HuR Function and Translational State Analysis Following Global Brain Ischemia and Reperfusion

摘要

Prolonged translation arrest in post-ischemic hippocampal CA1 pyramidal neurons precludes translation of induced stress genes and directly correlates with cell death. We evaluated regulation of mRNAs containing adenine and uridine rich elements (ARE) by assessing HuR protein and hsp70 mRNA nuclear translocation, HuR polysome binding, and translation state analysis of CA1 and CA3 at 8 hr reperfusion after 10 min global cerebral ischemia. There was no difference between CA1 and CA3 at 8 hr of reperfusion in nuclear or cytoplasmic HuR protein or hsp70 mRNA, or HuR polysome association, suggesting neither mechanism contributed to post-ischemic outcome. Translation state analysis revealed that 28% and 58% of unique mRNAs significantly different between 8hR and NIC, in CA3 and CA1, respectively, were not polysome-bound. There was significantly greater diversity of polysome-bound mRNAs in reperfused CA3 compared to CA1, and in both regions ARE-containing mRNAs accounted for 4% – 5% of the total. These data indicate that post-transcriptional ARE-containing mRNA regulation occurs in reperfused neurons and contributes to post-ischemic outcome. Understanding the differential responses of vulnerable and resistant neurons to ischemia will contribute to the development of effective neuroprotective therapies.