Global Transcriptomic Profiling of Cortex and Striatum: Cerebral Injury after Ischemia/Reperfusion in a Mouse Model

Abstract

Objective: This study aims to investigate the molecular mechanism of injury development in the cortex and the striatum after cerebral ischemia/reperfusion (I/R).

Methods: Gene expression data (GSE23160) in the cortex and the striatum of an intraluminal middle cerebral artery occlusion-I/R mouse model (N = 12) and sham controls (N = 4) were downloaded from the Gene Expression Omnibus. Limma package was used to identify the differentially expressed genes (DEGs) between the I/R (2, 8, and 24 hours) and control groups. Correlation analysis was then performed to identify the highly correlated differentially expressed genes (HCDEGs). STRING and Cytoscape software were used to construct a protein-protein interaction (PPI) network of HCDEGs. Furthermore, Venny 2.0 was used to identify common overlapped DEGs whose transcription factors (TFs) were predicted using iRegulon in Cytoscape.

Results: For the cortex and the striatum, 2295 and 2282 DEGs were respectively identified between the I/R group and the controls, and were classified into 3 and 2 correlation modules. For each module, a PPI network was constructed, and Toll-like receptor 2 (Tlr2, degree = 25), interleukin 1β (Il1b, degree = 21), and heme oxygenase-1 (Hmox1, degree = 17) had high connective degrees. Furthermore, 29 common overlapped DEGs were found across time and tissue, which might be targeted by 13 TFs. Especially, Tlr2, Il1b, and Hmox1 were targeted by myeloblastosis protein (Myb, target count = 16) and FBJ osteosarcoma protein (Fos, target count = 15). Moreover, plasminogen activator urokinase receptor (Plaur) was targeted by Fos, and it was an HCDEG in correlation modules of both cortex and striatum. Upregulation of Tlr2, Il1b, Hmox1, and Plaur in I/R injury was confirmed using quantitative polymerase chain reaction and immunohistochemical staining.

Conclusion: Tlr2, Il1b, Hmox1, and Plaur regulated by Myb and Fos might participate in cortex and striatum injury after cerebral I/R.

Keywords: Cerebral ischemia; differentially expressed genes; ischemia/reperfusion injury; transcription factor; weighted correlation network analysis.