Roles of Mitochondrial Genome-Encoded Circular RNAs (mecciRNAs) in Human Diseases: Potential Biomarkers and Therapeutic Targets.

Generation of energy and maintenance of homeostasis in eukaryotic cells depends on organelles known as mitochondria, which have their own circular genomes and take part in a number of metabolic activities and cellular events. Bioinformatics techniques and RNA-sequencing (RNA-seq) have helped unravel intricacy of the transcripts originating from mitochondria. Numerous mitochondrial noncoding RNAs (mt-ncRNAs) have been identified in the recent studies, and they are crucial for both mitochondrial and other cellular processes. According to the recently published research, circular RNAs (circRNAs) are endogenous macromolecules with covalent closure at the 5' and 3' ends, which are one of the novel subtypes of ncRNAs. CircRNAs are mostly found in the cytoplasm and nucleus, although this kind of ncRNA can also be detected in mitochondria. Mitochondrial genome-encoded circular RNAs (mecciRNAs) play key roles in regulating cellular phenotypes and progressive illness by sponging microRNA (miRNA) and interacting with the RNA binding proteins (RBP). In this review, we focus on the recent research on the regulatory mechanism and possible functions of mecciRNAs in pathophysiology of various diseases.