Inositol polyphosphate 5-phosphatase OCRL (OCRL)

Inositol polyphosphate 5-phosphatase OCRL (OCRL) is a phosphoinositide metabolizing enzyme primarily located in endolysosomal compartments and early endocytic sites, where it hydrolyzes phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂) and, to a lesser extent, phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P₃)[4][3]. OCRL is essential for maintaining phosphoinositide balance critical for membrane trafficking, endocytosis, lysosomal dynamics, and cytoskeletal organization[1][3][4][5]. Mutations in the OCRL gene lead to X-linked disorders: Lowe syndrome, characterized by congenital cataracts, neurological impairment, and renal Fanconi syndrome, and Dent disease 2, a milder renal disorder[1][2][4][6]. Loss of OCRL function results in abnormal accumulation of PI(4,5)P₂, impaired trafficking and recycling of receptors (including megalin/LRP2) in proximal tubule cells, and lysosomal dysfunction[1][3][4][5]. OCRL interacts with endocytic machinery such as clathrin and SNX9 and plays a specialized role in receptor-mediated endocytosis and the regulation of actin polymerization on endosomes[3][5]. Deficiency of OCRL protein cannot be compensated in humans, leading to progressive multisystemic disease manifestations[1][4]. Direct pharmacological targeting of OCRL is not available, and clinical management is supportive[4].

Other names

Inositol polyphosphate 5-phosphatase OCRL-1Lowe oculocerebrorenal syndrome proteinDent disease 2 proteinDent-2 proteinDENT2phosphatidylinositol 3,4,5-trisphosphate 5-phosphataseOCRL1OCRL-1INPP5FLOCRNPHL2oculocerebrorenal syndrome of Lowe protein