Abstract
In mammalian cells, the Golgi complex is structured in the form of a continuous membranous system composed of stacks connected by tubular bridges: the “Golgi ribbon.” At the onset of mitosis, the Golgi complex undergoes a multi-step fragmentation process that is required for its correct partition into the dividing cells. Importantly, inhibition of Golgi disassembly results in cell-cycle arrest at the G2 stage, which indicates that accurate inheritance of the Golgi complex is monitored by a “Golgi mitotic checkpoint.” Moreover, mitotic Golgi disassembly correlates with the release of a set of Golgi-localized proteins that acquire specific functions during mitosis, such as mitotic spindle formation and regulation of the spindle checkpoint. Most of these events are regulated by small GTPases of the Arf and Rab families. Here, we review recent studies that are revealing the fundamental mechanisms, the molecular players, and the biological significance of mitotic inheritance of the Golgi complex in mammalian cells. We also briefly comment on how Golgi partitioning is coordinated with mitotic progression.
Highlights
The Golgi complex is the central organelle in the secretory pathway, and it mediates the modification, sorting and transport of proteins and lipids (De Matteis and Luini, 2008)
It consists of flat cisternae that are grouped into several stacks that are themselves laterally interconnected by tubular membrane “bridges” to form the “Golgi ribbon” (Sütterlin and Colanzi, 2010)
ERK2 is a downstream target of mitogen-activated protein (MAP) kinase kinase 1 (MEK1) and it phosphorylates GRASP55, which has been shown to be required for Golgi ribbon unlinking and mitotic progression (Duran et al, 2008; Feinstein and Linstedt, 2008; Xiang and Wang, 2010)
Summary
The Golgi complex is the central organelle in the secretory pathway, and it mediates the modification, sorting and transport of proteins and lipids (De Matteis and Luini, 2008). This novel cell-cycle checkpoint is not mediated by activation of the DNA-damage checkpoint; instead, it has been postulated to sense the integrity of the Golgi complex (Sütterlin et al, 2002; Hidalgo Carcedo et al, 2004) These studies have revealed that Golgi partitioning is an essential and required event for cell entry into mitosis. Why the Golgi ribbon is organized into stacks of cisternae in interphase remains an important unresolved issue It is questionable whether cisterna stacking is required for Mitotic segregation of the Golgi complex involves progressive and reversible disassembly of the Golgi ribbon into dispersed fragments (Figure 1), to allow correct partitioning of the Golgi membranes between daughter cells (Shorter and Warren, 2002; Colanzi et al, 2003; Altan-Bonnet et al, 2004). These two assays have provided a highly manipulable approach, within which the sequence of morphological events can be precisely followed by electron microscopy or biochemical analysis
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