文献类型： 外文期刊

作者： Ma, Y. F. ¹ ; Batistel, F. ⁴ ; Xu, T. L. ⁵ ; Han, L. Q. ⁶ ; Bucktrout, R. ² ; Liang, Y. ² ; Coleman, D. N. ² ; Parys, C.; ¹ ;

作者机构： 1.Inner Mongolia Acad Agr & Anim Husb Sci, Inst Anim Nutr & Feed, Hohhot 010031, Peoples R China

2.Univ Illinois, Dept Anim Sci, Urbana, IL 61801 USA

3.Univ Illinois, Div Nutr Sci, Urbana, IL 61801 USA

4.Utah State Univ, Dept Anim Dairy & Vet Sci, Logan, UT 84322 USA

5.Nanjing Agr Univ, Coll Vet Med, Nanjing 210095, Jiangsu, Peoples R China

6.Henan Agr Univ, Dept Anim Sci & Vet Med, Zhengzhou 450002, Henan, Peoples R China

7.Evonik Nutr & Care GmbH, D-63457 Hanau, Germany

关键词： lactation; transition period; amino acid; mammary gland

期刊名称：JOURNAL OF DAIRY SCIENCE （ 影响因子：4.034； 五年影响因子：4.354 ）

ISSN： 0022-0302

年卷期： 2019 年 102 卷 5 期

页码：

收录情况： SCI

摘要： The main objective was to evaluate the effect of increasing the supply of Met around parturition on abundance and phosphorylation of insulin-and mechanistic target of rapamycin complex 1 (mTORC1)-related signaling proteins along with mRNA abundance of milk protein and fat synthesis-related genes in postpartal mammary tissue. A basal control diet (control) or the basal diet plus ethyl-cellulose rumen-protected Met (0.9 g/kg of dry matter intake; Mepron, Evonik Nutrition & Care GmbH, Hanau-Wolfgang, Germany) were fed (n = 30 cows/diet) from d -28 to 60 relative to parturition. Mammary tissue and blood plasma were harvested from the same cows (n = 5/diet) in the control and Met groups at d 21 postpartum for mRNA, protein, and AA analysis. Increasing the supply of Met led to greater milk protein percentage and milk yield along with greater ratio of phosphorylated (p-) AKT to total AKT. The ratio of p-mTORC1 to total mTORC1 did not differ, but ratio of p-RPS6 to total ribosomal protein S6 (RPS6) was lower in response to Met supply. These responses were associated with greater mRNA abundance of the signaling proteins Janus kinase 2 (JAK2) and insulin receptor substrate 1 (IRS1). Greater Met supply also upregulated mRNA abundance of high-affinity cationic (SLC7A1) and sodium-coupled AA transporters (SLC38A1, SLC38A2); leucyl-tRNA (LARS), valyl-tRNA (VARS), and isoleucyl-tRNA synthetases (IARS); glucose transport solute carrier family 2 member 3 (SLC2A1); glucose transport solute carrier family 2 member 3 (SLC2A3); and casein alpha-s1 (CSN1S1). The mRNA abundance of components of the unfolded protein response, such as x-box binding protein 1 (XBP1) and activating transcription factor 6 (ATF6), were upregulated, and protein phosphatase 1, regulatory subunit 15A (PPP1R15A) was downregulated in response to greater Met supply. Overall, the data suggest that increased dry matter intake, greater phosphorylation status of AKT, upregulation of glucose and AA transporters, and transcripts of tRNases in response to enhanced Met supply might have compensated for a reduction in ribosome biogenesis due to a lower ratio of p-RPS6 to total RPS6. Together, these cellular responses constitute a mechanism whereby Met supply can regulate milk protein synthesis in early lactation.