JNK2 controls fragmentation of the Golgi complex and the G2/M transition through phosphorylation of GRASP65

• Published in: Journal of cell science Vol. 128; no. 12; pp. 2249 - 2260
• Main Authors: Cervigni, Romina Ines, Bonavita, Raffaella, Barretta, Maria Luisa, Spano, Daniela, Ayala, Inmaculada, Nakamura, Nobuhiro, Corda, Daniela, Colanzi, Antonino
• Format: Journal Article
• Language: English
• Published: England 15.06.2015
• Subjects: Animals; Blotting, Western; Cell Division - physiology; Cell Proliferation; Cells, Cultured; Flow Cytometry; G2 Phase - physiology; Golgi Apparatus - metabolism; Golgi Apparatus - pathology; Golgi Matrix Proteins; HeLa Cells; Humans; Kidney - cytology; Kidney - metabolism; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microscopy, Fluorescence; Mitogen-Activated Protein Kinase 9 - metabolism; Mitosis - physiology; Phosphorylation; Rats; RNA, Small Interfering - genetics; GRASP65; Golgi complex; JNK; Cell cycle
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.164871

In mammalian cells, the Golgi complex is composed of stacks that are connected by membranous tubules. During G2, the Golgi complex is disassembled into isolated stacks. This process is required for entry into mitosis, indicating that the correct inheritance of the organelle is monitored by a 'Golgi mitotic checkpoint'. However, the regulation and the molecular mechanisms underlying this Golgi disassembly are still poorly understood. Here, we show that JNK2 has a crucial role in the G2-specific separation of the Golgi stacks through phosphorylation of Ser277 of the Golgi-stacking protein GRASP65 (also known as GORASP1). Inhibition of JNK2 by RNA interference or by treatment with three unrelated JNK inhibitors causes a potent and persistent cell cycle block in G2. JNK activity becomes dispensable for mitotic entry if the Golgi complex is disassembled by brefeldin A treatment or by GRASP65 depletion. Finally, measurement of the Golgi fluorescence recovery after photobleaching demonstrates that JNK is required for the cleavage of the tubules connecting Golgi stacks. Our findings reveal that a JNK2-GRASP65 signalling axis has a crucial role in coupling Golgi inheritance and G2/M transition.