The Golgi mitotic checkpoint is controlled by BARS-dependent fission of the Golgi ribbon into separate stacks in G2.
The Golgi ribbon is a complex structure of many stacks interconnected by tubules that undergo fragmentation during mitosis through a multistage process that allows correct Golgi inheritance. The fissioning protein CtBP1-S/BARS (BARS) is essential for this, and is itself required for mitotic entry: a block in Golgi fragmentation results in cell-cycle arrest in G2, defining the 'Golgi mitotic checkpoint'. Here, we clarify the precise stage of Golgi fragmentation required for mitotic entry and the role of BARS in this process. Thus, during G2, the Golgi ribbon is converted into isolated stacks by fission of interstack connecting tubules. This requires BARS and is sufficient for G2/M transition. Cells without a Golgi ribbon are independent of BARS for Golgi fragmentation and mitotic entrance. Remarkably, fibroblasts from BARS-knockout embryos have their Golgi complex divided into isolated stacks at all cell-cycle stages, bypassing the need for BARS for Golgi fragmentation. This identifies the precise stage of Golgi fragmentation and the role of BARS in the Golgi mitotic checkpoint, setting the stage for molecular analysis of this process.
Colanzi
Antonino
A
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy. colanzi@negrisud.it
Hidalgo Carcedo
Cristina
C
Persico
Angela
A
Cericola
Claudia
C
Turacchio
Gabriele
G
Bonazzi
Matteo
M
Luini
Alberto
A
Corda
Daniela
D
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D016195:G2 Phase; D006056:Golgi Apparatus / Q000502:physiology* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis
D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein