TRIM62 facilitates influenza A virus entry by regulating WASH-dependent endosomal trafficking.

Endocytosis enables efficient cargo uptake while restricting uncontrolled cellular entry, yet how this balance is enforced during endocytic uptake remains poorly understood. Using influenza A virus (IAV) as a model cargo, we reveal a previously unrecognized role for the pentameric WASH complex (WASH) as a regulatory hub that integrates both permissive and inhibitory functions to control viral endocytosis. While the WASH subunits WASH1, CCDC53, SWIP, and Strumpellin collectively promote IAV entry, the FAM21 subunit acts antagonistically. Our data suggest that FAM21-mediated association of WASH with the retromer subunit VPS35 restrains the pro-endocytic activity of WASH, thereby limiting viral uptake. This inhibitory FAM21-VPS35 axis is counteracted by the E3 ubiquitin ligase TRIM62, which maintains WASH in a retromer-free, endocytically competent state that facilitates viral internalization. Beyond IAV, the WASH1 subunit and VPS35 also exhibit opposing roles during cholera toxin B uptake, suggesting a broader function in lipid raft-mediated endocytosis. Together, our findings establish WASH as a key determinant of IAV endocytosis, with TRIM62 modulating retromer-mediated restriction to facilitate productive viral entry.