Phospholipase A2 expression in human and rodent insulin-secreting cells.
The expression of different isoforms of phospholipase A2 in human and rat islets of Langerhans and in the clonal B-cell lines, HIT-T15 and RINm5F has been investigated, using polyclonal antisera specific to human cytosolic (cPLA2) or human Groups I and II secretory (sPLA2) isoforms. Abundant levels of a 100-kDa protein corresponding to cPLA2 were detected in cytosolic extracts of human islets. A 100-kDa cPLA2 was not detectable in rat islets, RINm5F or HIT-T15 cells using an anti-cPLA2 serum raised against cloned human cPLA2 cDNA, despite the antiserum being cross-reactive with cPLA2 from rat kidney. Human and rat islets were found to express a 21-kDa protein immunoreactive with Group I sPLA2 antiserum. Group II sPLA2 was not detected in human or rat islets. RIN cells did not express detectable levels of either Group I or Group II sPLA2, but HIT cells expressed variable quantities of Group II sPLA2. These differences in PLA2 expression suggest that caution should be exercised when extrapolating conclusions about lipid-derived signalling molecules from insulin-secreting cell lines to normal islets of Langerhans.
D000818:Animals; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007118:Immunoassay; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000201:enzymology*; D007527:Isoenzymes / Q000378:metabolism*; D007583:Jejunum / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D008970:Molecular Weight; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats
D007328:Insulin; D007527:Isoenzymes; D010741:Phospholipases A; D054467:Phospholipases A2