PMID- 14966273 OWN - NLM STAT- MEDLINE DCOM- 20040401 LR - 20210526 IS - 0270-7306 (Print) IS - 1098-5549 (Electronic) IS - 0270-7306 (Linking) VI - 24 IP - 5 DP - 2004 Mar TI - Differential roles of insulin receptor substrates in brown adipocyte differentiation. PG - 1918-29 AB - Insulin promotes adipocyte differentiation via a complex signaling network involving multiple insulin receptor substrates (IRSs). In cultured brown preadipocytes, expression of IRS-1 and IRS-2 mRNAs and proteins was at relatively high levels before and after differentiation into mature fat cells, while IRS-3 transcript was not detectable in preadipocytes but increased during the course of differentiation, and IRS-4 mRNA was barely detected in both states. To determine more precisely the roles of various IRS proteins in adipogenesis, we established and characterized brown preadipocyte cell lines from wild-type and IRS knockout (KO) animals. While wild-type, IRS-2 KO, and IRS-4 KO cells fully differentiated into mature adipocytes, IRS-3 KO cells showed a moderate defect in differentiation and IRS-1 KO cells exhibited a severe defect in the process. Cells lacking both IRS-1 and IRS-3 completely failed to differentiate. Expression of the adipogenic markers peroxisome proliferator-activated receptor gamma (PPARgamma), CCAAT/enhancer-binding protein alpha, fatty acid synthase, glucose transporter 4, and the transcription factor signal transducer and activator of transcription 5, as well as the brown-fat-specific markers PPARgamma coactivator 1 alpha and uncoupling protein 1, mirrored the differentiation pattern. Reconstitution of the IRS-1 KO cells with IRS-1 and IRS-4, but not IRS-2 or IRS-3, compensated for the lack of differentiation in IRS-1 KO cells. A chimeric molecule containing the N terminus of IRS-1 and the C terminus of IRS-2, but not one with the N terminus of IRS-2 and the C terminus of IRS-1, also rescued differentiation. Expression of Wnt 10a, a molecule known to inhibit adipogenesis, was dramatically increased in the IRS-1 KO cells, and this could be reduced by overexpression of IRS-1 or IRS-4, which was correlated with restoration of differentiation. These data indicate that both IRS-1 and -3 play important roles in the differentiation of brown adipocytes and that the N terminus of IRS-1 is more important for this function of the molecule. Although IRS-4 is not essential for the process, overexpression of IRS-4 can compensate for the deficiency in differentiation in IRS-1 KO cells. FAU - Tseng, Yu-Hua AU - Tseng YH AD - Research Division, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA. FAU - Kriauciunas, Kristina M AU - Kriauciunas KM FAU - Kokkotou, Efi AU - Kokkotou E FAU - Kahn, C Ronald AU - Kahn CR LA - eng GR - R01 DK055545/DK/NIDDK NIH HHS/United States GR - R01 DK033201/DK/NIDDK NIH HHS/United States GR - DK55545/DK/NIDDK NIH HHS/United States GR - DK33201/DK/NIDDK NIH HHS/United States GR - DK101183/DK/NIDDK NIH HHS/United States GR - F32 DK101183/DK/NIDDK NIH HHS/United States PT - Journal Article PT - Research Support, U.S. Gov't, P.H.S. PL - United States TA - Mol Cell Biol JT - Molecular and cellular biology JID - 8109087 RN - 0 (Adaptor Proteins, Signal Transducing) RN - 0 (Biomarkers) RN - 0 (IRS1 protein, human) RN - 0 (IRS2 protein, human) RN - 0 (IRS3P protein, human) RN - 0 (IRS4 protein, human) RN - 0 (Insulin) RN - 0 (Insulin Receptor Substrate Proteins) RN - 0 (Intracellular Signaling Peptides and Proteins) RN - 0 (Irs1 protein, mouse) RN - 0 (Irs2 protein, mouse) RN - 0 (Irs3 protein, mouse) RN - 0 (Irs4 protein, mouse) RN - 0 (Phosphoproteins) RN - 0 (RNA, Messenger) RN - 42HK56048U (Tyrosine) RN - EC 2.7.10.1 (Receptor, Insulin) RN - EC 2.7.11.24 (Mitogen-Activated Protein Kinases) SB - IM MH - Adaptor Proteins, Signal Transducing MH - Adipocytes/cytology/*physiology MH - Adipose Tissue, Brown/*cytology MH - Animals MH - Biomarkers MH - Cell Differentiation/*physiology MH - Cells, Cultured MH - Humans MH - Insulin/metabolism MH - Insulin Receptor Substrate Proteins MH - Intracellular Signaling Peptides and Proteins MH - MAP Kinase Signaling System/physiology MH - Mice MH - Mice, Knockout MH - Mitogen-Activated Protein Kinases/metabolism MH - Phosphoproteins/genetics/*metabolism MH - Phosphorylation MH - RNA, Messenger/metabolism MH - Receptor, Insulin/metabolism MH - Tyrosine/metabolism PMC - PMC350563 EDAT- 2004/02/18 05:00 MHDA- 2004/04/02 05:00 PMCR- 2004/03/01 CRDT- 2004/02/18 05:00 PHST- 2004/02/18 05:00 [pubmed] PHST- 2004/04/02 05:00 [medline] PHST- 2004/02/18 05:00 [entrez] PHST- 2004/03/01 00:00 [pmc-release] AID - 1528 [pii] AID - 10.1128/MCB.24.5.1918-1929.2004 [doi] PST - ppublish SO - Mol Cell Biol. 2004 Mar;24(5):1918-29. doi: 10.1128/MCB.24.5.1918-1929.2004.