Novel Roles of GATA1 in Regulation of Angiogenic Factor AGGF1 and Endothelial Cell Function

Abstract

AGGF1 is an angiogenic factor, and its deregulation is associated with a vascular malformation consistent with KlippelTrenaunay syndrome (KTS). This study defines the molecular mechanism for transcriptional regulation of AGGF1 expression. Transcription of AGGF1 starts at two nearby sites, ؊367 and ؊364 bp upstream of the translation start site. Analyses of 5-and 3-serial promoter deletions defined the core promoter/regulatory elements, including two repressor sites (from ؊1971 to ؊3990 and from ؊7521 to ؊8391, respectively) and two activator sites (a GATA1 consensus binding site from ؊295 to ؊300 and a second activator site from ؊129 to ؊159). Both the GATA1 site and the second activator site are essential for AGGF1 expression. A similar expression profile was found for GATA1 and AGGF1 in cells (including various endothelial cells) and tissues. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that GATA1 was able to bind to the AGGF1 DNA in vitro and in vivo. Overexpression of GATA1 increased expression of AGGF1. We identified one rare polymorphism ؊294C>T in a sporadic KTS patient, which is located in the GATA1 site, disrupts binding of GATA1 to DNA, and abolishes the GATA1 stimulatory effect on transcription of AGGF1. Knockdown of GATA1 expression by siRNA reduced expression of AGGF1, and resulted in endothelial cell apoptosis and inhibition of endothelial capillary vessel formation and cell migration, which was rescued by purified recombinant human AGGF1 protein. These results demonstrate that GATA1 regulates expression of AGGF1 and reveal a novel role for GATA1 in endothelial cell biology and angiogenesis.The AGGF1 gene, previously known as VG5Q, encodes an angiogenic factor with 714 amino acid residues (1). AGGF1 was identified through genetic analysis of Klippel-Trenaunay syndrome (KTS, MIM #149000), 2 which is a congenital vascular disorder composed of capillary malformations, venous malformations or varicose veins, and hypertrophy of the affected tissues (2-5). KTS is a congenital disorder, but most cases are sporadic. The genetic basis of KTS is complex and may involve multiple genes, environmental factors, and their interactions (6). To date, identification of susceptibility genes associated with KTS has relied upon gross cytogenetic defects reported in KTS patients. Three chromosomal abnormalities have been identified in three separate KTS patients: two balanced translocations t(5.11)(q13.3;p15.1) and t(8,14)(q22.3;q13), and an extra supernumerary ring chromosome 18 (7-9). Chromosomal breakpoints involved in KTS translocation t(5;11)(q13.3; p15.1) have been fully characterized. No gene has been identified within a 100-kb region flanking the chromosome 11p15.1 translocation breakpoint. In contrast, the chromosome 5p13.3 breakpoint is located in the promoter/regulatory region of the AGGF1 gene and leads to increased transcriptional activation of AGGF1 by 3-fold (1). The results suggest that deregulation of AGGF1 is associated with KTS. However, the molecular mech...

X‐linked thrombocytopenia with thalassemia displays bone marrow reticulin fibrosis and enhanced angiogenesis: Comparisons with primary myelofibrosis

“…A high expression of VEGF in PMF megakaryocytes was seen also in an earlier study [18]. AGGF1 is reported to be under transcriptional control of GATA1 [14]. AGGF1 staining was positive in 91 % of XLTT megakaryocytes, compared to 100% in controls and PMF (Fig.…”

“…Low staining of VEGF and AGGF1 in XLTT BM may relate to observations (available for VEGF via www.sabiosciences.com) that the promoter regions of their genes contain binding sites for GATA1 [14]. However, it is not clear if a transcription deficit accounts for their lower protein contents in XLTT because posttranscriptional mechanisms may also be of importance.…”

“…We focus also on the relationship between thrombopoiesis and angiogenesis. Since transcription of angiogenic growth factor-1 (AGGF1) was found to be regulated by GATA1 in endothelial cells [14], AGGF1 expression was investigated, together with expressions of vascular endothelial and connective tissue growth factors (VEGF and CTGF) in megakaryocytes and BM blood vessels. Moreover, we assessed abundance of vascular pericytes since they have been suggested to be fibrogenic [15].…”

Targeting AGGF1 (angiogenic factor with G patch and FHA domains 1) for Blocking Neointimal Formation After Vascular Injury

“…The data in this study and in other reported publications27, 30, 33, 37 suggest that there is a receptor for AGGF1. The receptor for AGGF1 has not been reported yet and we are actively pursuing it.…”

Aggf1 attenuates hepatic inflammation and activation of hepatic stellate cells by repressing Ccl2 transcription

“…Plasmids, transfection, and reporter assay FLAG-tagged Aggf1, Ccl2 promoter-luciferase construct, and NF-κB/p65 expression construct have been described previously [14][15][16][17][18] . Transient transfections were performed with Lipofectamine 2000 (Invitrogen, Carlsbad, CA, USA).…”