RESUMO
Tumor suppressor p53 (TP53) is frequently mutated in cancer, often resulting not only in loss of its tumor-suppressive function but also acquisition of dominant-negative and even oncogenic gain-of-function traits. While wild-type p53 levels are tightly regulated, mutants are typically stabilized in tumors, which is crucial for their oncogenic properties. Here, we systematically profiled the factors that regulate protein stability of wild-type and mutant p53 using marker-based genome-wide CRISPR screens. Most regulators of wild-type p53 also regulate p53 mutants, except for p53 R337H regulators, which are largely private to this mutant. Mechanistically, FBXO42 emerged as a positive regulator for a subset of p53 mutants, working with CCDC6 to control USP28-mediated mutant p53 stabilization. Additionally, C16orf72/HAPSTR1 negatively regulates both wild-type p53 and all tested mutants. C16orf72/HAPSTR1 is commonly amplified in breast cancer, and its overexpression reduces p53 levels in mouse mammary epithelium leading to accelerated breast cancer. This study offers a network perspective on p53 stability regulation, potentially guiding strategies to reinforce wild-type p53 or target mutant p53 in cancer.
Assuntos
Mutação , Estabilidade Proteica , Proteína Supressora de Tumor p53 , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Animais , Humanos , Camundongos , Feminino , Sistemas CRISPR-Cas , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Ubiquitina Tiolesterase/genética , Ubiquitina Tiolesterase/metabolismo , Regulação Neoplásica da Expressão Gênica , Repetições Palindrômicas Curtas Agrupadas e Regularmente EspaçadasRESUMO
The Hippo pathway is a conserved and critical regulator of tissue growth. The FERM protein Expanded is a key signaling hub that promotes activation of the Hippo pathway, thereby inhibiting the transcriptional co-activator Yorkie. Previous work identified the polarity determinant Crumbs as a primary regulator of Expanded. Here, we show that the giant cadherin Fat also regulates Expanded directly and independently of Crumbs. We show that direct binding between Expanded and a highly conserved region of the Fat cytoplasmic domain recruits Expanded to the apicolateral junctional zone and stabilizes Expanded. In vivo deletion of Expanded binding regions in Fat causes loss of apical Expanded and promotes tissue overgrowth. Unexpectedly, we find Fat can bind its ligand Dachsous via interactions of their cytoplasmic domains, in addition to the known extracellular interactions. Importantly, Expanded is stabilized by Fat independently of Dachsous binding. These data provide new mechanistic insights into how Fat regulates Expanded, and how Hippo signaling is regulated during organ growth.