High-resolution two-dimensional polyacrylamide gel electrophoresis reveals a glucose-response protein of 65 kDa in pancreatic islet cells.

Abstract

High-resolution two-dimensional PAGE was used to search for glucose-response proteins in isolated pancreatic islets that were labeled with [35S]methionine at ambient glucose concentrations of 0-18 mM. A 65-kDa protein, isoelectric focusing point of approximately 6.6-7.0, was discovered that showed at least a 20-fold stimulation of radiolabeling when glucose in the labeling medium was increased from 3 to 18 mM, in contrast to a 2.5-fold enhancement of label incorporation into total islet proteins. This 65-kDa protein is evident after 30 min of labeling with 18 mM glucose and is preferentially synthesized compared to its nearest neighbors after both 30 and 60 min of labeling. Glucose induction of the 65-kDa protein was virtually blocked by D-mannoheptulose. Glucose induction of this 65-kDa protein is in practically all aspects comparable to glucose induction of insulin and glucokinase in pancreatic 13 cells. A working hypothesis is developed proposing that glucose-response proteins or "glucospondins" are pivotal constituents of pancreatic islet cells and that their discovery and exploration promise new insights into normal and pathological islet cell function.Physiologically elevated blood glucose influences pancreatic p cells thoroughly. Insulin release is stimulated (1) and insulin biosynthesis is augmented within minutes after glucose levels increase (2-4). If hyperglycemia persists for hours or even longer p cells become sensitized to glucose and ultimately they respond with hypertrophy and hyperplasia (5). Those multifarious p-cell responses promoted by high glucose can be expected to be associated with the activation ofknown and proposed glucose-response genes and the enhanced biosynthesis ofcorresponding glucose-response proteins. Insulin (6, 7) and glucokinase (8) Abbreviations: KIC, a-ketoisocaproate; 2-D, two-dimensional; GSP, glucospondin. 5494The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Unraveling pancreatic islet biology by quantitative proteomics

“…In the early 1990s, 2DE studies by Collins et al . revealed numerous islet proteins altered after glucose stimulation; however, these glucose-responsive proteins were not identified at that time [63,64]. More than a decade later, Ahmed et al .…”

Proteomic and transcriptomic analysis for streptozotocin‐induced diabetic rat pancreas in response to fungal polysaccharide treatments

“…Other investigators have used 2-DE to describe insulin secretory granule biogenesis, exocytosis, and the effect of glucose on b-cells [16][17][18]. More recent studies have analyzed the proteome of pancreatic islets, but have not directly addressed the pathogenesis of T1DM [17][18][19][20][21][22]. More recently, pancreatic islets have been studied by proteome analysis to investigate the effect of the insulin-sensitizer drug Rosiglitazone on protein expression [23,24].…”

Glucose-Regulated Gene Expression Maintaining the Glucose-Responsive State of β-Cells

“…In pioneering studies, Collins et al (19,20) analyzed via two-dimensional gel electrophoresis 35 S-methioninelabeled proteins extracted from whole islets that were exposed in vivo or in vitro to either low or high glucose. Using this technique, ϳ2,000 different islet protein spots were identified.…”