ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2019, Vol. 50 ›› Issue (6): 1198-1207.doi: 10.11843/j.issn.0366-6964.2019.06.010

• ANIMAL BIOTECHNOLOGY AND REPRODUCTION • Previous Articles     Next Articles

The Effects of Tumor Necrosis Factor-α (TNF-α) on the Expression of HIF-1α and HSP70 in Yak Oocytes and the Subsequent Embryo Development

XU Tao, PAN Yangyang, HE Honghong, LI Guyue, ZHANG Huizhu, ZHAO Ling, CUI Yan, YU Sijiu*   

  1. Technology and Research Center of Gansu Province for Embryonic Engineering of Bovine and Sheep & Goat, College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
  • Received:2018-11-21 Online:2019-06-23 Published:2019-06-23

Abstract: The aim of this study was to investigate the effects of tumor necrosis factor-α (TNF-α) on yak oocytes maturation in vitro, the expression of epidermal growth factor (HIF-1α) and heat shock protein receptor (HSP70) in yak oocytes and the subsequent embryo development. In this experiment, TNF-α with different concentrations (0, 10, 25, 50 ng·mL-1) were added to in vitro maturation medium of yak oocytes. After the cumulus-oocyte complexes (COCs) matured, the oocyte maturation rate and the development rate of early embryos after in vitro fertilization were counted. The HIF-1α and HSP70 genes of yak were amplified by RT-PCR. The mRNA and protein expression of HIF-1α and HSP70 were detected by real-time PCR (qRT-RCR), Western blotting and immunofluorescence staining. The results showed that:1) The addition of TNF-α to the oocyte maturation medium promoted the maturation rate of oocytes. With the increase of TNF-α concentration, the maturation rate, cleavage rate and blastocyst rate of oocytes increased gradually. When the concentration of TNF-α was 25 ng·mL-1, the maturation rate and cleavage rate of oocytes reached the highest, 84.98% and 66.85%, respectively, and the blastocyst rate also reached 21.48%, which were significantly higher than that in the control group(P<0.05). 2) With the increase of TNF-α concentration, the expression level of HIF-1α decreased gradually. When the concentration of TNF-α was 0 ng·mL-1, the expression level of HIF-1α was the highest, which was significantly higher than that in other groups (P<0.01). The expression level of HIF-1α was the lowest when the concentration of TNF-α was 50 ng·mL-1, which was sig-nificantly lower than that in other groups (P<0.01). Immunofluorescence assay showed that HIF-1α was expressed in both cumulus cells and oocytes. 3) When the concentration of TNF-α was 25 ng·mL-1, the expression level of HSP70 was the highest, which was significantly higher than that in other groups (P<0.01), and when the concentration of TNF-α reached 50 ng·mL-1, the expression level of HSP70 was the lowest. The results showed that TNF-α significantly increased the developmental capacity of oocytes during maturation of yak oocytes in vitro, and also induced the expression of HSP70 and inhibited the expression of HIF-1α. These would provide a theoretical basis for exploring the role of TNF-α, HIF-1α and HSP70 in the reproductive process of yak and the impact on embryo development.

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