College of Agriculture, Guangdong Ocean University, Zhanjiang, 524088, P. R. China.
College of Animal Science, Jilin University, Changchun, 130062, P. R. China.
J Dairy Sci. 2020 Jul;103(7):6661-6671. doi: 10.3168/jds.2019-17415. Epub 2020 Apr 29.
The CD44 gene encodes a cell-surface glycoprotein that participates in a variety of biological processes such as cell interactions, adhesion, hematopoiesis, and tumor metastasis. We compared the transcriptome in bovine mammary epithelial cells (bMEC) of Chinese Holstein dairy cows producing milk of high and low fat contents. Our results suggest that CD44 might be a candidate gene affecting milk fat synthesis. In the present study, the overexpression of the CD44 gene increased the contents of intracellular triglycerides (TG) and cholesterol (CHOL), whereas knockdown of the CD44 gene decreased bMEC CHOL and TG contents. Gas chromatography analysis of fatty acid composition showed that the contents of α-linolenic acid, palmitic acid, and cis-8,11,14-eicosatrienoic acid were altered due to changes in the level of expression of the CD44 gene. Additionally, elaidic acid, palmitoleic acid, tridecanoic acid, and oleic acid were markedly reduced in the CD44 gene overexpression group compared with the control group. On the contrary, cis-5,8,11,14-eicosatetraenoic acid and stearic acid were markedly increased in the CD44 knockdown group compared with the control group. And RT Profiler PCR array (Qiagen, CLAB24070A Frankfurt, Germany) further suggested that overexpression or knockdown of the CD44 gene altered expression levels of functional genes associated with lipid metabolism. The present data indicate that CD44 plays a key regulatory role in lipid metabolism in bMEC.
CD44 基因编码一种细胞表面糖蛋白，参与多种生物学过程，如细胞相互作用、黏附、造血和肿瘤转移。我们比较了中国荷斯坦奶牛产高、低脂奶的乳腺上皮细胞（bMEC）的转录组。我们的结果表明，CD44 可能是影响乳脂合成的候选基因。在本研究中，CD44 基因的过表达增加了细胞内甘油三酯（TG）和胆固醇（CHOL）的含量，而 CD44 基因的敲低降低了 bMEC CHOL 和 TG 的含量。脂肪酸组成的气相色谱分析表明，由于 CD44 基因表达水平的变化，α-亚麻酸、棕榈酸和顺式-8,11,14-二十碳三烯酸的含量发生了改变。此外，与对照组相比，CD44 基因过表达组中的反式油酸、棕榈油酸、十三烷酸和油酸明显减少。相反，与对照组相比，CD44 基因敲低组中的顺式-5,8,11,14-二十碳四烯酸和硬脂酸明显增加。并且 RT Profiler PCR 阵列（Qiagen，CLAB24070A Frankfurt，德国）进一步表明，CD44 基因的过表达或敲低改变了与脂质代谢相关的功能基因的表达水平。本数据表明，CD44 在 bMEC 的脂质代谢中发挥关键调节作用。
