Expression of insulin receptor mRNA and insulin receptor substrate 1 in pancreatic islet beta-cells.
The expression of insulin receptor mRNA was examined in rat pancreatic islet cells by single-cell reverse transcriptase (RT)-polymerase chain reaction (PCR). Single cells from disaggregated islets were individually isolated in a microcapillary pipet, and the beta-cells were identified by amplification of the mRNA for insulin. We found that in single beta-cells, the mRNA for the insulin receptor was also expressed. The fraction of single islet cells expressing both insulin receptor and insulin mRNAs corresponds closely to the fraction of beta-cells in the disaggregated islet cell preparation. These results indicate that normal beta-cells have the potential to express authentic insulin receptors. Immunohistochemical analysis was insufficiently sensitive for assaying insulin receptor protein; however, insulin receptor substrate 1 (IRS-1) was readily immunolocalized in islet beta-cells. Since IRS-1 links several cell surface receptors, including those for insulin and IGF-I, to distal signal transduction pathways, our observations indicate that hormonal regulation of islet beta-cells potentially involves the same signal transduction pathway that mediates insulin and growth factor signaling in peripheral insulin target tissue cell types.
Harbeck
M C
MC
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
Louie
D C
DC
Howland
J
J
Wolf
B A
BA
Rothenberg
P L
PL
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D007150:Immunohistochemistry; D055504:Insulin Receptor Substrate Proteins; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000096:biosynthesis*; D015398:Signal Transduction; D014158:Transcription, Genetic
D017931:DNA Primers; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D012333:RNA, Messenger; D011972:Receptor, Insulin