Conjugated linoleic acid synthesis-related protein proteasome subunit α 5 (PSMA5) is increased by vaccenic acid treatment in goat mammary tissue

• Published in: Journal of dairy science 2012-08, Vol.95 (8), p.4286-4297
• Main Authors: Jin, Y.C., Li, Z.H., Hong, Z.S., Xu, C.X., Han, J.A., Choi, S.H., Yin, J.L., Zhang, Q.K., Lee, K.B., Kang, S.K., Song, M.K., Kim, Y.J., Kang, H.S., Choi, Y.J., Lee, H.G.
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; Biological and medical sciences; biosynthesis; Blotting, Western; Cattle; Cell Line; conjugated linoleic acid; conjugated linoleic acid biosynthesis; Electrophoresis, Gel, Two-Dimensional - veterinary; epithelial cells; Female; Food industries; Fundamental and applied biological sciences. Psychology; gene expression; goat milk; goats; Goats - metabolism; intravenous injection; lactation; Linoleic Acids, Conjugated - analysis; Linoleic Acids, Conjugated - genetics; Linoleic Acids, Conjugated - metabolism; macropain) subunit; mammary glands; Mammary Glands, Animal - metabolism; mammary tissue; mass spectrometry; messenger RNA; Milk - chemistry; Milk and cheese industries. Ice creams; Oleic Acids - pharmacology; proteasome (prosome; proteasome endopeptidase complex; proteins; Real-Time Polymerase Chain Reaction; RNA - chemistry; RNA - genetics; Spectrometry, Mass, Electrospray Ionization - veterinary; stearoyl-CoA desaturase; Terrestrial animal productions; two-dimensional gel electrophoresis; vaccenic acid; Vertebrates; Western blotting; α type 5 (PSMA5)
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2011-4281

This study was conducted to identify proteins associated with the endogenous synthesis of conjugated linoleic acid (CLA) from trans-vaccenic acid (TVA; trans-11 C18:1, a precursor for CLA endogenous synthesis) in mammary tissues. Six lactating goats were divided into 2 groups. One group was given an intravenous bolus injection of TVA (150mg) twice daily over 4 d; the other group received saline injections. Treatment with TVA increased the concentration of cis-9,trans-11 CLA and TVA in goat milk. Additionally, TVA treatment increased the expression of stearoyl-CoA desaturase (SCD) in mammary tissue. Using 2-dimensional gel electrophoresis and electrospray ionization quadrupole time-of-flight mass spectrometry, 3 proteins affected by infusions of TVA were identified. Proteasome (prosome, macropain) subunit α type 5 (PSMA5) was upregulated, whereas peroxiredoxin-1 and translationally controlled tumor protein 1 were downregulated in TVA-treated animals compared with the vehicle-injected controls. Only the effect of TVA on PSMA5 could be confirmed by Western blot analysis. To further explore the regulation of PSMA5 in mammary epithelial cells when TVA is converted into CLA, we used a differentiated bovine mammary epithelial cell line treated with TVA for 6h. Changes in cis-9,trans-11 CLA concentrations and mRNA expression patterns of both SCD and PSMA5 were monitored. The concentration of cis-9,trans-11 CLA increased after TVA treatment. The mRNA expression level of PSMA5 was significantly elevated to 6h, but SCD mRNA expression only increased in 2h after TVA treatment. These results indicate that PSMA5 is highly expressed in goat mammary tissue and bovine mammary epithelial cells when TVA is converted into CLA. Our data suggest that PSMA5 protein is associated with CLA biosynthesis in mammary tissue.