TY - JOUR
T1 - Sirtuin 1 is involved in oleic acid-induced calf hepatocyte steatosis via alterations in lipid metabolism-related proteins
AU - Ding, Hongyan
AU - Li, Yu
AU - Liu, Leihong
AU - Hao, Ning
AU - Zou, Suping
AU - Jiang, Qianming
AU - Liang, Yusheng
AU - Ma, Nana
AU - Feng, Shibing
AU - Wang, Xichun
AU - Wu, Jinjie
AU - Loor, Juan J.
N1 - Publisher Copyright:
© 2021 Oxford University Press. All rights reserved.
PY - 2021/10/1
Y1 - 2021/10/1
N2 - Sirtuin 1 (SIRT1), an NAD-dependent protein deacetylase, plays a central role in the control of lipid metabolism in nonruminants. However, the role of SIRT1 in hepatic lipid metabolism in dairy cows with fatty liver is not well known. Thus, we used isolated primary bovine hepatocytes to determine the role of SIRT1 in protecting cells against oleic acid (OA)-induced steatosis. Recombinant adenoviruses to overexpress (AD-GFP-SIRT1-E) or knockdown (AD-GFP-SIRT1-N) SIRT1 were used for transduction of hepatocytes. Calf hepatocytes isolated from five female calves (1 d old, 30 to 40 kg) were used to determine both time required and the lowest dose of OA that could induce triacylglycerol (TAG) accumulation. Analyses indicated that 0.25 mM OA for 24 h was suitable to induce TAG accumulation. In addition, OA not only led to an increase in TAG, but also upregulated mRNA and protein abundance of sterol regulatory element-binding transcription factor 1 (SREBF1) and downregulated SIRT1 and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PPARGC1A). Thus, these in vitro conditions were deemed optimal for subsequent experiments. Calf hepatocytes were cultured and incubated with OA (0.25 mM) for 24 h, followed by adenoviral AD-GFP-SIRT1-E or AD-GFP-SIRT1-N transduction for 48 h. Overexpression of SIRT1 led to greater protein and mRNA abundance of SIRT1 along with fatty acid oxidation-related genes including PPARGC1A, peroxisome proliferator-activated receptor alpha (PPARA), retinoid X receptor α (RXRA), and ratio of phospho-acetyl-CoA carboxylase alpha (p-ACACA)/total acetyl-CoA carboxylase alpha (ACACA). In contrast, it resulted in lower protein and mRNA abundance of genes related to lipid synthesis including SREBF1, fatty acid synthase (FASN), apolipoprotein E (APOE), and low-density lipoprotein receptor (LDLR). The concentration of TAG decreased due to SIRT1 overexpression. In contrast, silencing SIRT1 led to lower protein and mRNA abundance of SIRT1, PPARGC1A, PPARA, RXRA, and greater protein and mRNA abundance of SREBF1, FASN, APOE, and LDLR. Further, those responses were accompanied by greater content of cellular TAG and total cholesterol (TC). Overall, data from these in vitro studies indicated that SIRT1 is involved in the regulation of lipid metabolism in calf hepatocytes subjected to an increase in the supply of OA. Thus, it is possible that alterations in SIRT1 abundance and activity in vivo contribute to development of fatty liver in dairy cows.
AB - Sirtuin 1 (SIRT1), an NAD-dependent protein deacetylase, plays a central role in the control of lipid metabolism in nonruminants. However, the role of SIRT1 in hepatic lipid metabolism in dairy cows with fatty liver is not well known. Thus, we used isolated primary bovine hepatocytes to determine the role of SIRT1 in protecting cells against oleic acid (OA)-induced steatosis. Recombinant adenoviruses to overexpress (AD-GFP-SIRT1-E) or knockdown (AD-GFP-SIRT1-N) SIRT1 were used for transduction of hepatocytes. Calf hepatocytes isolated from five female calves (1 d old, 30 to 40 kg) were used to determine both time required and the lowest dose of OA that could induce triacylglycerol (TAG) accumulation. Analyses indicated that 0.25 mM OA for 24 h was suitable to induce TAG accumulation. In addition, OA not only led to an increase in TAG, but also upregulated mRNA and protein abundance of sterol regulatory element-binding transcription factor 1 (SREBF1) and downregulated SIRT1 and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PPARGC1A). Thus, these in vitro conditions were deemed optimal for subsequent experiments. Calf hepatocytes were cultured and incubated with OA (0.25 mM) for 24 h, followed by adenoviral AD-GFP-SIRT1-E or AD-GFP-SIRT1-N transduction for 48 h. Overexpression of SIRT1 led to greater protein and mRNA abundance of SIRT1 along with fatty acid oxidation-related genes including PPARGC1A, peroxisome proliferator-activated receptor alpha (PPARA), retinoid X receptor α (RXRA), and ratio of phospho-acetyl-CoA carboxylase alpha (p-ACACA)/total acetyl-CoA carboxylase alpha (ACACA). In contrast, it resulted in lower protein and mRNA abundance of genes related to lipid synthesis including SREBF1, fatty acid synthase (FASN), apolipoprotein E (APOE), and low-density lipoprotein receptor (LDLR). The concentration of TAG decreased due to SIRT1 overexpression. In contrast, silencing SIRT1 led to lower protein and mRNA abundance of SIRT1, PPARGC1A, PPARA, RXRA, and greater protein and mRNA abundance of SREBF1, FASN, APOE, and LDLR. Further, those responses were accompanied by greater content of cellular TAG and total cholesterol (TC). Overall, data from these in vitro studies indicated that SIRT1 is involved in the regulation of lipid metabolism in calf hepatocytes subjected to an increase in the supply of OA. Thus, it is possible that alterations in SIRT1 abundance and activity in vivo contribute to development of fatty liver in dairy cows.
KW - dairy cow
KW - lipid metabolism
KW - sirtuin1
KW - steatosis
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U2 - 10.1093/jas/skab250
DO - 10.1093/jas/skab250
M3 - Article
C2 - 34436591
AN - SCOPUS:85118096259
SN - 0021-8812
VL - 99
JO - Journal of animal science
JF - Journal of animal science
IS - 10
M1 - skab250
ER -