Effects of heat stress on plasminogen activator related in milk protein in bovine mammary epithelial cells and mid lactating Holstein cow milk

IF 2.9 2区 生物学 Q2 BIOLOGY
Min-Kyeong Choi , Jang-Hoon Jo , Jung-Woo Lim , Jalil Ghassemi Nejad , Hong-Gu Lee
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Abstract

Heat stress (HS) is a significant factor in reducing milk yield and protein in dairy cows. However, studies on the mechanisms underlying HS-induced reductions in milk protein are limited. This study investigated the effects of HS on the plasminogen activator (PA) in bovine mammary alveolar cells (MAC-T) and cow milk to investigate milk protein reduction under hyperthermia. In an in vivo study, milk samples were collected from thirty mid-lactating Holstein cows in different seasons with varying temperature–humidity index (severe–moderate, SM; moderate–mild, MM; and mild–comfortable, MC). The average daily milk yield of cows was 33.93 ± 0.98 kg; cows were fed a TMR diet, delivered twice daily, and ad libitum access to water. The SM group had the highest (P < 0.05) milk uPA concentrations (1.48 ng/mL), followed by the MM group (0.43 ng/mL). Milk protein levels were lower (P < 0.05) in the SM group (3.1 %), which was exposed to more HS than the MM (3.35 %) and MC (3.46 %) groups. To determine whether HS also alters PA expression in MAC-T cells, cells were subjected to HS at 41 °C for 2 h, with recovery at 37 °C for 8 h. HS increased (P < 0.05) mRNA expression levels of heat shock protein 70 (HSP70), urokinase-PA (uPA), and tissue-PA (tPA). HS upregulated HSP70 expression (P < 0.05) and tended to raise uPA protein expression (P = 0.096). Although HS did not affect protein synthesis in MAC-T cells, cortisol, insulin, and prolactin did not affect uPA or tPA expressions in MAC-T cells. These results suggest that HS contributes to decreased milk protein content through elevated PA in the alveolar lumen rather than impaired protein synthesis in MAC-T cells. Additionally, these HS-induced mechanisms in PA provide an additional clue explaining dairy cows' decreased milk protein levels.
热应激对奶牛乳腺上皮细胞和泌乳中期荷斯坦奶牛乳蛋白相关纤溶酶原激活物的影响
热应激(HS)是奶牛产奶量和蛋白质降低的重要因素。然而,对hs诱导牛奶蛋白减少的机制的研究是有限的。本研究研究了HS对牛乳腺肺泡细胞(MAC-T)和牛奶中纤溶酶原激活物(PA)的影响,以探讨高温下牛奶蛋白的减少。在一项体内研究中,采集了30头泌乳中期荷斯坦奶牛在不同季节、不同温湿指数(中重度,SM;中重度,MM;轻度舒适,MC)下的乳样。奶牛平均日产奶量为33.93±0.98 kg;饲喂TMR饲粮,每日两次,并可随意取水。乳中uPA浓度SM组最高(1.48 ng/mL) (P < 0.05), MM组次之(0.43 ng/mL)。SM组乳蛋白水平较低(P < 0.05) (3.1%), HS暴露量高于MM组(3.35%)和MC组(3.46%)。为了确定HS是否也改变了MAC-T细胞中PA的表达,我们将细胞置于41℃高温下2小时,37℃高温下8小时恢复。HS增加了热休克蛋白70 (HSP70)、尿激酶-PA (uPA)和组织-PA (tPA) mRNA的表达水平(P < 0.05)。HS上调HSP70表达(P < 0.05),有上调uPA蛋白表达的趋势(P = 0.096)。虽然HS不影响MAC-T细胞中的蛋白质合成,但皮质醇、胰岛素和催乳素不影响MAC-T细胞中uPA或tPA的表达。这些结果表明,HS通过提高肺泡腔内PA而不是破坏MAC-T细胞的蛋白质合成来降低乳蛋白含量。此外,这些hs诱导的PA机制为奶牛乳蛋白水平下降提供了额外的线索。
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来源期刊
Journal of thermal biology
Journal of thermal biology 生物-动物学
CiteScore
5.30
自引率
7.40%
发文量
196
审稿时长
14.5 weeks
期刊介绍: The Journal of Thermal Biology publishes articles that advance our knowledge on the ways and mechanisms through which temperature affects man and animals. This includes studies of their responses to these effects and on the ecological consequences. Directly relevant to this theme are: • The mechanisms of thermal limitation, heat and cold injury, and the resistance of organisms to extremes of temperature • The mechanisms involved in acclimation, acclimatization and evolutionary adaptation to temperature • Mechanisms underlying the patterns of hibernation, torpor, dormancy, aestivation and diapause • Effects of temperature on reproduction and development, growth, ageing and life-span • Studies on modelling heat transfer between organisms and their environment • The contributions of temperature to effects of climate change on animal species and man • Studies of conservation biology and physiology related to temperature • Behavioural and physiological regulation of body temperature including its pathophysiology and fever • Medical applications of hypo- and hyperthermia Article types: • Original articles • Review articles
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