Response to Different Oxygen Partial Pressures and Evolution Analysis of Apoptosis-Related Genes in Plateau Zokor ().

The plateau zokor () is a native species of the Qinghai-Tibet Plateau that spends its entire life underground in sealed burrows with hypoxic conditions. The present study aimed to assess the sequence characteristics of apoptosis-related genes and the response to different oxygen partial pressures (pO) in plateau zokor and Sprague-Dawley rats. The sequences of the p53-induced protein with a death domain (Pidd), p53-upregulated modulator of apoptosis (Puma), insulin-like growth factor binding protein 3 (Igfbp3), and apoptosis protease-activating factor 1 (Apaf1) were evaluated concerning homology and convergent evolution sites, and their mRNA levels were evaluated in different tissues under 14.13 (3,300 m) and 16.12 kPa (2,260 m) pO conditions. Our results showed that, (1) the sequences of the apoptosis-related genes in plateau zokor were highly similar to those of , followed by ; (2). Pidd, Puma, Igfbp3, and Apaf1 of plateau zokor were found to have five, one, two, and five convergent sites in functional domains with , respectively. Lastly (3), under low pO, the expression of and was downregulated in the lung of plateau zokors. In turn, and were upregulated in the liver and lung, and was upregulated in the skeletal muscle of plateau zokor under low pO. In Sprague-Dawley rats, low pO downregulated and expression in the liver and downregulated and in the lung and skeletal muscle separately. In contrast, low pO upregulated expression in the liver and skeletal muscle of Sprague-Dawley rats. Overall, the expression patterns of , , and showed the opposite pattern in the liver, lung, and skeletal muscle, respectively, of plateau zokor as compared with Sprague-Dawley rats. In conclusion, for the long-time adaptation to hypoxic environments, , , , and of plateau zokor underwent convergent evolution, which we believe may have led to upregulation of their levels under low oxygen partial pressures to induce apoptosis, so as to suppress tumorigenesis under hypoxic environments in plateau zokor.