HIF-1α deletion partially rescues defects of hematopoietic stem cell quiescence caused by Cited2 deficiency.
Cited2 is a transcriptional modulator involved in various biologic processes including fetal liver hematopoiesis. In the present study, the function of Cited2 in adult hematopoiesis was investigated in conditional knockout mice. Deletion of Cited2 using Mx1-Cre resulted in increased hematopoietic stem cell (HSC) apoptosis, loss of quiescence, and increased cycling, leading to a severely impaired reconstitution capacity as assessed by 5-fluorouracil treatment and long-term transplantation. Transcriptional profiling revealed that multiple HSC quiescence- and hypoxia-related genes such as Egr1, p57, and Hes1 were affected in Cited2-deficient HSCs. Because Cited2 is a negative regulator of HIF-1, which is essential for maintaining HSC quiescence, and because we demonstrated previously that decreased HIF-1α gene dosage partially rescues both cardiac and lens defects caused by Cited2 deficiency, we generated Cited2 and HIF-1α double-knockout mice. Additional deletion of HIF-1α in Cited2-knockout BM partially rescued impaired HSC quiescence and reconstitution capacity. At the transcriptional level, deletion of HIF-1α restored expression of p57 and Hes1 but not Egr1 to normal levels. Our results suggest that Cited2 regulates HSC quiescence through both HIF-1-dependent and HIF-1-independent pathways.
Department of Biochemistry and Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA.
Jinwei
J
Du
Yu
Y
Chen
Qiang
Q
Li
Xiangzi
X
Han
Cindy
C
Cheng
Zhengqi
Z
Wang
David
D
Danielpour
Sally L
SL
Dunwoodie
Kevin D
KD
Bunting
Yu-Chung
YC
Yang
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction; D012097:Repressor Proteins / Q000172:deficiency* / Q000235:genetics; D015534:Trans-Activators / Q000172:deficiency* / Q000235:genetics
C110087:Cited2 protein, mouse; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012097:Repressor Proteins; D015534:Trans-Activators