Mitochondrial miRNAs (mitomiRs): Plausible key players of metabolic stress induced sub-fertility in high yielding cows
Animal Breeding, Animal Nutrition, Animal Husbandry
Final Report Abstract
Dairy cows frequently experience negative energy balance (NEB) during the perinatal period as energy demands are not met via feed intake. NEB leads to the mobilization of fat reserves, raising levels of free fatty acids (FFAs) in blood plasma, which infiltrates the follicular fluid and affect ovarian follicle function. In this study, we explored the role of FFAs on ovarian follicular granulosa cells, which are the primary source of female sex steroid (estradiol) production. Our findings indicate contrasting effects for saturated and unsaturated fatty acids: unsaturated FFAs such as oleic acid (OA) and alpha-linolenic acid (ALA) decrease estradiol production, while saturated FFAs such as palmitic (PA) and stearic (SA) acids increase estradiol levels compared to control. Under physiological conditions, however, both types of FFAs coexist in blood and follicular fluid. Our analysis of the combined effect of OA, PA, and SA on granulosa cell estradiol production revealed no significant impact, suggesting that the physiological mixture of FFAs may yield a net neutral effect. We also assessed how elevated FFAs influence glucose metabolism in granulosa cells. Results showed that unsaturated fatty acid treatments induce glucose consumption and drive the metabolic reprogramming by increasing the aerobic glycolysis. In contrast, saturated fatty acids did not affect glucose metabolism. Mitochondrial membrane potential (MMP) analysis revealed that unsaturated fatty acids lower the MMP, indicating reduced mitochondrial activity, that has not been observed with saturated FFAs. Combined treatment of both FFA types had yet again no effect on MMP but slightly yet significantly inhibited glucose uptake compared to BSA. These findings suggest that saturated and unsaturated FFAs produce opposing effects on steroid production and energy metabolism in granulosa cells. However, under physiological conditions, they pose a net neutral effect. Additional analysis highlighted that the AKT and MAPK3/1 signaling pathways are activated by unsaturated FFAs, influencing estradiol production (through regulation of CYP19A1) and glucose metabolism. Since physiological NEFA mixtures do not induce significant alternations in GCs function, we have used only OA and PA treatments to determine the mitomiR profiles in GCs. Various steps have been taken to prevent contamination of cytoplasmic RNA species. RNA sequencing showed no distinct clustering of PA, OA and BSA samples in PCA analysis. Furthermore, mitomiRs did not show significant differences in their expression between different groups analyzed. Let-7a-5p is one of the most abundant mitomiR in all the groups, which is involved in the regulation of mitochondrial gene expression and oxidative phosphorylation. We conducted genome-wide gene expression analysis of BSA and physiological NEFA mixture treated cells. Results revealed that 176 genes are differently regulated by NEFA mixture and are involved in energy metabolism, insulin sensitivity, and cell death. In conclusion, our results suggest that elevated FFAs may not directly impact granulosa cell steroid production in physiological conditions. Though mitomiRs regulate the mitochondrial processes, current research finds no significant regulation of mitomiR expression by FFAs. Future research could explore the impact of elevated NEFA on the production gonadotropins, oocyte maturation and developmental competence for providing further insights into metabolic stress-induced subfertility in dairy animals.
Publications
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Non-esterified fatty acids in the ovary: friends or foes?. Reproductive Biology and Endocrinology, 18(1).
Baddela, Vijay Simha; Sharma, Arpna & Vanselow, Jens
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Estradiol production of granulosa cells is unaffected by the physiological mix of nonesterified fatty acids in follicular fluid. Journal of Biological Chemistry, 298(10), 102477.
Baddela, Vijay Simha; Michaelis, Marten; Sharma, Arpna; Plinski, Christian; Viergutz, Torsten & Vanselow, Jens
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Palmitic acid protects granulosa cells from oleic acid induced steatosis and rescues progesterone production via cAMP dependent mechanism. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 1867(8), 159159.
Baddela, Vijay Simha; Sharma, Arpna; Plinski, Christian & Vanselow, Jens
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ERK1/2-SOX9/FOXL2 axis regulates ovarian steroidogenesis and favors the follicular–luteal transition. Life Science Alliance, 6(10), e202302100.
Baddela, Vijay Simha; Michaelis, Marten; Tao, Xuelian; Koczan, Dirk & Vanselow, Jens
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Saturated fatty acids inhibit unsaturated fatty acid induced glucose uptake involving GLUT10 and aerobic glycolysis in bovine granulosa cells. Scientific Reports, 14(1).
Tao, Xuelian; Rahimi, Maryam; Michaelis, Marten; Görs, Solvig; Brenmoehl, Julia; Vanselow, Jens & Baddela, Vijay Simha
