| The plateau zokor(Myospalaxbaileyi)is a specialized subterranean rodent that lives on the Qinghai-Tibet Plateau,and has successfully adapted to hypoxic environment.Raised expression of vascular endothelial growth factor(VEGF)and enhanced microvessel density(MVD)in tissues enable subterranean rodents to adapt to hypoxic sealed burrows.However,the expression of VEGF is inhibited by decreases in oxygen content,which is different from what obtains in Sprague Dawley(SD)rats.It may be related to p53 binding to HIF-1?,through enhancing the downstream transcription of angiogenesis-related target genes to inhibit the unlimited growth of microvessels in hypoxic environment.In this paper,the sequence of coding region of p53 and its downstream target genes related to angiogenesis inhibition in plateau zokor was analyzed by bioinformatics,and the expression pattern of p53 and its downstream target genes related to angiogenesis inhibition in plateau zokor at different altitudes was studied.The plateau zokor has high homology with the Nannospalax galili.We found that glycine(Gly,G)at position 309 of p53 gene mutated to aspartate(Asp,D)in plateau zokor by p53 sequence analysis of several species.There are two parallel evolutionary sites(89 Ser,95Pro)between plateau zokor and Nannospalax galili.We think these two parallel evolutionary sites may enhance the adaptability of underground rodents to hypoxic environment.The alignment of HIF-1? amino acid sequences of human,plateau zokor and SD rat revealed that 552 non-polar amino acid alanine(Gla,A)of 507-579 amino acids on the binding sequence of p53 and HIF-1? mutated to threonine(Thr,T)which may enhance the affinity between p53 and HIF-1?,thus enhancing the ability of p53 to regulate its downstream target gene for inhibiting angiogenesis.The expression levels of p53,TSP-1,PAI-1,KAI-1,Maspin and BAI-1 in liver,lung,stomach,intestine and skeletal muscle of plateau zokor at 3300 m altitude were significantly higher than those at 2260 m altitude.However,the expression levels of p53 and target genes in different tissues of SD rat were not significantly different at different altitudes,indicating that the expression patterns of target genes inhibiting angiogenesis are different.Evolutionary analysis showed that there were four parallel evolutionary sites(185Asp,270 Thr,536Glu and 1092Thr)which significantly affected the function of TSP-1 gene in plateau zokor and Nannospalax galili.Among them that 185 Asp and 270 Thr were located in NH2 terminal domain,536 Glu in Type I and 1092 Thr in COOH terminal domain.The parallel evolutionary site 334 Val in PAI-1 gene of plateau zokor and Nannospalax galili in COOH terminal domain show significant effects on their functions.Maspin gene has four positive selection sites(229Glu,346 His,352Arg and 374Pro)which have significant effects on its function,and these four sites are located around the active site ring.Compared with SD rats,the changes of polarity of these sites may enhance the binding ability with corresponding proteins,thereby enhancing the inhibition of angiogenesis.According to the standard curve method,the expression levels of TSP-1,PAI-1 and Maspin in liver,lung and skeletal muscle tissues of plateau zokor at 3300 m altitude were significantly higher than those at 2260 m altitude.However,there was no significant difference in the expression levels of the three target genes between different altitudes.These results suggest that plateau zokor and SD rat p53 pathway inhibit angiogenesis target genes expression pattern is different due to long-term evolution.In conclusion,for long time adaption to the hypoxia environment of sealed burrows in Myospalax baileyi,the expression of p53 pathway inhibit angiogenesis target genes up-regulated and the structure of coding gene changed may enhanced the ability of anti-angiogenesis. |
PDF Full Text Request