Semaphorin3A elevates vascular permeability and contributes to cerebral ischemia-induced brain damage

Abstract

Semaphorin 3A (Sema3A) increased significantly in mouse brain following cerebral ischemia. However, the role of Sema3A in stroke brain remains unknown. Our aim was to determine wether Sema3A functions as a vascular permeability factor and contributes to ischemic brain damage. Recombinant Sema3A injected intradermally to mouse skin, or stereotactically into the cerebral cortex, caused dose- and time-dependent increases in vascular permeability, with a degree comparable to that caused by injection of a known vascular permeability factor vascular endothelial growth factor receptors (VEGF). Application of Sema3A to cultured endothelial cells caused disorganization of F-actin stress fibre bundles and increased endothelial monolayer permeability, confirming Sema3A as a permeability factor. Sema3A-mediated F-actin changes in endothelial cells were through binding to the neuropilin2/VEGFR1 receptor complex, which in turn directly activates Mical2, a F-actin modulator. Down-regulation of Mical2, using specific siRNA, alleviated Sema3A-induced F-actin disorganization, cellular morphology changes and endothelial permeability. Importantly, ablation of Sema3A expression, cerebrovascular permeability and brain damage were significantly reduced in response to transient middle cerebral artery occlusion (tMCAO) and in a mouse model of cerebral ischemia/haemorrhagic transformation. Together, these studies demonstrated that Sema3A is a key mediator of cerebrovascular permeability and contributes to brain damage caused by cerebral ischemia.

Amplification of F-Actin Disassembly and Cellular Repulsion by Growth Factor Signaling

“…Interestingly, Mical has also been implicated in working with different growth factors including HGF, VEGF, EGF, and NGF (Deng, et al, 2016; Hou, et al, 2015; Lundquist, et al, 2014; Ashida, et al, 2006), but the role of these growth factors in regulating Mical-mediated F-actin disassembly is unknown. In a reciprocal way, Mical is best known to carry out the F-actin destabilizing effects of the cellular repellent Sema and its Plexin receptor (Hung, et al, 2010; Terman, et al, 2002) – and Abl, likewise, has been implicated in Sema/Plex signaling but its role in this process is unclear (Procaccia, et al, 2014; O’Connor, et al, 2008; Shimizu, et al, 2008; Moresco, et al, 2005; Toyofuku, et al, 2004).…”

Regulated methionine oxidation by monooxygenases

“…EMT is an essential process for embryo formation and development, but also for metastasis (for a review see 123 ). At the same time, MICAL2 was reported as a key protein for cell migration during metastasis in prostate and breast cancer models 115,119,124 and also during changes in endothelial permeability mediated by vascular endothelial growth factor receptor 1 (VEGFR1) in response to Sem3A treatment both in cell culture and in vivo 125 . The three MICAL genes have different subcellular localization and a different pattern of expression in cells and mammalian tissues, with MICAL1 being mostly cytosolic and MICAL2 and 3 enriched in the nuclear fraction, probably due to the presence of a bipartite nuclear localization signal (NLS) downstream of the LIM domain 109,120,121 (Figure 3).…”

Actin filaments—A target for redox regulation

“…Functional studies have also gone on to reveal prominent localization of MICALs with F‐actin structures and important roles for MICALs in regulating multiple neuronal and non‐neuronal actin dependent events. For instance, multiple different cell culture assays using primary cells and cell lines including neurons/neuronal‐like cells (dorsal root ganglion neurons, hippocampal neurons, PC12 cells), fibroblasts (mouse embryonic fibroblasts [MEFs], NIH 3T3 cells), endothelial cells (rat brain capillary endothelial [RBEC] cells), kidney cells (podocytes, HEK 293 cells, COS‐7 cells), and cancer cell lines (HeLa cells, 786‐O kidney cancer cells, MERO‐14 pleural cancer cells) have been used to characterize the effects of MICALs on F‐actin dynamics and morphology [Schmidt et al, ; Grigoriev et al, ; Hung et al, ; Morinaka et al, ; Giridharan et al, ; Hung et al, ; Lee et al, ; Lundquist et al, ; Van Battum et al, ; Aggarwal et al, ; Hou et al, ; Mariotti et al, ]. Likewise, both genetic and knockdown experiments in invertebrates and mammals indicate important roles for MICALs in non‐neuronal functions including cell viability [Ashida et al, ; Zhou et al, ; Loria et al, ; Mariotti et al, ], skeletal muscle morphology and function [Beuchle et al, ; Hung et al, ], immunity [Lee et al, ], podocyte (kidney) cell shape and function [Aggarwal et al, ], and cardiovascular integrity [Lundquist et al, ; Hou et al, ].…”