miRNA-19a exerts an anti-apoptotic effect in spinal cord injured rats via the PTEN pathway

Contusion spinal cord injury is involved in a number of cellular, biochemical and molecular changes. We studied the overall expression pattern of miRNAs on day 1 and 3 after spinal cord injury and the involved pathways.

A spinal cord injury model was developed by contusion injury in rats. Microarray analysis and qRT-PCR were done for expression of miRs. The Basso, Beattie and Bresnahan (BBB) locomotor score was determined after spinal injury. Lesions at the injured site were analyzed by cresyl staining. Western blot analysis was carried out to analyze protein levels. Immunohistochemical staining was done to evaluate immunoreactivity. TUNEL assay was performed to determine the number of apoptotic cells.

The microarray analysis data suggested that about eight miRs were upregulated whereas four were downregulated in rats subjected to spinal cord injury on day 1. On comparing sham operated rats from the day 3 group two miRs were overexpressed and four were downregulated. miR-19a was the most deregulated. miR-19a antagomir was used as an inhibitor, which aggravated the functional deficit, decreased the protection of spinal cord tissue and elevated the number of apoptotic cells. The treatment of miR-19a antagomir increased the expression of FasL along with PTEN, but it failed to affect the levels of PDCD4.

The results suggested that miR-19a plays a potential role in halting the neuronal cell death spinal cord injury and that the protective role of miR-19a may be due to its regulatory effect on pro-apoptotic genes.