Neuropilin-1 Is a Direct Target of the Transcription Factor E2F1 during Cerebral Ischemia-Induced Neuronal Death In Vivo

Abstract

The nuclear transcription factor E2F1 plays an important role in modulating neuronal death in response to excitotoxicity and cerebral ischemia. Here, by comparing gene expression in brain cortices from E2F1 ؉/؉ and E2F1 ؊/؊ mice using a custom high-density DNA microarray, we identified a group of putative E2F1 target genes that might be responsible for ischemia-induced E2F1-dependent neuronal death. Neuropilin 1 (NRP-1), a receptor for semaphorin 3A-mediated axon growth cone collapse and retraction, was confirmed to be a direct target of E2F1 based on (i) the fact that the NRP-1 promoter sequence contains an E2F1 binding site, (ii) reactivation of NRP-1 expression in E2F1 ؊/؊ neurons when the E2F1 gene was replaced, (iii) activation of the NRP-1 promoter by E2F1 in a luciferase reporter assay, (iv) electrophoretic mobility gel shift analysis confirmation of the presence of an E2F binding sequence in the NRP-1 promoter, and (v) the fact that a chromatin immunoprecipitation assay showed that E2F1 binds directly to the endogenous NRP-1 promoter. Interestingly, the temporal induction in cerebral ischemia-induced E2F1 binding to the NRP-1 promoter correlated with the temporal-induction profile of NRP-1 mRNA, confirming that E2F1 positively regulates NRP-1 during cerebral ischemia. Functional analysis also showed that NRP-1 receptor expression was extremely low in E2F1 ؊/؊ neurons, which led to the diminished response to semaphorin 3A-induced axonal shortening and neuronal death. An NRP-1 selective peptide inhibitor provided neuroprotection against oxygenglucose deprivation. Taken together, these findings support a model in which E2F1 targets NRP-1 to modulate axonal damage and neuronal death in response to cerebral ischemia.

The transcription factor E2F1 and the SR protein SC35 control the ratio of pro-angiogenic versus antiangiogenic isoforms of vascular endothelial growth factor-A to inhibit neovascularization in vivo

“…Therefore, these data indicate that E2F1 downregulates the expression level of pro-angiogenic VEGF xxx transcripts. To test whether this effect was specific for VEGF xxx transcripts, we analysed the expression level of neuropilin-1, the co-receptor of VEGFR-2 that was recently identified as a new E2F1 transcriptional target gene (Jiang et al, 2007). Upon E2F1 overexpression, we found that the level of neuropilin-1 mRNA was slightly increased, whereas the expression of neuropilin-2 was not affected (Figure 1a, lower panel).…”

Molecular blockade of VEGFR2 in human epithelial ovarian carcinoma cells

“…For example, in HeLa cells NRP-1 expression is controlled by SP1, AP1, and CCAAT box transcription factors, 42 whereas in neurons E2F1 factor binds directly to the endogenous NRP-1 promoter to positively regulate its expression. 43 Production of SHH ligand and pathway activity is related to NRP-1 expression, and NRP-1 knockdown leads to reduced SHH, Gli-1, and E-cadherin production in renal carcinoma cells. 26 Similarly, blockade of the SHH pathway leads to reduced expression of E-cadherin, b 1 integrin, and VEGF in EOC cells.…”

Semaphorin 3A is a retrograde cell death signal in developing sympathetic neurons

“…Besides its role in regulating neuronal morphology, accumulating evidence suggests that Sema3A induces neuronal apoptosis (Gagliardini and Fankhauser, 1999;Shirvan et al, 1999Shirvan et al, , 2002Ben-Zvi et al, 2006). Despite recent progress, whether Sema3A, Npn1 and plexins are physiologically relevant in developmental cell death in vivo, and the mechanisms underlying semaphorin-induced apoptosis, remain poorly understood (Ben-Zvi et al, 2006Jiang et al, 2007Jiang et al, , 2010Haupt et al, 2010). Here we identify Sema3A as a retrograde death signal for developing sympathetic neurons.…”