AUTHOR=Iqbal Ambreen , Ziyi Pan , Yu Haibin , Jialing Li , Haochen Wu , Jing Fan , Ping Jiang , Zhihui Zhao 

TITLE=C4BPA: A Novel Co-Regulator of Immunity and Fat Metabolism in the Bovine Mammary Epithelial Cells

JOURNAL=Frontiers in Genetics

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2021.830566

DOI=10.3389/fgene.2021.830566

ISSN=1664-8021

ABSTRACT=<p>The C4b binding protein alpha (C4BPA) chain primarily engages in critical inflammatory and coagulation processes. The previous transcriptomic analysis showed that <italic>C4BPA</italic> is a differentially expressed gene in lower and higher fat content mammary gland cell lines from Chinese Holstein. This study aimed to investigate the effects of <italic>C4BPA</italic> on the inflammation and milk fat synthesis in bMECs by <italic>C4BPA</italic> knockdown and overexpression. The results highlighted that knockdown of <italic>C4BPA</italic> in bMECs could suppress the mRNA and protein expression of <italic>IL-6, IL-8, IL-12</italic>, and the TLR-4/NF-κB pathway-related genes and promote the expression of complement and coagulation cascade pathways related genes as well as <italic>TNF-α</italic>. Moreover, knockdown of <italic>C4BPA</italic> expression in bMECs reduced the content of triglyceride (TG) and cholesterol (CHOL) in bMECs, increased NEFA content, reduced mRNA and protein expression of <italic>ACSL1</italic> and <italic>PPARA</italic>, and increased the mRNA and protein expression of <italic>ELOVL6</italic>, <italic>FADS1</italic>, and <italic>LPL</italic>. The bMECs, with the overexpression of <italic>C4BPA</italic>, showed the enhanced expression of <italic>TLR-4/NF-κB</italic> linked genes, <italic>IL-6</italic>, <italic>IL-8</italic>, <italic>IL-12</italic>, and mRNA and protein level while reduced mRNA expression of <italic>TNF-α</italic>, compliment, and coagulation cascade related genes was observed. In bMECs, overexpression of <italic>C4BPA</italic> enhanced the content of TG and CHOL while reducing NEFA and stimulated the mRNA and protein expression of <italic>ACSL1</italic>, <italic>PPARA</italic>, and <italic>PPARG</italic> genes while inhibiting the mRNA and protein expression of <italic>FADS1</italic> and <italic>LPL</italic> genes. Our results show that <italic>C4BPA</italic> not only regulates the lipid metabolism through the PPAR signaling pathway in bMECs but also contributes to the inflammatory response through TLR-4/NF-κB and the complement and coagulation cascade pathways. This study, for the first time, provides the primary basis for understanding the role of <italic>C4BPA</italic> in immunity and fat metabolism, which enables the researchers for innovative direction to investigate genes associated with fat metabolism and immunity. This study also advocates that the breeders must pay attention to such type of genes with multiple functions during animal breeding.</p>