Histochemical mapping of hnRNP A2/B1 in rat brain after ischemia-reperfusion insults

J Histochem Cytochem. 2010 Aug;58(8):695-705. doi: 10.1369/jhc.2010.955021. Epub 2010 Apr 26.

Abstract

Cerebral ischemia-reperfusion (I/R) insults result in neuronal cell death, brain tissue loss, and severe neurological deficits. However, the underlying mechanism is still not fully understood. Heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 belongs to a family of RNA-binding proteins that plays a central role in pre-mRNA processing. Recent studies have revealed that hnRNP A2/B1 may be involved in the progress of I/R; therefore, the present study aimed to examine expression patterns of hnRNP A2/B1 to better understand posttranscriptional regulations in cerebral I/R insults. Focal cerebral I/R models were induced by right middle cerebral artery occlusion (MCAO) for 120 min followed by 3, 6, 12, 24, 48, and 72 hr of reperfusion in male Sprague-Dawley rats. We employed immunohistochemistry to examine expression of hnRNP A2/B1 in rat cerebral cortex (including cingulate cortex, striate cortex, temporal cortex, and piriform cortex) and hippocampus after I/R insults. Results showed that expression of hnRNP A2/B1 was significantly downregulated in cerebral cortex and hippocampus from 3 to 24 hr of reperfusion after MCAO for 120 min, but significantly upregulated at 48 hr of reperfusion. Unexpectedly, translocation of hnRNP A2/B1 from nucleus to cytoplasm and even to neurites was observed in cerebral cortex at 3 hr of reperfusion, reaching a peak at 24 hr of reperfusion, but not in hippocampus, indicating different posttranscriptional regulation patterns in different brain regions. Interestingly, translocation of hnRNP A2/B1 was only observed in cerebral cortex with MCAO but not in the opposite side, suggesting an I/R-specific expression pattern in the brain. Our data suggest that hnRNP A2/B1 participates in posttranscriptional regulation of neurons in cerebral cortex and hippocampus that suffered I/R insults, although posttranscriptional regulation is more extensive in neuronal cells of cerebral cortex than in hippocampus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / metabolism
  • Brain / pathology*
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / pathology
  • Gene Expression Regulation
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / analysis
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / genetics
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism*
  • Hippocampus / metabolism
  • Hippocampus / pathology
  • Immunohistochemistry
  • Male
  • Middle Cerebral Artery / metabolism
  • Neurons / metabolism
  • Neurons / pathology
  • Protein Transport
  • Rats
  • Rats, Sprague-Dawley
  • Reperfusion Injury / pathology*

Substances

  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B