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Simple Summary: The lungs are key organs in mammals that shows adaptive changes in response to high altitude, and yaks (Bos grunniens) have adapted their lungs well to the hypoxic environment of Tibetan Plateau after a long period of evolution and natural selection. However, the long-term life of lowland cattle on the plateau can cause symptoms such as pulmonary arterial hypertension, wherein the abnormal proliferation of pulmonary vascular smooth muscle cells leads to the remodeling of the pulmonary vasculature, which is the main cause of pulmonary arterial hypertension. The underlying molecular mechanisms of lung adaptation to hypoxia in yaks remain largely unknown. In this study, we constructed stably transfected yak cell lines overexpressing PDK1 via lentiviral transfection, and we cultured yellow cattle and yak PASMCs, as well as PDK1-OEcon/OE, under normoxia and 10% O2 to explore the effects of hypoxia on the PDK1 and TGF-β/Smad signaling pathways in yak PASMCs. This will provide theoretical data at the cellular and molecular levels, along with basic information to further elucidate the mechanism of the PDK1-mediated TGF-β/Smad signaling pathway in yak PASMCs induced by hypoxia. The aim of this study was to investigate the effects of hypoxia-induced phenotype, glucose metabolism, ROS levels, and the PDK1-mediated regulation of TGF-β/Smad signaling in yellow cattles, yaks, and those overexpressing PDK1 PASMCs using growth curves, flow cytometry, scratch experiments, glucose and lactic acid assays, RT-qPCR, and Western blotting. The results showed that hypoxia significantly promoted proliferation, migration, antiapoptosis, ROS levels, glucose consumption, and lactate production in yellow cattle PASMCs (p < 0.05), and the cells were dedifferentiated from the contractile phenotype; conversely, hypoxia had no significant effect on yak PASMCs (p > 0.05). PDK1 overexpression significantly promoted proliferation, antiapoptosis, glucose consumption, and lactate production in yak PASMCs under normoxia and hypoxia (p < 0.05), decreased their migration levels under hypoxia (p < 0.05), and dedifferentiated the contractile phenotype of the cells. Overexpression of PDK1 in yak PASMCs is detrimental to their adaptation to hypoxic environments. Yak PASMCs adapted to the effects of hypoxia on lung tissue by downregulating the expression of genes related to the PDK1 and TGF-β/Smad signaling pathways. Taken together, the regulation of PDK1-mediated TGF-β/Smad signaling may be involved in the process of yaks' adaptation to the hypoxic environment of the plateau, reflecting the good adaptive ability of yaks. The present study provides basic information to further elucidate the mechanism of PDK1-mediated TGF-β/Smad signaling induced by hypoxia in the lungs of yaks, as well as target genes for the treatment of plateau diseases in humans and animals. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of hypoxia-induced phenotype, glucose metabolism, ROS levels, and the PDK1-mediated regulation of TGF-β/Smad signaling in yellow cattles, yaks, and those overexpressing PDK1 PASMCs using growth curves, flow cytometry, scratch experiments, glucose and lactic acid assays, RT-qPCR, and Western blotting. The results showed that hypoxia significantly promoted proliferation, migration, antiapoptosis, ROS levels, glucose consumption, and lactate production in yellow cattle PASMCs (p < 0.05), and the cells were dedifferentiated from the contractile phenotype; conversely, hypoxia had no significant effect on yak PASMCs (p > 0.05). PDK1 overexpression significantly promoted proliferation, antiapoptosis, glucose consumption, and lactate production in yak PASMCs under normoxia and hypoxia (p < 0.05), decreased their migration levels under hypoxia (p < 0.05), and dedifferentiated the contractile phenotype of the cells. Overexpression of PDK1 in yak PASMCs is detrimental to their adaptation to hypoxic environments. Yak PASMCs adapted to the effects of hypoxia on lung tissue by downregulating the expression of genes related to the PDK1 and TGF-β/Smad signaling pathways. Taken together, the regulation of PDK1-mediated TGF-β/Smad signaling may be involved in the process of yaks’ adaptation to the hypoxic environment of the plateau, reflecting the good adaptive ability of yaks. The present study provides basic information to further elucidate the mechanism of PDK1-mediated TGF-β/Smad signaling induced by hypoxia in the lungs of yaks, as well as target genes for the treatment of plateau diseases in humans and animals.

The purpose of this study was to compare between the histochemical characteristics and the expression of epidermal growth factor (EGF) and it's receptor (EGFR) in the submandibular gland (SMG) of adult yaks and yellow cattle. The SMG tissues of yaks and yellow cattles were collected for histochemical, immunohistochemical (IHC), immunofluorescence (F‐IHC)，real‐time quantitative polymerasechain reaction (RT‐qPCR) and Western blotting methods. The results showed that the striated ducts of SMG were highly developed and connected to the intercalated ducts, which were shorter and directly connected to the acini. Compared with yellow cattle, yak SMG contains more mucous acini. Immunofluorescence showed significant expression of EGF and its receptor in both striated and intercalated ducts of these two species of cattle. Statistical analysis divulged that the distribution density of EGF and EGFR in the SMG of the yak was both significantly higher than that in yellow cattle (p < 0.05). Furthermore, the mRNA expression of EGF and EGFR in yak SMG was also higher than that in yellow cattle. The above results indicated that the intercalated ducts and striated ducts are the main expression sites of EGF and EGFR, the acidic mucin and EGF secreted from SMG of yak were more than that from yellow cattle. The results of this study provide powerful data for the study of physiological functions of submaxillary gland in ruminants and also provide important clues for the study of adaptive physiological mechanisms in plateau organisms. [ABSTRACT FROM AUTHOR]

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Bioactive components in five tisues (longissimus muscle (LSM), biceps femoris muscle (BFM), liver (LV), subcutaneous adipose tissue (SAT), and abdominal adipose tissue (AAT)) of yak in Tibet and yellow cattle in Hubei were investigated. Yak was significantly higher (p<0.01) than yellow cattle in the squalene content of lipids of BFM (59.82/19.07 mg/100g), LSM (20.99/7.81 mg/100g) and LV (6.94/2.67 mg/100g), respectively, but not in SAT and AAT (p>0.05). Yak was also significantly higher (p<0.05) than yellow cattle in the total tocopherol content. Additionally, yak hepatic lipids showed the highest content of saturated fatty acids (58.11%) and polyunsaturated fatty acids (PUFA, 25.81%) and the lowest content of monounsaturated fatty acids (MUFA, 16.08%), while yellow cattle AAT had the highest content of MUFA (47.54%) and the lowest content of PUFA (2.36%). The considerable differences between the two in composition suggest that the five tissues of yak are potential sources of bioactive components and essential fatty acids for humans. Practical applications: The results from the analysis of the contents of squalene, tocopherols, total lipids，moisture, ash, and pH and fatty acid profile in the studied tissues of Tibet yak and Hubei yellow cattle provide useful information for developing functional foods using yak meat or other tissues as materials. Comparison of squalene and total tocopherol contents in different tissues of yak and yellow cattle. [ABSTRACT FROM AUTHOR]