MicroRNA‐382 silencing induces a mitonuclear protein imbalance and activates the mitochondrial unfolded protein response in muscle cells

• Published in: Journal of cellular physiology Vol. 234; no. 5; pp. 6601 - 6610
• Main Authors: Dahlmans, Dennis, Houzelle, Alexandre, Andreux, Pénélope, Wang, Xu, Jörgensen, Johanna A., Moullan, Norman, Daemen, Sabine, Kersten, Sander, Auwerx, Johan, Hoeks, Joris
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-05-2019; John Wiley and Sons Inc
• Subjects: Aging; Animals; Antisense oligonucleotides; Coding; Deoxyribonucleic acid; DNA; DNA microarrays; Electron transport; Gene expression; Genes; Hsp60 protein; Metabolism; Mice; microRNA; MicroRNAs - genetics; miRNA; mitochondria; Mitochondria - metabolism; Mitochondria, Muscle - metabolism; Mitochondrial DNA; Mitochondrial Proteins - metabolism; Muscle Fibers, Skeletal - metabolism; Muscle, Skeletal - metabolism; Muscles; Musculoskeletal system; Myotubes; Oligonucleotides; Original; Original s; Oxygen consumption; Protein arrays; Protein folding; protein stress; Proteins; Quality control; Ribonucleic acid; Ribosomal proteins; Ribosomal Proteins - metabolism; RNA; Skeletal muscle; Unfolded Protein Response - genetics; protein stress; microRNA; skeletal muscle; mitochondria
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.27401

Proper mitochondrial function plays a central role in cellular metabolism. Various diseases as well as aging are associated with diminished mitochondrial function. Previously, we identified 19 miRNAs putatively involved in the regulation of mitochondrial metabolism in skeletal muscle, a highly metabolically active tissue. In the current study, these 19 miRNAs were individually silenced in C2C12 myotubes using antisense oligonucleotides, followed by measurement of the expression of 27 genes known to play a major role in regulating mitochondrial metabolism. Based on the outcomes, we then focused on miR‐382‐5p and identified pathways affected by its silencing using microarrays, investigated protein expression, and studied cellular respiration. Silencing of miRNA‐382‐5p significantly increased the expression of several genes involved in mitochondrial dynamics and biogenesis. Conventional microarray analysis in C2C12 myotubes silenced for miRNA‐382‐5p revealed a collective downregulation of mitochondrial ribosomal proteins and respiratory chain proteins. This effect was accompanied by an imbalance between mitochondrial proteins encoded by the nuclear and mitochondrial DNA (1.35‐fold, p < 0.01) and an induction of HSP60 protein (1.31‐fold,
p < 0.05), indicating activation of the mitochondrial unfolded protein response (mtUPR). Furthermore, silencing of miR‐382‐5p reduced basal oxygen consumption rate by 14% (
p < 0.05) without affecting mitochondrial content, pointing towards a more efficient mitochondrial function as a result of improved mitochondrial quality control. Taken together, silencing of miR‐382‐5p induces a mitonuclear protein imbalance and activates the mtUPR in skeletal muscle, a phenomenon that was previously associated with improved longevity.
In the current study, microRNA‐382‐5p was identified as a regulator of mitochondrial biogenesis and dynamics at mRNA levels. Silencing of miRNA‐382‐5p in C2C12 myotubes revealed a collective downregulation of mitochondrial ribosomal proteins and respiratory chain proteins. MiR‐382 silenced C2C12 showed a mitonuclear protein imbalance that led to the activation of the mitochondrial unfolded protein response and a reduced basal oxygen consumption rate without affecting mitochondrial content.