Comparative transcriptome analyses of cardiac tissue reveals differential gene expression profiles in sheep in response to altitudinal adaptation

The present study aims to elucidate the transcriptomic changes occurring in the cardiac tissue of sheep breeds acclimated to highland versus lowland regions in India. The Changthangi sheep thrives in cold arid highlands of Ladakh in contrast to the Muzzafarnagri sheep which is native to the sub-tropical plains characterized by sweltering heat and high humidity. Four biological replicates of heart tissue from each breed were used to generate the RNA sequencing data. Both breeds exhibited high expression of genes related to crucial cardiac functions such as muscle contraction, hypertrophy and calcium ion homeostasis. Differential gene expression analysis identified distinct expression profiles associated with altitudinal adaptation, with enrichment of apoptotic signals in Changthangi and glycosaminoglycan metabolism in Muzzafarnagri sheep. Gene co-expression network highlighted the significance of apoptosis and EGFR pathway that may orchestrate adaptive responses to low oxygen levels in Changthangi sheep found in high altitude. The nodal genes identified in Muzzafarnagri sheep play essential roles in stress responses and MAPK signaling pathways, pivotal for cellular adaptation and survival under adverse conditions. The key genes identified within our study present compelling candidates for future studies in altitudinal adaptation in ovines. This comprehensive analysis provides valuable insights into the genetic basis of cardiac adaptation to altitude in sheep, shedding light on the molecular pathways involved in physiological adjustments to high-altitude environments.