title: Regulated in development and DNA damage responses -1 (REDD1) protein contributes to insulin signaling pathway in adipocytes.
abstract: REDD1 (Regulated in development and DNA damage response 1) is a hypoxia and stress response gene and is a negative regulator of mTORC1. Since mTORC1 is involved in the negative feedback loop of insulin signaling, we have studied the role of REDD1 on insulin signaling pathway and its regulation by insulin. In human and murine adipocytes, insulin transiently stimulates REDD1 expression through a MEK dependent pathway. In HEK-293 cells, expression of a constitutive active form of MEK stabilizes REDD1 and protects REDD1 from proteasomal degradation mediated by CUL4A-DDB1 ubiquitin ligase complex. In 3T3-L1 adipocytes, silencing of REDD1 with siRNA induces an increase of mTORC1 activity as well as an inhibition of insulin signaling pathway and lipogenesis. Rapamycin, a mTORC1 inhibitor, restores the insulin signaling after downregulation of REDD1 expression. This observation suggests that REDD1 positively regulates insulin signaling through the inhibition of mTORC1 activity. In conclusion, our results demonstrate that insulin increases REDD1 expression, and that REDD1 participates in the biological response to insulin.
authors.affiliation: INSERM U 1065, Mediterranean Research Centre for Molecular Medicine, Team: Cellular and Molecular Physiopathology of obesity and diabetes, Nice, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Regazzetti
authors.forename: Karine
authors.initials: K
authors.lastname: Dumas
authors.forename: Yannick
authors.initials: Y
authors.lastname: Le Marchand-Brustel
authors.forename: Pascal
authors.initials: P
authors.lastname: Peraldi
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Tanti
authors.forename: Sophie
authors.initials: S
authors.lastname: Giorgetti-Peraldi
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation; D057809:HEK293 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D059748:Proteolysis; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C469991:DDIT4 protein, human; D007328:Insulin; D014157:Transcription Factors; D046988:Proteasome Endopeptidase Complex