The role for the EMC complex in RAS oncogene-driven tumor progression

• Grant number: 21/08652-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): November 01, 2021
• Effective date (End): October 31, 2022
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Enilza Maria Espreafico
• Grantee: Gustavo Manoel Brandão
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Twelve years ago, genetic and biochemical interaction studies revealed an abundant and evolutionarily conserved protein complex that resides in the endoplasmic reticulum membrane (ER) and was named ER membrane protein complex (EMC). More recent studies suggest a role for EMC during membrane protein biogenesis. Biochemical reconstitution experiments show that EMC can directly mediate the insertion of transmembrane protein domains (TMDs) into the lipid bilayer and translocate tail-anchored (TA) proteins to the ER membrane. Furthermore, together with sec61, EMCs are essential in the translocation of nascent and newly synthesized polypeptide precursors of many membrane proteins, including G-protein coupled receptors. RAS proteins do not have TMD domains and are not Sec61 clients. However, the enzymes responsible for post-translational modifications of RAS are multipass transmembrane proteins of the ER. After undergoing a series of post-translational modifications on the ER, RAS molecules are transported by vesicular trafficking to the plasma membrane. Thus, our group postulated that the EMC complex may play a role in the process of post-translational modifications of RAS. Consistent with this hypothesis, data obtained in our laboratory showed that EMC is required for the localization of the chimeric oncoprotein GFP-HRASV12 to the plasma membrane and the underlying biochemical mechanisms are being addressed in a project currently supported by FAPESP. However, if EMC function is required for other RAS paralogs, since three genes in the human genome encode RAS (HRAS, KRAS, and NRAS), and if it is equally required for the mutant and wild-type forms remains unanswered. This project aims to investigate this question by determining the requirement of EMCs for the normal subcellular distribution and function of the NRAS paralog, both mutant and wild-type forms, in the context of cancer-derived cell lines. For this proposal, we will use an NRASQ61L mutant melanoma cell line and BRAFV600E mutant cell lines. Given that up to 30% of the human cancers are driven by RAS mutation and there is an increasing optimism for new inhibitors of RAS, we understand that this project has potential to provide relevant contributions.(AU)