title: Characterization of carbonic anhydrase IX interactome reveals proteins assisting its nuclear localization in hypoxic cells.
abstract: Carbonic anhydrase IX (CA IX) is a transmembrane protein affecting pH regulation, cell migration/invasion, and survival in hypoxic tumors. Although the pathways related to CA IX have begun to emerge, molecular partners mediating its functions remain largely unknown. Here we characterize the CA IX interactome in hypoxic HEK-293 cells. Most of the identified CA IX-binding partners contain the HEAT/ARM repeat domain and belong to the nuclear transport machinery. We show that the interaction with two of these proteins, namely XPO1 exportin and TNPO1 importin, occurs via the C-terminal region of CA IX and increases with protein phosphorylation. We also demonstrate that nuclear CA IX is enriched in hypoxic cells and is present in renal cell carcinoma tissues. These data place CA IX among the cell-surface signal transducers undergoing nuclear translocation. Accordingly, CA IX interactome involves also CAND1, which participates in both gene transcription and assembly of SCF ubiquitin ligase complexes. It is noteworthy that down-regulation of CAND1 leads to decreased CA IX protein levels apparently via affecting its stability. Our findings provide the first evidence that CA IX interacts with proteins involved in nuclear/cytoplasmic transport, gene transcription, and protein stability, and suggest the existence of nuclear CA IX protein subpopulations with a potential intracellular function, distinct from the crucial CA IX role at the cell surface.
authors.affiliation: CEINGE Biotecnologie Avanzate SCaRL, Naples, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Buanne
authors.forename: Giovanni
authors.initials: G
authors.lastname: Renzone
authors.forename: Francesca
authors.initials: F
authors.lastname: Monteleone
authors.forename: Monica
authors.initials: M
authors.lastname: Vitale
authors.forename: Simona Maria
authors.initials: SM
authors.lastname: Monti
authors.forename: AnnaMaria
authors.initials: A
authors.lastname: Sandomenico
authors.forename: Corrado
authors.initials: C
authors.lastname: Garbi
authors.forename: Donatella
authors.initials: D
authors.lastname: Montanaro
authors.forename: Marina
authors.initials: M
authors.lastname: Accardo
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Troncone
authors.forename: Miriam
authors.initials: M
authors.lastname: Zatovicova
authors.forename: Lucia
authors.initials: L
authors.lastname: Csaderova
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
authors.forename: Silvia
authors.initials: S
authors.lastname: Pastorekova
authors.forename: Andrea
authors.initials: A
authors.lastname: Scaloni
authors.forename: Giuseppina
authors.initials: G
authors.lastname: De Simone
authors.forename: Nicola
authors.initials: N
authors.lastname: Zambrano
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015687:Cell Hypoxia; D057809:HEK293 Cells; D006801:Humans; D010766:Phosphorylation; D060066:Protein Interaction Maps; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; C486317:CAND1 protein, human; D011506:Proteins; D014157:Transcription Factors; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases