Carson L. Stacy¹, David E. Lee1, Jacob L. Brown1, Megan E. Rosa1, Jordyn N. Henry1, Lemuel A. Brown1, Richard A. Perry Jr.1, Tyrone A. Washington1 & Nicholas P. Greene¹

¹Human Performance Laboratory, University of Arkansas, Fayetteville, Arkansas

Mitochondria-encoded proteins are essential to cellular respiration and metabolic health. These proteins are transcribed and translated from mitochondrial DNA into proteins involved in oxidative phosphorylation. mRNA translation of the mitochondrial genome may be altered by obesity. However, to our knowledge, the effect of Western diet and lifestyle physical activity on gene expression of mitochondrial translation factors has not been assessed. PURPOSE: To determine the impact of Western diet-induced obesity on mitochondrial mRNA translation regulators and if physical activity may impact these factors. METHODS: C57BL6/J mice (n=40) were placed on a normal chow (~15% fat, n=20) or Western diet (~42% fat + 1.5g/kg cholesterol, n=20) for 4 weeks. After the 4 weeks, half of the normal chow (NC) and Western diet (WD) groups were given access to a running wheel (voluntary wheel running [VWR], 10 NC and 10 WD) while the other half (10 NC and 10 WD) of each group remained sedentary (SED) for another 4 week interval. After the 8 weeks, animals were euthanized and samples were processed for mRNA expression of Mitochondrial Translation Inititation Factors 2 and 3 (mtIF2 and mtIF3), Translational Activator of Cytochrome Oxidase-1 (TACO1) and Mitochondrial Elongation Factor-Tu (TUFM) by qPCR. Data were analyzed by 2X2 ANOVA (diet [NC vs. WD] X activity [SED vs. VWR]) with α set at PRESULTS: mtIF2 and mtIF3 gene expression were suppressed by Western diet (approx. 50% reduction in WD-SED compared to NC-SED) while TACO1 and TUFM appeared unaffected. No significant effect of VWR was observed for any of the measured variables. CONCLUSION: These data suggest that Western diet-induced obesity does not affect the expression of all factors involved in mitochondrial translation. However, significant suppression of genes involved in the initiation phase of mitochondrial translation indicates that Western diet-induced obesity may disrupt mitochondrial translation in the initiation phase. This disruption may contribute to a decreased number of proteins which are essential to cellular respiration. This suppression may contribute to the decreased oxidative phosphorylation capacity associated with obesity. Lifestyle physical activity does not appear to be a viable way to alter the expression of genes that control mitochondrial translation.

This investigation was funded by the University of Arkansas

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