TY - JOUR
T1 - Short communication
T2 - The antilipogenic effect of trans-10,cis-12 conjugated linoleic acid in bovine mammary epithelial cells is associated with proteasome activity and ATP production
AU - Shi, H. B.
AU - Tai, D. M.
AU - Wang, C.
AU - Liu, J. X.
AU - Loor, J. J.
AU - Liu, H. Y.
N1 - Funding Information:
This research was supported by the grants from the National Natural Science Foundation of China (grant no. 31702090) and the China Agriculture Research System (grant no. CARS-36). The authors have not stated any conflicts of interest.
Publisher Copyright:
© 2020 American Dairy Science Association
PY - 2020/10
Y1 - 2020/10
N2 - Proteasomes play a widespread role in the control of protein abundance via degrading ubiquitinated proteins. Activity of proteasomes is regulated by constitutive ATPases that respond to intracellular concentrations of ATP. Although recent data suggest a role of proteasomes in fatty acid metabolism, whether lipogenic activity in mammary cells is responsive to ATP concentrations and proteasome activity is unknown. To investigate whether proteasomes play a role in milk fat depression induced by trans-10,cis-12 conjugated linoleic acid (t10,c12 CLA), a bovine mammary epithelial cell line was treated with t10,c12 CLA for 24 h before analysis of lipogenic protein abundance. Western blot analysis of inactive sterol response element-binding protein-1 (pSREBP1) and active (nSREBP1) fragments indicated a decrease in abundance induced by exogenous t10,c12 CLA. At 150 nM t10,c12 CLA, abundance of both pSREBP1 and nSREBP1 was lowest, and decreased from basal levels by 16 and 64%, respectively. Exogenous t10,c12 CLA had no effect on abundance of peroxisome proliferator-activated receptor-gamma (PPARγ), but at 150 and 300 nM it decreased abundance of SREBF chaperone (SCAP). Inhibition of proteasome activity via incubation with MG-132 (a proteasome inhibitor) alone had no effect on pSREBP1, nSREBP1, PPARγ, or SCAP abundance. However, when cells were pre-incubated with MG-132, treatment with t10,c12 CLA reduced pSREBP1 (∼27%) and nSREBP1 (∼41%) abundance without affecting PPARγ or SCAP. Compared with the control, exogenous t10,c12 CLA increased ATP concentrations, and MG-132 alone had no effect. However, ATP concentration decreased markedly in cells incubated with both MG-132 and t10,c12 CLA. Combined with the alteration of SCAP and nSREBP1, the increase of ATP concentrations with t10,c12 CLA suggested that this fatty acid influenced the function of the SREBP1-SCAP complex through altering proteasome activity. Collectively, the current data highlight a role of proteasomes and intracellular ATP concentrations in the antilipogenic effect induced by t10,c12 CLA that leads to milk fat depression.
AB - Proteasomes play a widespread role in the control of protein abundance via degrading ubiquitinated proteins. Activity of proteasomes is regulated by constitutive ATPases that respond to intracellular concentrations of ATP. Although recent data suggest a role of proteasomes in fatty acid metabolism, whether lipogenic activity in mammary cells is responsive to ATP concentrations and proteasome activity is unknown. To investigate whether proteasomes play a role in milk fat depression induced by trans-10,cis-12 conjugated linoleic acid (t10,c12 CLA), a bovine mammary epithelial cell line was treated with t10,c12 CLA for 24 h before analysis of lipogenic protein abundance. Western blot analysis of inactive sterol response element-binding protein-1 (pSREBP1) and active (nSREBP1) fragments indicated a decrease in abundance induced by exogenous t10,c12 CLA. At 150 nM t10,c12 CLA, abundance of both pSREBP1 and nSREBP1 was lowest, and decreased from basal levels by 16 and 64%, respectively. Exogenous t10,c12 CLA had no effect on abundance of peroxisome proliferator-activated receptor-gamma (PPARγ), but at 150 and 300 nM it decreased abundance of SREBF chaperone (SCAP). Inhibition of proteasome activity via incubation with MG-132 (a proteasome inhibitor) alone had no effect on pSREBP1, nSREBP1, PPARγ, or SCAP abundance. However, when cells were pre-incubated with MG-132, treatment with t10,c12 CLA reduced pSREBP1 (∼27%) and nSREBP1 (∼41%) abundance without affecting PPARγ or SCAP. Compared with the control, exogenous t10,c12 CLA increased ATP concentrations, and MG-132 alone had no effect. However, ATP concentration decreased markedly in cells incubated with both MG-132 and t10,c12 CLA. Combined with the alteration of SCAP and nSREBP1, the increase of ATP concentrations with t10,c12 CLA suggested that this fatty acid influenced the function of the SREBP1-SCAP complex through altering proteasome activity. Collectively, the current data highlight a role of proteasomes and intracellular ATP concentrations in the antilipogenic effect induced by t10,c12 CLA that leads to milk fat depression.
KW - ATP
KW - proteasome
KW - protein expression
KW - trans-10,cis-12 conjugated linoleic acid
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U2 - 10.3168/jds.2019-17872
DO - 10.3168/jds.2019-17872
M3 - Article
C2 - 32828501
AN - SCOPUS:85089587071
SN - 0022-0302
VL - 103
SP - 9096
EP - 9101
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 10
ER -