Zhu Jiangjiang, Sun Yuting, Luo Jun, Wu Min, Li Jianhua, Cao Yanhong
Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
Guangxi Institute of Animal Husbandry, Guangxi Zhuang Autonomous Region, Nanning 530000, China.
Int J Mol Sci. 2015 Jan 14;16(1):1806-20. doi: 10.3390/ijms16011806.
Specificity protein 1 (SP1) is a ubiquitous transcription factor that plays an important role in controlling gene expression. Although important in mediating the function of various hormones, the role of SP1 in regulating milk fat formation remains unknown. To investigate the sequence and expression information, as well as its role in modulating lipid metabolism, we cloned SP1 gene from mammary gland of Xinong Saanen dairy goat. The full-length cDNA of the SP1 gene is 4376 bp including 103 bp of 5'UTR, 2358 bp of ORF (HM_236311) and 1915 bp of 3'UTR, which is predicted to encode a 786 amino acids polypeptide. Phylogenetic tree analysis showed that goat SP1 has the closest relationship with sheep, followed by bovines (bos taurus, odobenus and ceratotherium), pig, primates (pongo, gorilla, macaca and papio) and murine (rattus and mus), while the furthest relationship was with canis and otolemur. Expression was predominant in the lungs, small intestine, muscle, spleen, mammary gland and subcutaneous fat. There were no significant expression level differences between the mammary gland tissues collected at lactation and dry-off period. Overexpression of SP1 in goat mammary epithelial cells (GMECs) led to higher mRNA expression level of peroxisome proliferator-activated receptor-γ (PPARγ) and lower liver X receptor α (LXRα) mRNA level, both of which were crucial in regulating fatty acid metabolism, and correspondingly altered the expression of their downstream genes in GMECs. These results were further enhanced by the silencing of SP1. These findings suggest that SP1 may play an important role in fatty acid metabolism.
特异性蛋白1（SP1）是一种普遍存在的转录因子，在控制基因表达中起重要作用。尽管SP1在介导各种激素的功能方面很重要，但其在调节乳脂肪形成中的作用仍不清楚。为了研究其序列和表达信息，以及它在调节脂质代谢中的作用，我们从西农萨能奶山羊的乳腺中克隆了SP1基因。SP1基因的全长cDNA为4376 bp，包括5'UTR的103 bp、开放阅读框（ORF，HM_236311）的2358 bp和3'UTR的1915 bp，预计编码一个786个氨基酸的多肽。系统发育树分析表明，山羊SP1与绵羊的关系最密切，其次是牛（黄牛、海象和白犀牛）、猪、灵长类动物（猩猩、大猩猩、猕猴和狒狒）和鼠类（大鼠和小鼠），而与犬类和懒猴的关系最远。SP1在肺、小肠、肌肉、脾脏、乳腺和皮下脂肪中表达占优势。泌乳期和干奶期采集的乳腺组织之间的表达水平没有显著差异。在山羊乳腺上皮细胞（GMECs）中过表达SP1导致过氧化物酶体增殖物激活受体-γ（PPARγ）的mRNA表达水平升高，而肝脏X受体α（LXRα）的mRNA水平降低，这两者在调节脂肪酸代谢中都至关重要，并相应地改变了它们在GMECs中的下游基因的表达。SP1沉默进一步增强了这些结果。这些发现表明，SP1可能在脂肪酸代谢中起重要作用。
