Deciphering tissue-specific expression profiles of mitochondrial genome-encoded tRNAs and rRNAs through transcriptomic profiling in buffalo.

Abstract

Mitochondria, essential for cellular energy production through oxidative phosphorylation (OXPHOS), integrate mt-DNA and nuclear-encoded genes. This cooperation extends to the mitochondrial translation machinery, involving crucial mtDNA-encoded RNAs: 22 tRNAs (mt-tRNAs) as adapters and two rRNAs (mt-rRNAs) for ribosomal assembly, enabling mitochondrial-encoded mRNA translation. Disruptions in mitochondrial gene expression can strongly impact energy generation and overall animal health. Our study investigates the tissue-specific expression patterns of mt-tRNAs and mt-rRNAs in buffalo. To investigate the expression patterns of mt-tRNAs and mt-rRNAs in different tissues and gain a better understanding of tissue-specific variations, RNA-seq was performed on various tissues, such as the kidney, heart, brain, and ovary, from post-pubertal female buffaloes. Subsequently, we identified transcripts that were differentially expressed in various tissue comparisons. The findings reveal distinct expression patterns among specific mt-tRNA and mt-rRNA genes across various tissues, with some exhibiting significant upregulation and others demonstrating marked downregulation in specific tissue contexts. These identified variations reflect tissue-specific physiological roles, underscoring their significance in meeting the unique energy demands of each tissue. Notably, the brain exhibits the highest mtDNA copy numbers and an abundance of mitochondrial mRNAs of our earlier findings, potentially linked to the significant upregulation of mt-tRNAs in brain. This suggests a plausible association between mtDNA replication and the regulation of mtDNA gene expression. Overall, our study unveils the tissue-specific expression of mitochondrial-encoded non-coding RNAs in buffalo. As we proceed, our further investigations into tissue-specific mitochondrial proteomics and microRNA studies aim to elucidate the intricate mechanisms within mitochondria, contributing to tissue-specific mitochondrial attributes. This research holds promise to elucidate the critical role of mitochondria in animal health and disease.