ABSTRACT
The response to DNA damage, which regulates nuclear processes such as DNA repair, transcription, and cell cycle, has been studied thoroughly. However, the cytoplasmic response to DNA damage is poorly understood. Here, we demonstrate that DNA damage triggers dramatic reorganization of the Golgi, resulting in its dispersal throughout the cytoplasm. We further show that DNA-damage-induced Golgi dispersal requires GOLPH3/MYO18A/F-actin and the DNA damage protein kinase, DNA-PK. In response to DNA damage, DNA-PK phosphorylates GOLPH3, resulting in increased interaction with MYO18A, which applies a tensile force to the Golgi. Interference with the Golgi DNA damage response by depletion of DNA-PK, GOLPH3, or MYO18A reduces survival after DNA damage, whereas overexpression of GOLPH3, as is observed frequently in human cancers, confers resistance to killing by DNA-damaging agents. Identification of the DNA-damage-induced Golgi response reveals an unexpected pathway through DNA-PK, GOLPH3, and MYO18A that regulates cell survival following DNA damage.
Subject(s)
DNA Damage , DNA-Activated Protein Kinase/metabolism , Golgi Apparatus/metabolism , Membrane Proteins/metabolism , Myosins/metabolism , Amino Acid Sequence , Animals , Cell Line , Cell Survival , Cells, Cultured , Humans , Membrane Proteins/chemistry , Mice , Molecular Sequence Data , Phosphorylation , Rats , Sequence AlignmentABSTRACT
Golgi membranes, from yeast to humans, are uniquely enriched in phosphatidylinositol-4-phosphate (PtdIns(4)P), although the role of this lipid remains poorly understood. Using a proteomic lipid-binding screen, we identify the Golgi protein GOLPH3 (also called GPP34, GMx33, MIDAS, or yeast Vps74p) as a PtdIns(4)P-binding protein that depends on PtdIns(4)P for its Golgi localization. We further show that GOLPH3 binds the unconventional myosin MYO18A, thus connecting the Golgi to F-actin. We demonstrate that this linkage is necessary for normal Golgi trafficking and morphology. The evidence suggests that GOLPH3 binds to PtdIns(4)P-rich trans-Golgi membranes and MYO18A conveying a tensile force required for efficient tubule and vesicle formation. Consequently, this tensile force stretches the Golgi into the extended ribbon observed by fluorescence microscopy and the familiar flattened form observed by electron microscopy.
