RAB7A: THE MASTER REGULATOR OF VESICULAR TRAFFICKING

The membrane flow of eukaryotic cells occurs through vesicles that bud from a donor compartment, move and fuse with an acceptor compartment. Rab (Ras-related in brain), which belong to the Ras superfamily of small GTPases, emerged as a central player of vesicle mobility in both secretory and endocytic pathway, Rab7a being a master regulator of late endocytic trafficking. Elucidation of how mutant or dysregulated Rab7 GTPase and accessory proteins contribute to organ specific and systemic disease remains an area of intensive study and an essential foundation for effective drug targeting. Mutation of Rab7 or associated regulatory proteins causes numerous human genetic diseases. Cancer and neurodegeneration represent examples of acquired human diseases resulting from the up- or down-regulation or aberrant function of Rab7. The broad range of physiologic processes affected by altered Rab7 activity is based on its pivotal roles in membrane trafficking and signaling. The Rab7-regulated processes of cargo sorting, cytoskeletal translocation of vesicles and appropriate docking and fusion with the target membranes control cell metabolism, growth and differentiation. In this review, role of Rab7 in endocytosis is evaluated to illustrate normal function and the consequences of dysregulation resulting in human disease. Selected examples are designed to illustrate how defects in Rab7 activity alter endocytic trafficking that underlie neurologic, lipid storage, and bone disorders as well as cancer. Biomedical Reviews 2014; 25: 67-81.