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Mar 2007 Human molecular genetics

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


Massey-Harroche D, Delgrossi MH, Lane-Guermonprez L, Arsanto JP, Borg JP, Billaud M, Le Bivic A


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.

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