Characterization and comparative transcriptomic analysis of high-altitude adaptation in Tibetan chicken using RNA-sequencing

Tibetan chicken, an indigenous breed, inhabit highland regions and are crucial livestock for local Tibetans. Compared with other chicken breeds that have migrated from lowlands to highlands, Tibetan chicken exhibits superior physiological adaptations to high-altitude environments. However, the genetic mechanisms underlying these adaptations remain unclear. Herein, we generated high-quality RNA-sequencing data from the heart samples of 19 adult lowland and Tibetan chickens subjected to hypoxic and normoxic conditions for 5 weeks. We explored the relationships between chicken populations and the environment using different expression gene detection and weighted gene co-expression network analysis (WGCNA). The Tibetan chicken genome was analyzed for positive selection pressures associated with high-altitude adaptation, to reveal 63 candidate genes primarily involved in heart development and apoptotic signaling pathways, including PARK7, which was then validated using quantitative real-time polymerase chain reaction (qRT-PCR). Further hypoxia-induced cardiomyocyte model tests showed the cardioprotective function of PARK7 by cell viability assay, indicating the cardioprotective function of PARK7 in chickens under low-oxygen conditions. Our findings provided new insights into the genetic basis of high-altitude adaptation in Tibetan chickens and offered values for breeding programs aimed at enhancing the resilience of livestock in challenging environments.