Biopolym. Cell. 2007; 23(4):318-323.
Structure and Function of Biopolymers
Interaction of serine/threonine protein phosphatase 5 with the protein products of tumour suppressor gene Tsc2
1, 2Malanchuk O. M., 1Palchevskyy S. S., 2Pozur V. K., 1, 3Gout I. T., 1Filonenko V. V.
  1. Institute of Molecular Biology and Genetics, NAS of Ukraine
    150, Akademika Zabolotnoho Str., Kyiv, Ukraine, 03680
  2. Taras Shevchenko National University of Kyiv
    64, Volodymyrska Str., Kyiv, Ukraine, 01033
  3. University College London
    Gower Str., London WC1E 6BT, UK


Tuberous sclerosis (TSC) is a tumour disease caused by mutations in Tsc1 or Tsc2 genes. Both protein products of Tsc1 and Tsc2 form an intracellular complex possessing GTPase-activating (GAP) activity towards a small GTP binding protein Rheb. The activity of TSC1/2 complex is regulated by multiple phosphorylations of TSC2 mediated by several kinases, such as PKB/Akt, AMP-activated kinase (AMPK), ERK, MK2 and RSK1. So far, very little is known about the molecular mechanisms of TSC2 dephosphorylation. In the yeast two-hybrid screening, we have identified a number of potential TSC2 binding partners including protein phosphatase 5 (PP5). In this study, we provide the evidence that the interaction between TSC2 and PP5 also occurs in mammalian cells. Using TSC2+/+, p53–/– mouse embryo fibroblasts (MEFs) transiently overexpressing myc-PP5, we showed in the immunoprecipitation assay that TSC2 specifically associates with myc-PP5 in exponentially growing cells. The physiological relevance of identified interaction, especially the involvement of PP5 in the dephosphorylation of major regulatory sites is currently under investigation.
Keywords: TSC2, tuberous sclerosis, PP5, protein-protein interactions


[1] Plank TL, Yeung RS, Henske EP. Hamartin, the product of the tuberous sclerosis 1 (TSC1) gene, interacts with tuberin and appears to be localized to cytoplasmic vesicles. Cancer Res. 1998;58(21):4766-70.
[2] van Slegtenhorst M, Nellist M, Nagelkerken B, Cheadle J, Snell R, van den Ouweland A, Reuser A, Sampson J, Halley D, van der Sluijs P. Interaction between hamartin and tuberin, the TSC1 and TSC2 gene products. Hum Mol Genet. 1998;7(6):1053-7.
[3] Kwiatkowski DJ. Tuberous sclerosis: from tubers to mTOR. Ann Hum Genet. 2003;67(Pt 1):87-96.
[4] Garami A, Zwartkruis FJ, Nobukuni T, Joaquin M, Roccio M, Stocker H, Kozma SC, Hafen E, Bos JL, Thomas G. Insulin activation of Rheb, a mediator of mTOR/S6K/4E-BP signaling, is inhibited by TSC1 and 2. Mol Cell. 2003;11(6):1457-66.
[5] Inoki K, Li Y, Xu T, Guan KL. Rheb GTPase is a direct target of TSC2 GAP activity and regulates mTOR signaling. Genes Dev. 2003;17(15):1829-34.
[6] Saucedo LJ, Gao X, Chiarelli DA, Li L, Pan D, Edgar BA. Rheb promotes cell growth as a component of the insulin/TOR signalling network. Nat Cell Biol. 2003;5(6):566-71.
[7] Stocker H, Radimerski T, Schindelholz B, Wittwer F, Belawat P, Daram P, Breuer S, Thomas G, Hafen E. Rheb is an essential regulator of S6K in controlling cell growth in Drosophila. Nat Cell Biol. 2003;5(6):559-65.
[8] Tee AR, Manning BD, Roux PP, Cantley LC, Blenis J. Tuberous sclerosis complex gene products, Tuberin and Hamartin, control mTOR signaling by acting as a GTPase-activating protein complex toward Rheb. Curr Biol. 2003;13(15):1259-68.
[9] Zhang Y, Gao X, Saucedo LJ, Ru B, Edgar BA, Pan D. Rheb is a direct target of the tuberous sclerosis tumour suppressor proteins. Nat Cell Biol. 2003;5(6):578-81.
[10] Potter CJ, Huang H, Xu T. Drosophila Tsc1 functions with Tsc2 to antagonize insulin signaling in regulating cell growth, cell proliferation, and organ size. Cell. 2001;105(3):357-68.
[11] Tapon N, Ito N, Dickson BJ, Treisman JE, Hariharan IK. The Drosophila tuberous sclerosis complex gene homologs restrict cell growth and cell proliferation. Cell. 2001;105(3):345-55.
[12] Gao X, Zhang Y, Arrazola P, Hino O, Kobayashi T, Yeung RS, Ru B, Pan D. Tsc tumour suppressor proteins antagonize amino-acid-TOR signalling. Nat Cell Biol. 2002;4(9):699-704.
[13] Goncharova EA, Goncharov DA, Eszterhas A, Hunter DS, Glassberg MK, Yeung RS, Walker CL, Noonan D, Kwiatkowski DJ, Chou MM, Panettieri RA Jr, Krymskaya VP. Tuberin regulates p70 S6 kinase activation and ribosomal protein S6 phosphorylation. A role for the TSC2 tumor suppressor gene in pulmonary lymphangioleiomyomatosis (LAM). J Biol Chem. 2002;277(34):30958-67.
[14] Inoki K, Li Y, Zhu T, Wu J, Guan KL. TSC2 is phosphorylated and inhibited by Akt and suppresses mTOR signalling. Nat Cell Biol. 2002;4(9):648-57.
[15] Manning BD, Tee AR, Logsdon MN, Blenis J, Cantley LC. Identification of the tuberous sclerosis complex-2 tumor suppressor gene product tuberin as a target of the phosphoinositide 3-kinase/akt pathway. Mol Cell. 2002;10(1):151-62.
[16] Hengstschl?ger M, Rodman DM, Miloloza A, Hengstschl?ger-Ottnad E, Rosner M, Kubista M. Tuberous sclerosis gene products in proliferation control. Mutat Res. 2001;488(3):233-9.
[17] Inoki K, Zhu T, Guan KL. TSC2 mediates cellular energy response to control cell growth and survival. Cell. 2003;115(5):577-90.
[18] Shamji AF, Nghiem P, Schreiber SL. Integration of growth factor and nutrient signaling: implications for cancer biology. Mol Cell. 2003;12(2):271-80.
[19] Barford D. Molecular mechanisms of the protein serine/threonine phosphatases. Trends Biochem Sci. 1996;21(11):407-12.
[20] Tonks NK, Neel BG. From form to function: signaling by protein tyrosine phosphatases. Cell. 1996;87(3):365-8.
[21] Cohen PT. Novel protein serine/threonine phosphatases: variety is the spice of life. Trends Biochem Sci. 1997;22(7):245-51.
[22] Chen MX, McPartlin AE, Brown L, Chen YH, Barker HM, Cohen PT. A novel human protein serine/threonine phosphatase, which possesses four tetratricopeptide repeat motifs and localizes to the nucleus. EMBO J. 1994;13(18):4278-90.
[23] Blatch GL, L?ssle M. The tetratricopeptide repeat: a structural motif mediating protein-protein interactions. Bioessays. 1999;21(11):932-9.
[24] Chen MS, Silverstein AM, Pratt WB, Chinkers M. The tetratricopeptide repeat domain of protein phosphatase 5 mediates binding to glucocorticoid receptor heterocomplexes and acts as a dominant negative mutant. J Biol Chem. 1996;271(50):32315-20.
[25] Morita K, Saitoh M, Tobiume K, Matsuura H, Enomoto S, Nishitoh H, Ichijo H. Negative feedback regulation of ASK1 by protein phosphatase 5 (PP5) in response to oxidative stress. EMBO J. 2001;20(21):6028-36.
[26] Chinkers M. Targeting of a distinctive protein-serine phosphatase to the protein kinase-like domain of the atrial natriuretic peptide receptor. Proc Natl Acad Sci U S A. 1994;91(23):11075-9.
[27] Ollendorff V, Donoghue DJ. The serine/threonine phosphatase PP5 interacts with CDC16 and CDC27, two tetratricopeptide repeat-containing subunits of the anaphase-promoting complex. J Biol Chem. 1997;272(51):32011-8.
[28] Lubert EJ, Hong Y, Sarge KD. Interaction between protein phosphatase 5 and the A subunit of protein phosphatase 2A: evidence for a heterotrimeric form of protein phosphatase 5. J Biol Chem. 2001;276(42):38582-7.
[29] Malanchuk OM, Pozur V, Panasyuk GG, Nemazanyy IO, Filonenko VV, Gout IT, Palchevskyy SS. Identification of novel binding partners for tuberous sclerosis complex 2 (TSC2) by yeast two-hybrid approach. Exp Oncol. 2005;27(3):186-90.
[30] Dan HC, Sun M, Yang L, Feldman RI, Sui XM, Ou CC, Nellist M, Yeung RS, Halley DJ, Nicosia SV, Pledger WJ, Cheng JQ. Phosphatidylinositol 3-kinase/Akt pathway regulates tuberous sclerosis tumor suppressor complex by phosphorylation of tuberin. J Biol Chem. 2002;277(38):35364-70.
[31] Roux PP, Ballif BA, Anjum R, Gygi SP, Blenis J. Tumor-promoting phorbol esters and activated Ras inactivate the tuberous sclerosis tumor suppressor complex via p90 ribosomal S6 kinase. Proc Natl Acad Sci U S A. 2004;101(37):13489-94.
[32] Li Y, Inoki K, Vacratsis P, Guan KL. The p38 and MK2 kinase cascade phosphorylates tuberin, the tuberous sclerosis 2 gene product, and enhances its interaction with 14-3-3. J Biol Chem. 2003;278(16):13663-71.
[33] Corradetti MN, Inoki K, Bardeesy N, DePinho RA, Guan KL. Regulation of the TSC pathway by LKB1: evidence of a molecular link between tuberous sclerosis complex and Peutz-Jeghers syndrome. Genes Dev. 2004;18(13):1533-8.