Ning Liang 1 , 2 , 3 , Chi Zhang 1 , 2 , 3 , Patricia Dill 1 , 2 , 3 , 4 , Ganna Panasyuk 1 , 2 , 3 , Delphine Pion 1 , 2 , 3 , Vonda Koka 1 , 2 , 3 , Morgan Gallazzini 1 , 2 , 3 , Eric N. Olson 5 , Hilaire Lam 6 , Elizabeth P. Henske 6 , Zheng Dong 7 , Udayan Apte 8 , Nicolas Pallet 9 , 10 , Randy L. Johnson 11 , Fabiola Terzi 1 , 2 , 3 , David J. Kwiatkowski 12 , Jean-Yves Scoazec 13 , Guido Martignoni 14 , 15 , Mario Pende , 1 , 2 , 3
20 October 2014
Liang et al. find that the tumor suppressors TSC1 and TSC2, defects in which underlie the genetic disease Tuberous Sclerosis Complex (TSC), drive the mTOR-dependent autophagosomal destruction of the transcriptional activator YAP. Blocking YAP inhibited the abnormal proliferation of TSC1/2-deficient human cells and reversed TSC-like disease symptoms in mosaic Tsc1 mutant mice.
Genetic studies have shown that the tuberous sclerosis complex (TSC) 1–TSC2–mammalian target of Rapamycin (mTOR) and the Hippo–Yes-associated protein 1 (YAP) pathways are master regulators of organ size, which are often involved in tumorigenesis. The crosstalk between these signal transduction pathways in coordinating environmental cues, such as nutritional status and mechanical constraints, is crucial for tissue growth. Whether and how mTOR regulates YAP remains elusive. Here we describe a novel mouse model of TSC which develops renal mesenchymal lesions recapitulating human perivascular epithelioid cell tumors (PEComas) from patients with TSC. We identify that YAP is up-regulated by mTOR in mouse and human PEComas. YAP inhibition blunts abnormal proliferation and induces apoptosis of TSC1–TSC2-deficient cells, both in culture and in mosaic Tsc1 mutant mice. We further delineate that YAP accumulation in TSC1/TSC2-deficient cells is due to impaired degradation of the protein by the autophagosome/lysosome system. Thus, the regulation of YAP by mTOR and autophagy is a novel mechanism of growth control, matching YAP activity with nutrient availability under growth-permissive conditions. YAP may serve as a potential therapeutic target for TSC and other diseases with dysregulated mTOR activity.