Angiopoietin 2 Mediates the Differentiation and Migration of Neural Progenitor Cells in the Subventricular Zone after Stroke

Michael Chopp,Xian Shuang Liu,Rui Lan Zhang,Mei Lu,Zheng Gang Zhang,Ann Hozeska-Solgot,Ben Buller,Sara C. Gregg

doi:10.1074/jbc.m109.006551

Abstract

Ischemic stroke stimulates neurogenesis in the adult rodent brain. The molecules underlying stroke-induced neurogenesis have not been fully investigated. Using real-time reverse transcription-PCR, we found that stroke substantially up-regulated angiopoietin 2 (ANG2), a proangiogenic gene, expression in subventricular zone neural progenitor cells. Incubation of neural progenitor cells with recombinant human ANG2 significantly increased the number of beta-III tubulin-positive cells, a marker of immature neurons, but did not alter the number of glial fibrillary acidic protein (GFAP)-positive cells, a marker of astrocytes, suggesting that ANG2 promotes neuronal differentiation. Blockage of the ANG2 receptor, Tie2, with small interference RNA (siRNA)-Tie2 attenuated recombinant human ANG2 (rhANG2)-increased beta-III tubulin mRNA levels compared with levels in the progenitor cells transfected with control siRNA. Chromatin immunoprecipitation analysis revealed that CCAAT/enhancer-binding protein (C/EBP beta) up-regulated by rhANG2 bound to beta-III tubulin, which is consistent with published data that there are several C/EBP beta binding sites in the promoter of beta-III tubulin gene. In addition, rhANG2 enhanced migration of neural progenitor cells measured by single neurosphere assay. Blockage of Tie2 with siRNA-Tie2 and a Tie2-neutralizing antibody did not suppress ANG2-enhanced migration. However, inhibition of matrix metalloproteinases with GM6001 blocked ANG2-enhanced migration. Collectively, our data suggest that interaction of ANG2, a proangiogenic factor, with its receptor Tie2 promotes neural progenitor cell differentiation into neuronal lineage cells, whereas ANG2 regulates neural progenitor cell migration through matrix metalloproteinases, which do not require its receptor Tie2.

Highlights

Grants PO1 NS23393, PO1 NS42345, and RO1 HL064766. □S The on-line version of this article contains supplemental Data I and II. 1 To whom correspondence should be addressed: Dept. of Neurology, Henry neurons throughout lifetime [1,2,3,4,5]
Stroke Up-regulates angiopoietin 2 (ANG2) Expression in subventricular zone (SVZ) Neural Progenitor Cells—To analyze the effects of stroke on ANG expression in neural progenitor cells, SVZ cells from non-ischemic mice or mice subjected to 7 days after middle cerebral artery occlusion (MCAo) were isolated using Laser Capture Microdissection (LCM)
The present study shows that MCAo up-regulates ANG2, a proangiogenic factor, in SVZ neural progenitor cells

Summary

Introduction

Grants PO1 NS23393, PO1 NS42345, and RO1 HL064766. □S The on-line version of this article (available at http://www.jbc.org) contains supplemental Data I and II. 1 To whom correspondence should be addressed: Dept. of Neurology, Henry neurons throughout lifetime [1,2,3,4,5]. In addition to vascular endothelial growth factor, stroke up-regulates ANG2 expression in SVZ neural progenitor cells [26]. In the present study we investigated the effect of ANG2 on differentiation and migration of adult SVZ progenitor cells.

Results

Conclusion