title: Division of the intermediate compartment at the onset of mitosis provides a mechanism for Golgi inheritance.
abstract: As mammalian cells prepare for mitosis, the Golgi ribbon is first unlinked into its constituent stacks and then transformed into spindle-associated, pleiomorphic membrane clusters in a process that remains enigmatic. Also, it remains unclear whether Golgi inheritance involves the incorporation of Golgi enzymes into a pool of coat protein I (COPI) vesicles, or their COPI-independent transfer to the endoplasmic reticulum (ER). Based on the observation that the intermediate compartment (IC) at the ER-Golgi boundary is connected to the centrosome, we examined its mitotic fate and possible role in Golgi breakdown. The use of multiple imaging techniques and markers revealed that the IC elements persist during the M phase, maintain their compositional and structural properties and remain associated with the mitotic spindle, forming circular arrays at the spindle poles. At G2/M transition, the movement of the pericentrosomal domain of the IC (pcIC) to the cell centre and its expansion coincide with the unlinking of the Golgi ribbon. At prophase, coupled to centrosome separation, the pcIC divides together with recycling endosomes, providing novel landmarks for mitotic entry. We provide evidence that the permanent IC elements function as way stations during the COPI-dependent dispersal of Golgi components at prometa- and metaphase, indicating that they correspond to the previously described Golgi clusters. In addition, they continue to communicate with the vesicular 'Golgi haze' and thus are likely to provide templates for Golgi reassembly. These results implicate the IC in mitotic Golgi inheritance, resulting in a model that integrates key features of the two previously proposed pathways.
authors.affiliation: Department of Biomedicine and Molecular Imaging Center, University of Bergen, Jonas Lies Vei 91, N-5009 Bergen, Norway.
authors.forename: Michaël
authors.initials: M
authors.lastname: Marie
authors.forename: Hege A
authors.initials: HA
authors.lastname: Dale
authors.forename: Nina
authors.initials: N
authors.lastname: Kouprina
authors.forename: Jaakko
authors.initials: J
authors.lastname: Saraste
mesh_terms: D000642:Ammonia-Lyases / Q000378:metabolism; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002451:Cell Compartmentation / Q000187:drug effects; D016000:Cluster Analysis; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D008361:Mannosidases / Q000378:metabolism; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D051381:Rats; D018000:Receptors, Peptide / Q000378:metabolism; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism; D020761:rab1 GTP-Binding Proteins / Q000378:metabolism
chemical_list: C064459:KDEL receptor; D018000:Receptors, Peptide; D020126:Brefeldin A; D008361:Mannosidases; C038829:mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase; D020761:rab1 GTP-Binding Proteins; D000642:Ammonia-Lyases