Evolutionary Analysis Of HIF-1α And HIF-2α Gene In Primates

Primates are one order of Mammalia under Phylum Chordata. Nonhuman primates are much similar with human in morphology, physiology and biochemistry metabolism. And this made primates always be a focus for research. Oxygen homeostasis is the basic premise of the biological activity of cellular life. Hypoxia-inducible factor (hypoxia-inducible factors, HIFs) is the main factor to maintain the oxygen balance adjustment, which was a dimmer assembled by two subunit a and β.HIF-a subunit has three isomers:HIF-la, HIF-2a and HIF-3a. Among them, HIF-la and HIF-2a are the important regulatory factor responses to hypoxic in cell. In this research, we detected the molecular evolutionary of HIF-1α and HIF-2a, and try to explore the primates respond to this natural selection and the adaptation and evolution.In this reaserch, we get four type of primates HIF-1α and HIF-2a complete coding sequence, by PCR amplification and sequencing technology, they are golden monkey (Pygathrix roxellanae), Tibetan macaque(Macaca thibetana), Flat-topped monkey (Macaca leonina) and Douc langur (Pygathrix nemaeus). Meanwhile we blast in public databases to get the complete coding region sequences of HIF-la and HIF-2a, for other 10 primates.With gene coding sequences of HIF-1α and HIF-2a in the 14 primate’s species, MEGA6.0 and Lasergene software package were used for sequence analysis of nucleotide and amino acid sequences of features, and the built-in software program Bioedit sequence similarity calculation, NCBI Online prediction of protein domains, respectively. After this, the adjacent (NJ) and maximum likelihood (ML) method was used for the reconstruction of two gene phylogenetic tree. With all this work, we try to explore the evolution of HIF-1α and HIF-2a in evolution theory, the main results and conclusions of this thesis are as follow;(1) In our research, we have obtained complete coding sequences (CDS) of HIF-1α and HIF-2a sequences of four primates:gold monkeys, Tibetan macaque, flat-topped monkey and douc monkey. The full-length for HIF-1α coding region is 2481 bp, and HIF-2a are 2610 bp for genus Pygathrix,2595 bp for Genus Macaca. From GenBank and Ensembl public databases we downloaded sequences of other primate species.(2)Compared the homology of HIF-1α and HIF-2a, with all the sequences of primates we had, the similarity for HIF-1α and HIF-2a between nucleotide and amino acid sequences were above the average. HIF-1α nucleotide homology is more than 93% and amino acid homology over 95%; HIF-2a nucleotide homology is more than 87% amino acid homology in more than 88%.The entire ape subfamily showed more higher homology with prosimians than new or old world monkey.(3)The protein domains for HIF-1α and HIF-2a have been simulated on NCBI. And we found the domain in them were much similar and especially confirmed, especially for bHLH-PAS, ODD and C-TAD.(4)The phylogenetic tree of HIF-1α and HIF-2a constructed by two models: Neighbor-joining method and maximum likelihood method. In this study, NJ and ML trees have the same tree topology consistent with primate phylogenetic relationship. They formed 6 clusters:human, great ape, lesser ape, old world monkeys, new world monkeys and prosimian monkeys, and the differences between branches have been well supported.(5) PAML package has been used to estimate the rate of evolution in primates; the result showed that HIF-1α and HIF-2a was underwent strongly purifying selection and has been functional constraint, that means they are very important for sustaining life.The rates of evolution of HIF-2a in primates are obviously different among species, but HIF-1α not.In this study, we explore the phylogenetic and selection pressure HIF-1α and HIF-2a gene of primates in molecular evolutionary, try to understand the impact of HIF-1α and HIF-2a gene in all kinds of disease in mammals.