Sex Differences in Heart Mitochondria: Relationship to Diastolic Dysfunction

As part of genetic studies of heart failure in mice, we observed that heart mitochondrial DNA levels and function tend to be reduced in females as compared to males. We also observed that expression of genes encoding mitochondrial proteins were higher in males than females in human cohorts. Heart failure with preserved ejection fraction (HFpEF) exhibits a sex bias, being more common in women than men, and we hypothesized that mitochondrial sex differences might underlie this bias. We tested this in a panel of genetically diverse inbred strains of mice, termed the Hybrid Mouse Diversity Panel (HMDP). Indeed, we found that mitochondrial gene expression was highly correlated with diastolic function, a key trait in HFpEF. Consistent with this, studies of a “two-hit” mouse model of HFpEF confirmed that mitochondrial function differed between sexes and was strongly associated with a number of HFpEF traits. By integrating data from human heart failure and the mouse HMDP cohort, we identified the mitochondrial protein Acsl6 as a genetic determinant of diastolic function. We validated its role in HFpEF using adenoviral over-expression in the heart. We conclude that sex differences in mitochondrial function underlie, in part, the sex bias in diastolic function. C57BL/6J mice were placed on either a control diet (chow) or a high-fat diet supplemented with L-NAME. Heart tissue was isolated from the resulting 8 pairs of male mice and 7 pairs of female mice and RNA extracted from these hearts were sequenced. Differential expression was performed on the resulting counts.