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We previously reported that perirenal adipocytes in yak calves undergo a remarkable transformation during the early postnatal period (1–30 days), during which lipid droplets (LDs) consolidate from numerous small multilocular structures into a single unilocular droplet. However, the molecular mechanisms underlying this developmental transition remain poorly understood. Perilipin 1 (PLIN1), which is highly expressed in adipocytes, promotes the formation of unilocular LDs and plays a critical role in regulating lipolysis. Based on these findings, we aimed to elucidate the role of PLIN1 in unilocular LD formation in perirenal adipocytes. PLIN1 expression and localization were analyzed in perirenal adipose tissue of yak calves at different postnatal stages (1 and 30 days) and during in vitro adipocyte differentiation. Functional roles of PLIN 1 were assessed using inhibition experiments to evaluate its effects on lipid droplet morphology, lipid accumulation, and the expression of lipolysis-related genes and proteins. In addition, cold exposure experiments were performed to examine changes in thermogenic and lipolytic markers. The results of the current study revealed that PLIN 1 was localized in both brown and white adipocytes, with significantly higher mRNA and protein expression levels in 30-day-old calves than in 1-day-old calves. During in vitro perirenal adipocyte differentiation, PLIN 1 mRNA expression peaked on day nine. Notably, inhibition of PLIN 1 led to reduced LD size and lipid accumulation, elevated free fatty acid (FFA) content, and upregulation of mRNA and protein expression of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). Furthermore, cold exposure increased the expression levels of PLIN 1, HSL , ATGL , UCP 1, PPARα , PGC -1 α , and COX 7 A 1, and elevated UCP1 protein abundance. In conclusion, our findings indicate that PLIN1 mediates LDs growth and lipolysis in the perirenal adipocytes of yak calves, thereby providing theoretical insights into the molecular mechanisms governing the brown-to-white phenotypic transition during early postnatal development in yaks.
Bai et al. (Mon,) studied this question.