Calcium and calmodulin stimulate phospholipase A<sub>2</sub> and fusion of ‐ATPase‐containing membrane vesicles isolated from pig gastric mucosa

Olaisson, Hans; Mårdh, Sven; Arvidson, Gösta

doi:10.1111/j.1748-1716.1990.tb09014.x

Cited by 5 publications

(1 citation statement)

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“…Very recently, Olaisson et al [36] reported that PLA, activity was associated with membrane fractions enriched in H, K-ATPase, which catalyzes acid secretion and is a marker enzyme for the apical and tubulovesicular membranes of the parietal cells. They also suggested that PLA, participated in calciumenhanced fusion of the H, K-ATPase containing membrane vesicles [37]. Since pancreatic-type PLA, of rat stomach was enriched in particulate fractions as well as in soluble fractions [5], it is interesting to determine whether or not the PLA, in the H, K-ATPase-containing membrane is of the pancreatic type.…”

Section: Discussionmentioning

confidence: 99%

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type

Tojo

Zhao

Okamoto

1993

European Journal of Biochemistry

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Guinea pig gastric mucosa and juice contained exceptionally high phospholipase-A, activity, whereas the activity in the pancreas was only minimal. Phospholipases A, were purified to homogeneity from these three tissues. Structural evidence, including the sequence of the NH,-tenninal41 residues, the amino-acid composition and the molecular mass (1 3 902 % 3 Da) determined accurately by mass spectrometry, showed that the gastric mucosa enzyme belongs to the pancreatic type. An unique feature of the sequence is the substitution of Phe for the hitherto invariant Tyr28 in the calcium-binding loop of pancreatic phospholipases A,. The affinity of the guinea pig enzyme for Ca2+ in the presence of substrate was, however, identical to that of the rat enzyme with Tyr28, suggesting the interaction of a phenolic hydroxyl group of the Tyr with its neighboring residues is not significantly linked to the binding of Ca". The NH,-terminal sequences and immunochemical properties of the enzymes purified from the gastric juice and pancreas were identical to those of the gastric mucosa enzyme. The distribution of cells immunoreactive with anti-(gastric PLA , ) immuno-' globulin in the stomach was quite similar to that of the chief cells. Unlike in pancreas of other animals, the prophospholipase A, was not detectable in gastric mucosa or juice homogenates treated with diisopropyl fluorophosphate or in column effluents during purification under acidic conditions. An appreciable prophospholipase-A,-activating activity was not detectable in gastric mucosa extracts at low pH relevant to gastric juice, using rat prophospholipase A, as substrate. This opposes the activation of secreted proenzyme in the gastric juice.Phospholipase A, (PLA,) catalyzes the hydrolysis of fatty-acyl ester bond at the sn-2 position of glycerophospholipids and produces free fatty acids and lysophospholipids. Pancreatic PLA2 has been purified to homogeneity from pancreas of several animal species and its physicochemical properties and reaction mechanism have been extensively studied as a typical lipolytic enzyme [l]. It has been believed to be the major enzyme for digesting dietary and biliary glycerophospholipids in the small intestine, since the intestinal absorption of phospholipids requires their prior hydrolyses to lysophospholipids [2, 31. Fauvel et al., however, presented evidence for the lack of this important enzyme in guinea pig pancreas and proposed the compensatory action of basic lipases with high phospholipase-A, activity on intestinal phospholipid digestion [41.Correspondence to H.

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Section: Discussionmentioning

confidence: 99%

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type

Tojo

Zhao

Okamoto

1993

European Journal of Biochemistry

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Topographical distribution of cells in the rat submandibular gland duct system with special reference to dark cells and tuft cells

Sato

Miyoshi

1998

Anat. Rec.

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The duct system of the rat submandibular gland consists of the intercalated duct, the granular convoluted tubule, the striated duct, the excretory duct, the main excretory duct, and the salivary bladder. The duct system contains special cell types, such as dark cells and tuft cells, in addition to principal cells. However, little is known about cell distribution in the duct system. The purpose of the present study was to examine cell distribution and to perform a morphometric analysis of the duct system. Transmission and scanning electron microscopy were used to examine the duct system of the rat submandibular gland. Six regions in the duct system, the striated duct, the interlobular excretory duct, the 5-mm proximal excretory duct from the hilus, the main excretory duct at the hilus, the 10-mm distal main excretory duct from the hilus, and the salivary bladder, were investigated. Morphometric and statistical analyses of the data were then performed. The epithelium of the duct system consisted of a heterogeneous cell population. Dark cells and tuft cells were present throughout the duct system. The principal, dark, and tuft cells were distinguished by their different microvilli by using a scanning electron microscope. The frequency of these cells in the total epithelial cell population was as follows: The percentage of principal cells in the six regions of the duct system varied from 87.5% to 94.4%, that of dark cells varied from 4.1% to 7.2%, and that of tuft cells varied from 1.8% to 7.2%. The number of principal and tuft cells was significantly different between the striated duct and the main excretory duct at the hilus (P Ͻ 0.01). However, no significant difference in number of dark cells throughout the duct system was observed (P Ͼ 0.05). The abundance of the principal, dark, and tuft cells in the duct system of the rat submandibular gland was determined. Few tuft cells were distributed in the striated duct, and most were found at the hilus. Dark cells were distributed equally throughout the duct system. Anat. Rec. 252:159-164, 1998.

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Interactions between Ca2+- and cAMP-dependent stimulatory pathways in parietal cells

Mårdh

1996

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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Isolated rat parietal cells were used to investigate the role of intracellular Ca2+ in the action of cAMP-dependent secretagogues and cross talk between cAMP- and Ca2+ -dependent stimulatory pathways. Aminopyrine accumulation (an index of acid produced and trapped by the parietal cells), cytosolic free Ca2+, morphological transformation and cell viability were used to investigate parietal cell function and stimulation. The increase of cytosolic free Ca2+ promoted by gastrin, or carbachol, was abolished by the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, 10 microM). Also, the morphological transformations induced by dibutyryladenosine 3':5'-cyclic monophosphate (DBcAMP), gastrin, and Sp-adenosine-cyclic-3', 5'-monophosphothioate (Sp-cAMPS) were completely abolished by BAPTA (10 microM). In aminopyrine accumulation the action of 1 mM DBcAMP was dose-dependently reduced by BAPTA. The Ca2+ ionophore A23187 alone, in the range of 1 pM to 1 microM, had no effect but it dose-dependently potentiated the action of 1 mM DBcAMP in aminopyrine accumulation. The inhibitory actions of BAPTA on DBcAMP- and histamine-stimulated aminopyrine accumulation were dose-dependently reversed by A23187. Histamine-stimulated protein kinase activity and viability parameters as cellular lactate dehydrogenase (LDH) and trypan blue exclusion were not changed by BAPTA. These results indicated that in isolated parietal cells: (1) the action of cAMP-dependent secretagogues in aminopyrine accumulation and morphological transformation are dependent on cytosolic free Ca2+; (2) Ca2+ -induced morphological transformation is essential for aminopyrine accumulation; (3) a threshold level of one second messenger is required for stimulation of aminopyrine accumulation by the other second messenger.

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Calcium and calmodulin stimulate phospholipase A₂ and fusion of ‐ATPase‐containing membrane vesicles isolated from pig gastric mucosa

Cited by 5 publications

References 36 publications

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type

Topographical distribution of cells in the rat submandibular gland duct system with special reference to dark cells and tuft cells

Interactions between Ca2+- and cAMP-dependent stimulatory pathways in parietal cells

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Calcium and calmodulin stimulate phospholipase A2 and fusion of ‐ATPase‐containing membrane vesicles isolated from pig gastric mucosa

Cited by 5 publications

References 36 publications

Purification and characterization of guinea pig gastric phospholipase A2 of the pancreatic type

Purification and characterization of guinea pig gastric phospholipase A2 of the pancreatic type

Topographical distribution of cells in the rat submandibular gland duct system with special reference to dark cells and tuft cells

Interactions between Ca2+- and cAMP-dependent stimulatory pathways in parietal cells

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Calcium and calmodulin stimulate phospholipase A₂ and fusion of ‐ATPase‐containing membrane vesicles isolated from pig gastric mucosa

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type

Purification and characterization of guinea pig gastric phospholipase A₂ of the pancreatic type