title: TSC2 mediates cellular energy response to control cell growth and survival.
abstract: Mutations in either the TSC1 or TSC2 tumor suppressor gene are responsible for Tuberous Sclerosis Complex. The gene products of TSC1 and TSC2 form a functional complex and inhibit the phosphorylation of S6K and 4EBP1, two key regulators of translation. Here, we describe that TSC2 is regulated by cellular energy levels and plays an essential role in the cellular energy response pathway. Under energy starvation conditions, the AMP-activated protein kinase (AMPK) phosphorylates TSC2 and enhances its activity. Phosphorylation of TSC2 by AMPK is required for translation regulation and cell size control in response to energy deprivation. Furthermore, TSC2 and its phosphorylation by AMPK protect cells from energy deprivation-induced apoptosis. These observations demonstrate a model where TSC2 functions as a key player in regulation of the common mTOR pathway of protein synthesis, cell growth, and viability in response to cellular energy levels.
authors.affiliation: Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Inoki
authors.forename: Tianqing
authors.initials: T
authors.lastname: Zhu
authors.forename: Kun-Liang
authors.initials: KL
authors.lastname: Guan
mesh_terms: D055372:AMP-Activated Protein Kinases; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000235:genetics; D019069:Cell Respiration / Q000235:genetics*; D002470:Cell Survival / Q000235:genetics; D004734:Energy Metabolism / Q000502:physiology*; D039642:Eukaryotic Initiation Factors; D005508:Food Deprivation / Q000502:physiology; D005947:Glucose / Q000172:deficiency; D006801:Humans; D051379:Mice; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; C499527:Eif4ebp1 protein, mouse; D039642:Eukaryotic Initiation Factors; D009097:Multienzyme Complexes; D010750:Phosphoproteins; D012097:Repressor Proteins; C000624653:TSC2 protein, human; C000624654:Tsc2 protein, mouse; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D017346:Protein Serine-Threonine Kinases; D038762:Ribosomal Protein S6 Kinases, 70-kDa; C448959:ribosomal protein S6 kinase, 70kD, polypeptide 2; D055372:AMP-Activated Protein Kinases; D005947:Glucose