PtdIns4KII? generates endosomal PtdIns(4)P and is required for receptor sorting at early endosomes.

ABSTRACT: Phosphatidylinositol 4-kinase II? (PtdIns4KII?) localizes to the trans-Golgi network and endosomal compartments and has been implicated in the regulation of endosomal traffic, but the roles of both its enzymatic activity and the site of its action have not been elucidated. This study shows that PtdIns4KII? is required for production of endosomal phosphatidylinositol 4-phosphate (PtdIns(4)P) on early endosomes and for the sorting of transferrin and epidermal growth factor receptor into recycling and degradative pathways. Depletion of PtdIns4KII? with small interfering RNA significantly reduced the amount of vesicular PtdIns(4)P on early endosomes but not on Golgi membranes. Cells depleted of PtdIns4KII? had an impaired ability to sort molecules destined for recycling from early endosomes. We further identify the Eps15 homology domain-containing protein 3 (EHD3) as a possible endosomal effector of PtdIns4KII?. Tubular endosomes containing EHD3 were shortened and became more vesicular in PtdIns4KII?-depleted cells. Endosomal PtdIns(4,5)P2 was also significantly reduced in PtdIns4KII?-depleted cells. These results show that PtdIns4KII? regulates receptor sorting at early endosomes through a PtdIns(4)P-dependent pathway and contributes substrate for the synthesis of endosomal PtdIns(4,5)P2.

SUBMITTER: Henmi Y 

PROVIDER: S-EPMC4791142 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature