Cloning of HSP90, expression and localization of HSP70/90 in different tissues including lactating/non-lactating yak (Bos grunniens) breast tissue

Expression Analysis of Molecular Chaperones Hsp70 and Hsp90 on Development and Metabolism of Different Organs and Testis in Cattle (Cattle-yak and Yak)

Hsp70 and Hsp90 play an important role in testis development and spermatogenesis regulation, but the exact connection between Hsp70 and Hsp90 and metabolic stress in cattle is unclear. Here, we focused on the male cattle−yak and yak, investigated the expression and localization of Hsp70 and Hsp90 in their tissues, and explored the influence of these factors on development and metabolism. In our study, a total of 54 cattle (24 cattle−yaks and 30 yaks; aged 1 day to 10 years) were examined. The Hsp90 mRNA of the cattle−yak was first cloned and compared with that of the yak, and variation in the amino acid sequence was found, which led to differences in protein spatial structure. Using real-time quantitative PCR (RT-qPCR) and Western blot (WB) techniques, we investigated whether the expression of Hsp70 and Hsp90 mRNA and protein are different in the cattle−yak and yak. We found a disparity in Hsp70 and Hsp90 mRNA and protein expression in different non-reproductive organs and in testicular tissues at different stages of development, while high expression was observed in the testes of both juveniles and adults. Moreover, it was intriguing to observe that Hsp70 expression was significantly high in the yak, whereas Hsp90 was high in the cattle−yak (p < 0.01). We also examined the location of Hsp70 and Hsp90 in the testis by immunohistochemical (IHC) and immunofluorescence (IF) techniques, and the results showed that Hsp70 and Hsp90 were positive in the epithelial cells, spermatogenic cells, and mesenchymal cells. In summary, our study proved that Hsp70 and Hsp90 expressions were different in different tissues (kidney, heart, cerebellum, liver, lung, spleen, and testis), and Hsp90 expression was high in the testis of the cattle−yak, suggesting that dysplasia of the cattle−yak may correlate with an over-metabolism of Hsp90.

Effects of PHD and HSP90 on erythropoietin production in yak (Bos grunniens) renal interstitial fibroblast-like cells under hypoxia

Erythropoietin (EPO), a central protein of erythropoiesis, plays an important role during hypoxia adaptation and is regulated by hypoxia-inducible factor (HIF). However, there is no report on EPO-producing cells and their regulatory mechanisms in yak (Bos grunniens). To understand EPO production and regulation of yak, kidneys from different age of yak were collected and expression of EPO, hypoxia-inducible factor 1 alpha (HIF-1α), and hypoxia-inducible factor 2 alpha (HIF-2α) were detected. Then renal tubule epithelial cells (RTECs) and peritubular interstitial fibroblast-like (RIFs) cells were isolated and cultured to determine their EPO production abilities. Subsequently, the cells were treated with dimethyloxalylglycine (DMOG) and Geldanamycin (GA), which are inhibitors of prolyl-4-hydroxylase domain (PHD) and heat shock protein 90 (HSP90) respectively, and siRNAs of HIF-1α and HIF-2α to explore their effect on EPO production and regulation. The results showed that expressions of EPO, HIF-1α, and HIF-2α were different in the different age groups of yak. High DMOG concentration caused a corresponding increase in the levels of HIF-1α and HIF-2α in RIFs and RTECs, however, EPO levels increased in RIFs only and was not detected at any concentration in RTECs; suggesting that EPO was produced in RIFs. Upon treating RIFs with siRNAs of HIF-1α and HIF-2α, we found that EPO was regulated by PHD through HIF-2α. In addition, increasing GA concentration caused a decrease in expression of HSP90, HIF-1α, HIF-2α, and EPO in RIFs. In conclusion, these findings support our proposition that PHD regulates EPO via HIF-2α in yak RIFs, while HSP90 impelled EPO expression.

Oocyte quality and heat shock proteins in oocytes from bovine breeds adapted to the tropics under different conditions of environmental thermal stress

In order to evaluate the influence of thermal stress on physiological parameters, and the oocyte quality of Girolando (n = 12) and adapted Pantaneira (n = 12) cattle, twelve sessions of ultrasound guided follicular aspiration (OPU) were performed, between January and November 2014 (during dry (May-September) and rainy season (October-April) in Brazil). The recovered cumulus-oocyte complexes (COCs) were selected and classified, according to quality, immediately after OPU. The oocytes were then stored in 3% paraformaldehyd before conducting immunofluorescence analysis under confocal microscopy to identify HSP70 and 90 proteins. Before each OPU session, the rectal temperature (RT) and respiratory frequency (RF) of each animal were measured. The black globe humidity index (BGHI) was calculated on the day of the OPUs and 90 days before each OPU session, and related to the thermal stress of the animals. The quality of oocytes from Girolando cattle, but not Pantaneira, showed a negative relationship with BGHI of 90 days before OPU. RT of both breeds did not exceed normal values for cattle below BGHI 95. BGHI variation on the day of OPU did not affect RF of the adapted Pantaneira breed (p = 0.3221). On the other hand, Girolando cattle showed a positive relationship between RF and BGHI (p = 0.0103). With increasing BGHI, the amount of HSP70 increased in Girolando oocytes, however, decreased in the Pantaneira breed. We have not observed a relationship between HSP 90 and BGHI, however Girolando cattle produced a greater amount of this protein in relation to the Pantaneira breed. In conclusion, higher BGHIs, 90 days before OPU session, negatively affect oocyte quality of Girolando cattle and positively affect oocyte quality of the Pantaneira breed. Higher BGHIs on the day of the OPU session negatively affected the respiratory frequency of the Girolando breed, and lead to a higher recruitment of HSP70 to protect oocyte maturation. The opposite pattern was observed for Pantaneira. In addition, Pantaneira cattle produced twice as much as HSP70 as Girolando cattle, suggesting that a natural higher production of this protein could be involved in the mechanisms of adaptation to heat conditions.

Regulation by Hsp27/P53 in testis development and sperm apoptosis of male cattle (cattle-yak and yak)

Heat shock protein 27 (Hsp27)/protein 53 (P53) plays an important role in testis development and spermatozoa regulation, but the relationship between Hsp27/P53 and infertility in cattle is unclear. Here, we focus on male cattle-yak and yak to investigate the expression and localization of Hsp27/P53 in testis tissues and to explore the influence of Hsp27/P53 on infertility. In our study, a total of 54 cattle (24 cattle-yak and 30 yak) were examined. The Hsp27 and P53 messenger RNA (mRNA) of cattle-yak were cloned, and amino acid variations in Hsp27 and P53 were found; the variations led to differences in the protein spatial structure compared with yak. We used real-time quantitative polymerase chain reaction and western blot to investigate whether the expression of Hsp27/P53 mRNA and protein was different in cattle-yak and yak. We found that the expression levels of Hsp27/P53 mRNA and protein were different in the testis developmental stages and the highest expression was observed in testicles during adulthood. Moreover, the Hsp27 expression was significantly higher in yak, whereas P53 expression was higher in cattle-yak (p < 0.01). On this basis, we detected the location of Hsp27/P53 in the testis by immunohistochemistry and immunofluorescence. The results demonstrated that Hsp27 was located in spermatogenic cells at different developmental stages and mesenchymal cells of the yak testicles. However, P53 was located in the primary spermatocyte and interstitial cells of the cattle-yak testicles. In summary, our study proved that the expression of Hsp27/P53 differed across the testis developmental stages and the expression of P53 was higher in the testis of cattle-yak, which suggested that the infertility of cattle-yak may be caused by the upregulation of P53.

Adaptation strategies of yak to seasonally driven environmental temperatures in its natural habitat

The gradual increase of ambient temperature (TA) at high altitude can cause heat stress as an effect of climate change and may shift the traditional habitat of yak to further higher altitude. Therefore, an attempt has been made in this study to evaluate the thermo-adaptability of yaks to different seasons at high altitude. The adaptive capabilities of yaks were assessed based on different heat tolerance tests in relation to changes in rectal temperature (RT; °F), respiration rate (RR; breaths/min), pulse rate (PR; beats/min), and plasma heat shock protein (HSP) profile. The experiment was conducted in 24 yaks, divided into three groups based on age as calf (n = 8), adult (n = 8), and lactating cow (n = 8). Thermal adaptability was determined by temperature humidity index (THI), dairy search index (DSI), and Benezra's thermal comfort index (BTCI) along with HSP70 profile. The THI was higher (P < 0.01) in summer than winter which increased from lowest (40.87) to highest (61.03) in summer by 20 points, where yaks were under heat load beyond THI 52. The RT (100.09 ± 0.18 °F), RR (21.76 ± 0.18), and PR (59.78 ± 0.32) increased by 23-35%, and this was correlated to the higher values of DSI exceeding 1 in calves (1.35 ± 0.03), lactating cows (1.29 ± 0.04), and adults (1.23 ± 0.32) during summer in comparison to winter (0.98 ± 0.02). The BTCI also showed values greater (P < 0.01) than 2 in calves (3.47 ± 0.27), lactating cows (3.23 ± 0.28), and adults (2.98 ± 0.29) which reflected 49-75% increase in rectal temperature and respiration rate during summer. Further, heat stress was substantiated by threefold higher (P < 0.01) level of plasma HSP70 in calves (189.61 ± 3.90 pg/ml) followed by lactating cows (168.62 ± 3.03 pg/ml) and adults (155.33 ± 2.30 pg/ml) against the winter average of 87.92 ± 3.19 pg/ml. Present results revealed that yaks were experiencing heat stress in summer at an altitude of 3000 m above sea level and calves were more prone to heat stress followed by lactating cows and adults.