Department of Animal, Veterinary and Food Sciences, University of Idaho, Moscow, ID, 83844, USA.
Interdisciplinary Center for Biotechnology Research, Proteomics and Mass Spectrometry Core, University of Florida, Gainesville, FL, 32611, USA.
Sci Rep. 2022 Apr 22;12(1):6637. doi: 10.1038/s41598-022-10461-z.
Exposure to heat stress during a cow's dry period disrupts mammary gland remodeling, impairing mammary function and milk production during the subsequent lactation. Yet, proteomic changes in the mammary gland underlying these effects are not yet known. We investigated alterations in the mammary proteome and phosphoproteome during lactation as a result of dry period heat stress using an isobaric tag for relative and absolute quantitation (iTRAQ)-based approach. Cows were cooled (CL; n = 12) with fans and water soakers in a free stall setting or were heat stressed through lack of access to cooling devices (HT; n = 12) during the entire dry period (approximately 46 days). All cows were cooled postpartum. Mammary biopsies were harvested from a subset of cows (n = 4 per treatment) at 14, 42, and 84 days in milk. Overall, 251 proteins and 224 phosphorylated proteins were differentially abundant in the lactating mammary gland of HT compared to CL cows. Top functions of differentially abundant proteins and phosphoproteins affected were related to immune function and inflammation, amino acid metabolism, reactive oxygen species production and metabolism, tissue remodeling, and cell stress response. Patterns of protein expression and phosphorylation are indicative of increased oxidative stress, mammary gland restructuring, and immune dysregulation due to prior exposure to dry period heat stress. This study provides insights into the molecular underpinnings of disrupted mammary function and health during lactation arising from prior exposure to dry period heat stress, which might have led to lower milk yields.
奶牛干奶期暴露于热应激会破坏乳腺重塑，损害泌乳期的乳腺功能和产奶量。然而，这些影响下乳腺的蛋白质组变化尚不清楚。我们使用基于相对和绝对定量同位素标记（iTRAQ）的方法，研究了干奶期热应激对泌乳期乳腺蛋白质组和磷酸蛋白质组的影响。奶牛在自由卧床环境中通过风扇和水浸式冷却器（CL；n = 12）或通过缺乏冷却设备（HT；n = 12）来进行冷却，整个干奶期（约 46 天）都受到热应激。所有奶牛产后都进行了冷却。从每个处理组的一部分奶牛（n = 4 头/处理）中采集了泌乳期 14、42 和 84 天的乳腺活检。总体而言，与 CL 奶牛相比，HT 奶牛泌乳期乳腺中 251 种蛋白质和 224 种磷酸化蛋白质的丰度存在差异。差异丰度蛋白质和磷酸化蛋白质的主要功能与免疫功能和炎症、氨基酸代谢、活性氧物质的产生和代谢、组织重塑和细胞应激反应有关。蛋白质表达和磷酸化模式表明，由于先前暴露于干奶期热应激，导致氧化应激增加、乳腺结构重塑和免疫失调，这可能导致产奶量下降。本研究为泌乳期由于先前暴露于干奶期热应激而导致的乳腺功能和健康受损的分子基础提供了新的见解。
