Neuropilin-1 modulates vascular endothelial growth factor-induced poly(ADP-ribose)-polymerase leading to reduced cerebrovascular apoptosis

• Published in: Neurobiology of disease 2013-11, Vol.59, p.111-125
• Main Authors: Mey, Lilli, Hörmann, Mareike, Schleicher, Nadine, Reuter, Peter, Dönges, Simone, Kinscherf, Ralf, Gassmann, Max, Gerriets, Tibo, Al-Fakhri, Nadia
• Format: Article
• Language: English
• Subjects: AKT protein; Animals; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Cells, Cultured; Cerebral ischemia; Cerebrovascular disease; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelial Cells - physiology; Gene Expression Regulation - drug effects; Gene Expression Regulation - genetics; Humans; Indoles - pharmacology; Infarction, Middle Cerebral Artery - drug therapy; Infarction, Middle Cerebral Artery - metabolism; Infarction, Middle Cerebral Artery - pathology; Male; Neurology; Neurons - drug effects; Neurons - pathology; Neuropilin-1; Neuropilin-1 - metabolism; PARP; Poly(ADP-ribose) Polymerases - genetics; Poly(ADP-ribose) Polymerases - metabolism; Protein Kinase Inhibitors - pharmacology; Pyrroles - pharmacology; Rat middle cerebral artery occlusion model; Rats; Rats, Wistar; Signal Transduction - drug effects; Time Factors; Umbilical Veins - cytology; Vascular endothelial growth factor; Vascular Endothelial Growth Factor A - metabolism; Vascular Endothelial Growth Factor A - pharmacology
• ISSN: 0969-9961; 1095-953X
• DOI: 10.1016/j.nbd.2013.06.009

Abstract Cerebral ischemia is encompassed by cerebrovascular apoptosis, yet the mechanisms behind apoptosis regulation are not fully understood. We previously demonstrated inhibition of endothelial apoptosis by vascular endothelial growth factor (VEGF) through upregulation of poly(ADP-ribose)-polymerase (PARP) expression. However, PARP overactivation through oxidative stress can lead to necrosis. This study tested the hypothesis that neuropilin-1 (NP-1), an alternative VEGF receptor, regulates the response to cerebral ischemia by modulating PARP expression and, in turn, apoptosis inhibition by VEGF. In endothelial cell culture, NP-1 colocalized with VEGF receptor-2 (VEGFR-2) and acted as its coreceptor. This significantly enhanced VEGF-induced PARP mRNA and protein expression demonstrated by receptor-specific inhibitors and VEGF-A isoforms. NP-1 augmented the inhibitory effect of VEGF/VEGFR-2 interaction on apoptosis induced by adhesion inhibition through the αV-integrin inhibitor cRGDfV. NP-1/VEGFR-2 signal transduction involved JNK and Akt. In rat models of permanent and temporary middle cerebral artery occlusion, the ischemic cerebral hemispheres displayed endothelial and neuronal apoptosis next to increased endothelial NP-1 and VEGFR-2 expression compared to non-ischemic cerebral hemispheres, sham-operated or untreated controls. Increased vascular superoxide dismutase-1 and catalase expression as well as decreased glycogen reserves indicated oxidative stress in the ischemic brain. Of note, protein levels of intact PARP remained stable despite pro-apoptotic conditions through increased PARP mRNA production during cerebral ischemia. In conclusion, NP-1 is upregulated in conditions of imminent cerebrovascular apoptosis to reinforce apoptosis inhibition and modulate VEGF-dependent PARP expression and activation. We propose that NP-1 is a key modulator of VEGF maintaining cerebrovascular integrity during ischemia. Modulating the function of NP-1 to target PARP could help to prevent cellular damage in cerebrovascular disease.