title: The role of Rab6a and phosphorylation of non-muscle myosin IIA tailpiece in alcohol-induced Golgi disorganization.
abstract: Abnormalities in the Golgi apparatus function are important to the development of alcoholic liver injury. We recently reported that Golgi disorganization in ethanol (EtOH)-treated hepatocytes is caused by impaired dimerization of the largest Golgi matrix protein, giantin. However, little is known about the mechanism which forces fragmentation. Here, in both HepG2 cells overexpressing alcohol dehydrogenase and in rat hepatocytes, we found that EtOH administration reduces the complex between giantin and Rab6a GTPase and results in the S1943 phosphorylation of non-muscle Myosin IIA (NMIIA) heavy chain, thus facilitating NMIIA association with Golgi enzymes, as detected by biochemical approaches and 3D Structured Illumination Microscopy. We revealed that NMIIA-P-S1943 competes with giantin for the Rab6a dimer, which was converted to monomer after Golgi fragmentation. Therefore, Rab6a plays a dual role in the Golgi, serving as master regulator of Golgi organization and disorganization, and that NMIIA and giantin engage in a "tug-of-war". However, the inhibition of F-actin and downregulation of NMIIA or overexpression of NMHC-IIAΔtailpiece, as well the overexpression of dominant negative Rab6a(T27N), preserved a compact Golgi phenotype. Thus, the actomyosin complex forces EtOH-induced Golgi disorganization, and the targeting of NMIIA-P-S1943 may be important for preventing the damaging effects of alcohol metabolism on the cell.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, the Fred and Pamela Buffett Cancer Center, 985870 Nebraska Medical Center, Omaha, NE 68198-5870, USA.
authors.forename: Armen
authors.initials: A
authors.lastname: Petrosyan
authors.affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA.|Nebraska Western Iowa Health Care System, VA Service, Department of Research Service, Omaha, NE, USA.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Casey
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, the Fred and Pamela Buffett Cancer Center, 985870 Nebraska Medical Center, Omaha, NE 68198-5870, USA.|Nebraska Western Iowa Health Care System, VA Service, Department of Research Service, Omaha, NE, USA.
authors.forename: Pi-Wan
authors.initials: PW
authors.lastname: Cheng
mesh_terms: D000426:Alcohol Dehydrogenase / Q000378:metabolism; D000818:Animals; D018929:Cell Culture Techniques; D000431:Ethanol / Q000494:pharmacology*; D006056:Golgi Apparatus / Q000187:drug effects* / Q000201:enzymology; D000077614:Golgi Matrix Proteins / Q000378:metabolism; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008297:Male; D024507:Nonmuscle Myosin Type IIA / Q000378:metabolism*; D010766:Phosphorylation; D017208:Rats, Wistar; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000077614:Golgi Matrix Proteins; C094135:Rab6 protein; C087574:macrogolgin; D000431:Ethanol; D000426:Alcohol Dehydrogenase; D024507:Nonmuscle Myosin Type IIA; D020691:rab GTP-Binding Proteins