Loss of RNA binding protein, human antigen R enhances mitochondrial elongation by regulating Drp1 expression in SH-SY5Y cells

Abstract

Mitochondria are essential for providing the energy necessary for neuronal function. Dysregulation of mitochondrial dynamics has been linked with the pathogenesis of many neurodegenerative diseases. Dynamin related protein 1 (Drp1) participates in fission activity in the mitochondria, and post-translational modifications to Drp1 modulate complex mitochondrial dynamics. However, the regulation of Drp1 at the post-transcriptional level remains poorly understood. In this study, we found that the RNA-binding protein Hu antigen R (HuR) post-transcriptionally regulates Drp1 expression. HuR interacts with Drp1 mRNA at its 3' untranslated region. Depletion of HuR reduces Drp1 expression, which leads to mitochondrial elongation in SH-SY5Y neuroblastoma cells. In contrast, ectopic expression of HuR enhances Drp1 expression, which promotes mitochondrial fragmentation in response to treatment with the mitochondrial complex 1 inhibitor MPP⁺. In addition, depletion of HuR suppressed the generation of mitochondrial ROS and cytotoxicity in MPP⁺ treated cells. Taken together, these findings suggest that HuR controls mitochondrial morphology via regulation of Drp1.

Keywords: Drp1; HuR; MPP+; Mitochondria; RBP; SH-SY5Y cells.