Somatic and germline gain-of-function point mutations in RAF, one of the first oncogenes to be discovered in humans, delineate a group of tumor-prone syndromes known as the RASopathies. In this study, we document the first human phenotype resulting from the germline loss-of-function of the proto-oncogene RAF1 (a.k.a. CRAF). In a consanguineous family, we uncovered a homozygous p.Thr543Met variant segregating with a neonatal lethal syndrome with cutaneous, craniofacial, cardiac, and limb anomalies. Structure-based prediction and functional tests using human knock-in cells showed that threonine 543 is essential to: (i) ensure RAF1's stability and phosphorylation, (ii) maintain its kinase activity toward substrates of the MAPK pathway, and (iii) protect from stress-induced apoptosis mediated by ASK1. In Xenopus embryos, mutant RAF1T543M failed to phenocopy the effects of normal and overactive FGF/MAPK signaling, confirming its hypomorphic activity. Collectively, our data disclose the genetic and molecular etiology of a novel lethal syndrome with progeroid features, highlighting the importance of RTK signaling for human development and homeostasis.
Bibliographical noteKAUST Repository Item: Exported on 2023-05-05
Acknowledgements: We are grateful to all the individuals and the family for their participation in this research. We are grateful to all members of the Reversade laboratory for support and constructive feedback. BR holds the inaugural A*STAR Investigatorship from the Agency for Science, Technology and Research in Singapore, and is a fellow of the Branco Weiss Foundation and a National Research Foundation and EMBO Young Investigator. This work was also supported by an inaugural Use-Inspired Basic Research (UIBR) central fund from the Genome Institute of Singapore and core funding from the BESE and the Smart-Health Initiative (KAUST, Saudi Arabia). NEB gratefully acknowledges Koç University Research Center for Translational Medicine (KUTTAM), funded by the Republic of Turkey Ministry of Development. NEB is funded by a 2232 International Fellowship for Outstanding Researchers Program of Scientific and Technological Research Council of Turkey (TÜBİTAK) (Project No: 118C318).
ASJC Scopus subject areas
- Molecular Medicine