Screening Of CircRNAs Related To Hypoxia Adaptability In Tibetan Cattle

Tibet is located in a high altitude area with harsh environment and low oxygen content.Tibetan cattle are yellow cattle breeds that have been locally improved in Tibet,and have good adaptability to the harsh environment of plateau hypoxia.Sanjiang Cattle is an excellent local breed formed through long-term selection and breeding,with long body and strong adaptability.Circ RNA is a kind of highly abundant,evolutionarily conserved endogenous non-coding RNA produced by specific exons,which has regulatory functions in various physiological processes.In this study,high-throughput sequencing of brain and cerebellar tissues of 3.5-year-old female Tibetan cattle and Sanjiang cattle was performed to screen differentially expressed circRNAs and related signaling pathways.The results obtained are as follows:A total of 56 586 circRNAs were detected with the prediction software find?circ(40 686 in Tibetan cattle and 44 909 in Sanjiang cattle).The length of circRNAs is mainly distributed among 100 and 1 500 nt,and divided into six types of sources.Among of them,the number of circRNAs from exons is the largest,and the reverse splicing type of the node sequence is mainly the classic GT-AG type.There are 858 differentially expressed circRNAs in the brain tissues of Sanjiang cattle and Tibetan cattle,and 3 275 differentially expressed circRNAs in the cerebellar tissue;3 130 circRNAs are expressed in the brain and cerebellar tissues of Sanjiang cattle.395 circRNAs expressed in brain and cerebellum tissue.The host genes of significantly DEcircRNAs in two cattle were mainly involved in five biological processes,including cellular processes,single biological processes,metabolic processes,biological regulation,and stress response.In terms of signaling pathways,glutamic acid synapses,MAPK signaling pathways,inflammatory mediators of TRP channels,insulin secretion,thyroid hormone synthesis,and platelet activation are noted.The host genes of circRNAs related to hypoxia regulation were screened as VEGFC(novel?circ?052002),HIF1A(novel?circ?025779),EGLN1(novel?circ?052755),and ANGPT1(novel?circ?033827),which provide clues for the subsequent study of the specific regulatory mechanism of circRNA.Analysis of the differentially DEcircRNA regulatory network revealed that 825 mi RNAs interacted with circRNAs,which 17 mi RNAs were involved in hypoxic regulation.Select 7 mi RNAs(mi R-103-3p?mi R-103-5p?mi R-107-3p?mi R-210-5p?mi R-126-5p ? mi R-195-5p ? mi R-181-5p)to construct circRNA-mi RNA-m RNA network interaction model.A total of 49 circRNAs including novel?circ?000325,novel?circ?000403,novel?circ?000167,novel?circ?000087,and 68 m RNAs,which revealed that these circRNAs may play an important role in Tibetan cattle hypoxia adaptability.Six randomly selected DEcircRNAs with different abundances for RNase R enzyme resistance detection and real-time PCR.The results showed that the expression of circRNAs in the brain and cerebellum were consistented with the predicted expression trend,and resistanted to RNase R enzyme.Combined with agarose gel electrophoresis and Sanger sequencing results,the obtained circRNAs were circular transcript.In this study,circRNA expression profiles and differential expression information obtained by RNA-seq technology in brain tissues and cerebellar tissues of Sanjiang cattle and Tibetan cattle at different altitudes.From the perspective of circRNA,to explore the expression pattern and molecular function of circRNA related to hypoxia adaptability in Tibetan cattle brain tissue under high altitude and extreme environmental stress.The results have important theoretical significance for further studying the regulation of circRNA in hypoxia in large mammals.