TY - JOUR
T1 - Regulation of peroxisome proliferator-activated receptor-γ activity by mammalian target of rapamycin and amino acids in adipogenesis
AU - Kim, Jae Eun
AU - Chen, Jie
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2004/11
Y1 - 2004/11
N2 - Adipocyte differentiation is a developmental process that is critical for metabolic homeostasis and nutrient signaling. The mammalian target of rapamycin (mTOR) mediates nutrient signaling to regulate cell growth, proliferation, and diverse cellular differentiation. It has been reported that rapamycin, the inhibitor of mTOR and an immunosuppressant, blocks adipocyte differentiation, but the mechanism underlying this phenomenon remains unknown. Here we show that mTOR plays a critical role in 3T3-L1 preadipocyte differentiation and that mTOR kinase activity is required for this process. Rapamycin specifically disrupted the positive transcriptional feedback loop between CCAAT/enhancer-binding protein-α and peroxisome proliferator-activated receptor-γ (PPAR-γ), two key transcription factors in adipogenesis, by directly targeting the transactivation activity of PPAR-γ. In addition, we demonstrate for the first time that PPAR-γ activity is dependent on amino acid sufficiency, revealing a molecular link between nutrient status and adipogenesis. The results of our further investigation have led us to propose a model in which the mTOR pathway and the phosphatidylinositol 3-kinase/Akt pathway act in parallel to regulate PPAR-γ activation during adipogenesis by mediating nutrient availability and insulin signals, respectively. It is interesting that troglitazone (a thiazolidinedione drug) reversed the inhibitory effects of rapamycin and amino acid deprivation, implicating therapeutic values of thiazolidinedione drugs to counter certain side effects of rapamycin as an immunosuppressant.
AB - Adipocyte differentiation is a developmental process that is critical for metabolic homeostasis and nutrient signaling. The mammalian target of rapamycin (mTOR) mediates nutrient signaling to regulate cell growth, proliferation, and diverse cellular differentiation. It has been reported that rapamycin, the inhibitor of mTOR and an immunosuppressant, blocks adipocyte differentiation, but the mechanism underlying this phenomenon remains unknown. Here we show that mTOR plays a critical role in 3T3-L1 preadipocyte differentiation and that mTOR kinase activity is required for this process. Rapamycin specifically disrupted the positive transcriptional feedback loop between CCAAT/enhancer-binding protein-α and peroxisome proliferator-activated receptor-γ (PPAR-γ), two key transcription factors in adipogenesis, by directly targeting the transactivation activity of PPAR-γ. In addition, we demonstrate for the first time that PPAR-γ activity is dependent on amino acid sufficiency, revealing a molecular link between nutrient status and adipogenesis. The results of our further investigation have led us to propose a model in which the mTOR pathway and the phosphatidylinositol 3-kinase/Akt pathway act in parallel to regulate PPAR-γ activation during adipogenesis by mediating nutrient availability and insulin signals, respectively. It is interesting that troglitazone (a thiazolidinedione drug) reversed the inhibitory effects of rapamycin and amino acid deprivation, implicating therapeutic values of thiazolidinedione drugs to counter certain side effects of rapamycin as an immunosuppressant.
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U2 - 10.2337/diabetes.53.11.2748
DO - 10.2337/diabetes.53.11.2748
M3 - Article
C2 - 15504954
AN - SCOPUS:7044234995
VL - 53
SP - 2748
EP - 2756
JO - Diabetes
JF - Diabetes
SN - 0012-1797
IS - 11
ER -