Mitotic Golgi vesiculation involves mechanisms independent of Ser25 phosphorylation of GM130

During mitosis, the Golgi undergoes two sequential fragmentation steps to break from ribbon to individual stacks, then from stacks to vesicles. While the mechanism that regulates the first step has been studied, it remains obscure how the second vesiculation step is regulated. It has been suggested...

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Published in:Cell cycle (Georgetown, Tex.) Tex.), 2010-08, Vol.9 (15), p.3172-3177
Main Authors: Sundaramoorthy, Sriramkumar, Goh, Justin Bryan Gumagay, Rafee, Shazmina, Murata-Hori, Maki
Format: Article
Language:English
Subjects:
Amino Acid Substitution - genetics
Animals
Autoantigens - metabolism
Binding
Biology
Bioscience
Calcium
Cancer
CDC2 Protein Kinase - metabolism
Cell
Cell Line
Cycle
Golgi Apparatus - metabolism
Green Fluorescent Proteins - metabolism
Landes
Membrane Proteins - metabolism
Mitosis
Organogenesis
Phosphorylation
Phosphoserine - metabolism
Protein Transport
Proteins
Rats
Recombinant Fusion Proteins - metabolism
RNA, Small Interfering - metabolism
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Summary:During mitosis, the Golgi undergoes two sequential fragmentation steps to break from ribbon to individual stacks, then from stacks to vesicles. While the mechanism that regulates the first step has been studied, it remains obscure how the second vesiculation step is regulated. It has been suggested that Cdk1-dependent phosphorylation of the cis-Golgi matrix protein GM130 regulates the second step. Here we have tested if phorphorylation of GM130 by Cdk1 is required for Golgi vesiculation and mitotic progression. Inhibition of Cdk1 caused a failure of Golgi vesiculation and defects in chromosome congression/segregation. Expression of non-phosphorylatable mutant of GM130 (GM130S25A) in cells depleted of endogenous GM130 caused no apparent defects in Golgi vesiculation and mitotic progression. Similarly, no apparent defects in Golgi vesiculation and mitotic progression were observed when GM130S25A was expressed in GM130-deficient CHO cells. Our observations suggest that while Cdk1 based phosphorylation is essential for mitotic Golgi vesiculation, mammalian cells could possess redundant, S25 phosphorylation of GM130 independent pathways that ensure Golgi vesiculation and mitotic progression.
ISSN:1538-4101
1551-4005
DOI:10.4161/cc.9.15.12522