African rodent, no other source of NGF has been convincingly shown to synthesize the alpha and gamma subunits, and they may well be irrelevant to NGFs actions.

The new human tissue kallikrein gene family: structure, function, and association to disease

The human tissue kallikrein gene family was, until recently, thought to consist of only three genes. Two of these human kallikreins, prostate-specific antigen and human glandular kallikrein 2, are currently used as valuable biomarkers of prostatic carcinoma. More recently, new kallikrein-like genes have been discovered. It is now clear that the human tissue kallikrein gene family contains at least 15 genes. All genes share important similarities, including mapping at the same chromosomal locus (19q13.4), significant homology at both the nucleotide and protein level, and similar genomic organization. All genes encode for putative serine proteases and most of them are regulated by steroid hormones. Recent data suggest that at least a few of these kallikrein genes are connected to malignancy. In this review, we summarize the recently accumulated knowledge on the human tissue kallikrein gene family, including gene and protein structure, predicted enzymatic activities, tissue expression, hormonal regulation, and alternative splicing. We further describe the reported associations of the human kallikreins with various human diseases and identify future avenues for research.

Adenovirus-mediated kallikrein gene delivery reverses salt-induced renal injury in Dahl salt-sensitive rats

BACKGROUND

The tissue kallikrein-kinin system has been shown to play a role in cardiac and renal functions. In this study, we investigated the ability of kallikrein gene delivery to reverse salt-induced cardiac hypertrophy and renal injury in Dahl salt-sensitive rats.

METHODS

Adenovirus harboring the human tissue kallikrein gene, Ad.CMV-cHK, was delivered intravenously into Dahl salt-sensitive rats suffering from hypertension, cardiac hypertrophy and renal damage induced by a high salt diet (4% NaCl) for four weeks.

RESULTS

Expression of human kallikrein mRNA was detected in rat kidney, heart, aorta and liver, and immunoreactive human kallikrein levels were measured in the serum and urine of rats receiving gene delivery. A single injection of Ad.CMV-cHK caused a significant reduction of blood pressure for more than two weeks. Kallikrein gene transfer caused left ventricular mass reduction and elevated glomerular filtration rate, renal blood flow, urinary excretion, urinary kinin, nitrite/nitrate content, cGMP and cAMP levels. Morphological investigations showed that kallikrein gene transfer caused a significant reversal in salt-induced tissue and organ damage. In the heart, cardiac hypertrophy and fibrosis were reduced, and in the kidney, both glomerular sclerotic lesions and tubular damage were reversed.

CONCLUSIONS

Adenovirus-mediated kallikrein gene delivery is effective in reversing salt-induced cardiac hypertrophy and renal injury in Dahl-salt sensitive rats.

Comparative study of kallikrein-like serine proteinases from rat submandibular glands

The present investigation describes the comparative properties, particularly the substrate specificity of three kallikrein-like serine proteinases (I, II and III) purified from rat submandibular gland extract (Bedi, G.S., Prep. Biochem. 22,67-81, 1992). The physico-chemical and immunological properties of three proteinases were compared by Western blot analysis, immunodiffusion, immuno-electrophoresis, amino terminal sequence analysis, molecular weight determination and isoelectric focusing. Detailed substrate specificity of these proteinases was determined using chromogenic substrates, synthetic peptides and native proteins. The chromogenic substrate tosyl-gly-pro-arg-pNA was hydrolyzed preferentially by Proteinase I. The replacement of pro at the P2 position with bulky hydrophobic residues phe and leu completely abolished the hydrolysis by Proteinase I. The hydrolysis of the chromogenic substrates by Proteinase II was also affected by the amino acid residue present at the P2 position in the order of pro > gly > val > leu > phe. Neither Proteinase I nor Proteinase II hydrolyzed substrates in which arg was replaced with lys at the P1 position. Proteinase III was reactive against all the chromogenic substrates with arg or lys at the P1 position. Synthetic polypeptides T-kinin-leu and insulin B chain were resistant to cleavage by both Proteinase I and II and were cleaved specifically at arg-X peptide bond by Proteinase III. Tonin-like activity of Proteinase II was confirmed by cleavage of the angiotensin 1-14 at phe-his linkage to generate two fragments DRVYIHPF and HLLVYS respectively. All three proteinases cleaved human high molecular weight kininogen but only Proteinase III could cleave T-kininogen. Proteinase III was also reactive towards human and bovine fibronectin, fibrinogen and gelatin. Several other salivary and serum proteins were resistant to cleavage by these proteinases. Although the three enzymes are immunologically related, they differ with respect to size, isoelectric point, amino terminal sequence and inhibition profile.

Characterization of kallikrein cDNAs from the African rodent Mastomys

Kallikreins comprise a family of serine proteases that are required for the processing of hormone precursors, thereby controlling many physiological processes including blood flow, ion transport, and inflammation. In rodents such as mouse, rat, and Mastomys, many kallikreins are expressed in the submandibular gland (SMG), but only a limited number, notably true tissue (glandular) kallikrein, are expressed in the kidney. We report here the cloning and characterization of kallikrein cDNAs from the Mastomys SMG. Two of these are expressed in the kidney as well as in the SMG, and one may code for the true tissue kallikrein of Mastomys. A third kallikrein is expressed only in the SMG and bears some resemblance to a murine nerve growth factor-associated protein. The existence of a family of Mastomys SMG kallikreins suggests that these enzymes act as prohormone-processing enzymes in Mastomys. DNA sequence analysis and hybridization studies demonstrate that, although Mastomys kallikreins are very similar in structure to both mouse and rat kallikreins, their expression patterns differ. The expression of more than one Mastomys glandular kallikrein in the kidney is similar to that in the rat, but the sequence and nonsexually dimorphic expression of the putative tissue kallikrein most closely resembles mouse. Mastomys represents an interesting hybrid between mouse and rat, providing an important animal model for studies of kallikrein expression and regulation.

Human eccrine sweat contains tissue kallikrein and kininase II

We attempted to determine the level of sweat kallikrein (kininogenase) and to purify and characterize it using sweat collected over a white petrolatum barrier. Thermally induced eccrine sweat obtained from 24 healthy subjects showed kallikrein activity of 24.4 ng kinins generated/1 mg of sweat protein when heated plasma was used as the substrate and 16.1 ng kinin when purified low molecular weight bovine kininogen was used as the substrate. Sweat was sequentially purified by Sephacryl S-200, diethyaminoethyl Sephacel, and fast flow liquid chromatography Mono Q chromatography. Sweat kallikrein had a M(r) of 40,000 and was inhibited by aprotinin but not by soybean trypsin inhibitor. The peptide generated by sweat kallikrein was identified as lys-bradykinin using reverse phase high-performance liquid chromatography and by its amino acid sequence. Anti-human urinary kallikrein immunoglobulin G neutralized the sweat kallikrein activity completely, indicating that the sweat kallikrein is the glandular type. Purified sweat and salivary kallikrein showed similar M(r) and responses to inhibitors and antibodies. Using immunohistochemistry, kallikrein activity was localized in luminal ductal cells and in the peripheral rim of secretory coil segments, presumably the outer membrane of the myoepithelium. We also observed kininase activity in sweat at M(r) 160,000, which was inhibited by ethylenediamine tetraacetic acid, captopril, and angiotensin converting enzyme inhibitor peptide, indicating that it is kininase II (or angiotensin converting enzyme). Sweat also contains abundant non-kallikrein hydrolases for S-2266 and S-2302. The demonstration of glandular kallikrein, its tissue localization, and the presence of kininase II in sweat provide the basis for future studies on the physiologic role of the kallikrein/kinin system in the eccrine sweat gland.

Immunohistochemical demonstration of tissue kallikrein in the neurons of rat brain

The distribution of tissue kallikrein (EC.3.4.21.35) in the rat brain was investigated by an enzyme-linked immunosorbent assay (ELISA) and immunohistochemical technique using antiserum against rat urinary kallikrein. More than 75% of the total amount of kallikrein in the extracts of the cerebral cortex and brain stem was determined by the ELISA to be in the form of prokallikrein, suggesting that the greater part of the enzyme exists in the form of pro-enzyme in the central nervous system. Furthermore, immunohistochemical examination revealed that, although the kallikrein-positive cells were widespread and scattered in the brain, the immunoreactive substances preferentially locate in the neuronal cell bodies and their processes in both the cerebral cortex and brainstem.

Purification of rat urinary kallikrein: comparative studies with rat submandibular gland kallikrein-like serine protease

A 427-fold purification of rat urinary kallikrein (RUK) was achieved in three steps involving chromatography on columns of DEAE-Sepharose CL-6B, gel filtration on Sephadex G-100 and affinity chromatography on a column of benzamidine-Sepharose. Purified enzyme showed a single band on SDS-PAGE with an estimated molecular weight of 43,000. The amino-terminal sequences of the first 25 residues of RUK resemble the reported sequence for true kallikrein and share 80% identity with rat submandibular gland (RSMG) kallikrein-like serine protease. The RUK is highly reactive towards kallikrein substrates Bz-pro-phe-arg-pNA and DL-val-leu-arg-pNA, and plasmin substrate D-val-leu-lys-pNA. RSMG enzyme is more reactive towards Bz-val-gly-arg-pNA and tosyl-gly-pro-arg-pNA, preferential chromogenic substrates for trypsin-like proteases and thrombin, respectively. Both leupeptin and aprotinin inhibit RUK strongly, but soy bean trypsin inhibitor has no effect on this enzyme. RSMG enzyme is poorly inhibited by any of these inhibitors. The data suggest that although both enzymes are members of tissue kallikrein multigene family, urinary enzyme is a true kallikrein and RSMG enzyme is a kallikrein-like serine protease with different substrate specificity.

Substrate specificities of tissue kallikrein and T-kininogenase: their possible role in kininogen processing

The present studies demonstrate the importance of subsite interactions in determining the cleavage specificities of kallikrein gene family proteinases. The effect of substrate amino acid residues in positions P3-P'3 on the catalytic efficiency of tissue kallikreins (rat, pig, and horse) and T-kininogenase was studied using peptidyl-pNA and intramolecularly quenched fluorogenic peptides as substrates. Kinetic analyses show the different effects of D-amino acid residues at P3, Pro at P'2, and Arg at either P'1 or P'3 on the hydrolysis of substrates by tissue kallikreins from rat and from horse or pig. T-Kininogenase was shown to differ from tissue kallikrein in its interactions at subsites S2, S'1, and S'2. As a result of these differences, Abz-FRSR-EDDnp with Arg at P'2 is a good substrate for tissue kallikreins from horse, pig, and rat but not for T-kininogenase. Abz-FRRP-EDDnp and Abz-FRAPR-EDDnp with Pro at P'2 (rat high molecular weight kininogen sequence) are susceptible to rat tissue kallikrein but not to tissue kallikreins from horse and pig. Arg at P'3 increased the susceptibility of the Arg-Ala bond to rat tissue kallikrein. These data explain the release of bradykinin by rat tissue kallikrein and of kallidin by tissue kallikreins from other animal species. Abz-FRLV-EDDnp and Abz-FRLVR-EDDnp (T-kininogen sequence) are good substrates for T-kininogenase but not for tissue kallikrein. Arg at the leaving group (at either P'1, P'2, or P'3) lowers the Km values of T-kininogenase while Val at P'2 increases its kcat values.(ABSTRACT TRUNCATED AT 250 WORDS)

Arginine specific endopeptidases modify the aggregation properties of a synthetic peptide derived from Alzheimer beta/A4 amyloid

A synthetic peptide corresponding to the first 28 amino acids of the Alzheimer disease amyloid beta/A4 peptide (3.2 kDa) aggregated to a high molecular weight (15 kDa) on SDS/urea polyacrylamide gels. Proteinase K, V8 protease, trypsin, and endopeptidase Lys-C readily degraded the aggregate. By contrast, when digested by endopeptidase Arg-C, a new polypeptide aggregate of higher molecular weight (16 kDa) was observed on denaturing gels without degraded smaller products. The new aggregate was comprised of three peptides: an intact beta/A4(1-28) and partially degraded peptides beta/A4(1-5) plus beta/A4(6-28). The results were confirmed by treatment of beta/A4 with other arginine-specific proteases: the gamma subunit of nerve growth factor and clostripain. The results indicate that arginine-specific proteases, including a growth factor processing enzyme, can nick aggregated beta/A4(1-28) amyloid and alter the configuration to produce a more complex aggregated form. If similar highly specific proteolytic mechanisms occur in the Alzheimer disease brain, the processing may promote the formation of high molecular weight aggregates that contribute to the development of relatively insoluble senile plaque core protein.

Purification and characterization of kallikrein-like serine proteases from rat submandibular glands

The purification and characterization of kallikrein-like proteases from rat submandibular glands is described. The proteolytic activity of each fraction during purification was monitored on the synthetic substrate N-alpha-tosyl-L-arginine methyl ester (TAME). The purification scheme involved ammonium sulfate precipitation, chromatography on columns of DEAE-Sepharose and Sephadex G-100 and chromatofocusing. Three TAME-hydrolytic activity peaks were eluted from DEAE-Sepharose as unbound fraction (Pool 1), at 125 mM NaCl (Pool 2) and at 250 mM NaCl concentration (Pool 4). Pool 1 further resolved into two protease fractions (1A1 and 1A2), pool 2 into three protease fractions (2A1, 2A2 and 2A3) and pool 4 gave a single major protease peak (4A1) by chromatofocusing on PBE-94. Protease pools 2A2, 2A3, and 4A1 each gave a single band on SDS-polyacrylamide gel electrophoresis with an estimated molecular weight of 34 kDa, 46 kDa and 46 kDa respectively. Pools 1A1, 1A2, 2A1 and 2a2 gave a single precipitin line with anti-rat glandular kallikrein antibodies. 2A3 and 4A1 did not react with these antibodies. Synthetic substrates DL-val-leu-arg-pNA and Bz-pro-phe-arg-pNA, specific for kallikrein-like proteases, were hydrolyzed preferentially by 2A3 and 4A1 but were poor substrates for 1A1, 1A2, 2A1 and 2A2.

Purification and characterization of new arginine esteropeptidase from the soluble fraction of human submaxillary glands

An arginine esteropeptidase was completely purified from the soluble fraction of human submaxillary glands. The molecular weight was calculated to be 12,000, having 2 species of subunits. The study of the effect of inhibitors confirmed the enzyme's serine protease-like characteristics. The best ester and amide substrates were Tos-Arg-OMe and D-Ile-Pro-Arg-pNA, respectively.

Localization of kallikrein gene family proteases in rat tissues

Monoclonal antibodies specific for three kallikrein gene family enzymes (tissue kallikrein, esterase A and tonin) have been used to determine the tissue and cellular distributions of these proteases as well as their association with other relevant molecules (kininogen, kallikrein-binding protein, and Na,K-ATPase alpha-subunit). Secretion of these enzymes from salivary glands was also analyzed. The results of these localization studies provide important clues to the functions of different members of this closely related family of serine proteases.

Crystallization and characterization of the high molecular weight form of nerve growth factor (7 S NGF)

A high molecular weight form of nerve growth factor (7 S NGF) has been crystallized in two crystal forms from polyethylene glycol 4000 by the vapour diffusion technique. The orthorhombic form A belongs to the space group P2(1)2(1)2(1) and has cell dimensions of a = 95.6, b = 96.5 and c = 147.0 A. With synchrotron X-ray radiation, these crystals diffract to 2.8 A resolution. They contain an intact 7 S NGF complex in the asymmetric unit. The tetragonal form B, which grows at similar conditions to the A form, belongs to the space group P4(1)2(1)2 (or P4(3)2(1)2) with unit cell dimensions of a = 97.4, b = 97.4 and c = 308.3 A. These crystals diffract to 3.6 A resolution and contain one 7 S complex per asymmetric unit. Native X-ray data have been collected to 3.3 A for the A form and to 5.0 A for the B form, both using synchrotron radiation.

The NGF complex from the African rat Mastomys natalensis

The 7S NGF complex from the male mouse submaxillary gland consists of the alpha, gamma, and beta subunits in the ratio alpha 2 gamma 2 beta. The beta (NGF) subunit contains all the known biolocial activity of 7S NGF. The alpha and gamma subunits are both members of glandular kallikrein gene family, yet only gamma subunit has protease activity. The gamma subunit plays a role in the processing of preproNGF to its mature form, while the role of the alpha subunit is not yet understood. Despite the fact that 7S NGF has been extensively characterized, no other NGF complex has been characterized, nor have the alpha or gamma subunits been observed in tissues which express NGF. We have therefore purified and characterized the NGF complex from the submaxillary glands of the rat Mastomys natalensis in order to more fully understand the roles of the alpha and gamma subunits. The NGF complex from M. natalensis contains subunits similar to those found in mouse 7S NGF. Although similar, there are significant differences between mouse and M. natalensis NGF complexes, especially in the degree of post-translational modification of the gamma and NGF subunits, the expression of esterase activity and the ease with which the complexes dissociate. Evidence is presented that suggests that the NGF complex from M. natalensis may consist of subunits in the ratio alpha 2 gamma beta. The amino acid sequence of the M. natalensis NGF suggests some, but not all, ways in which these differences arise.

beta-NGF-endopeptidase: structure and activity of a kallikrein encoded by the gene mGK-22

Mouse nerve growth factor (NGF) is cleaved at a histidine-methionine bond to release an NH2-terminal octapeptide (NGF1-8). The enzyme responsible, beta-NGF-endopeptidase, is structurally and functionally similar to gamma-NGF and epidermal growth factor-binding protein (EGF-BP) and cleaves mouse low molecular weight kininogen to produce bradykinin-like activity. These data have suggested that, like gamma-NGF and EGF-BP, beta-NGF-endopeptidase is a mouse glandular kallikrein. Evidence for a physiological role for NGF1-8 encouraged studies to further characterize the structure and function of this enzyme. Purified beta-NGF-endopeptidase migrated as a single band on isoelectric focusing and reducing SDS-polyacrylamide gels. As was expected, it removed NGF1-8 from NGF. Interestingly, enzymatic activity on an artificial substrate, and on NGF, was inhibited by NGF1-8 and by bradykinin. These studies further supported the view that beta-NGF-endopeptidase acts on both NGF and kininogen. The first 30 NH2-terminal amino acids of beta-NGF-endopeptidase were sequenced. This analysis demonstrated that the enzyme is encoded by the gene designated mGK-22 (Evans et al., 1987). The sequence of this gene corresponds to that of EGF-BP type A (Anundi et al., 1982; Drinkwater et al., 1987), and so studies were performed to determine whether or not beta-NGF-endopeptidase participates in EGF complex formation. Chromatographic and kinetic data gave no evidence that beta-NGF-endopeptidase is an EGF-binding protein. Our studies suggest that contamination of high molecular weight (HMW) EGF preparations with beta-NGF-endopeptidase erroneously led to earlier designation of the product of mGK-22 as an EGF-BP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of parotid submandibular and sublingual saliva on wound healing in rats

1. The effectiveness of wound licking with parotid, submandibular or sublingual saliva on wound healing was evaluated in selectively sialadenectomized rats. 2. The rate of healing of experimentally induced cutaneous wounds was evaluated macroscopically by photography at 0, 2, 4 and 6 days after surgery. 3. Sialadenectomy of all major glands significantly slowed down wound healing compared to sham-operated controls. 4. Parotid licking had no effect compared to controls; submandibular licking and sublingual licking appeared to be very effective. 5. The results suggest that saliva promotes wound healing in experimentally induced cutaneous wounds by communal licking; this is a result of the submandibular and sublingual saliva and not the parotid saliva.

Localization of chromogranins, non-neuron-specific enolase, and different forms of somatostatins in the submandibular salivary glands of mice

The localizations of chromogranins A, B, and C, neuron-specific enolase (NSE, gamma gamma-type) and non-NSE (alpha alpha-type), and different forms of somatostatins were immunocytochemically identified. The localizations were compared with those of epidermal growth factor (EGF) and nerve growth factor (NGF) in the submandibular salivary glands (SMG) of male mice at five to six weeks of age, with use of a variety of antibodies and the peroxidase-antiperoxidase (PAP) and avidin-biotin complex (ABC) detection methods. In the SMG of male mice, the major chromogranin present was chromogranin A, whereas chromogranins B and C were not detected at these ages by either method. Chromogranin A-like immunoreactivity was located in the granular convoluted tubule (GCT) cells of the SMG, whereas non-NSE immunoreactivity was observed throughout the duct system and in some acinar-associated cells. NSE was not detected in any part of the SMG. The distribution of chromogranin A and somatostatins in the GCT cells was similar to that of EGF and NGF. Our results strongly suggest that chromogranin A and somatostatins, but not chromogranin B or C, may be useful as a means of differentiation of the cells in the duct system of the SMG responsible for the production of biologically-active factors.

The expression of two kallikrein gene family members in the rat kidney

The mRNAs for two kallikrein gene family members expressed in the rat kidney have been characterized. One mRNA (PS) has previously been found in the pancreas and submaxillary gland and encodes true kallikrein. The second mRNA (K1) encodes a novel kallikrein-like enzyme expressed in the kidney and submaxillary gland that retains many of the key amino acid residues for the characteristic enzymatic cleavage specificity of kallikrein. Two oligonucleotide hybridization probes specific for the K1 mRNA demonstrate that the K1 mRNA is expressed in the kidney and submaxillary gland, but in none of the other eight tissues known to express one or more members of the rat kallikrein gene family. The K1 mRNA is the dominant kallikrein-related mRNA of the kidney, expressed at roughly 10 times the level of the true kallikrein (PS) mRNA. In the submaxillary gland the K1 mRNA is expressed at roughly one-fourth the level of true kallikrein mRNA.

Pancreatic kallikrein gene expression: effects of glucocorticoids in vivo and in vitro

We examined the role of glucocorticoids in the regulation of pancreatic glandular kallikrein gene expression in vivo and in vitro. Adult male rats were adrenalectomized (Adx). Corticosterone pellets were administered to maintain either physiologic (Adx 1+) or high physiologic (Adx 3+) plasma corticosterone levels. Pancreatic kallikrein mRNA levels were examined by Northern hybridization and quantitated by slot-blot hybridization. Adrenalectomy resulted in a 75% +/- 14% (n = 4) increase in kallikrein mRNA as compared with sham-operated controls. This increase was completely reversed by exogenous corticosterone replacement to normal physiologic concentrations. Replacement with high corticosterone levels (Adx 3+) resulted in a decrease of kallikrein mRNA levels to 53% +/- 4% (n = 4) of controls. A significant negative correlation was observed between individual kallikrein mRNA levels and plasma corticosterone (r = -0.81, n = 12). In vitro, using the rat pancreatic acinar cell line AR42J, dexamethasone decreased kallikrein mRNA steady-state levels in a time- and dose-dependent manner. These data, therefore, indicate that physiologic concentrations of plasma corticosterone decrease pancreatic kallikrein mRNA levels in vivo, and that this is a direct effect on pancreatic acinar cells.

Structure and chromosomal localization of the human renal kallikrein gene

Glandular kallikreins are a family of proteases encoded by a variable number of genes in different mammalian species. In all species examined, however, one particular kallikrein is functionally conserved in its capacity to release the vasoactive peptide, Lys-bradykinin, from low molecular weight kininogen. This kallikrein is found in the kidney, pancreas, and salivary gland, showing a unique pattern of tissue-specific expression relative to other members of the family. We have isolated a genomic clone carrying the human renal kallikrein gene and compared the nucleotide sequence of its promoter region with those of the mouse renal kallikrein gene and another mouse kallikrein gene expressed in a distinct cell type. We find four sequence elements conserved between renal kallikrein genes from the two species. We have also shown that the human gene is localized to 19q13, a position analogous to that of the kallikrein gene family on mouse chromosome 7.

Immunocytochemical localization of a kallikrein-like serine protease (esterase A) in rat salivary glands

Light and electron microscopic (EM) immunocytochemical methods have been used to localize arginine esterase A, a kinin-generating enzyme immunologically similar to tissue kallikrein, in rat salivary glands. Both polyclonal and monoclonal antibodies to arginine esterase A were used in these studies. By means of a polyclonal antiserum, esterase A was found in granular tubules of submandibular glands and in striated ducts of all three major salivary glands, in a distribution similar to that of tissue kallikrein. With recently developed specific monoclonal antibodies to esterase A, this enzyme was localized in the granules of some (but not all) granular convoluted tubule cells (GCT) and along the basal membranes (but not in apical granules) of striated ducts. By an EM immunoperoxidase method, esterase A was localized subcellularly in granules of some GCT cells and along the basal cell membranes of the tubule and duct system. Thus, this enzyme is found in some sites (GCT granules) shared with tissue kallikrein, but in some unique sites, i.e., basal membranes of striated ducts. The polyclonal antibody used in the present study cross-reacted with tissue kallikrein, but when absorbed with kallikrein, it gave the staining pattern characteristic of monoclonal antibody to esterase A.

The NGF and kallikrein genes of mouse, the African rat Mastomys natalensis and man: their distribution and mode of expression in the salivary gland

The kallikrein genes and their expression in the salivary glands of mouse, the African rat Mastomys natalensis and human were compared. The Mastomys kallikrein genes comprise a family of genes similar to those of mouse. Androgen markedly enhances transcription of glandular nerve growth factor (NGF) and kallikrein in both male and female Mastomys suggesting the presence of testosterone regulated kallikrein genes for growth factor precursor-processing in both sexes. In contrast, although a kallikrein transcript was detected in human salivary glands of the same size as the mouse or Mastomys transcript no difference in the amount of transcript was seen in adult male or female. The absence of kallikrein genes regulated by testosterone and of NGF transcripts in the human implies that there is no human equivalent of the mouse salivary 7S NGF complex.

Identification and expression of kallikrein gene family in rat submandibular and prostate glands using monoclonal antibodies as specific probes

Panels of monoclonal antibodies to three vasoactive peptide-producing enzymes: tissue kallikrein, tonin and arginine esterase A were developed, characterized and used as probes for identification of tissue-specific expression. In addition, immunoblot analyses were performed, using monospecific monoclonal antibodies which did not show cross-reactivity to related-purified enzymes in enzyme-linked immunosorbant assay (ELISA), and radioimmunoassay. We obtained the following results. In rat submandibular gland extract, the expression of 38 kDa kallikrein, 32 kDa tonin, and 18 kDa heavy chain of esterase A was identified by monoclonal antibodies to kallikrein (V4D11), tonin (1F11), and esterase A (5A10, 6C11, and 4B12), respectively. In the prostate gland, a 32 kDa kallikrein-like protein was identified by monoclonal antibodies to esterase A (5A10, 6C11 and 4B12) and by antibodies recognizing both tonin and esterase A (5A5), but not by antibody to kallikrein (V4D11) or to tonin (1F11, 1G6) in Western blot analysis. The esterase A-like enzyme in the prostate gland was found within the cytoplasm of ductal epithelial cells by using monoclonal anti-esterase A antibody (5A10) but not by employing anti-tonin antibody (1F11). These results indicate that tissue kallikrein, tonin, and esterase A are all expressed in the submandibular gland, while only esterase A or an esterase A-like enzyme is expressed in the prostate gland. The specific monoclonal antibodies can be used as probes for the identification and expression of the kallikrein gene-family enzymes.

Developmental changes of esteroprotease and androgen receptors in the mouse submandibular gland

The activities of p-tosyl-L-arginine methyl ester (TAMEase) and cytosolic and nuclear androgen receptors in the submandibular glands of male and female mice were determined at various developmental stages. In males, the activity of TAMEase was detectable at four weeks after birth, and thereafter it increased rapidly. Cytosolic androgen receptor increased gradually with age, whereas nuclear androgen receptor, which was minimal one week after birth, increased remarkably four weeks after birth. In females, the minimal activity of TAMEase was detectable at five weeks after birth and increased very slowly with age. Cytosolic receptor increased with age, but nuclear receptor level was unchanged. These findings suggest that the appearance of TAMEase was in accordance with an elevation of nuclear androgen receptor in mice submandibular glands.

Electron microscopic immunostaining of nerve growth factor: secretagogue stimulated submandibular glands

Immunocytochemical localization of nerve growth factor (NGF) was assessed on thin sections of plastic-embedded male mouse submandibular glands by electron microscopy. Both control and secretagogue-stimulated glands were examined. NGF was localized in granules of both granular convoluted tubule (GCT) cells and transition cells. The latter were intermediate in morphology between GCT cells and striated duct cells. Both large and small granules were immunostained in GCT cells; however, considerable variability in immunostaining intensity was observed in both sizes of granules but especially in the small granules of transition cells. Rough endoplasmic reticulum (RER) in both cell types exhibited NGF immunoreactivity. No Golgi-associated immunostaining was observed. Following alpha-adrenergic stimulation with phenylephrine, NGF-containing granules were sharply reduced because of extensive degranulation. Pools of immunostained secretory material suggested intracellular fusion of NGF-containing granules. Immunostaining was also observed on membrane fragments found within large vacuoles in GCT cells. Evidence of NGF secretion after beta-adrenergic or cholinergic stimulation was less dramatic. In isoproterenol-stimulated GCT cells there was evidence of fusion of small, apical, NGF-stained granules. These cells also possessed heavily immunostained apical membrane blebs. Pilocarpine-stimulated cells exhibited pleomorphic immunostained apical granules but less apical membrane immunostaining. Abundant basal lysosomes appearing in GCT cells after pilocarpine stimulation did not stain for NGF.

Growth-promoting activity in serum-free medium of kallikreinlike arginylesteropeptidases from rat submaxillary gland

The characterization and purification of the growth-promoting activity present in rat submaxillary gland extracts, known to be required for the proliferation of adipose precursor cells in serum-free medium, have been undertaken. Fractionation of the extracts by ion-exchange chromatography, gel filtration, and affinity chromatography on immobilized benzamidine allowed the copurification of the mitogenic activity with two distinct arginylesteropeptidases of apparent molecular weight 25,000; one of these enzymes has been purified to homogeneity and shown to be immunologically related to tonin, a well-characterized kallikreinlike protease from submaxillary gland. The specificity of both enzymes was similar to that of plasma and glandular kallikreins, as indicated by the relative rates of hydrolysis of peptide p-nitroanilide substrates. Prior treatment of the kallikreinlike proteases with phenylmethylsulfonylfluoride or aprotinin abolished completely both mitogenic and arginylesteropeptidase activities, indicating that enzymatic activity was essential for the manifestation of their growth-promoting ability. The kallikreinlike proteases from rat submaxillary gland were able to replace thrombin to support the proliferation of Chinese hamster lung fibroblasts in serum-free medium. These results underline the role of proteases in controlling cell growth and are discussed in light of adipose tissue development.

Direct radioimmunoassay of rat urinary kallikrein: its application to the determination of active and inactive kallikrein concentration after HPLC analysis

Rat urinary kallikrein (RUK) was purified to apparent homogeneity by a three-step procedure and antibodies were raised in rabbits. Renal kallikrein exists as an active and an inactive form. A specific radioimmunoassay (RIA) was developed to measure directly the total kallikrein. The antibody used in this radioimmunoassay recognized both forms. No cross reactivity was detected with trypsin, esterase A or human urine. When iodinated rat urinary kallikrein was used, the detection range was between 0.125 and 16 ng with 6.5% intraassay variation and 8.1% between assay variation. Intrarenal kallikrein was measured in renal tissue after homogeneisation and solubilisation. Correlations between this RIA and the kininogenase activity or the amidolytic activity were highly significant. Since kallikrein exists as an inactive precursor the direct measurement of the total immunoreactive protein differs from activities determinations. An HPLC ion exchange system has been developed to separate active and inactive forms directly from urine, with a recovery of 79 +/- 11%. This procedure permits measurement of inactive forms. Rat urine contains as much inactive kallikrein as active kallikrein.

Nerve growth factor immunoreactivity in mouse kidney: an immunoelectron microscopic study

We have recently reported the immunolocalization of nerve growth factor (NGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of NGF by the preembedding immunoperoxidase method for electron microscopy. NGF immunoreactivity was present in the connecting tubule cells of the distal nephron. These cells showed immunostaining associated with the Golgi complex, vesicles, rough endoplasmic reticulum (RER), and polyribosomes. The intercalated cells, in contrast, lacked immunoreactivity.

Trypsin activation, partial characterization, and distribution of kallikrein-like and thrombin-like proteases in the neurointermediate lobe of the rat pituitary

This study examined whether the neurointermediate lobe (NIL) of the rat pituitary contains latent kallikrein- and thrombin-like proteases activated by trypsin. Partial characterization of such proteases was attempted. Also examined were the distribution of proteolytic activity within the NIL and levels in both male and female lobes. NIL homogenates were assayed for proteolytic activity at pH 8.0 before and after incubation with trypsin (10 micrograms/ml). Trypsin caused a 10-fold activation of kallikrein-like activity and a 40-fold activation of thrombin-like activity in NIL homogenates. The kallikrein-like activity was separated into two components using diethylaminoethyl-Sephadex. The predominant kallikrein-like protease was a potent kininogenase closely related or identical to glandular kallikrein and was almost exclusively localized to the intermediate lobe. The second kallikrein-like protease (kallikrein A) was a weak kininogenase sensitive to inhibition by both soybean trypsin inhibitor and aprotinin and was similarly concentrated in both the neural lobe and the intermediate lobe. The thrombin-like protease was sensitive to inhibition by hirudin (a specific thrombin inhibitor), clotted fibrinogen, and was slightly more concentrated in the neural lobe than in the intermediate lobe. NILs from female rats contained approximately 40% less kallikrein activity than NILs from male rats but did not differ in their content of thrombin-like activity.