Loss of Functional Non‐Coding RNA Diversity in Diabetic Cardiac Mitochondria

Abstract

Individuals with diabetes mellitus are predisposed to cardiovascular complications, but no effective predictive or therapeutic measure is in place to prevent these morbidities. Maintenance of cardiac function is heavily dependent on mitochondrial bioenergetics, making the regulation of mitochondria crucial in understanding cardiac pathologies. Both declining cardiovascular health as well as diminished mitochondrial efficiency have been separately correlated with disruption of non‐coding RNA (ncRNA) presence and activity. The recent detection of ncRNA within mitochondria by our lab and others has led us to investigate whether or not certain disease states could dysregulate ncRNA distribution and function inside the organelle. The objective of this study was to identify ncRNAs impacted within the mitochondrion by type 2 diabetes mellitus in human patients and evaluate the downstream effects caused by their dysregulation. Cytoplasm and mitochondria from human atrial appendages in type 2 diabetic (n=7) and non‐diabetic (n=7) patients were isolated and RNA purified for high‐throughput sequencing. In silico analyses of differentially expressed ncRNA revealed potential functions relevant to mitochondrial bioenergetics and cardiac dysfunction, primarily through targeting of mitochondrial and cytoplasmic mRNA but additionally for interactions between ncRNAs themselves. Approximately 20 tRNAs, 6 rRNAs, 447 lncRNAs, and 154 miRNAs were identified through mitochondrial sequencing, using a mean count value greater than 50 as a cutoff for baseline expression. Of these, all 6 rRNAs as well as 41 lncRNAs and 140 miRNAs were significantly downregulated in expression in type 2 diabetics compared to non‐diabetics. In contrast, 37 lncRNAs were significantly increased relative to non‐diabetic patients. The majority of lncRNAs and miRNAs were determined to have RNA‐binding properties, either for mRNAs or other non‐coding RNAs, based on predictive software and databases such as LncBase, NPInter, and miRcode. The mRNAs identified as targets for dysregulated miRNAs were correlated with regulation of proteins such as insulin, Akt, ERK1/2, and similarly metabolically‐crucial factors according to Ingenuity Pathway Analysis, implying cytoplasmic activity despite being found in the mitochondrion. Additionally, various cellular pathways influencing growth and viability were identified to be potentially impacted by miRNA dysregulation. Overall this study reveals a loss of non‐coding RNA diversity within type 2 diabetic cardiac mitochondria, which could contribute to mitochondrial dysfunction and ultimately cardiovascular morbidities associated with type 2 diabetes mellitus. These findings may also support ncRNA as therapeutic and diagnostic targets for type 2 diabetic cardiac complications.Support or Funding InformationThis work was supported by: The National Heart, Lung, and Blood Institute [R01 HL‐128485] (JMH), American Heart Association [AHA‐17PRE33660333] (QAH), West Virginia IDeA Network of Biomedical Research WV‐INBRE support by National Institute of Health Grant [P20GM103434], and the Community Foundation for the Ohio Valley Whipkey Trust.