Heat stress induces sphingomyelin and ceramide turnover to prime apoptosis in chicken follicular granulosa cells

報告時間：2025-6-20
報告地點：Room 407
指導老師：Hsin-I Chiang
學生：Chi-Yun Chang
摘要

Heat stress (HS) affects ovarian function and follicular development in laying hens, leading to reduced egg production. Apoptosis of granulosa cells (GC) plays a key role in small white follicle (SWF) atresia. GC secrete sex steroids, and elevated progesterone (P4) levels are regarded as a marker of follicular maturation. Studies have shown that intracellular ceramide (Cer) is a critical second messenger in inducing GC apoptosis. Both Cer and sphingomyelin (SM) belong to the sphingolipid family and are involved in various physiological processes, including apoptosis and cell differentiation. Sphingomyelin synthases (SMS) play a pivotal role in Cer/SM turnover by catalyzing the turnover of Cer and phosphatidylcholine (PC) into SM and diacylglycerol (DAG). Although SMS-mediated Cer/SM turnover has been shown to regulate cell survival and proliferation, its role under HS conditions in poultry remains largely unexplored. This study aimed to explore the relationship between HS-induced GC apoptosis and Cer/SM turnover using SMS2 overexpression (OE) and knockdown (KD) models. The result showed SMS2 protein expression decreased 30 minutes after HS and gradually recovered, with more significant changes in OE and KD groups during recovery. SM levels increased after HS in the control group, then declined, while OE and KD groups showed an opposite trend. Cer levels rose in all groups after HS, with OE showing a smaller increase and rapid recovery, whereas KD accumulated Cer. CCK-8 assays showed significant reductions in cell viability after HS, especially in the Blank and KD groups. Caspase 3/7 activity increased at 180 minutes post-HS and peaked at 2 hours of recovery in all groups, but remained lower in KD than OE. In conclusion, HS induces GC apoptosis through SMS2-regulated Cer/SM turnover, contributing to follicular atresia.

Keywords: heat stress, granulosa cells, ceramide, sphingomyelin, chickens
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