scholarly journals vH+-ATPase-induced intracellular acidification is critical to glucose-stimulated insulin secretion

2019 ◽  
Author(s):  
Akshata R. Naik ◽  
Brent J. Formosa ◽  
Rishika G. Pulvender ◽  
Asiri G. Liyanaarachchi ◽  
Bhanu P. Jena
Keyword(s):  
Plasma Membrane ◽  
Insulin Secretion ◽  
Secretory Vesicles ◽  
Intracellular Acidification ◽  
Cell Secretion ◽  
Atpase Inhibitor ◽  
Cell Plasma Membrane ◽  
Min6 Cells ◽  
Cell Plasma ◽  
Glucose Stimulated Insulin Secretion

ABSTRACTSwelling of secretory vesicles is critical for the regulated expulsion of intra-vesicular contents from cells during secretion. At the secretory vesicle membrane of the exocrine pancreas and neurons, GTP-binding G proteins, vH+-ATPase, potassium channels and AQP water channels, are among the players implicated in vesicle volume regulation. Here we report in insulin secreting MIN6 cells, the requirement of vH+-ATPase-mediated intracellular acidification, on glucose-stimulated insulin release. MIN6 cells exposed to the vH+-ATPase inhibitor Bafilomycin A show decreased acidification of the cytosolic compartment that include insulin-carrying granules. Additionally, a loss of insulin granule association with the cell plasma membrane is demonstrated and results in a decrease in glucose-stimulated insulin secretion and accumulation of intracellular insulin. These results suggest that vH+-ATPase-mediated intracellular acidification is required both at the level of secretory vesicles and the cell plasma membrane for cell secretion.

scholarly journals Cell Secretion: Current Structural and Biochemical Insights

2010 ◽  
Vol 10 ◽  
pp. 2054-2069 ◽  
Author(s):  
Saurabh Trikha ◽  
Elizabeth C. Lee ◽  
Aleksandar M. Jeremic
Keyword(s):  
Plasma Membrane ◽  
Secretory Vesicles ◽  
Intercellular Signaling ◽  
Cell Secretion ◽  
Membrane Structures ◽  
Calcium Dependent ◽  
Cell Plasma ◽  
Membrane Bound ◽  
And Control ◽  
Fusion Pores

Essential physiological functions in eukaryotic cells, such as release of hormones and digestive enzymes, neurotransmission, and intercellular signaling, are all achieved by cell secretion. In regulated (calcium-dependent) secretion, membrane-bound secretory vesicles dock and transiently fuse with specialized, permanent, plasma membrane structures, called porosomes or fusion pores. Porosomes are supramolecular, cup-shaped lipoprotein structures at the cell plasma membrane that mediate and control the release of vesicle cargo to the outside of the cell. The sizes of porosomes range from 150nm in diameter in acinar cells of the exocrine pancreas to 12nm in neurons. In recent years, significant progress has been made in our understanding of the porosome and the cellular activities required for cell secretion, such as membrane fusion and swelling of secretory vesicles. The discovery of the porosome complex and the molecular mechanism of cell secretion are summarized in this article.

scholarly journals Functional Reconstitution of the Insulin-Secreting Porosome Complex in Live Cells

Endocrinology ◽  
2016 ◽  
Vol 157 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Akshata R. Naik ◽  
Sanjana P. Kulkarni ◽  
Kenneth T. Lewis ◽  
Douglas J. Taatjes ◽  
Bhanu P. Jena
Keyword(s):  
Insulin Secretion ◽  
Lipid Membranes ◽  
Cell Types ◽  
Live Cells ◽  
New Paradigm ◽  
Β Cells ◽  
Min6 Cells ◽  
Cell Plasma ◽  
Elevated Glucose ◽  
Glucose Stimulated Insulin Secretion

Abstract Supramolecular cup-shaped lipoprotein structures called porosomes embedded in the cell plasma membrane mediate fractional release of intravesicular contents from cells during secretion. The presence of porosomes, have been documented in many cell types including neurons, acinar cells of the exocrine pancreas, GH-secreting cells of the pituitary, and insulin-secreting pancreatic β-cells. Functional reconstitution of porosomes into artificial lipid membranes, have also been accomplished. Earlier studies on mouse insulin-secreting Min6 cells report 100-nm porosome complexes composed of nearly 30 proteins. In the current study, porosomes have been functionally reconstituted for the first time in live cells. Isolated Min6 porosomes reconstituted into live Min6 cells demonstrate augmented levels of porosome proteins and a consequent increase in the potency and efficacy of glucose-stimulated insulin release. Elevated glucose-stimulated insulin secretion 48 hours after reconstitution, reflects on the remarkable stability and viability of reconstituted porosomes, documenting the functional reconstitution of native porosomes in live cells. These results, establish a new paradigm in porosome-mediated insulin secretion in β-cells.

Functional Organization of the Porosome Complex and Associated Structures Facilitating Cellular Secretion

Physiology ◽  
2009 ◽  
Vol 24 (6) ◽  
pp. 367-376 ◽  
Author(s):  
Bhanu P. Jena
Keyword(s):  
Plasma Membrane ◽  
Functional Organization ◽  
Secretory Activity ◽  
Human Platelets ◽  
Frog Neuromuscular Junction ◽  
Cell Secretion ◽  
Cell Plasma Membrane ◽  
Cell Plasma ◽  
Membrane Bound ◽  
Cellular Secretion

Porosomes, the universal secretory machinery at the cell plasma membrane, are cup-shaped supramolecular lipoprotein structures, where membrane-bound vesicles transiently dock and fuse to release intravesicular contents during cell secretion. In this review, the discovery of the porosome and its structure, dynamics, composition, and functional reconstitution are outlined. Furthermore, the architecture of porosome-like structures such as the “canaliculi system” in human platelets and various associated structures such as the T-bars at the Drosophila synapse or the “beams,” “ribs,” and “pegs” at the frog neuromuscular junction, each organized to facilitate a certain specialized secretory activity, are briefly discussed.

Stimulation of Tumor-Specific Immunity Using Tumor Cell Plasma Membrane Antigen

Methods ◽  
1997 ◽  
Vol 12 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Matthew F Mescher ◽  
Elena Savelieva
Keyword(s):  
Plasma Membrane ◽  
Tumor Cell ◽  
Cell Plasma Membrane ◽  
Specific Immunity ◽  
Cell Plasma ◽  
Stimulation Of

PROTEIN KINASE ACTIVITY ASSOCIATED WITH THE FAT CELL PLASMA MEMBRANE

1981 ◽  
Vol 9 (2) ◽  
pp. 232P-232P
Author(s):  
G. J. Belsham ◽  
R. W. Brownsey ◽  
R. M. Denton
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Fat Cell ◽  
Cell Plasma Membrane ◽  
Cell Plasma

Gastrointestinal Cell Plasma Membrane Wounding and Resealing In Vivo

1989 ◽  
Vol 96 (5) ◽  
pp. 1238-1248 ◽  
Author(s):  
Paul L. McNeil ◽  
Susumu Ito
Keyword(s):  
Plasma Membrane ◽  
Cell Plasma Membrane ◽  
Cell Plasma

scholarly journals A murine model of Charcot-Marie-Tooth disease 4F reveals a role for the C-terminus of periaxin in the formation and stabilization of Cajal bands

2018 ◽  
Vol 3 ◽  
pp. 20 ◽  
Author(s):  
Diane L. Sherman ◽  
Peter J. Brophy
Keyword(s):  
Plasma Membrane ◽  
Schwann Cell ◽  
Laminin Receptor ◽  
Cell Plasma Membrane ◽  
Charcot Marie Tooth ◽  
Charcot Marie Tooth Disease ◽  
C Terminus ◽  
Cell Plasma ◽  
Inherited Neuropathies ◽  
Tooth Disease

Charcot-Marie-Tooth (CMT) disease comprises up to 80 monogenic inherited neuropathies of the peripheral nervous system (PNS) that collectively result in demyelination and axon degeneration. The majority of CMT disease is primarily either dysmyelinating or demyelinating in which mutations affect the ability of Schwann cells to either assemble or stabilize peripheral nerve myelin. CMT4F is a recessive demyelinating form of the disease caused by mutations in the Periaxin (PRX) gene. Periaxin (Prx) interacts with Dystrophin Related Protein 2 (Drp2) in an adhesion complex with the laminin receptor Dystroglycan (Dag). In mice the Prx/Drp2/Dag complex assembles adhesive domains at the interface between the abaxonal surface of the myelin sheath and the cytoplasmic surface of the Schwann cell plasma membrane. Assembly of these appositions causes the formation of cytoplasmic channels called Cajal bands beneath the surface of the Schwann cell plasma membrane. Loss of either Periaxin or Drp2 disrupts the appositions and causes CMT in both mouse and man. In a mouse model of CMT4F, complete loss of Periaxin first prevents normal Schwann cell elongation resulting in abnormally short internodal distances which can reduce nerve conduction velocity, and subsequently precipitates demyelination. Distinct functional domains responsible for Periaxin homodimerization and interaction with Drp2 to form the Prx/Drp2/Dag complex have been identified at the N-terminus of Periaxin. However, CMT4F can also be caused by a mutation that results in the truncation of Periaxin at the extreme C-terminus with the loss of 391 amino acids. By modelling this in mice, we show that loss of the C-terminus of Periaxin results in a surprising reduction in Drp2. This would be predicted to cause the observed instability of both appositions and myelin, and contribute significantly to the clinical phenotype in CMT4F.

Human GLUT-2 overexpression does not affect glucose-stimulated insulin secretion in MIN6 cells

1995 ◽  
Vol 269 (5) ◽  
pp. E897-E902
Author(s):  
H. Ishihara ◽  
T. Asano ◽  
K. Tsukuda ◽  
H. Katagiri ◽  
K. Inukai ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Utilization ◽  
Glucose Sensing ◽  
Min6 Cells ◽  
Over Expression ◽  
Twofold Increase ◽  
Glucose Stimulated Insulin Secretion ◽  
Glucose Responsiveness

Accumulated evidence suggests that GLUT-2, in addition to its role in glucose transport, may also have other functions in glucose-stimulated insulin secretion. As a first step in addressing this possibility, we have engineered MIN6 cells overexpressing human GLUT-2 by transfection with human GLUT-2 cDNA. Stable transformants harboring human GLUT-2 cDNA exhibited an approximately twofold increase in 3-O-methyl-D-glucose uptake at 0.5 and 15 mM. Glucokinase activity or glucose utilization measured by conversion of [5-3H]glucose to [3H]H2O was not, however, altered in the MIN6 cells overexpressing human GLUT-2. Furthermore, glucose-stimulated insulin secretion was not affected by over-expression of human GLUT-2. An abundance of GLUT-2, therefore, does not correlate with the glucose responsiveness of cells in which glycolysis is regulated at the glucose phosphorylating step. These data suggest that GLUT-2 by itself does not have significant functions other than its role in glucose transport in glucose sensing by MIN6 cells.

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