Evidence for specific binding of tolbutamide to the plasma membrane of the pancreatic B-cells

1973 ◽  
Vol 10 (5) ◽  
pp. 1052-1060 ◽  
Author(s):  
Janove Sehlin
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Specific Binding ◽  
Pancreatic B Cells

scholarly journals Activation of alpha-2-adrenoceptors results in an increase in F-actin formation in HIT-T15 pancreatic B-cells

1995 ◽  
Vol 307 (1) ◽  
pp. 169-174 ◽  
Author(s):  
H C Cable ◽  
A el-Mansoury ◽  
N G Morgan
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
B Cells ◽  
Fluorescence Microscopy ◽  
Pertussis Toxin ◽  
Actin Polymerization ◽  
Secretory Granules ◽  
Rhodamine Phalloidin ◽  
Late Step ◽  
Pancreatic B Cells

1. Alpha-2-adrenoceptor agonists, such as noradrenaline, are potent inhibitors of insulin secretion, and it has been suggested that they control a late step in the pathway of exocytosis. We have investigated whether this could be related to a change in the extent of actin polymerization in the pancreatic B-cell, since actin microfilaments are implicated in regulating the access of secretory granules to the plasma membrane prior to exocytosis. 2. Cultured HIT-T15 pancreatic B-cells responded to noradrenaline with an increase in F-actin content, as judged by a rise in the fluorescence output after probing of the cells with phalloidin (a toxin which binds specifically to F-actin) conjugated to rhodamine. The response to noradrenaline was rapid, dose-dependent and sustained and could be reproduced by the highly selective alpha-2-agonist UK14,304. Examination of HIT-T15 cells by fluorescence microscopy after treatment with rhodamine-phalloidin, revealed a significant localization of F-actin immediately adjacent to the plasma membrane. The pattern of F-actin distribution in the cells was not altered dramatically by noradrenaline, although the intensity of staining close to the plasma membrane appeared to be slightly reduced. 3. The increase in F-actin content induced by noradrenaline and UK14,304 was inhibited significantly by the alpha-2-antagonist idazoxan but not by the alpha-1-selective antagonist prazosin. Pretreatment of HIT-T15 cells with pertussis toxin did not lead to any direct alteration in F-actin content, although the toxin significantly modified the responses induced by noradrenaline and UK14,304. In each case, cells incubated for 24 h with pertussis toxin responded to the alpha-2-agonist with an enhanced fluorescence output, indicating that F-actin levels had increased still further. This did not correlate with any gross change in the distribution of F-actin as judged by fluorescence microscopy. 4. The results demonstrate that alpha-2-adrenoceptors are coupled to control of actin polymerization in HIT-T15 cells. They suggest that regulation of F-actin formation could be a component of the mechanism by which alpha-2-agonists mediate inhibition of insulin secretion.

scholarly journals Freeze-fracture of membrane fusions during exocytosis in pancreatic B-cells.

1977 ◽  
Vol 75 (1) ◽  
pp. 23-30 ◽  
Author(s):  
L Orci ◽  
A Perrelet ◽  
D S Friend
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
Secretory Granule ◽  
Mammalian Cells ◽  
Freeze Fracture ◽  
Total Clearance ◽  
Close Apposition ◽  
Fracture Appearance ◽  
Pancreatic B Cells ◽  
Glucose Stimulated Insulin Secretion

To examine the freeze-fracture appearance of membrane alterations at sites of exocytosis in mammalian cells, we studied the secretory granule and plasma membrane of rat pancreatic B-cells during glucose-stimulated insulin secretion. Constant features observed were the scarcity of particles in secretory-granule P-fracture faces and the almost total clearance of intramembranous particles in P-and E fracture faces of the plasma membrane in areas of close apposition of these two membranes preceding fusion; also observed was the temporary persistence of particle-cleared regions after the fusion was completed. Our observations thus support the concept that membranes fuse at sites of closely apposed, particle-free regions and that the physiologically created clear areas found in freeze-fracture replicas of the plasma membrane are the hallmarks of incipient or recent membrane fusion.

Activation by adrenaline of a low-conductance G protein-dependent K+ channel in mouse pancreatic B cells

Nature ◽  
1991 ◽  
Vol 349 (6304) ◽  
pp. 77-79 ◽  
Author(s):  
Patrik Rorsman ◽  
Krister Bokvist ◽  
Carina Ämmälä ◽  
Per Arkhammar ◽  
Per-Olof Berggren ◽  
...  
Keyword(s):  
B Cells ◽  
G Protein ◽  
K Channel ◽  
Pancreatic B Cells

scholarly journals Phospholipid flippases enable precursor B cells to flee engulfment by macrophages

2018 ◽  
Vol 115 (48) ◽  
pp. 12212-12217 ◽  
Author(s):  
Katsumori Segawa ◽  
Yuichi Yanagihashi ◽  
Kyoko Yamada ◽  
Chigure Suzuki ◽  
Yasuo Uchiyama ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
B Cell ◽  
Developmental Stages ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Wild Type ◽  
Immature B Cells ◽  
T Lymphoma ◽  
Precursor B Cells

ATP11A and ATP11C, members of the P4-ATPases, are flippases that translocate phosphatidylserine (PtdSer) from the outer to inner leaflet of the plasma membrane. Using the W3 T lymphoma cell line, we found that Ca2+ ionophore-induced phospholipid scrambling caused prolonged PtdSer exposure in cells lacking both the ATP11A and ATP11C genes. ATP11C-null (ATP11C−/y) mutant mice exhibit severe B-cell deficiency. In wild-type mice, ATP11C was expressed at all B-cell developmental stages, while ATP11A was not expressed after pro−B-cell stages, indicating that ATP11C−/y early B-cell progenitors lacked plasma membrane flippases. The receptor kinases MerTK and Axl are known to be essential for the PtdSer-mediated engulfment of apoptotic cells by macrophages. MerTK−/− and Axl−/− double deficiency fully rescued the lymphopenia in the ATP11C−/y bone marrow. Many of the rescued ATP11C−/y pre-B and immature B cells exposed PtdSer, and these cells were engulfed alive by wild-type peritoneal macrophages, in a PtdSer-dependent manner. These results indicate that ATP11A and ATP11C in precursor B cells are essential for rapidly internalizing PtdSer from the cell surface to prevent the cells’ engulfment by macrophages.

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