Endosomal recycling tubule scission and integrin recycling involve the membrane curvature-supporting protein LITAF

Abstract

Recycling to the cell surface requires the scission of tubular membrane intermediates emanating from endosomes. Here we identify the monotopic membrane protein LITAF (LPS-Induced TNF Activating Factor) and the related CDIP1 (Cell Death Involved p53 target 1) as novel membrane curvature proteins that contribute to recycling tubule scission. Recombinant LITAF supports high membrane curvature, shown by its ability to reduce proteoliposome size. The membrane domains of LITAF and CDIP1 partition strongly into ∼50 nm diameter tubules labelled with the recycling markers Pacsin2, ARF6 and SNX1, and the recycling cargoes MHC Class I and CD59. Partitioning of LITAF into tubules is impaired by mutations linked to Charcot Marie Tooth disease type 1C. Meanwhile, depletion of LITAF and CDIP1 results in the expansion of tubular recycling compartments and stabilised Rab11 tubules, pointing to a function for LITAF/CDIP1 in membrane scission. Consistent with this, depletion of LITAF and CDIP1 impairs integrin recycling and cell migration.