Insulin induces heme oxygenase-1 through the phosphatidylinositol 3-kinase/Akt pathway and the Nrf2 transcription factor in renal cells.
Heme oxygenase-1 catalyzes the breakdown of heme and is protective in models of kidney transplantation. In this study we describe the induction of heme oxygenase-1 mRNA and protein by insulin. Following treatment with insulin, a five-fold increase in heme oxygenase-1 mRNA and a four-fold increase in protein expression were observed in renal adenocarcinoma cells; insulin-induced heme oxygenase-1 expression was also demonstrated in mouse primary tubular epithelial cells. The induction of heme oxygenase-1 in renal adenocarcinoma cells was blocked by actinomycin D and cycloheximide and was abolished by the phosphatidylinositol 3-kinase inhibitor, LY294002, but not by the inactive analog LY303511. Overexpressing a dominant-negative form of Akt abrogated the heme oxygenase-1-inducing effects of insulin, whereas cells transfected with a constitutively active Akt construct demonstrated an increase in heme oxygenase-1 promoter activity and protein expression. The transcription factor NF-E2-related factor-2 was found to translocate to the nucleus following insulin treatment in a phosphatidylinositol 3-kinase-dependent manner. Pretreatment with NF-E2-related factor-2 small-interfering RNA abolished insulin-induced heme oxygenase-1 induction. Insulin was also found to activate the mitogen-activated protein kinase cascades p38 and extracellular signal-related kinase; however, inhibition of these pathways with SB202190 and PD98059 did not alter insulin-induced heme oxygenase-1 expression. Thus, insulin induces heme oxygenase-1 mRNA and protein expression in renal cells in a phosphatidylinositol 3-kinase/Akt and NF-E2-related factor-2-dependent manner.
Harrison
Ewen M
EM
Tissue Injury and Repair Group, University of Edinburgh, UK. mail@ewenharrison.com
McNally
Stephen J
SJ
Devey
Luke
L
Garden
O J
OJ
Ross
James A
JA
Wigmore
Stephen J
SJ
D000230:Adenocarcinoma; D000818:Animals; D045744:Cell Line, Tumor; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D051547:Heme Oxygenase-1 / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007680:Kidney Neoplasms; D007684:Kidney Tubules / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
D007328:Insulin; D051267:NF-E2-Related Factor 2; D012333:RNA, Messenger; D051547:Heme Oxygenase-1; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt