Avian MOTS-c characterized, revealing sequence divergence and metabolic regulation via AKT pathway.

Current understanding of mitochondrial peptides like MOTS-c, crucial for regulating energy metabolism, gene expression, and immune processes, is largely derived from mammalian studies. While MOTS-c is known to influence glucose homeostasis and insulin sensitivity in humans and mice, its presence, evolutionary conservation, and functional significance in avian species, particularly poultry, remained unexplored. This knowledge gap limits a comprehensive understanding of MOTS-c's broader physiological impact and its potential applications in animal health or comparative biology.

Researchers identified and characterized MOTS-c coding sequences across major poultry species using bioinformatics analysis, including sequence alignment and phylogenetic studies of mRNA and protein. Tissue expression profiling of chicken MOTS-c was conducted across multiple organs, and the effect of fasting on heart MOTS-c expression was evaluated. Furthermore, primary chicken hepatocytes were treated with MOTS-c for 24 hours to investigate its functional impact on metabolic pathways via enrichment analysis, with Western blot validation confirming AKT signaling activation.

Bioinformatics revealed high sequence similarity in MOTS-c coding regions between avian and mammalian species. However, a single nucleotide deletion was identified in avian sequences at the position corresponding to the fourth amino acid residue of mammalian homologs, resulting in divergent downstream amino acid sequences, though several residues remained conserved. Phylogenetic analysis of mRNA sequences grouped pigeons with mammals, while protein sequences showed poultry and mammals forming separate branches, highlighting significant divergence. Tissue expression profiling demonstrated widespread distribution of chicken MOTS-c across multiple tissues, with the highest expression levels observed in the heart. Fasting significantly reduced heart MOTS-c expression, suggesting a role in metabolic regulation. Functional analysis in primary hepatocytes following 24 hours of MOTS-c treatment showed significant enrichment of the ribosome, oxidative phosphorylation, and key signaling pathways, including PI3K-AKT and JAK-STAT. Western blot validation further confirmed MOTS-c-mediated activation of the AKT signaling pathway.