Evaluating survivin gene expression changes in adult mice following sciatic nerve injury

Because of the necessity of more effective treatments for the nervous system injuries and considering the role of survivin in cellular proliferation and apoptotic cell death, we have monitored survivin gene expression changes during the course of regeneration in injured sciatic nerves and also L4-L6 segments of spinal cord. We used adult male NMRI mice as a model. After anesthetizing the animals, the right sciatic nerve was transected and at the indicated times (3, 6, 12, 24, 48, 96 and 144 hours) the animals were sacrificed and both distal and proximal segments of the transected sciatic nerve, intact left sciatic nerve and L4-L6 segments of spinal cord were dissected. The total RNA was extracted from each sample and semi-quantitative RT-PCR with specific primers for survivin and also 2-microglobulin genes, as an internal control, was performed. To determine cellular distribution of survivin protein, 6 days (144 hours) after the axotomy, survivin protein expression was evaluated using immunohistochemistry technique. Our results demonstrated the expression of both survivin140 and survivin40 in distal and proximal segments of sciatic nerve with different intensity, where the expression of survivin140 was higher than survivin40. In spinal cord segments, only survivin140 expression was detected. In Immunohistochemistry analysis of spinal cord segments, both the nuclear and cytoplasmic distribution of survivin protein was observed. In contrast, survivin protein has not been detected in either distal or proximal segments of sciatic nerve. Our data suggest that survivin is differentially expressed and spliced during the course of regeneration in damaged nerve and spinal cord. It seems that manipulation of expression and/or splicing of survivin could potentially affect the process of regeneration in nerve and/or spinal cord injuries.