title: The AE2 anion exchanger is necessary for the structural integrity of the Golgi apparatus in mammalian cells.
abstract: The structural integrity of the Golgi apparatus is known to be dependent on multiple factors, including the organizational status of microtubules, actin and the ankyrin/spectrin-based Golgi membrane skeleton, as well as vesicular trafficking and pH homeostasis. In this respect, our recently identified Golgi-associated anion exchanger, AE2, may also be of importance, since it potentially acts as a Golgi pH regulator and as a novel membrane anchor for the spectrin-based Golgi membrane skeleton. Here, we show that inhibition (>75%) of AE2 expression by antisense oligonucleotides in COS-7 cells results in the fragmentation of the juxtanuclear Golgi apparatus and in structural disorganization of the Golgi stacks, the cisternae becoming generally shorter, distorted, vesiculated and/or swollen. These structural changes occurred without apparent dissociation of the Golgi membrane skeletal protein Ankyrin(195), but were accompanied by the disappearance of the well-focused microtubule-organizing center (MTOC), suggesting the involvement of microtubule reorganization. Similar changes in Golgi structure and assembly of the MTOC were also observed upon transient overexpression of the EGFP-AE2 fusion protein. These data implicate a clear structural role for the AE2 protein in the Golgi and in its cytological positioning around the MTOC.
authors.affiliation: Department of Biochemistry, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland.
authors.forename: Katja
authors.initials: K
authors.lastname: Holappa
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Muñoz
authors.forename: Gustavo
authors.initials: G
authors.lastname: Egea
authors.forename: Sakari
authors.initials: S
authors.lastname: Kellokumpu
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins; D017487:Ankyrins; D017920:Antiporters; D019556:COS Cells; D002522:Chlorocebus aethiops; D006056:Golgi Apparatus / Q000648:ultrastructure*; D007425:Intracellular Membranes / Q000737:chemistry / Q000648:ultrastructure; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D022101:Microtubule-Organizing Center / Q000648:ultrastructure; D008870:Microtubules / Q000648:ultrastructure; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D064606:SLC4A Proteins; D014162:Transfection
chemical_list: D027321:Anion Transport Proteins; D017487:Ankyrins; D017920:Antiporters; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D064606:SLC4A Proteins