Effects of Low Oxygen Tension on Transcriptome of Yak (Bos grunniens) Cumulus Cells
LI Rui-Zhe1,2, XU Jing-Tao2, SUN Yong-Gang2, MA Zhi-Jie2, CHEN Sheng-Mei2, LUO Yu-Zhu1,*
1 College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China; 2 Qinghai Academy of Animal Science and Veterinary Medicine, Xining 810016, China
Abstract：Cumulus cells are important supporting cells of oocytes. Quality of cumulus cells influences in vitro maturation and developmental competence of oocytes. Low oxygen tension was beneficial for in vitro maturation and developmental competence of yak (Bos grunniens) oocytes, whereas whether the beneficial effects were exerted through cumulus cells has not been reported. In order to investigate the effects of low oxygen tension on transcriptome of yak cumulus cells, maturation of yak cumulus-oocyte complex (COC) was carried out at 5% and 20% O2, respectively. Then cumulus cells were collected for RNA-seq, screening of differentially expressed genes (DEGs) and qRT-PCR verification. The results showed that 8 yak cumulus cell transcriptomic libraries were obtained and total data size was 56.17 Gb; gene expression analysis showed that a total of 13 584 genes were expressed of the two groups and 270 DEGs were identified, among which 229 DEGs were up-regulated in 5% O2 and 41 DEGs were up-regulated in 20% O2; Gene Ontology (GO) and KEGG pathway analysis showed that DEGs were mostly enriched in glycolysis, cumulus cell expansion and cumulus-oocyte signaling et al.; 6 711 new genes and 7 209 new transcripts, among which 829 new transcripts had protein coding potential, were found in unannotated region of the yak reference genome. qRT-PCR results were consistent with the sequencing data. Taken together, above results indicated that low oxygen tension might induce yak cumulus cells to have a similar transcriptomic profile to those matured in vivo and therefore promote the maturation and developmental competence of yak oocytes. The present study provides a reference for further study of the effect of oxygen tension on the mechanism of cumulus cell-oocyte interaction in the process of in vitro maturation of yak oocytes.
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