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Molecules 2013, 18(1), 263-275; doi:10.3390/molecules18010263

Proteomic and Functional Analyses Reveal MAPK1 Regulates Milk Protein Synthesis

Key laboratory of Dairy Science of Education Ministry, Northeast Agricultural University, Harbin 150030, Heilongjiang, China
* Author to whom correspondence should be addressed.
Received: 18 October 2012 / Revised: 11 December 2012 / Accepted: 18 December 2012 / Published: 27 December 2012
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L-Lysine (L-Lys) is an essential amino acid that plays fundamental roles in protein synthesis. Many nuclear phosphorylated proteins such as Stat5 and mTOR regulate milk protein synthesis. However, the details of milk protein synthesis control at the transcript and translational levels are not well known. In this current study, a two-dimensional gel electrophoresis (2-DE)/MS-based proteomic technology was used to identify phosphoproteins responsible for milk protein synthesis in dairy cow mammary epithelial cells (DCMECs). The effect of L-Lys on DCMECs was analyzed by CASY technology and reversed phase high performance liquid chromatography (RP-HPLC). The results showed that cell proliferation ability and β-casein expression were enhanced in DCMECs treated with L-Lys. By phosphoproteomics analysis, six proteins, including MAPK1, were identified up-expressed in DCMECs treated with 1.2 mM L-Lys for 24 h, and were verified by quantitative real-time PCR (qRT-PCR) and western blot. Overexpression and siRNA inhibition of MAPK1 experiments showed that MAPK1 upregulated milk protein synthesis through Stat5 and mTOR pathway. These findings that MAPK1 involves in regulation of milk synthesis shed new insights for understanding the mechanisms of milk protein synthesis.
Keywords: proteomic; L-lysine; dairy cow mammary epithelial cells; MAPK1; Stat5; mTOR proteomic; L-lysine; dairy cow mammary epithelial cells; MAPK1; Stat5; mTOR
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Lu, L.-M.; Li, Q.-Z.; Huang, J.-G.; Gao, X.-J. Proteomic and Functional Analyses Reveal MAPK1 Regulates Milk Protein Synthesis. Molecules 2013, 18, 263-275.

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