Structural Organization and Function of the Golgi Ribbon During Cell Division

Abstract

The Golgi complex has a central role in the secretory traffic. In vertebrate cells it is generally organized in polarized stacks of cisternae that are laterally connected by membranous tubules, forming a structure known as Golgi ribbon. The steady state ribbon arrangement results from a dynamic equilibrium between formation and cleavage of the membrane tubules connecting the stacks. This balance is of great physiological relevance as the unlinking of the ribbon during G2 is required for mitotic entry. A block of this process induces a potent G2 arrest of the cell cycle, indicating that a mitotic "Golgi checkpoint" controls the correct pre-mitotic segregation of the Golgi ribbon. Then, after mitosis onset, the Golgi stacks undergo an extensive disassembly, which is necessary for proper spindle formation. Notably, several Golgi-associated proteins acquire new roles in spindle formation and mitotic progression during mitosis. Here we summarize the current knowledge about the basic principle of the Golgi architecture and its functional relationship with cell division to highlight crucial aspects that need to be addressed to help us understand the physiological significance of the ribbon and the pathological implications of alterations of this organization.

Keywords: Golgi ribbon; cancer; checkpoint; mitosis; spindle.

FIGURE 1

Schematic description of GC disassembly during G2 and functional connections with mitosis. During G2, the GC is unlinked into stacks, leading to the activation of a Src/Aurora-A signaling axis that drives centrosome maturation and entry into mitosis. After mitosis onset, the Golgi stacks are disassembled into dispersed vesicles and clusters. Golgi-associated proteins, including GM130 and p115, are repurposed to form a bipolar, symmetric and correctly oriented spindle that mediates the inheritance of proteins necessary for GC ribbon reformation at mitotic exit.