Tuberin, p27 and mTOR in different cells

Amino Acids. 2009 Feb;36(2):297-302. doi: 10.1007/s00726-008-0066-1. Epub 2008 Apr 2.


Mutations in the genes TSC1 or TSC2 cause the autosomal dominantly inherited tumor suppressor syndrome tuberous sclerosis, which is characterized by the development of tumors, named hamartomas, in different organs. The TSC gene products, hamartin and tuberin, form a complex, of which tuberin is assumed to be the functional component. Both, hamartin and tuberin have been implicated in the control of the cell cycle by activating the cyclin-dependent kinase inhibitor p27 and in cell size regulation by inhibiting the mammalian target of rapamycin (mTOR) a regulator of the p70 ribosomal protein S6 kinase (p70S6K) and its target the ribosomal protein S6. The tuberin/hamartin complex was shown to protect p27 from protein degradation. Within the mTOR signaling pathway tuberin harbors GTPase activating (GAP) potential toward Rheb, which is a potent regulator of mTOR. In this study, we have analyzed the protein levels of tuberin, p27, cyclin D1, mTOR and phospho mTOR Ser2448 (activated mTOR), S6 and phospho S6 Ser240/244 (activated S6) and as controls alpha-tubulin and topoisomerase IIbeta, in ten different cells, including primary normal cells, immortalized and transformed cell lines.

MeSH terms

  • Cell Line
  • Cell Line, Tumor
  • Cyclin D1 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p27
  • DNA Topoisomerases, Type I / metabolism
  • Epithelial Cells / metabolism
  • Fibroblasts / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Isoenzymes / metabolism
  • Protein Kinases / biosynthesis*
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases
  • Tuberous Sclerosis Complex 1 Protein
  • Tuberous Sclerosis Complex 2 Protein
  • Tubulin / metabolism
  • Tumor Suppressor Proteins / biosynthesis*


  • CDKN1B protein, human
  • Intracellular Signaling Peptides and Proteins
  • Isoenzymes
  • TSC1 protein, human
  • TSC2 protein, human
  • Tuberous Sclerosis Complex 1 Protein
  • Tuberous Sclerosis Complex 2 Protein
  • Tubulin
  • Tumor Suppressor Proteins
  • Cyclin D1
  • Cyclin-Dependent Kinase Inhibitor p27
  • Protein Kinases
  • MTOR protein, human
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • DNA Topoisomerases, Type I