Downregulation of CASTOR1 Inhibits Heat-Stress-Induced Apoptosis and Promotes Casein and Lipid Synthesis in Mammary Epithelial Cells

Naringenin alleviates heat stress-induced liver injury in Ningdu yellow chickens by decreasing RIPK3 and PDC binding

Naringenin, a flavonoid extract, possesses anti-inflammatory, antioxidant, hepatoprotective, antitumor, and antineurotoxic properties. This study investigated the antiheat stress effects in broilers by adding 200mg/kg naringenin to the diet of Ningdu yellow chicken under heat stress conditions. Heat stress conditions was controlled at 37±2°C (7:00 a.m.-7:00 p.m.) and 24±2°C (7:00 p.m.-7:00 a.m.) at humidity maintained at 60-65%. The results suggest that naringenin elevated the body weight and the ratio of liver mass to weight of Ningdu yellow chicken significantly. Additionally, naringenin significantly reduces heat stress level, improves liver function and antioxidant capacity. Meanwhile, the levels of necroptosis indexes (CYLD, RIPK1, RIPK3 and MLKL) and oxidative stress indexes (PDC, PYGL, GLUL and GLUD1) are downregulated by naringenin. Naringenin mitigated liver damage by decreasing inflammatory indexes caused by heat stress, including NF-κB, IL-1β, IL-18 and HMGB1. This anti-inflammatory effect arose through the downlink binding of the necroptosis index (RIPK3) and the oxidative stress index (PDC) as shown in results of fluorescence co-localization and co-immunoprecipitation. The use of naringenin in poultry may be a possible feed additive to address clinical heat stress.

UFBP1 Ameliorates Heat Stress-Induced Apoptosis via Mitochondria-Mediated Pathway in Bovine Mammary Epithelial Cells

Heat stress in dairy cows is aggravated by Global warming, which negatively affects their performance and health, especially high yielding cows are more susceptible to high temperature and humidity in summer. Besides increasing body temperature and reducing feed intake, heat stress also compromises mammary gland function by inducing apoptosis in bovine mammary epithelial cells (BMECs). UFBP1 (Ufm1-binding protein 1) serves as an essential component of ufmylation, is crucial for the preservation of cellular homeostasis. However, little is known about its contribution to heat stress-induced apoptosis in BMECs. Therefore, the present study aimed to elucidate the effect of UFBP1 on heat stress-induced apoptosis through knockdown and overexpression of UFBP1 in BMECs. The results showed that heat stress triggered cell apoptosis (increased apoptosis rate and Bax/Bcl-2 protein expression) and decreased the expression of genes associated with the production of milk fat and protein both in vivo and in vitro studies. Furthermore, UFBP1 silencing aggravated the high-temperature-induced cell damage, and overexpression of UFBP1 attenuated heat stress-induced mitochondrial dysfunction, as evidenced by increased mitochondrial membrane potential (MMP), ATP synthesis and NAD+/NADH ratio, as well as the reduced reactive oxygen species (ROS) generation. Importantly, the mitochondrial apoptosis pathway triggered by heat stress was blocked by UFBP1, as indicated by the reduced apoptosis rate and Bax/Bcl-2 protein expression. In addition, UFBP1 restored the expression of milk fat and protein-related genes in heat-stressed BMECs. In conclusion, these findings indicate that UFBP1 may serve as a promising therapeutic target for ameliorating heat stress in dairy cows, thereby providing novel theoretical insights into the mitigation of adverse thermal stress effects on livestock productivity.

Upregulating mTOR/S6 K Pathway by CASTOR1 Promotes Astrocyte Proliferation and Myelination in Gpam-/--induced mouse model of cerebral palsy

GPAM, a key enzyme for lipid synthesis, is predominantly expressed in astrocytes (ASTs), where it facilitates lipid supply for myelin formation. Our previous studies identified GPAM as a novel causative gene for cerebral palsy (CP) and led to the development of a CP mouse model with GPAM deficiency (Gpam-/-). The model closely recapitulated the clinical phenotype of children with CP, due to the restricted proliferation of ASTs in the brain, reduced the amount of lipid, thinner brain white matter, and myelin dysplasia. The mammalian target of rapamycin (mTOR) pathway plays an important role in cell proliferation and lipid synthesis. Cytosolic arginine sensor (CASTOR1) interacts with GATOR2 to regulate mTOR complex 1 (mTORC1). Targeted degradation of CASTOR1 can activate the mTOR pathway. However, it remains unclear the involvement of mTOR pathway in neurological diseases such as CP. In this study, we demonstrated that the mTOR pathway was inhibited in Gpam-/- mice. Notably, CASTOR1 could regulate the activity of mTOR/S6K pathway, functioning as a negative upstream regulator. Furthermore, inhibition of CASTOR1 upregulated mTOR/S6K signaling, promoting astrocyte proliferation and myelination, which in turn enhanced motor function in the Gpam-/--induced CP mouse model. Collectively, these findings reveal the role of astrocytic mTOR in the pathogenesis of CP mice, broaden the therapeutic strategies, and provide a promising candidate target for CP treatment.

L-arginine alleviates heat stress-induced mammary gland injury through modulating CASTOR1-mTORC1 axis mediated mitochondrial homeostasis

As global warming intensifies, extreme heat is becoming increasingly frequent. These extreme heatwaves have decreased the milk production of dairy animals such as cows and goats and have caused significant damage to the entire dairy industry. It is known that heat stress (HS) can induce the apoptosis and autophagy of mammary epithelial cells (MECs), leading to a decrease in lactating MECs. L-arginine can effectively attenuate HS-induced decreases in milk yield, but the exact mechanisms are not fully understood. In this study, we found that HS upregulated the arginine sensor CASTOR1 in mouse MECs. Arginine activated mTORC1 activity through CASTOR1 and promoted mitochondrial biogenesis through the mTORC1/PGC-1α/NRF1 pathway. Moreover, arginine inhibited mitophagy through the CASTOR1/PINK1/Parkin pathway. Mitochondrial homeostasis ensures ATP synthesis and a stable cellular redox state for MECs under HS, further alleviating HS-induced damage and improving the lactation performance of MECs. In conclusion, these findings reveal the molecular mechanisms by which L-arginine relieves HS-induced mammary gland injury, and suggest that the intake of arginine-based feeds or feed additives is a promising method to increase the milk yield of dairy animals in extreme heat conditions.