Angiogenic growth factors augment K-Cl cotransporter expression in erythroid cells via hypoxia-inducible factor-1α.
The potassium chloride cotransporters (KCC) family of proteins are widely expressed and are involved in the transepithelial movement of potassium and chloride ions and the regulation of cell volume. KCC activity is high in reticulocytes, and contributes to the dehydration of sickle red blood cells. Because plasma levels of both vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) are elevated in sickle cell individuals, and VEGF has been shown to increase KCC expression in other cells, we hypothesized that VEGF and PlGF influence KCC expression in erythroid cells. Both VEGF and PlGF treatment of human erythroid K562 cells increased both mRNA and protein levels of KCC1, KCC3b, and KCC4. VEGF- and PlGF-mediated cellular signaling involved VEGF-R1 and downstream effectors, specifically, PI-3 kinase, p38 MAP kinase, mTOR, NADPH-oxidase, JNK kinase, and HIF-1α. VEGF and PlGF-mediated transcription of KCC3b and KCC4 involved hypoxia response element (HRE) motifs in their promoters, as demonstrated by promoter analysis, EMSA and ChiP. These results were corroborated in vivo by adenoviral-mediated overexpression of PlGF in normal mice, which led to increased expression of mKCC3 and mKCC4 in erythroid precursors. Our studies show that VEGF and PlGF regulate transcription of KCC3b and KCC4 in erythroid cells via activation of HIF-1α, independent of hypoxia. These studies provide novel therapeutic targets for regulation of cell volume in RBC precursors, and thus, amelioration of dehydration in RBCs in sickle cell disease.
Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Biochemistry and Molecular Biology, Keck School of Medicine of the University of Southern California, Los Angeles, California.
Caryn S
CS
Gonsalves
Scott
S
Crable
Sharat
S
Chandra
Wei
W
Li
Vijay K
VK
Kalra
Clinton H
CH
Joiner
D000818:Animals; D015687:Cell Hypoxia; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D020014:K562 Cells; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000235:genetics / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology; D027981:Symporters / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic; D014161:Transduction, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000494:pharmacology*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000187:drug effects / Q000502:physiology; D000096922:K Cl- Cotransporters
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009363:Neoplasm Proteins; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D027981:Symporters; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D000096922:K Cl- Cotransporters; C497442:HIF1A protein, human; C000608036:PGF protein, human; C000608037:Pgf protein, mouse; C467484:VEGFA protein, human