RESEARCH

Our long-term goal is to understand the mechanisms that regulate the mitotic division of the Golgi in mammalian cells. As cells grow and divide, vital cellular structures including genetic material and cellular organelles need to be duplicated and partitioned between the two daughter cells. Accurate partitioning is crucial to sustain proper cellular functions since defects in mitosis can lead to loss of vital cellular structures. While the mechanism of chromosome segregation has been extensively studied, little is known about the inheritance of membrane-bound organelles. Given that the Golgi is an essential cellular organelle that cannot be generated de novo, a template must be inherited during mitosis to sustain cellular function over generations. To achieve faithful partitioning, the single copy of the Golgi ribbon is disassembled into vesicles in early mitosis, which upon cell division fuse to reform a functional Golgi in both daughter cells.

Since the Golgi is in constant exchange with the endoplasmic reticulum (ER) in interphase, it was thought that the Golgi is merged and partitioned together with the ER in mitosis, a process resembling the inheritance of the nuclear envelope. However, we established that the Golgi is partitioned by an entirely different mechanism. We showed that Golgi membranes stay separated from the ER, which prevents unregulated activation of the signaling pathways involved in lipid metabolism and stress response. We further demonstrated that, instead of the ER, the spindle apparatus plays a critical role in inheriting an intact Golgi ribbon. In addition, our recent studies on the Golgi structural protein GRASP65 explored a regulatory framework that integrates organelle maintenance, protein trafficking and cell polarization.