COMMD5/HCaRG Hooks Endosomes on Cytoskeleton and Coordinates EGFR Trafficking

Abstract

Summary: COMMD5/HCaRG is involved in tissue repair, and its low expression is associated with tumorigenicity. Cell growth, migration, and differentiation are controlled by COMMD5. We previously reported that COMMD5 inhibited the growth of renal carcinoma cells by regulating expression or phosphorylation of ErbB members. Here, we demonstrate that COMMD5 is crucial for the stability of the cytoskeleton. Its silencing leads to a major re-organization of actin and microtubule networks. The N terminus of COMMD5 binds to the endosomal Rab5, and its C terminus, including the COMMD domain, binds to the cytoskeletal scaffolding. COMMD5 participates in long-range endosome transport, including epidermal growth factor receptor (EGFR) recycling, and provides the strength to deform and assist the scission of vesicles into sorting endosomes. This study establishes the molecular mechanism by which COMMD5 acts as an adaptor protein to coordinate endosomal trafficking and reveals its important role for EGFR transport and activity. : COMMD5/HCaRG is involved in endocytic trafficking. Campion et al. describe the link between COMMD5, the cytoskeletal proteins actin and tubulin, and Rab5-associated endosomes in epithelial cells. COMMD5 directly interacts with actin and tubulin at one end and Rab5 at the other end to drive membrane proteins across endosomal compartments and thereby regulate EGFR trafficking and activation and directional cell migration. Keywords: COMMD5/HCaRG, endosome trafficking, early and recycling endosomes, Rab, receptor trafficking, EGFR, tubulin, microtubule, actin, migration