Meng Meijuan, Li Xuerui, Zhou Shendong, Shi Xiaoli, Shen Xiangzhen, Chang Guangjun
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
National Experimental Teaching Demonstration Center for Animal Science, Nanjing Agricultural University, Nanjing 210095, China.
J Agric Food Chem. 2024 Dec 4;72(48):26733-26745. doi: 10.1021/acs.jafc.4c06875. Epub 2024 Nov 21.
Ca is an important regulator of endoplasmic reticulum (ER) and mitochondrial function. Store-operated calcium entry (SOCE) serves as the predominant pathway for the influx of extracellular Ca into the cell. ORAI1, ORAI2, and ORAI3 are the main proteins of SOCE. Ca disturbance leads to ER stress and mitochondrial damage. β-Carotene (β-C) is a precursor of vitamin A and has anti-inflammatory and antioxidant effects. However, it remains unclear if β-C mitigates ER stress and mitochondrial dysfunction triggered by LPS and its underlying molecular mechanisms have not been fully elucidated in bovine mammary epithelial cells (BMECs). Therefore, the experiment aimed to explore the protective mechanism of β-C. Results showed that LPS increased the ORAI1 expression, and caused ER stress by upregulating the expression of ER stress-related genes and proteins in BMECs. LPS also caused mitochondrial dysfunction by decreasing mitochondrial fusion proteins and increasing mitochondrial division and apoptosis proteins. Silencing ORAI1 mitigated ER stress and mitochondrial impairment caused by LPS. Conversely, elevated ORAI1 levels induced similar stress and damage in BMECs. β-C pretreatment resulted in diminished ORAI1 expression and a reduction in ER stress and mitochondrial dysfunction triggered by LPS. However, ORAI1 overexpression blocked the protective effects of β-C. In conclusion, β-C alleviated the LPS-induced ER stress and mitochondria dysfunction in an ORAI1-dependent manner. Our findings provide a mechanistic basis for further exploration of the regulatory effects of β-C on mammary injuries.
钙是内质网（ER）和线粒体功能的重要调节因子。钙库操纵性钙内流（SOCE）是细胞外钙流入细胞的主要途径。ORAI1、ORAI2和ORAI3是SOCE的主要蛋白。钙紊乱会导致内质网应激和线粒体损伤。β-胡萝卜素（β-C）是维生素A的前体，具有抗炎和抗氧化作用。然而，β-C是否能减轻脂多糖（LPS）引发的内质网应激和线粒体功能障碍尚不清楚，其潜在分子机制在牛乳腺上皮细胞（BMECs）中也未得到充分阐明。因此，本实验旨在探索β-C的保护机制。结果表明，LPS增加了ORAI1的表达，并通过上调BMECs中内质网应激相关基因和蛋白的表达引起内质网应激。LPS还通过降低线粒体融合蛋白、增加线粒体分裂和凋亡蛋白导致线粒体功能障碍。沉默ORAI1可减轻LPS引起的内质网应激和线粒体损伤。相反，ORAI1水平升高在BMECs中诱导了类似的应激和损伤。β-C预处理导致ORAI1表达降低，并减少了LPS引发的内质网应激和线粒体功能障碍。然而，ORAI1过表达阻断了β-C的保护作用。总之，β-C以ORAI1依赖的方式减轻了LPS诱导的内质网应激和线粒体功能障碍。我们的研究结果为进一步探索β-C对乳腺损伤的调节作用提供了机制基础。
