title: Kelch-like 20 up-regulates the expression of hypoxia-inducible factor-2α through hypoxia- and von Hippel-Lindau tumor suppressor protein-independent regulatory mechanisms.
abstract: Despite their structural similarity, hypoxia-inducible factor (HIF)-1α and HIF-2α have distinct functional properties and exhibit distinct spatiotemporal expression patterns, suggesting that the expressions of the two proteins are regulated by different mechanisms. To clarify the HIF-2α-specific regulatory mechanism, we screened HIF-2α-associated proteins in a yeast two-hybrid system and identified kelch-like 20 (KLHL20). HIF-2α, but not HIF-1α, interacted with KLHL20. siRNA-mediated knockdown of KLHL20 decreased HIF-2α protein, but not HIF-2α mRNA or HIF-1α protein. Depletion of KLHL20 decreased hypoxia-induced HIF activity, and consequently resulted in decreased expression levels of HIF-2α-responsive genes such as VEGF and CITED2. In contrast, overexpression of KLHL20 increased the expression levels and transcriptional activities of the O(2)-sensitive wild-type and O(2)-insensitive mutant forms of HIF-2α. KLHL20 siRNA also inhibited HIF-2 activity in von Hippel-Lindau tumor suppressor protein (pVHL)-deficient 786-O cells. These results indicate that KLHL20 is a novel player that regulates HIF-2α protein expression through mechanisms independent of hypoxia and pVHL.
authors: Division of Applied Biological Chemistry, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 5998531, Japan.
authors: Yasuki
authors: Y
authors: Higashimura
authors: Takashi
authors: T
authors: Terai
authors: Ryoichi
authors: R
authors: Yamaji
authors: Takakazu
authors: T
authors: Mitani
authors: Masahiro
authors: M
authors: Ogawa
authors: Naoki
authors: N
authors: Harada
authors: Hiroshi
authors: H
authors: Inui
authors: Yoshihisa
authors: Y
authors: Nakano
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D053858:Metabolic Networks and Pathways; D010100:Oxygen / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D002352:Carrier Proteins; D010100:Oxygen; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D015534:Trans-Activators; D042461:Vascular Endothelial Growth Factor A; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C486381:CITED2 protein, human; C550011:KLHL20 protein, human; C497446:VHL protein, human