The essential role of Cited2, a negative regulator for HIF-1α, in heart development and neurulation

Abstract

Cited2 is a cAMP-responsive element-binding protein (CBP)͞p300 interacting transcriptional modulator and a proposed negative regulator for hypoxia-inducible factor (HIF)-1␣ through its competitive binding with HIF-1␣ to CBP͞p300. Disruption of the gene encoding Cited2 is embryonic lethal because of defects in the development of heart and neural tube. Morphological and Doppler echocardiographic analyses of Cited2 ؊/؊ embryos reveal severe cardiovascular abnormalities, including pulmonic arterial stenosis and ventricular septal defects accompanied by high peak outflow velocities, features of the human congenital cardiac defect termed tetralogy of Fallot. The mRNA levels of several HIF-1␣-responsive genes, such as vascular endothelial growth factor (VEGF), Glut1, and phosphoglycerate kinase 1, increased in the Cited2 ؊/؊ hearts. The increase of VEGF levels is significant, because defects in the Cited2 ؊/؊ embryos closely resemble the major defects observed in the VEGF transgenic embryos. Finally, compared with wild-type, cultured fibroblasts from Cited2 ؊/؊ embryos demonstrate an enhanced expression of HIF-1␣-responsive genes under hypoxic conditions. These observations suggest that functional loss of Cited2 is responsible for defects in heart and neural tube development, in part because of the modulation of HIF-1 transcriptional activities in the absence of Cited2. These findings demonstrate that Cited2 is an indispensable regulatory gene during prenatal development.

Developmental regulation of hypoxia-inducible factor 1 and prolyl-hydroxylases in pulmonary vascular smooth muscle cells

“…CITED2 is activated by hypoxia by HIF-1 itself, providing an additional layer of HIF-1 autoregulation by controlling HIF-1 ␣ access to CBP/p300, and therefore limiting HIF-1-dependent hypoxic response. Inactivation of HIF-1 target genes in CITED2 knockout mice seems to support the role of CITED2 as a HIF-1 competitor (20). Similar to PHD2 and FIH, CITED2 activation by hypoxia might indicate a role for this molecule in the rapid inactivation of the hypoxic response upon reoxygenation.…”

“…Similar to PHD2 and FIH, CITED2 activation by hypoxia might indicate a role for this molecule in the rapid inactivation of the hypoxic response upon reoxygenation. CITED2 may play a role in heart morphogenesis and the establishment of left-right asymmetry in the early embryo (20)(21)(22).…”

Cited2 modulates TGF-β-mediated upregulation of MMP9

“…MCF-10A was provided by Dr Amy Wilson-Delfosse (Case Western Reserve University). Primary MEF cultures were harvested and maintained as described (Yin et al, 2002). For generation of MEF cell lines, primary MEFs were immortalized by retroviral infection with a retroviral vector containing simian virus 40 LT antigen (Williams et al, 1988), provided by Dr David Williams (University of Cincinnati).…”

“…This is supported by the observation that hypoxia induces Cited2 expression. Elevated level of Cited2 then functions to downregulate hypoxia inducible factor (HIF)-1-driven transcription by competing with HIF-1a for binding to CBP/p300 Yin et al, 2002;Freedman et al, 2003). We and others have shown that disruption of the gene encoding Cited2 is embryonic lethal and causes defects in the development of heart and neural tube (Bamforth et al, 2001;Barbera et al, 2002;Yin et al, 2002).…”

Profiling and functional annotation of mRNA gene expression in pediatric rhabdomyosarcoma and Ewing's sarcoma

“…Furthermore, CITED2 acts as a repressor for hypoxia-inducible factor 1␣, (HIF1A), which in turn regulates important growth-regulatory target genes like VEGF, Glut1(SLC2A1) and phosphoglycerate kinase (PGK1). 45 …”