Coordinated regulation of the late secretory pathway within the Golgi complex

Intracellular transport is fundamental for the proper functions of the cell, as proteins and membranes must be localized properly to perform their function. The Golgi complex has a central role in secretory pathway. Following synthesis in the endoplasmic reticulum (ER), cargo molecules are transported to the Golgi, so that they can be converted to their proper glycosylation form and transported to their final destinations. From the structural perspective, the Golgi is a unique organelle consisting of a series of membrane stacks, as known as cisternae. As such, a longstanding challenge has been to understand how transport of cargoes through the Golgi is accomplished. Cisternal maturation has been thought to explain anterograde transport at the Golgi, but more recently, transport through tubules that connect the stacks has also been suggested. Here, we find that Rho GTPase, Cdc42 increases the anterograde transport by promoting the formation of the Golgi tubular structure. However, retrograde transport at the Golgi using COPI vesicle is regulated not only by Cdc42 but also by key lipids with different geometries. We further found that the polarized transport at the Golgi contributes to tumor invasiveness by promoting the formation of invadopodia. These findings advance the understanding of how cargo transported through the Golgi is accomplished, and also helps to explain how secretory pathway promotes tumor progression.