Major vault protein is part of an extracellular cement material in the Atlantic salmon louse (Lepeophtheirus salmonis).

Major vault protein (MVP) is the main component of the vault complex, which is a highly conserved ribonucleoprotein complex found in most eukaryotic organisms. MVP or vaults have previously been found to be overexpressed in multidrug-resistant cancer cells and implicated in various cellular processes such as cell signaling and innate immunity. The precise function of MVP is, however, poorly understood and its expression and probable function in lower eukaryotes are not well characterized.

Inhibition of Prenylation Promotes Caspase 3 Activation, Lamin B Degradation and Loss in Metabolic Cell Viability in Pancreatic β-Cells.

Background/aims: Lamins are intermediate filament proteins that constitute the main components of the lamina underlying the inner-nuclear membrane and serve to organize chromatin. Lamins (e.g.

Biology and Regulatory Roles of Nuclear Lamins in Cellular Function and Dysfunction.

Nuclear lamins, namely lamins A, B and C, surround the nucleoplasmic contents in a meshlike network called the nuclear lamina. These intermediate filaments provide a structural framework to the nuclear envelope (NE), play a role in arrangement of the chromatin within the nucleus, in DNA replication and also participate in DNA damage repair. In order for lamins to be involved in these important nuclear processes and to be functionally active, they undergo a series of post-translational modifications (farnesylation, endoproteolytic cleavage, carboxylmethylation etc.

VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells.

Aims/hypothesis: Rho GTPases (Ras-related C3 botulinum toxin substrate 1 [Rac1] and cell division cycle 42 [Cdc42]) have been shown to regulate glucose-stimulated insulin secretion (GSIS) via cytoskeletal remodelling, trafficking and fusion of insulin-secretory granules with the plasma membrane. GTP loading of these G proteins, which is facilitated by GDP/GTP exchange factors, is a requisite step in the regulation of downstream effector proteins. Guanine nucleotide exchange factor VAV2 (VAV2), a member of the Dbl family of proteins, has been identified as one of the GDP/GTP exchange factors for Rac1.

Phagocyte-like NADPH oxidase (Nox2) promotes activation of p38MAPK in pancreatic β-cells under glucotoxic conditions: Evidence for a requisite role of Ras-related C3 botulinum toxin substrate 1 (Rac1).

It is well established that glucotoxicity (caused by high glucose concentrations; HG) underlies pathogenesis of islet dysfunction in diabetes. We have recently demonstrated that Nox2 plays a requisite role in the generation of reactive oxygen species (ROS) under HG conditions, resulting in mitochondrial dysregulation and loss of islet β-cell function. Herein, we investigated roles of Nox2 in the regulation of downstream stress kinase (p38MAPK) activation under HG conditions (20mM; 24h) in normal rodent islets and INS-1 832/13 cells.

EHT 1864, a small molecule inhibitor of Ras-related C3 botulinum toxin substrate 1 (Rac1), attenuates glucose-stimulated insulin secretion in pancreatic β-cells.

Glucose-stimulated insulin secretion (GSIS) in the pancreatic β-cells entails a variety of signaling mechanisms including activation of small GTP-binding proteins (G-proteins). Previous studies from our laboratory in human islets, rodent islets and clonal β-cells have demonstrated that G-proteins (e.g.

Glucotoxic and diabetic conditions induce caspase 6-mediated degradation of nuclear lamin A in human islets, rodent islets and INS-1 832/13 cells.

Nuclear lamins form the lamina on the interior surface of the nuclear envelope, and regulate nuclear metabolic events, including DNA replication and organization of chromatin. The current study is aimed at understanding the role of executioner caspase 6 on lamin A integrity in islet β-cells under duress of glucotoxic (20 mM glucose; 24 h) and diabetic conditions. Under glucotoxic conditions, glucose-stimulated insulin secretion and metabolic cell viability were significantly attenuated in INS-1 832/13 cells.

Glucotoxic conditions induce endoplasmic reticulum stress to cause caspase 3 mediated lamin B degradation in pancreatic β-cells: protection by nifedipine.

Nuclear lamins form the lamina on the interior of the nuclear envelope, and are involved in the regulation of various cellular processes, including DNA replication and chromatin organization. Despite this evidence, little is known about potential alterations in nuclear metabolism, specifically lamin structure and integrity in isolated β-cells subjected to stress conditions, including chronic exposure to hyperglycemia (i.e.

Upregulation of phagocyte-like NADPH oxidase by cytokines in pancreatic beta-cells: attenuation of oxidative and nitrosative stress by 2-bromopalmitate.

Phagocyte-like NADPH oxidase (Nox2) has been shown to play regulatory roles in the metabolic dysfunction of the islet β-cell under the duress of glucolipotoxic conditions and exposure to proinflammatory cytokines. However, the precise mechanisms underlying Nox2 activation by these stimuli remain less understood. To this end, we report a time-dependent phosphorylation of p47phox, a cytosolic subunit of Nox2, by cytomix (IL-1β+TNFα+IFNγ) in insulin-secreting INS-1 832/13 cells.