Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pancreas of the cat was fractionated into its subcellular components by centrifugation through an exponential ficoll-sucrose density gradient in a zonal rotor. This enables a preparation of four fractions enriched in plasma membranes, endoplasmic reticulum, mitochondria and zymogen granules, respectively. The first fraction, enriched by 9- to 15-fold in the plasma membrane marker enzymes, hormone-stimulated adenylate cyclase, (Na+K+)-ATPase, and 5'-nucleotidase, is contaminated by membranes derived from endoplasmic reticulum but is virtually free from mitochondrial and zymogen-granule contamination. The second fraction from the zonal gradient shows only moderate enrichment of the above marker enzymes but contains a considerable quantity of plasma membrane marker enzymes and represents mostly rough endoplasmic reticulum. The third fraction contains the bulk of mitochondria and the fourth mainly zymogen granules as assessed by electron microscopy and marker enzymes for both mitochondria and zymogen granules, namely succinic dehydrogenase, trypsin and amylase. Further purification of the plasma membrane fractions by differential and sucrose step-gradient centrifugation yields plasma membranes enriched 40-fold in basal and hormone-stimulated adenylate cyclase and (Na+K+)-ATPase.
 ...
PMID:Studies on isolated subcellular components of cat pancreas. I. Isolation and enzymatic characterization. 14 36

Transgenic mice, bearing a fusion gene of rat elastase I promoter and SV40 T-antigen, developed acinar cell tumors of the pancreas, as predicted by the model. In addition, they developed insulinomas and somatostatin (delta)-cell hyperplasia of the pancreatic islets. The insulinomas and the delta-cell hyperplasia appeared to be functional, as evidenced by changes in plasma glucose, insulin, and somatostatin. Streptozotocin, which has been shown to inhibit pancreatic carcinogenesis in the hamster model, significantly reduced the numbers of insulinomas and delta-cell hyperplasias. Streptozotocin did not cause a statistically significant reduction in exocrine tumors.
Pancreas 1991 Jul
PMID:Inhibitory effect of streptozotocin on tumor development in transgenic mice bearing an elastase I-SV40 T-antigen fusion gene. 167 89

Pancreatic duct fragments were isolated from rat and hamster pancreas and were cultured in an agarose matrix for up to 8 weeks (rat) or 20 weeks (hamster). The fragments consisted predominantly of duct epithelium, lesser numbers of stromal and atrophied acinar cells, and small numbers of islet cells. Hamster ducts averaged 3 micrograms protein per duct while rat ducts averaged 1 microgram, and the protein:DNA ratio of both types of ducts was less than that of whole pancreas. Estimated average duct yields of 6% (hamster) and 1% (rat) were based on the protein content of the ducts. Duct viability was shown by the incorporation of 3H-thymidine and 3H-leucine into bulk DNA and protein and by autoradiography. gamma-Glutamyl transferase and (Na + K)-ATPase specific activities were slightly elevated while amylase was depressed in the ducts when compared with whole pancreas in both species. gamma-Glutamyl transferase was localized histochemically in both duct epithelium and in surviving acinar tissue, as seen in vivo. Amylase was shown by immunohistochemistry to be present within duct lumina and in atrophied acini and their lumina. Alkaline phosphatase and Mg-ATPase specific activities were elevated in the hamster, but reduced in the rat, when compared with whole pancreas. Hamster alkaline phosphatase and Mg-ATPase were localized by histochemistry to the duct stroma, where these enzymes are not detected in vivo. Carbonic anhydrase was found in the duct epithelium of both species, as in vivo, as well as in the duct stroma, unlike in vivo. Acid glycosaminoglycans, as revealed by alcian blue staining, were found at the apical surfaces and in the lumina of both kinds of ducts. Glutathione-S-transferase and glucose-6-phosphate dehydrogenase were elevated in rat ducts, but not in hamster ducts. The polypeptide compositions of cultured ducts, freshly isolated pancreatic islets, and whole pancreas were compared by one-dimensional sodium dodecyl sulfate polyacrylamide gradient gel electrophoresis. No duct-specific polypeptides were observed; the ducts were characterized mainly by the reduction or absence of polypeptides, including some zymogens, seen in whole pancreas.
Pancreas 1987
PMID:Biochemical and histochemical characterization of cultured rat and hamster pancreatic ducts. 244 50

Pancreatic ductal cell secretion has not been well characterized due to the difficulty in obtaining sufficient quantities of purified ductal cells. To determine if the MIA PaCa-2 cell line would provide a useful model for in vitro studies of pancreatic ductal cell secretion, the present study was designed to characterize these cells in greater detail. In this investigation, the human pancreatic undifferentiated cell line, MIA PaCa-2, was compared with PANC-1 cells (a human ductal cell line previously characterized), isolated rat and human ducts, acinar cells, and nonpancreatic cell lines. The results indicate that while the morphology of the MIA PaCa-2 cell line is nonpolarized and generally atypical of either ductal or acinar cells, the cell line has retained certain biochemical similarities to ductal cells. Additional morphological studies indicated (a) the presence of intermediate filaments characteristic of epithelial cells, (b) the absence of zymogen granules, and (c) an apparent basolateral plasma membrane localization of Na+, K+-ATPase. Similar to ductal cells, biochemical analyses indicated (a) the presence of Na+, K+-ATPase based on [3H]-ouabain binding assays, (b) high levels of carbonic anhydrase, (c) low levels of gamma-glutamyl transpeptidase, (d) nondetectable levels of amylase, and (e) protein composition and protein synthetic patterns comparable to PANC-1 cells. Finally, as with PANC-1 cells and isolated rat and human ducts, the major sulfated secretory product of MIA PaCa-2 cells was a protein with a molecular weight of approximately 660,000 to 1 million.(ABSTRACT TRUNCATED AT 250 WORDS)
Pancreas 1989
PMID:Comparative analysis of a human pancreatic undifferentiated cell line (MIA PaCa-2) to acinar and ductal cells. 247 96

Study of the products secreted by pancreatic ductal cells and analysis of the mechanisms involved in the discharge of these products have been limited by a lack of in vitro models available to experimentally approach this problem. To this aim, this investigation has been designed to determine if a human pancreatic carcinoma cell line of ductal origin (PANC-1) has maintained some of the differentiated characteristics of normal mammalian pancreatic ductal epithelium. Morphological and immunocytochemical studies indicated that, similar to isolated rat pancreatic ducts, the PANC-1 cell line contained (a) intermediate filaments of the epithelial class, (b) a basolateral plasma membrane localization of Na+, K+-ATPase, (c) complete tight junctions based on freeze-fracture analysis, (d) a cuboidal morphology when grown on Type I collagen-coated nitrocellulose filters or isolated amnion basement membrane, and (e) normal ductal epithelial ultrastructural features. Biochemical analysis indicated that, also similar to isolated rat and human pancreatic ducts, the PANC-1 cell line contained (a) gamma-glutamyltranspeptidase, (b) carbonic anhydrase, and (c) Na+, K+-ATPase based on [3H]ouabain binding assays. Comparative studies with other transformed lines indicated that PANC-1 cells have similarities to ductal lines such as MDCK cells but are markedly different from mesenchymally derived lines such as L cells. In addition, as with isolated rat and human ducts, PANC-1 cells synthesize and secrete sulfated proteins with a MW range of approximately 180K to 1 million daltons, with the predominant species being 660K daltons as indicated by gel filtration and sodium dodecyl sulfate polyacrylamide gel electrophoresis. These results indicate that the PANC-1 cell line has maintained at least some of the differentiated characteristics of normal pancreatic ductal epithelial cells and may be a useful system for study of ductal secretory products as well as the mechanisms involved in the discharge of these products.
Pancreas 1988
PMID:Morphological and biochemical characterization of a human pancreatic ductal cell line (PANC-1). 314 17

The present study was designed to examine the role of Ca2+ in the regulation of digestive enzyme synthesis, to determine whether changes in intracellular Ca2+ stores or cytosolic Ca2+ caused the observed effects, and to establish the steps in the pathway of protein synthesis where the regulation occurs. Protein synthesis, polysome size, and the ratio of completed to nascent polypeptides were measured as a function of Ca2+ in the intracellular stores and the cytoplasm of pancreatic acinar cells. Rat acini and rabbit pancreatic lobules were incubated in media containing 1 mM CaCl2 with the following additives: cholecystokinin (CCK) octapeptide; the inhibitors of microsomal Ca2+ ATPase, thapsigargin (THP) and 2,5-di(tertbutyl)-hydroquinone (BHQ); the intracellular Ca2+ chelator, 1,2-bis(O-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA); an inhibitor of translational initiation, 7-methylguanosine 5'-triphosphate; and an inhibitor of translation elongation, cyclohexamide. THP and BHQ depleted intracellular pools of Ca2+ and caused a sustained elevation in cytosolic [Ca2+]. Under these conditions, the polysome size diminished, and the ratio of completed proteins increased twofold relative to nascent polypeptides despite an overall decrease in net protein synthesis (55.3 +/- 2.7% of control). These effects paralleled those caused by incubation with 1 nM CCK. Incubation of pancreatic acini with BAPTA plus THP or BHQ depleted the pool [Ca2+] without changing the cytosolic [Ca2+]. In addition, these agents decreased the net protein synthesis (30.1 +/- 3.6% compared to control) and polysome size and increased the ratio of completed to nascent polypeptides to 2:1. These results suggest that depletion of intracellular stores of Ca2+ without changes in cytosolic [Ca2+] decreases protein synthesis at translational initiation.
Pancreas 1997 Mar
PMID:The role of calcium in the regulation of protein synthesis in the exocrine pancreas. 905 85

Pancreatic duct epithelial cells (PDECs) mediate the pancreatic secretion of fluid and electrolytes. Membrane K+ channels on these cells regulate intracellular K+ concentration; in combination with the Na+/H+ antiport and Na+,K+ adenosine triphosphatase (ATPase), they may also mediate serosal H+ secretion, balancing luminal HCO3- secretion. We describe the K+ conductances on well-differentiated and functional nontransformed cultured dog PDECs. Through 86Rb+ efflux studies, we demonstrated Ca(2+)-activated K+ channels that were stimulated by A23187, thapsigargin, and 1-ethyl-2-benzimidazolinone, but not forskolin. These conductances also were localized on the basolateral membrane because 86Rb+ efflux was directed toward the serosal compartment. Of the K+ channel blockers, BaCl2, charybdotoxin, clotrimazole, and quinidine, but not 4-aminopyridine, apamin, tetraethylammonium, or iberiotoxin, inhibited 86Rb+ efflux. This efflux was not inhibited by amiloride, ouabain, and bumetanide, inhibitors of the Na+/H+ antiport, the Na+,K(+)-ATPase pump, and the Na+,K+,2Cl- cotransporter, respectively. When apically permeabilized PDEC monolayers were mounted in Ussing chambers with a luminal-to-serosal K+ gradient, A23187 and 1-ethyl-2-benzimidazolinone stimulated a charybdotoxin-sensitive short-circuit current (Isc) increase. Characterization of K+ channels on these cultured PDECs, along with previous identification of Cl- channels (1), further supports the importance of these cells as models for pancreatic duct secretion.
Pancreas 1998 Nov
PMID:Calcium-activated potassium conductances on cultured nontransformed dog pancreatic duct epithelial cells. 982 Nov 76

ATP is an extracellular regulator in numerous physiological and pathologic processes. Recently, 7 different subtypes of purinoceptors were identified on either the basolateral or the luminal membrane of pancreatic duct cells. However, the in vivo regulatory role of ATP in pancreatic function has not been established. We investigated the possible regulatory role of endogenous ATP in pancreatic function by measuring ATP concentrations and ATPase activity in pancreatic juice obtained from anesthetized rats and guinea pigs and from human patients undergoing endoscopy. Juice was collected from the main pancreatic duct in rats and guinea pigs under basal conditions or during stimulation with CCK, bombesin, or secretin. In guinea pigs, CCK, bombesin, and secretin did not affect ATP output, although they did stimulate fluid secretion. ATPase activity in the juice was evaluated by measuring the rate of hydrolysis of added ATP. Consistent with the low ATP concentrations in rat pancreatic juice, we found high levels of ATPase activity in this species. This was confirmed by HPLC, which also showed the metabolites of ATP hydrolysis. Ecto-ATPase activity was demonstrated by enzyme histochemistry in both the pancreatic acini and ducts in rats, but it was not detectable in guinea pigs and humans. These differences in ATP levels and ATPase expression may indicate significant species differences in the purinergic regulation of pancreatic secretion.
Pancreas 2004 Jul
PMID:ATP and ATPase secretion by exocrine pancreas in rat, guinea pig, and human. 1521 Nov 12