Pan Jiajing, Jin Yongguo, Jin Haobo, Li Chengliang, Zhang Yan, Liu Yuanyi, Jin Guofeng, Zhao Jianying, He Lichao, Sheng Long
School of Food and Health, Beijing Technology and Business University, Beijing, China.
College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China.
J Sci Food Agric. 2023 Dec;103(15):7517-7528. doi: 10.1002/jsfa.12857. Epub 2023 Jul 26.
Lipid droplets (LDs) are important multifunctional organelles responsible for lipid metabolism of postmortem muscle. However, the dynamics in their building blocks (cores and layers) and phosphorylation of lipid droplet-related proteins (LDRPs) regulating meat lipolysis remain unknown at salt-stimulated conditions.
LDRPs extracted from cured porcine biceps femoris (1% and 3% salt) were subjected to label-free quantitative phosphoproteomic analysis and LDs morphological validation. Results indicated that 3% salt curing significantly decreased triglyceride (TG) content with increase in glycerol and decrease in LDs fluorescence compared to 1% salt curing. Comparative phosphoproteomics showed that there were significant changes in phosphorylation at 386 sites on 174 LDRPs between assayed groups (P < 0.05). These differential proteins were mainly involved in lipid and carbohydrate metabolism. Curing of 3% salt induced more site-specific phosphorylation of perilipin 1 (PLIN1, at Ser81) and adipose triglyceride lipase (ATGL, at Ser399) than 1%, whereas the phosphorylation (at Ser600) of hormone-sensitive lipase (HSL) was up-regulated. Ultrastructure imaging showed that LDs were mostly associated with mitochondria, and the average diameter of LDs decreased from 2.34 μm (1% salt) to 1.73 μm (3% salt).
Phosphoproteomics unraveled salt-stimulated LDRPs phosphorylation of cured porcine meat provoked intensified lipolysis. Curing of 3% salt allowed an enhanced lipolysis than 1% by up-regulating the phosphorylation sites of LDRPs and recruited lipases. The visible splitting of LDs, together with sarcoplasmic disorganization, supported the lipolysis robustness following 3% salt curing. The finding provides optimization ideas for high-quality production of cured meat products. © 2023 Society of Chemical Industry.
脂滴（LDs）是负责死后肌肉脂质代谢的重要多功能细胞器。然而，在盐刺激条件下，其组成部分（核心和层）的动态变化以及调节肉类脂肪分解的脂滴相关蛋白（LDRPs）的磷酸化情况仍不清楚。
对从腌制猪股二头肌（1%和3%盐）中提取的LDRPs进行了无标记定量磷酸化蛋白质组分析和脂滴形态学验证。结果表明，与1%盐腌制相比，3%盐腌制显著降低了甘油三酯（TG）含量，甘油增加，脂滴荧光降低。比较磷酸化蛋白质组学表明，测定组之间174种LDRPs的386个位点的磷酸化存在显著变化（P < 0.05）。这些差异蛋白主要参与脂质和碳水化合物代谢。3%盐腌制比1%盐腌制诱导更多的 perilipin 1（PLIN1，Ser81位点）和脂肪甘油三酯脂肪酶（ATGL，Ser399位点）的位点特异性磷酸化，而激素敏感性脂肪酶（HSL）的磷酸化（Ser600位点）上调。超微结构成像显示，脂滴大多与线粒体相关，脂滴的平均直径从1%盐时的2.34μm降至3%盐时的1.73μm。
磷酸化蛋白质组学揭示了盐刺激下腌制猪肉LDRPs的磷酸化引发了强化的脂肪分解。3%盐腌制通过上调LDRPs的磷酸化位点和募集脂肪酶，比1%盐腌制能增强脂肪分解。脂滴的明显分裂以及肌浆紊乱，支持了3%盐腌制后的脂肪分解强度。该发现为腌制肉制品的高质量生产提供了优化思路。© 2023化学工业协会。
