title: Coupling factor 6 attenuates CXCR4 expression through the HIF-1α and c-Src pathways and promotes endothelial apoptosis and inflammation.
abstract: Vascular endothelial cells are exposed to an acidic pH, and CXC chemokine receptor type 4 (CXCR4) is a key protective molecule against acidosis. We investigated the effect of coupling factor 6 (CF6), a novel proton import activator, on CXCR4 signaling and its molecular mechanism. CF6 decreased CXCR4 expression in human umbilical vein endothelial cells (HUVECs) in a time- and dose-dependent manner. Pretreatment with small interfering RNA (siRNA) for hypoxia-inducible factor (HIF)-1α or PP1, a specific c-Src inhibitor, attenuated the CF6-induced decrease in CXCR4 without affecting CF6-induced intracellular acidosis. Chromatin immunoprecipitation revealed that CF6 enhanced the interaction between HIF-1α and the CXCR4 promoter at the hypoxia response element. CF6 also enhanced protein-protein interactions between phospho-c-Src and histone deacetylase 3 (HDAC3), but did not affect the binding of HDAC3 to the CXCR4 promoter at the hypoxia response element. Apoptotic cells, as measured by an Annexin-V-FITC Propidium Iodide Kit, were increased by CF6 in normoxia and hypoxia at 24 h; however, this increase was abolished by pretreatment with either siRNA for HIF-1α or the CXCR4 ligand. The coronary arteries and perivascular tissues obtained from CF6-overexpressing transgenic mice showed a lower expression of CXCR4 in the heart, increased wall thickness and infiltration of CD16-positive, CD206-positive or apoptotic cells. CF6 decreases CXCR4 expression through both HIF-1α- and c-Src-mediated mechanisms in vascular endothelial cells. Because CXCR4 has an important role in survival function, CF6 may have a role in the progression of arteriosclerosis via these complex mechanisms.
authors.affiliation: Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: 1] Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan [2] Department of Hypertension Stroke Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Osanai
authors.affiliation: 1] Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan [2] Department of Hypertension Stroke Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tomita
authors.affiliation: Asubio Pharma, Faculty of Discovery and Biotechnology II, Chuo-ku, Kobe, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Magota
authors.affiliation: 1] Department of Cardiology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan [2] Department of Hypertension Stroke Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D042783:Endothelial Cells / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects*; D016391:Genes, src / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000494:pharmacology*; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology*; D051379:Mice; D008822:Mice, Transgenic; D025261:Mitochondrial Proton-Translocating ATPases / Q000494:pharmacology*; D010086:Oxidative Phosphorylation Coupling Factors / Q000494:pharmacology*; D019718:Receptors, CXCR4 / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010086:Oxidative Phosphorylation Coupling Factors; D019718:Receptors, CXCR4; C000628217:F(6) ATPase; D025261:Mitochondrial Proton-Translocating ATPases