Yong-Gang Yao

Johns Hopkins University, Baltimore, Maryland, United States

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Publications (3)11.6 Total impact

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    ABSTRACT: Vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) are key angiogenic stimulators during normal development and wound healing, as well as in a variety of pathological conditions. Recent studies have demonstrated a synergistic effect of VEGF and PlGF in pathological angiogenesis and suggest a role for PlGF in amplifying VEGF action in endothelial cells. We show here in the mouse model of oxygen-induced retinopathy that VEGF is significantly increased (P<0.01) in the retina at both the mRNA and protein levels. In this mouse model, PlGF was significantly upregulated in the retina at the protein level (P<0.01) without a corresponding change in mRNA levels. In cultured human retinal and umbilical vein endothelial cells, VEGF induced the production of PlGF protein by over 10-fold (P<0.01) in a dose-dependent manner through a post-transcriptional mechanism. The increased PlGF expression upon VEGF treatment was significantly reduced by inhibition of the protein kinase C (PKC) and MEK signaling pathways, as well as by treatment with the calcium ionophore A23187. Taken together, our findings demonstrate that VEGF can amplify its effects on endothelial cells by inducing the production of PlGF via a post-transcriptional mechanism in a PKC-dependent manner, and provide a potential link between PKC inhibition and amelioration of vascular complications in the development of angiogenic diseases.
    Preview · Article · Feb 2005 · FEBS Letters
  • Elia J Duh · Yong-Gang Yao · Manesh Dagli · Morton F Goldberg
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    ABSTRACT: To report a child with Knobloch syndrome (KS) with features of persistent fetal vasculature (PFV) and to discuss the possible role of endostatin in vascular remodeling of the fetal eye. Case report with enzyme-linked immunosorbent assay (ELISA) analysis of serum endostatin. Ocular examination, fluorescein angiography, echography, ELISA analysis of serum endostatin, and typing for pathogenic mutations in COL18A1. Slit-lamp examination in the left eye disclosed numerous findings of PFV, including an extensive persistent pupillary membrane, scarcity of iris crypts, and pigmented epicapsular stellate remnants on the anterior lens surface. Dilated fundus examination revealed a total posterior vitreous detachment, despite the young age of the patient, with numerous white intragel opacities that were compatible with remnants of the vasa hyaloidea propria. The fundus had a tesselated appearance with angiographically visible large choroidal vessels. There was a retinochoroidal staphyloma inferotemporal to the optic disc. There were no retinal vessels visible temporally, and there was no macular differentiation or foveal pit. Competitive ELISA analysis disclosed no detectable serum endostatin. None of the 8 reported pathogenic mutations in the COL18A1 gene was found in the patient. Persistent fetal vasculature may be a clinical and important manifestation in some patients with KS and can be explained by a deficiency in endostatin. Endostatin deficiency may result in reduced or delayed regression of fetal blood vessels in the eye (including the intravitreal compartment), thereby resulting in incomplete development of the normal vasculature in the retina. Our typing results for the reported COL18A1 mutations confirm the genetic heterogeneity of KS.
    No preview · Article · Nov 2004 · Ophthalmology
  • Yong-Gang Yao · Elia J Duh
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    ABSTRACT: The Down syndrome critical region 1 (DSCR1) gene (also known as MCIP1, Adapt78) encodes a regulatory protein that binds to calcineurin catalytic A subunit and acts as a regulator of the calcineurin-mediated signaling pathway. We show in this study that DSCR1 is greatly induced in endothelial cells in response to VEGF, TNF-alpha, and A23187 treatment, and that this up-regulation is inhibited by inhibitors of the calcineurin-NFAT (nuclear factor of activated T cells) signaling pathway as well as by PKC inhibition and a Ca(2+) chelator. We hypothesized that the up-regulation of DSCR1 gene expression in endothelial cells could act as an endogenous feedback inhibitor for angiogenesis by regulating the calcineurin-NFAT signaling pathway. Our transient transfection analyses confirm that the overexpression of DSCR1 abrogates the up-regulation of reporter gene expression driven by both the cyclooxygenase 2 and DSCR1 promoters in response to stimulators. Our results indicate that DSCR1 up-regulation may represent a potential molecular mechanism underlying the regulation of angiogenic genes activated by the calcineurin-NFAT signaling pathway in endothelial cells.
    No preview · Article · Sep 2004 · Biochemical and Biophysical Research Communications