Identification of a New Role of miR-199a-5p as Factor Implied in Neuronal Damage: Decreasing the Expression of Its Target X-Linked Anti-Apoptotic Protein (XIAP) After SCI.

Spinal cord injury (SCI) results in a cascade of primary and secondary damage, with apoptosis being a prominent cause of neuronal cell death. The X-linked inhibitor of apoptosis (XIAP) plays a critical role in inhibiting apoptosis, but its expression is reduced following SCI, contributing to increased neuronal vulnerability. This study investigates the regulatory role of miR-199a-5p on XIAP expression in the context of SCI. Using bioinformatic tools, luciferase reporter assays, and in vitro and in vivo models of SCI, we identified miR-199a-5p as a post-transcriptional regulator of XIAP. Overexpression of miR-199a-5p significantly reduced XIAP protein levels, although no changes were observed at the mRNA level, suggesting translational repression. In vivo, miR-199a-5p expression was upregulated at 3 and 7 days post-injury, while XIAP expression inversely decreased in both neurons and oligodendrocytes, being particularly significant in the latter at 7 dpi. These findings suggest that miR-199a-5p contributes to the downregulation of XIAP and may exacerbate neuronal apoptosis after SCI. Targeting miR-199a-5p could offer a potential therapeutic strategy to modulate XIAP levels and reduce apoptotic cell death in SCI.