Evidence for a molecular link between the tuberous sclerosis complex and the Crumbs complex

Hum Mol Genet. 2007 Mar 1;16(5):529-36. doi: 10.1093/hmg/ddl485. Epub 2007 Jan 18.

Abstract

In human, mutations in tuberous sclerosis complex protein 1 or 2 (TSC1/2 or hamartin/tuberin) cause tuberous sclerosis characterized by the occurrence of multiple hamartomas. On the other hand, mutations in the Crumbs homolog-1 (CRB1) gene cause retinal degeneration diseases including Leber congenital amaurosis and retinitis pigmentosa type 12. Here we report, using a two-hybrid assay, a direct molecular interaction between TSC2 C-terminal part and PDZ 2 and 3 of PATJ, a scaffold member of the Crumbs 3 (CRB 3) complex in human intestinal epithelial cells, Caco2. TSC2 interacts not only with PATJ, but also with the whole CRB 3 complex by GST-pull down assays. In addition, TSC2 co-immunoprecipitates and co-localizes partially with PATJ at the level of the tight junctions. Furthermore, depletion of PATJ from Caco2 cells induces an increase in mammalian Target Of Rapamycin Complex 1 (mTORC1) activity, which is totally inhibited by rapamycin. In contrast, in the same cells, inhibition of phosphoinositol-3 kinase (PI-3K) by wortmannin does not abolish rpS6 phosphorylation. These functional data indicate that the Crumbs complex is a potential regulator of the mTORC1 pathway, cell metabolism and survival through a direct interaction with TSC1/2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Caco-2 Cells
  • Chlorocebus aethiops
  • Humans
  • Membrane Glycoproteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism
  • Models, Biological
  • Protein Binding
  • Protein Kinases / genetics
  • Signal Transduction
  • TOR Serine-Threonine Kinases
  • Tight Junction Proteins
  • Tight Junctions / metabolism
  • Transcription Factors / metabolism
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins / chemistry
  • Tumor Suppressor Proteins / metabolism*
  • Up-Regulation / genetics

Substances

  • CRB3 protein, human
  • Membrane Glycoproteins
  • Membrane Proteins
  • PATJ protein, human
  • TSC2 protein, human
  • Tight Junction Proteins
  • Transcription Factors
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases