Evidence for a molecular link between the tuberous sclerosis complex and the Crumbs complex.
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.
Massey-Harroche
Dominique
D
IDBML, CNRS UMR6216, Case 907, Faculté des Sciences de Luminy, 13288 Marseille cedex 09, France.
Delgrossi
Marie-Hélène
MH
Lane-Guermonprez
Lydie
L
Arsanto
Jean-Pierre
JP
Borg
Jean-Paul
JP
Billaud
Marc
M
Le Bivic
André
A
D000818:Animals; D019556:COS Cells; D018938:Caco-2 Cells; D002522:Chlorocebus aethiops; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D062725:Tight Junction Proteins; D019108:Tight Junctions / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics
C472002:CRB3 protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C107903:PATJ protein, human; C000624653:TSC2 protein, human; D062725:Tight Junction Proteins; D014157:Transcription Factors; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases