In the pancreatic B cell, microtubules are thought to be involved in the process of insulin release. Their possible participation in the sequence of events leading from the biosynthesis and conversion of proinsulin to the release of newly synthesized insulin was investigated in rat isolated islets exposed to colchicine (0.1 mM). When the islets were preincubated for 30 min with colchicine and [3H]-leucine and, thereafter, incubated for two successive periods of 90 min each, still in the presence of colchicine, the release of preformed insulin was progressively inhibited and that of newly synthesized hormone delayed. When the islets were preincubated for 120 min with colchicine, subsequently pulse-labeled with [3H]leucine, and eventually examined by ultrastructural autoradiography, the export of newly synthesized proinsulin out of the rough endoplasmic reticulum, its transit through the Golgi complex, and its eventual packaging in secretory granules were all retarded. This situation was associated with a delayed conversion of proinsulin to insulin. Under the same experimental conditions, colchicine failed to affect the oxidation of glucose and adenylate charge in the islets. The effect of colchicine upon the release of preformed and newly synthesized insulin was not reproduced by lumicolchicine. It is concluded that colchicine interferes with the system controlling the intracellular transfer of secretory material from site of synthesis to site of release. This interference is likely to be linked to the effect of colchicine on microtubules.
F Malaisse-Lagae, M Amherdt, M Ravazzola, A Sener, J C Hutton, L Orci, W J Malaisse
Usage data is cumulative from April 2023 through April 2024.
Usage | JCI | PMC |
---|---|---|
Text version | 92 | 0 |
48 | 20 | |
Figure | 0 | 1 |
Scanned page | 209 | 2 |
Citation downloads | 11 | 0 |
Totals | 360 | 23 |
Total Views | 383 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.