Methylation is the most common form of in vivo miRNA modification (the Scientist)
It is thus not surprising that there is growing evidence that they are involved in a plethora of biological processes - biological processes in the course of which they occur naturally, processes like exercise, for example.
More recently, scientists have found out more and more about the way miRNAs play a decisive role in the adaptations that occur in the hours and days after you train. They are involved in protein synthesis, mitochondrial biogenesis, muscle repair and all the other processes you want to accelerate or improve n matter if your are doing resistance, endurance or any other exercise.
As of now, however, the focus is on the usual suspects (see Figure 1) like battling Hepatitis C with MiR-122, preventing or reversing cardiac remodeling with MiR-208, soothing inflammation with MiR-155, controlling or even reversing MiR-21, clearing or preventing atherosclerosis with MiR-92a, battling metabolic disease with MiR-33 or MiR-103/107, treating myeloproliferative diseases (non-leukemia proliferation of blood cells) with MiR-45 and triggering cardiac regeneration and repairing injury with MiR-15.
|Figure 2: In a 2011 study, scientists observed that differences in the miRNA response to a std. resistance training protocol explained the differential effects on leg muscle mass (Davidsen. 2011).|
Other studies, suggest that circulating miRNA, such as miRNA-486, which appears to be involved in the improvements in insulin sensitivity in response to exercise (Aoi. 2013), have similar important roles in the regulatory mechanisms that are induced by exercise. The mechanisms that are illustrated in Figure 3, are putative and based on the theory that miRNAs, much like cell-based hormones, facilitate a direct cell-to-cell communication and are therefore being secreted into the circulation, where they target neighboring cells to exert a paracrine functions (Chen. 2012).
- Aoi, Wataru, et al. "Muscle-enriched microRNA miR-486 decreases in circulation in response to exercise in young men." Front Physiol 4 (2013): 80.
- Chen, Xi, et al. "Secreted microRNAs: a new form of intercellular communication." Trends in cell biology 22.3 (2012): 125-132.
- Cheng, Cindy Sue, et al. "Cell density and joint microRNA-133a and microRNA-696 inhibition enhance differentiation and contractile function of engineered human skeletal muscle tissues." Tissue Engineering ja (2016).
- Davidsen, Peter K., et al. "High responders to resistance exercise training demonstrate differential regulation of skeletal muscle microRNA expression." Journal of Applied Physiology 110.2 (2011): 309-317.
- Meurer, S., K. Krüger, and F. C. Mooren. "MicroRNAs and Exercise." Dtsch Z Sportmed 67 (2016): 27-34.
- van Rooij, Eva, Angela L. Purcell, and Arthur A. Levin. "Developing microRNA therapeutics." Circulation research 110.3 (2012): 496-507.