Abstract
Introduction: Dysregulation of cardiac-enriched microRNA (miRNA) expression is linked to age-associated cardiovascular diseases (CVDs). However, the sex-specificity and age at which dysregulation occurs remain unclear. Given the conserved nature of miRNAs and short lifespan of D. melanogaster (fruit flies), we investigated age-related changes in the expression of cardiac enriched miRNAs (miR-1, -9, -34a, -133, target miRNAs) and their impact on the cardiac tube in male and female flies.
Methods: Cardiac tube tissues were collected from male and female flies (n=5 per group) at 7-day intervals from day 7 to 70. miRNAs and target mRNA gene (KCNQ, MRTF, SIRT2, CCN) expression were quantified by RT-qPCR (n=4-6 per group). Myofibril diameter was assessed by Masson's Trichrome staining (n=4-6) to determine the structural effects of hypertrophic miR-9.
Results: In females, miR-1 was downregulated with age (p= <0.0001), whereas in males, miR-9 (p= <0.0001) and miR-34a (p = 0.0017) were downregulated. Interestingly, miR-133 was downregulated in both sexes (p= <0.0001). In males, MRTF(miR-9 target) and CCN (miR-133 target) expression increased with age (p=0.016 and p=0.013, respectively), whereas in females, KCNQ (miR-1 target) and CCN expression decreased (p=0.03 and p=0.002, respectively). Myofibril thickness significantly increased with age in both sexes (p<0.0001). miR-9 downregulation may contribute to this effect in males, while the mechanism in females remains unclear.
Conclusion: This study provides novel insights into sex-specific miRNA dysregulation in cardiac aging, emphasizing the need to consider sex differences in miRNA-mediated cardiovascular aging and the potential of miRNAs as diagnostic tools in age-related CVDs.