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J R Goldenring

Publications and source records attributed to J R Goldenring.

At least 55 records · Page 3Linked to original sources
PubMed1996

Co-distribution of calmodulin-dependent protein kinase II and inositol trisphosphate receptors in an apical domain of gastrointestinal mucosal cells.

The Type 3 inositol 1,4,5-trisphosphate (InsP3) receptor is expressed at high levels in gastrointestinal tissues. This receptor has 16 potential phosphorylation sites for calcium/calmodulin-dependent protein kinase II (CaM kinase II). To determine if the Type 3 InsP3 receptor is likely to be a physiologic substrate for CaM kinase II, localizations of the Type 3 InsP3 receptor and CaM kinase II were compared in tissues of the gastrointestinal tract. Cellular and subcellular localizations were determined by immunofluorescence microscopy in rat intestine, pancreas, and stomach, and in isolated rabbit gastric glands. Both proteins were found in the apical region of intestinal enterocytes, pancreatic acinar cells, and gastric parietal, chief, and surface mucous cells. CaM kinase II was found throughout the entire intracellular canalicular F-actin domain of parietal cells, whereas the type 3 InsP3 receptor was restricted to the neck region. Thus, in several gastrointestinal tissues the Type 3 InsP3 receptor is specifically localized to a portion of the apical cytoskeletal domain in which resides the calcium-responsive effector CaM kinase II.

Animals↗
PubMed1996

Expression of trefoil peptides in the gastric mucosa of transgenic mice overexpressing transforming growth factor-alpha.

Overexpression of transforming growth factor-alpha (TGF-alpha) in the gastric mucosa of metallothionein-TGF alpha (MT-TGF alpha) transgenic mice leads to a marked alteration in the ontogeny of the fundic cellular lineages. Induction of the transgene leads to the over-production of mucous cells with a concomitant diminution in the development of parietal cell and chief cell lineages. We have sought to define more precisely the mucous cell lineages involved in the mucous cell hyperplasia in MT-TGF alpha mice by investigating the expression of trefoil peptides in MT-TGF alpha mice. MT-TGF alpha mice and their non-transgenic littermates were treated with cadmium sulfate beginning at 13 days of age. Animals were then sacrificed at intervals over the following 2 weeks and gastric mucosa was examined for expression of trefoil peptides and TGF alpha by immunohistochemistry and in situ hybridization. No TGF alpha mRNA expression could be demonstrated by in situ hybridization in non-transgenic mice. In MT-TGF alpha mice, in situ grains for TGF alpha mRNA were detected at the base of fundic glands in 13 day old animals, whereas the expression was observed more widely in the mucosa of older animals (28 days). TGF alpha immunoreactivity was observed in foveolar mucous cells and residual parietal cells in MT-TGF alpha mice at all ages. By in situ hybridization, pS2 mRNA was detected in the surface mucous cells in normal gastric mucosa. In MT-TGF alpha mice, pS2 mRNA was found throughout the expanded foveolar region. By in situ hybridization, spasmolytic peptide (SP) expression was observed in the region of the progenitor zone in both groups of mice. By immunohistochemistry, SP expression was noted in a broad band of mucous neck cells deep to the progenitor zone. No gastric expression of intestinal trefoil factor (ITF) was noted in either group of mice. The results demonstrate that the expansion of the foveolar mucous cell compartment in MT-TGF alpha mice is due to the hyperplasia of normal surface cells expressing their particular mucin-associated trefoil peptide, pS2.

Animals↗
PubMed1995

Distribution of A-kinase anchoring proteins in parietal cells.

Recent investigations have suggested that subcellular compartmentalization of second messenger responsive enzyme systems may be responsible for specific patterns of cellular activation. The type II cAMP-dependent kinase (A-kinase) is localized to particular subcellular domains through the binding of the regulatory subunit (RII) dimer to A-kinase anchoring proteins (AKAPs). Using a [32P]RII overlay assay, we have investigated the presence of AKAPs throughout the gastrointestinal tract, with specific emphasis focused on the gastric parietal cell. All gastrointestinal tissues contained at least one detectable AKAP (60 kDa), with five AKAPs (50-140 kDa) in fundic and antral mucosa. Isolated gastric glands contained four AKAPs. Two AKAPs (50 and 78 kDa) were detected in purified parietal cells, with the 78 kDa AKAP (AKAP78) specific to parietal cell enriched populations. RII-binding to all of these AKAPs was abolished by preincubation of [32P]RII with a synthetic peptide representing the RII-binding region of the AKAP, HT-31. AKAP78 was distributed throughout all membrane fractions of subfractionated parietal cells, with the largest amount of RII-binding detected in the light membrane fraction. Identification of A-kinase regulatory subunits by photoaffinity labeling with 8-azido-[32P]cAMP demonstrated that RII segregated into the same parietal cell subfractions as AKAP78. A majority (approximately 60%) of AKAP78 was detected in the Triton X-100-insoluble fraction, suggesting that this protein resides in a cytoskeletal domain. AKAP78 may be involved in localizing the type II A-kinase to specific intracellular locations in the parietal cell.

Animals↗
PubMed1995

PYY inhibition of VIP-stimulated ion transport in the rabbit distal ileum.

Vasoactive intestinal polypeptide (VIP) is the pathophysiologic mediator of several small intestinal hypersecretion states. VIP exerts its effect by binding mucosal receptors and ultimately increasing intracellular levels of cAMP. Peptide YY (PYY), a GI hormone concentrated in the distal ileum and colon, has been demonstrated to decrease VIP-mediated secretion in the colon through a specific Y4 mucosal receptor. Characterization of PYY's effect on VIP-stimulated small intestinal secretion may provide a basis for future therapeutic interventions. We hypothesized that ion transport in the small intestine is mediated through a novel Y receptor subtype. We performed Ussing chamber ion transport studies on rabbit ileum using VIP, PYY, and other pancreatic polypeptide (PP)-fold peptides in order to specifically examine: (1) the effects of VIP and PYY on basal and VIP-stimulated short circuit current (Isc), and (2) the changes in VIP-stimulated Isc in response to NPY, PP, leucine31,proline31 neuropeptide Y fragment, ([Leu31,Pro34]NPY) and the carboxy-terminal fragment of NPY (NPY13-36). VIP increased basal Isc in a concentration-dependent manner, while PYY decreased basal Isc. Graded concentrations of PYY decreased VIP-stimulated increases in Isc. PYY added prior to VIP had no effect on VIP-stimulated increases in ISC. Inhibition of VIP-stimulated Isc increases was seen with NPY, but not with [Leu31,Pro34]NPY, PP, or NPY13-36. This distinct pattern of binding affinity characterizes a novel Y receptor subtype. Additionally, increases in Isc by VIP despite pretreatment with PYY suggests that VIP-stimulated ion transport is mediated through mechanisms other than increases in cAMP.

Animals↗
PubMed1995

A novel serine-specific kinase activity associated with exocrine secretory granules.

Zymogen secretion from exocrine cells involves an exocytotic process that is highly regulated by the modification of cytoplasmic components at different cellular levels. In the present studies, purified secretory granules were prepared from rabbit gastric chief cells, rat pancreatic acinar cells, and parotid glands to characterize a Mg(2+)-dependent protein kinase activity. In chief cell granules, endogenous pepsinogen, a fortuitous substrate, was phosphorylated at optimal Mg2+ and K+ concentrations of 40 and 50 mM, respectively. Adenosine 3',5'-cyclic monophosphate, Ca2+, and calmodulin had no significant effects on the kinase activity. In contrast, Mn2+ or Zn2+ inhibited the kinase activity. In addition to pepsinogen, the exogenous substrates casein, myelin basic protein, and lysine-rich histone were also phosphorylated by the granule-associated kinase. All substrates were exclusively phosphorylated on serine residues. ATP, but not GTP, served as the donor in the phosphorate transfer reaction. Casein kinase (CK) inhibitors CKI-7 and dibromoribofuransylbenzimidazole at concentrations (10 microM) that significantly inhibited CK activities in the tissue homogenate failed to inhibit the granule-associated kinase activity. The kinase activity was localized to the granule membrane and could be removed from the membrane with either 5 mM EDTA or alkaline carbonate extraction. Furthermore, protease digestion sensitivity revealed that the kinase was localized on the cytoplasmic face of the granules. Our results therefore indicate that the secretory granules of exocrine gastric chief cells, pancreatic acini, and parotid acini possess a unique serine-specific protein kinase activity. The cytoplasmic orientation of the kinase activity suggests a possible role in vesicle processing or the exocytotic process.

Amino Acids↗
PubMed1995

Impaired cyclic nucleotide-dependent vasorelaxation in human umbilical artery smooth muscle.

Activation of either the adenylate cyclase pathway with forskolin or the guanylate cyclase pathway with sodium nitroprusside fails to induce active relaxation of serotonin-precontracted human umbilical artery smooth muscle (HUASM) but causes active relaxation of serotonin-precontracted bovine carotid artery smooth muscle (BCASM). This difference in response appears to be unique to HUASM in that all other vascular muscles exhibit relaxation in response to these substances. Forskolin and sodium nitroprusside stimulation leads to respective increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) concentrations in HUASM and BCASM. cAMP- and cGMP-dependent protein kinases are both present in HUASM and can be activated in homogenates of HUASM by the addition of exogenous cAMP and cGMP, respectively. When either forskolin or nitroprusside acts in BCASM, two low-molecular-weight proteins display an increase in the extent of phosphorylation. Neither protein shows such an increase when HUASM is treated with either agent. Thus the inability of HUASM to display active relaxation appears to be secondary to impaired activation of cyclic nucleotide-dependent protein kinases. The refractoriness to active relaxation may contribute to the vasospasm that occurs in the umbilical vasculature with parturition.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Histamine as an intermediate growth factor in genesis of gastric ECLomas associated with hypergastrinemia in mastomys.

Profound and sustained inhibition of gastric acid secretion has been associated with development of carcinoid tumors of the fundic enterochromaffin-like (ECL) cells in rodents. While ECL cell hyperplasia has been recognized in humans, the development of carcinoid tumors is rare and often confined to patients under treatment for gastrinoma related to the multiple endocrine neoplasia type I (MEN1) syndrome. The Mastomys was utilized as a model for the rapid induction of ECLomas by insurmountable acid secretory blockade induced by the pharmacologically irreversible H2-receptor antagonist, loxtidine. Loxtidine-induced ECL cell hyperplasia and neoplasia were compared in the absence of presence of cyproheptadine (0.5 mg/kg), an H1-receptor antagonist. Loxtidine administration resulted in a significant increase in ECL cell hyperplasia and neoplasia as well as an increase in ECL cell number, mucosal thickness, plasma gastrin levels, and stomach weight. Cyproheptadine ameliorated loxtidine-induced ECL cell hyperplasia and neoplasia and significantly decreased loxtidine-stimulated increases in ECL cell number. Nevertheless, cyproheptadine failed to alter the loxtidine-induced increase in plasma gastrin, stomach weight or mucosal height. The results indicate that cyproheptadine, an H1-receptor antagonist, inhibits loxtidine-induced ECL cell hyperplasia independent of any effects on serum gastrin.

Animals↗
PubMed1994

Enrichment of rab11, a small GTP-binding protein, in gastric parietal cells.

Parietal cell secretion of acid requires the coordinated fusion of H(+)-K(+)-adenosinetriphosphatase (ATPase)-containing tubulovesicles with a secretory canalicular target membrane. We have previously reported the presence of rab2 on parietal cell tubulovesicles (L. H. Tang, S. A. Stoch, I. M. Modlin, and J. R. Goldenring. Biochem. J. 285: 715-719, 1992). Since 60% of the small GTP-binding protein sequences obtained from parietal cells were > 95% homologous with human rab11 (J. R. Goldenring, K. R. Shen, H. D. Vaughan, and I.M. Modlin. J. Biol. Chem. 268: 18419-18422, 1993), we sought to study rab11 in gastric parietal cells. A complete rab11 sequence was obtained, and the deduced amino acid sequence of rabbit rab11 was identical to that for human. Rab11 mRNA was present throughout the gastrointestinal mucosa. mRNA for both rab11 and rab2 were enriched in isolated parietal cells compared with chief cells. A polyclonal antiserum against rab11 labeled a single 25-kDa band in isolated parietal cells. Immunostaining of rat fundic tissue demonstrated prominent staining of parietal cells. Rab11 staining cosegregated with alpha-H(+)-K(+)-ATPase staining in enriched preparations of rabbit parietal cell tubulovesicles. These results suggest that rab11 is enriched in parietal cells and is associated with intracellular tubulovesicles.

Amino Acid Sequence↗
PubMed1993

Inhibition of acid secretion in gastric parietal cells by the Ca2+/calmodulin-dependent protein kinase II inhibitor KN-93.

A novel Ca2+/calmodulin-dependent protein kinase II (CaM Kinase II) inhibitor, KN-93 potently inhibits gastric acid secretion from parietal cells. As previously reported (1), treatment of parietal cells with a selective inhibitor of CaM kinase II, KN-62 resulted in the inhibition of cholinergic-stimulated rabbit parietal cell secretion, whereas it failed to inhibit the histamine and forskolin response. In contrast effects of carbachol, histamine and forskolin were significantly inhibited by KN-93 with an IC50 of 0.15, 0.3 and 1 microM, respectively; these effects occurred without any changes in intracellular cyclic AMP and Ca2+ levels. In the present study we investigated the mechanism by which KN-93 acts upon the acid-secreting machinery of gastric parietal cells. Neither redistribution of the proton pump activity nor the morphological transformation were affected by KN-93. The drug only weakly inhibited the H+, K(+)-ATPase activity but strongly dissipated the proton gradient formed in the gastric membrane vesicles and reduced the volume of luminal space. Thus KN-93 acts at pH gradient formation whereas KN-62 acts only at CaM Kinase II.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Identification of a small GTP-binding protein, Rab25, expressed in the gastrointestinal mucosa, kidney, and lung.

Small GTP-binding proteins have been implicated in the regulation of many dynamic cellular processes. The carboxyl termini of parietal cell small GTP-binding proteins were cloned using a 3'-rapid amplification of cDNA ends (RACE) technique with a degenerate oligonucleotide primer based on the WDTAGQE consensus GTP-binding sequence. Six out of 53 clones demonstrated a novel Rab sequence, now designated Rab25. The complete sequence was obtained using 3'-RACE and revealed a deduced amino acid sequence having 63% identity with Rab11. The deduced amino acid sequence demonstrated a carboxyl-terminal CCQNI and also a novel GTP-binding site sequence of WDTAGLE. Nevertheless, recombinant Rab25 was able to bind GTP on blot. A major 1.2 kilobase Rab25 message was detected throughout the gastrointestinal mucosa and in lung and kidney tissue. No message was detected in brain, heart, liver, or skeletal muscle. In gastric tissue, Rab25 was absent in the bowel wall; among mucosal cells, it was highly enriched in parietal cells compared to chief cells. Rab25 mRNA was also detected in several colon carcinoma lines including LIM1215 and HT-29. The results indicate that Rab25 represents a novel member of the Rab family with an epithelial distribution.

Amino Acid Sequence↗
PubMed1993

Cyclic AMP-mediated release of peptide YY (PYY) from the isolated perfused rabbit distal colon.

We have investigated the role of the colonic nervous system in regulating the release of peptide YY (PYY) from the isolated perfused rabbit distal colon. In addition, we have studied the role of cAMP- and Ca(2+)-dependent mechanisms in mediating the release of PYY. We investigated three agents which stimulate increases in intracellular cAMP (vasoactive intestinal polypeptide (VIP), cholera toxin, and forskolin) and three agents which raise intracellular Ca2+ concentrations (substance P, carbachol, and the calcium ionophore A23187). The three cAMP-dependent agents, VIP (10(-7) M and 3 x 10(-7) M), cholera toxin (100 micrograms), and forskolin (10(-6) M and 10(-5) M) significantly stimulated release of PYY (P < 0.05). Tetrodotoxin (3 x 10(-6) M) did not alter forskolin (10(-5) M) stimulated release of PYY. Substance P (10(-9) M and 10(-8) M), carbachol (10(-5) M), and A23187 (10(-6) M) failed to stimulate the release of PYY. These results suggest that the colonic neurotransmitter VIP participates in the modulation of PYY release from rabbit distal colons. Further, these studies suggest that release of PYY is mediated by cAMP-dependent pathways.

Acetylcholine↗
PubMed1993

Transforming growth factor-alpha (TGF alpha) inhibition of parietal cell secretion: structural requirements for activity.

Parietal cells of the gastric fundus produce transforming growth factor-alpha (TGF alpha) which functions as a potent inhibitor of acid secretion. We have previously demonstrated that TGF alpha can inhibit aminopyrine uptake in isolated rabbit parietal cells. In this study, we have evaluated the components of TGF alpha structure which determine its ability to inhibit parietal cell function. Both human and rat TGF alpha inhibited histamine stimulation by increasing the EC50 for agonist stimulation. Three fragments containing the third loop domain of TGF alpha (rat TGF alpha 34-43, human TGF alpha 34-43 and human TGF alpha 34-50) all inhibited histamine stimulation with IC50 values 20, 33 and 4-fold higher, respectively, than that of the native molecule. Rat TGF alpha inhibited carbachol stimulation throughout an agonist dose response. Human TGF alpha was only effective in inhibiting carbachol if incubations were performed in the presence of air rather than 100% O2. In air incubation, all three of the TGF alpha fragments inhibited carbachol stimulation but, in contrast to the effects on histamine, the peptides all were virtually equipotent with the native molecule. The human sequence fragments, like the native human TGF alpha, elicited no inhibition when incubations were performed in the presence of 100% O2. The results suggest that there are pharmacological differences in the response of isolated parietal cells to TGF alpha-mediated inhibition of histamine and carbachol. In addition, in contrast with previous investigations on the mitogenic action of TGF alpha, third loop fragments of TGF alpha retain the capacity to inhibit aminopyrine accumulation.

Amino Acid Sequence↗
PubMed1993

Distribution of calcium/calmodulin-dependent protein kinase II in rat ileal enterocytes.

Ca2+/calmodulin (CaM)-dependent protein kinase II is a major effector of the Ca2+ signaling pathway. It has a wide tissue distribution and phosphorylates multiple substrates. Villus enterocytes from rat ileum contain a Ca2+/CaM-dependent kinase activity that phosphorylates the exogenous neural substrate synapsin I. This phosphorylation is blocked by a specific peptide inhibitor. Antibodies made to rat brain Ca2+/CaM-dependent protein kinase II label a single band with a relative molecular mass of approximately 50 kDa in isolated rat enterocytes by immunoblot. Almost one-half of this immunoreactive protein is preferentially found in a particulate compared with a soluble subcellular fraction of the enterocytes. Virtually all of the 50-kDa band in the particulate fraction is insoluble in nonionic detergent, suggesting that the kinase is associated with the enterocyte cytoskeleton. Antibodies to Ca2+/CaM-dependent protein kinase II immunocytochemically detect fibrillar structures concentrated in the terminal web region of intestinal epithelial cells that colocalized with myosin II. This enzyme may have a role in regulating the intestinal epithelial cytoskeleton.

Animals↗
PubMed1993

Tyrosine kinase activities in the modulation of stimulated parietal cell acid secretion.

The effects of protein tyrosine kinase (PTK) activities on the modulation of secretion were investigated in isolated rabbit parietal cells. Two classes of inhibitors, genistein (an inhibitor of both soluble and membrane-associated PTK activities) and an erbstatin analogue (an inhibitor of membrane-associated PTK activities), were tested against both secretagogue stimulation as well as transforming growth factor-alpha (TGF-alpha) inhibition. Pretreatment of rabbit parietal cells with 10(-7) M rat TGF-alpha resulted in inhibition of both histamine- and carbachol-stimulated [14C]-aminopyrine (AP) accumulation. TGF-alpha inhibition was totally reversed by simultaneous pretreatment of cells with 50 microM genistein or an erbstatin analogue, indicating that a receptor-associated PTK activity is likely involved in the inhibition of parietal cell secretion. Furthermore, genistein, but not the erbstatin analogue, potentiated histamine-stimulated AP accumulation with a change in EC50 from 1.9 to 0.5 microM. Similarly, genistein, but not the erbstatin analogue, potentiated the response to forskolin with a change in EC50 from 1.5 to 0.1 microM. Genistein had no effect on stimulation of AP uptake by either dibutyryladenosine 3',5'-cyclic monophosphate or carbachol. In addition, genistein failed to increase histamine or forskolin stimulation beyond the maximal level and had no significant effect on either cellular adenosine 3',5'-cyclic monophosphate production or intracellular Ca2+ concentration. These results suggest that a PTK-protein phosphotyrosine phosphatase system may be involved in the potentiation of the histamine signal by a mechanism independent of adenylate cyclase activation.

Animals↗
PubMed1993

Inhibition of VIP-stimulated ion transport by a novel Y-receptor phenotype in rabbit distal colon.

Neurocrine, endocrine, and paracrine regulators are critical to the control of colonic secretion. These studies have investigated the inhibition of vasoactive intestinal polypeptide (VIP)-stimulated ion transport by peptide YY (PYY) and other Y-class effectors in rabbit distal colonic mucosa mounted in Ussing chambers. PYY decreased basal short-circuit current (Isc) but did not significantly change either basal Na+ or Cl- flux. PYY inhibited VIP-stimulated increases in Isc by up to 86% and abolished VIP-induced Cl- secretion. PYY decreased VIP-generated increases in Isc by a tetrodotoxin-insensitive mechanism. PYY inhibited cholera toxin-stimulated as well as forskolin-stimulated increases in Isc but failed to alter stimulation by 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP). PYY decreased VIP-stimulated increases in tissue cAMP by 88% and forskolin-stimulated increases by 84%. PYY, neuropeptide Y (NPY), (Leu31,Pro34)-NPY, and pancreatic polypeptide (PP) all demonstrated potent inhibition of VIP-stimulated increases in Isc. PYY-(13-36) demonstrated little effect on VIP stimulation. Thus the rabbit distal colon possesses a novel Y-class receptor phenotype that demonstrates high affinity for all three PP-fold peptides, NPY, PYY, and PP.

Animals↗
PubMed1993

Partial agonism by gastrin for a cholecystokinin receptor mediating pepsinogen secretion.

Isolated gastric glands from rabbit were used to characterize the functional cholecystokinin (CCK)-like peptide receptors that mediate pepsinogen secretion. Pepsinogen secretion was stimulated by both CCK octapeptide sulfate (CCK-8) and A-71378, a selective CCK-A-type receptor agonist, with similar mean effective doses (1.0 and 0.8 nM, respectively). Compared with CCK-8, gastrin-17 (G-17-I) showed reduced potency and only partial efficacy for stimulation of pepsinogen secretion while inhibiting the maximal CCK-8-stimulated response. The nonpeptide inhibitors, asperlicin and L-364,718, inhibited pepsinogen secretion with identical pA2 values for antagonism of both CCK and gastrin, indicating that both peptides interact with the same functional receptor. Specific binding of [3H]CCK-8 to isolated chief cell membranes was displaced fully by both CCK and gastrin, indicating full receptor occupancy by both peptides. A novel synthetic peptide analogue, pseudogastrin [(Glu)5-Ala-Tyr-Nle-Gly-Trp-Nle-Asp-Phe-NH2], was used to investigate the structural basis for the lower potency and efficacy of G-17-I. The potency of CCK and gastrin analogues for pepsinogen secretion was found to be dependent on both sulfation of a tyrosine residue and the position of the tyrosine residue relative to the COOH-terminal phenylalanine amide. The efficacy appears to be determined partially by the extended NH2-terminal sequence of G-17-I. The results of the present study are interpreted to show that pepsinogen secretion is mediated by a CCK-A-type receptor and gastrin acts at the same receptor as a partial agonist.

Amino Acid Sequence↗