We describe a rapid and simple insulin RIA in which proinsulin and conversion intermediates do not interfere. Three monoclonal antibodies (S1, S2, and S53) were selected for their specificity (directed, respectively, against the B10 region, the junction between A chain and C-peptide, and the junction between B chain and C-peptide), their affinity constant (approximately 10(10) L/mol), and their...

We investigated the effects of olanzapine on cisplatin-induced pica (the consumption of non-nutrient materials such as kaolin) and glucose homeostasis in rats to clarify the effects of olanzapine when used as an anti-emetic drug. Rats were injected intraperitoneally (i.p.) with either 5 mg/kg cisplatin or saline. Additionally, 2 or 10 mg/kg olanzapine were administered i.p. to the rats 10 min b...

Insulin production in pancreatic beta cells is predominantly regulated through glucose control of proinsulin translation. Previously, this was shown to require sequences within the untranslated regions (UTRs) of the preproinsulin (ppI) mRNA. Here, those sequences were found to be sufficient for specific glucose-regulated proinsulin translation. Furthermore, an element 40-48 bp from the 5' end o...

Isolated rat islets of Langerhans were incubated for 60, 120, and 180 min and the incorporation of leucine-(3)H into proinsulin and insulin moieties was followed. Synthesis and release of these hormones could be followed by separate extractions of islets and incubation media. RELEASE OF NEWLY SYNTHESIZED PROINSULIN AND INSULIN OCCURRED UNDER THE FOLLOWING CONDITIONS: (a) incubation for greater ...

The C-peptide links the insulin A and B chains in proinsulin, providing thereby a means to promote their efficient folding and assembly in the endoplasmic reticulum during insulin biosynthesis. It then facilitates the intracellular transport, sorting, and proteolytic processing of proinsulin into biologically active insulin in the maturing secretory granules of the beta cells. These manifold fu...

Stromal cell-derived factor 2-like 1 (SDF2L1) is an endoplasmic reticulum (ER)-localized protein whose function is undefined. Here we show that SDF2L1 protein levels are increased in response to ER stress-inducing compounds, but not other cell stressors that we tested in insulinoma cell lines. SDF2L1 protein levels were also induced by expression of misfolded proinsulin in insulinoma cells and ...

Rat pancreatic islets were exposed to a combination of analogs of arginine (3 mM canavanine) and lysine (3 mM thialysine) for 2 h and then labeled with [3H]leucine in the continued presence of the analogs. Control islets were incubated in parallel without analogs. Prelabeled islets were then incubated for a 3-h chase period without analogs. Incorporation of the analogs blocked conversion of new...

We have shown previously that alloxan and streptozotocin, two major diabetogenic agents, cause DNA strand breaks in rat pancreatic islets and stimulate nuclear poly(ADP-ribose) synthetase, thereby .depleting intracellular NAD level and inhibiting proinsulin synthesis (Okamoto, H. (1981) Mol. Cell. Biochem 37, 43-61; Yamamoto, H., Uchigata, Y., and Okamoto, H. (1981) Nutune 294, 284-286). In the...

We have evaluated in situ hybridization histochemistry as a means of estimating simultaneously the level of prohormone mRNA and the dimensions of rat pancreatic islets. Localization of the 27-mer 32P-labeled oligonucleotide probes for rat proinsulin I, glucagon, and prosomatostatin I corresponded with localization of antibodies to the three hormones. In normal rats subjected to chronic hypergly...

Immunization against insulin, insulin B chain, or B chain peptide B(9-23) (preproinsulin peptide II(33-47)) prevents diabetes in the nonobese diabetic (NOD) mouse. Whether or not peptide II(33-47) is the only proinsulin determinant recognized by CD4 T cells remains unclear. Using two peptide libraries spanning the entire sequence of preproinsulin I and preproinsulin II, respectively, we identif...