A biochemical and immunohistochemical study of kallikrein in normal and isoproterenol-stimulated rat salivary glands during postnatal development

Positive selection shaped the convergent evolution of independently expanded kallikrein subfamilies expressed in mouse and rat saliva proteomes

We performed proteomics studies of salivas from the genome mouse (C57BL/6 strain) and the genome rat (BN/SsNHsd/Mcwi strain). Our goal was to identify salivary proteins with one or more of three characteristics that may indicate that they have been involved in adaptation: 1) rapid expansion of their gene families; 2) footprints of positive selection; and/or 3) sex-limited expression. The results of our proteomics studies allow direct comparison of the proteins expressed and their levels between the sexes of the two rodent species. Twelve members of the Mus musculus species-specific kallikrein subfamily Klk1b showed sex-limited expression in the mouse saliva proteomes. By contrast, we did not find any of the Rattus norvegicus species-specific kallikrein subfamily Klk1c proteins in male or female genome rat, nor transcripts in their submandibular glands. On the other hand, we detected expression of this family as transcripts in the submandibular glands of both sexes of Sprague-Dawley rats. Using the CODEML program in the PAML package, we demonstrate that the two rodent kallikrein subfamilies have apparently evolved rapidly under the influence of positive selection that continually remodeled the amino acid sites on the same face in the members of the subfamilies. Thus, although their kallikrein subfamily expansions were independent, this evolutionary pattern has occurred in parallel in the two rodent species, suggesting a form of convergent evolution at the molecular level. On the basis of this new data, we suggest that the previous speculative function of the species-specific rodent kallikreins as important solely in wound healing in males be investigated further. In addition to or instead of that function, we propose that their sex-limited expression, coupled with their rapid evolution may be clues to an as-yet-undetermined interaction between the sexes.

Epithelial expression of major histocompatibility complex (MHC) antigens in normal rat salivary and lacrimal glands

The presence and distribution of MHC class I and class II antigens within these glands of Wistar and Lewis rats was studied using monoclonal antibodies and an indirect immunoperoxidase technique. In rats of both strains and sexes, MHC class 1 antigens were expressed by ductal epithelium in addition to vascular endothelium and other connective tissue elements. Except for a small proportion of secretory cells within lacrimal glands, acini were uniformly negative for class I antigen. MHC class II immune response-associated (Ia) antigens were expressed by stromal dendritic cells in all glands. Glandular expression of Ia was limited to submandibular glands of the two strains. In Lewis rats, staining was detected in some striated and collecting ducts, whereas positive glandular reactivity in Wistar rats was predominantly within the granular-cell tubules. Quantitative histomorphometric studies of Wistar submandibular glands, taken from 2.5-60-week-old male and female animals, demonstrated a close relationship between the extent of glandular Ia reactivity and postnatal granular-cell tubule development. These results indicate that whilst constitutive expression of Ia is a feature of rat submandibular epithelium, the glandular components involved are strain dependent.

Changes in protein secretion by rat submandibular glands in response to isoproterenol, alpha-methylnoradrenaline, and clonidine during post-natal development

We studied developmental changes in salivary volumes and proteins secreted by the submandibular glands of male rats at weekly intervals from two to ten weeks of age in response to the beta 1-, alpha 1-, and alpha 2-adrenoceptor agonists, isoproterenol (IPR), alpha-methylnoradrenaline (alpha-mNA), and clonidine (Clonid). The types of proteins in saliva samples were determined and compared by isoelectric-focusing electrophoresis with the Phast system in both the gradient pH -3.5-to-5 and pH-3.5-to-9 gels by means of silver staining. Salivary volume and protein concentration in saliva samples elicited by IPR and alpha-mNA were positively related to the weight of the submandibular glands up to six or seven weeks of age, whereas in saliva elicited by Clonid, no relation was found in the protein concentration [corrected]. The isoelectric-focusing electrophoretic patterns of proteins secreted by the glands in response to three stimuli were different from each other during post-natal development. Within one stimulation, differences were also observed at two and three weeks of age for Clonid, and from seven weeks of age for the three stimuli, respectively. The alpha-type proteins, but not the beta-type proteins, were very similar to those in extracts from glands of rats at seven weeks of age. Almost all of the alpha-type proteins, but not the beta-type proteins, reacted with antibodies to two proteases. We conclude that functional maturation precedes morphological maturation in the submandibular glands of rats.

Exogenous melatonin: morphology and kallikrein activity of male Syrian hamster submandibular gland

Seven weeks of daily melatonin administration resulted in substantial reduction of convoluted duct cell granule population and kallikrein activity. Some reduction of intercalated duct cell granules was also observed. Testes weight and size was also dramatically reduced. All these changes were not observed after three weeks of melatonin injection.

Histochemical localization of ouabain-sensitive, K+-dependent p-nitrophenylphosphatase (Na+-K+-ATPase) activity in the submandibular gland of the mouse: effect of androgen, thyroid hormone, or postnatal age

Ouabain-sensitive Na+-K+-ATPase activity was localized histochemically in the submandibular gland of the mouse under various conditions using p-nitrophenylphosphate as substrate at pH 9. In untreated adult males and females, intense staining was seen in the basally striated portions of the epithelial cells lining the excretory and striated ducts. The region of the lateral cell membranes, but not of the apical plasmalemma, also stained. In granular convoluted tubules (GCTs), strong staining was seen only in a narrow band of the basalmost region of the cells; in males this stained region was thinner than in females, and frequently was absent. The baso-lateral margins of acinar and intercalated duct cells gave a very weak reaction. In untreated males, or in females that were treated with dihydrotestosterone, overall staining for the enzyme was always less than in untreated females, due to the diminished reactivity of androgen-stimulated GCT cells and the decreased number of striated ducts. However, in females treated with triiodothyronine, enhanced activity of Na+-K+-ATPase was indicated by stronger staining in all cell types, including the hypertrophied GCT cells. Na+-K+-ATPase activity was undetected in the submandibular glands at birth, but moderate staining was seen in the larger excretory and striated ducts by 5 days of age. From 10 days of age onward, intense staining was seen in the excretory and striated portions of the ramifying duct system. Developing GCT cells could not be distinguished from their precursor cells in the striated ducts until 25 days of age. These data indicate that the salt-handling capacity of the submandibular gland of the mouse varies with both endocrine status and age.

Release of kallikrein-like esterase and tonin from dispersed cells of the rat submandibular gland

Viable dispersed cell preparations of rat submandibular gland were obtained by a tissue-dissociation procedure using collagenase and gentle mechanical force. The cells released kallikrein-like esterase in a time- and calcium-dependent manner in response to noradrenaline (10 microM) at 30 degrees C. The net loss of kallikrein-like esterase content from the dispersed cells corresponded with the increase in kallikrein-like esterase activity in the suspending medium at all concentrations of noradrenaline. These results indicate the viability and functional integrity of this dispersed cell preparation of rat submandibular gland. alpha-Adrenoceptor agonists such as noradrenaline stimulated kallikrein-like esterase and tonin release in a dose-dependent manner, whereas the beta-adrenoceptor agonist isoprenaline and cholinoceptor agonist methacoline were both inactive. Noradrenaline-induced release of kallikrein-like esterase and tonin were completely blocked by prior addition of the alpha-adrenoceptor antagonist, phenoxybenzamine. It is concluded that the secretion of kallikrein-like esterase and tonin in rat submandibular gland is mediated only via stimulation of alpha-adrenoceptors.

Immunohistochemistry of tonin in rat submandibular gland during development, lactation and secretion

Tonin is a serine protease found in high concentrations in the submandibular gland (SMG) of the adult rat where it has been localized by immunohistochemistry in the granular ducts. The present study examined the development of tonin in the SMG, the effect of lactation and of stimulation of tonin release, using the peroxidase-antiperoxidase technique and antitonin. Tonin-like immunoreactivity first appeared in the primitive striated duct of the SMG on day 19 foetal and increased in intensity as the ducts developed into granular ducts. Reaction product in granules was seen on day 17 postpartum. Its localization within granules was established by immunochemistry of Sepharose beads to which had been coupled the contents of granules isolated from adult rats. The granular ducts of female rats, which are less developed than in the male, showed a marked increase in tonin-immunoreactivity during lactation. Stimulation of tonin secretion by isoprenaline caused massive discharge of tonin-like immunoreactivity into the lumen of the granular ducts during in vitro incubation. However, within one hour complete regranulation was apparent. The secretion was prevented by propranolol. The results indicate that tonin or a tonin-like substance appears in the rat submandibular gland late in gestation in ducts that presumably develop into granular ducts where it is found in abundance in granules in the adult, that the amount in females is increased during lactation, and that most of the granules are discharged during stimulation, only to be rapidly replaced.

Kallikrein and amylase contents in tissues from a mutant mouse model for human cystic fibrosis

Kallikrein and amylase activities are decreased in the pancreas and salivary glands from cri/cri homozygote mutant mice. Kallikrein is decreased in the cri/cri kidney too. With reference to nucleic acid concentrations there is no difference between control and mutant mice. The previously described electrolyte abnormalities of the cribriform degeneration (cri) mutant mouse, could be due to the abnormal activity of the kallikrein-kinin system on the transport mechanism of tubular cells in the organs mentioned. These findings represent a new step on our efforts to develop a useful animal model for human cystic fibrosis research.

Kallikrein-like activity in salivary glands using a new tripeptide substrate, including preliminary secretory studies and observations on mast cells

The tripeptide substrate D-val-leu-arg-4-methoxy-2-naphthylamine gave a precise localization of reaction product in cryostat sections of aldehyde-fixed salivary glands from a number of species, with Fast Blue B as the capture reagent. In submandibular glands, there was strong staining of the granules in granular tubules of rats and hamsters and somewhat less in mice. Submandibular striated ducts showed variable periluminal staining in a finer granular form; it was abundant in guinea-pigs, strong in cats but somewhat less pronounced in dogs. Parotid glands contained less reactivity with none detectable in hamsters and guinea-pigs. In the rabbit, neither gland showed any reaction. Mast cells were densely stained in glands from cats and dogs; they were less reactive in rats and unstained in the other species. The closely related 7-amino-4-trifluoromethylcoumarin derivative of the tripeptide has been found highly satisfactory for assessing activity in submandibular saliva from cats. Preliminary functional studies indicate that an extensive rapid secretion of enzyme occurs into saliva on sympathetic stimulation, with a corresponding depletion of reactive material from the striated ducts in tissue sections. Far less mobilization of enzyme occurs into saliva on parasympathetic stimulation with no obvious change in the histochemical reaction of striated ducts. The possible significance of these findings in cats is discussed. Extensive qualitative and quantitative studies are required to evaluate enzyme and substrate specificities in each species. Nevertheless, derivatives of D-val-leu-arg offer great promise for the functional testing of kallikrein-like reactivity both by histochemical means on cells and biochemically in their secretions.

Immunohistochemical localization of tonin in rat salivary glands and kidney

Tonin has been localized in salivary glands and kidney by the indirect immunofluorescence technique of Coons and by the unlabeled antibody technique of Sternberger. Both techniques gave identical results. Immunoreactive tonin was localized in the cytoplasm of granular convoluted tubular cells and on the apical surface of striated duct cells and collecting duct cells of the submandibular gland. In the parotid and sublingual glands, which lack granular cells, tonin was only found on the apical surface of striated duct and collecting duct cells. In the kidney, immunoreactive tonin was found only associated with cells of the distal convoluted tubules. After fixation with Bouin fluid or with ethanol, tonin was found not only on the apical surface of the cells but also in the apical and perinuclear cytoplasm. This cytoplasmic staining has been attributed to artefactual diffusion since, after fixation with formol-picric acid, the enzyme could only be localized on the apical surface of the tubular cells.

Synthesis of secretory and plasma membrane glycoproteins by striated duct cells of rat salivary glands as visualized by radioautography after 3H-fucose injection

The ability of the striated ducts of rat salivary glands to incorporate 3H-fucose into glycoprotein was studied by light and electron microscope radioautography. At 3.5 to 20 minutes after intravenous injection, the majority of the radioautographic grains in the ducts of the parotid gland were localized to the Golgi apparatus. By 40 minutes, the percentage of grains over the Golgi apparatus had decreased; a corresponding increase in grains occurred over small (0.1-0.4 micrometer) apical granules and the highly infolded basal and lateral plasma membranes. By two hours, less than 10% of the label was associated with the Golgi apparatus, while 26% and 28% were attributed to the apical granules and plasma membrane, respectively. By 8 to 12 hours after injection, the number of grains over the apical cytoplasm had decreased, suggesint luminal discharge of the apical granules. In contrast, the basal and lateral plasma membranes remained labeled up to 30 hours after injection as judged by the distribution of grains in light microscope radioautographs. Mitochondria appeared capable of independent incorporation of fucose, accounting for about 20% of the grains from ten minutes to two hours after injection. Comparable results were obtained in the striated ducts of the submandibular and sublingual glands. These results indicate that the striated duct cells readily incorporate 3H-fucose into newly-synthesized glycoproteins. A portion of these are secretory glycoproteins which are packaged and stored in the apical granules, and a portion are membrane glycoproteins which are incorporated into the extensive plasma membrane of these cells.

The distribution and secretion of kallikrein in some exocrine organs of the rat

Extractable kallikrein was quantitated in the submandibular, sublingual, and parotid glands and in the pancreas. No kallikrein was detected in the exorbital lacrimal glands and tears. The highest kallikrein concentrations (EU/ml) were in all major salivary gland secretions seen after alpha-adrenergic stimulation, less after beta-adrenergic and least after parasympathetic stimulation. When taking into account the large variations in salivary flow rate, alpha-adrenergic stimulation was in the parotid and particularly in the submandibular gland found to result in the highest kallikrein secretory activity measured by the kallikrein secretory rate(EU/min). This shows that the kallikrein-rich granular tubular cells are selectively activated through alpha-adrenergic sympathetic receptors. The differences observed in the parotid saliva were small and not always statistically significant. However, when cervical nerve stimulation was superimposed upon parasympathetic stimulation, kallikrein secretory rate as well as kallikrein concentration increased. The large individual variations in salivary gland kallikrein content and secretion and the rather small differences observed in kallikrein secretory rate after nervous stimulation of the parotid and sublingual glands, may indicate that the kallikrein-containing striated ducts are also influenced by factors other than the secretory nerves. The kallikrein concentration and secretory rate in urine was studied. A strong positive correlation between kallikrein secretory rate and fluid volume was found in urine but not in saliva.

Localization of kallikrein and its relation to other trypsin-like esterases in the rat pancreas. A comparison with the submandibular gland

Kallikrein was located by the direct immunofluorescence technique to the granule-containing luminal portion of pancreatic acinar cells. For the demonstration of the intracellular distribution of pancreas kallikrein, in vivo fixation of the gland was necessary. No kallikrein was found in the duct cells or in the islets of Langerhans. Quantitation by single radial immunodiffusion showed that the concentration of kallikrein in the presence was 1.32 +/- 51 microgram/g wet weight, i.e. 1/91 that of the rat submandibular gland. Bz-Arg-OEt-esterases were in the pancreas found as pro-enzyme but as active enzyme in the submandibular gland. Trypsin-like esterases, hydrolyzing epsilon-amino caproic acid naphtol-AS-D.HBr (ACA), were found in the active form in both submandibular gland and pancreatic homogenates. The submandibular gland contained per g wet weight 6 times as much ACA-esterase activity as the pancreas. In the submandibular gland, kallikrein and ACA-esterase activity were found together in practically all granular tubular cells. Thus, the granular tubular cell contains kallikrein as well as other trypsin-like enzymes like the ACA-esterase, and is in this way comparable to the pancreatic acinar cell. An extraglandular function of kallikrein is suggested for the pancreas in contrast to other kallikrein-containing exocrine organs.