The role of microRNAs in muscle wasting during ageing and disease
Sannicandro, Anthony J.
Sannicandro, Anthony J.
Loading...
Publication Date
2023-05-23
Type
Thesis
Downloads
Citation
Abstract
Sarcopenia is age-related muscle loss and management is complex. The mechanisms underpinning age-related decline in muscle health include defective muscle regeneration and deterioration of neuromuscular junctions. microRNAs are small, non-coding RNAs that regulate expression of genes and are implicated in the regulation of muscle. Using bioinformatics and small RNA-seq from human myoblasts, we detected miR-199a-5p to be upregulated in age and was predicted to regulate genes associated with sarcopenia. Therefore, we used C2C12 cells as myogenic model and NSC-34 cells as a neuron-like model in vitro, and adult and old C57BL/6 mice (adult 5-6 months, old 23-24 months) in vivo to determine the effect of miR-199a-5p overexpression and inhibition on muscle. Our data, in vitro, indicated the negative role of miR-199a-5p on myogenic differentiation and myotube size of C2C12 cells. Inhibition of miR-199a-5p in C2C12 also partially restored myotube atrophy resulting from tunicamycin-induced stress of myotubes and increased mitochondrial activity. We found ER stress protein GRP78 upregulated with miR-199a-5p overexpression in vitro. We also observed neuronal growth protein GAP43 to be differentially expressed in vitro with miR-199a-5p overexpression. Luciferase assay identified these as likely targets of miR-199a-5p. We found, in vivo, that miR-199a-5p inhibition did not significantly affect muscle size but did improve muscle force. We examined the neuromuscular junction and found miR-199a-5p overexpression contributed towards increased instance of abnormal morphology and fragmentation, and with miR-199a-5p inhibition this was somewhat reversed. Adult mice treated with miR-199a-5p exhibited reduced expression of GAP43 neuronal growth protein. In old mice, we also found significantly differentially expressed autophagy markers with miR-199a-5p overexpression. Using a model of muscle regeneration in adult and old mice, we found no significant changes to muscle size or function. We can conclude that upregulated miR-199a-5p may lead to muscle loss via a compromised neuromuscular junction, potentially driven by dysregulated miR-199a-5p targets, although more work is needed to precisely understand the nature of this relationship.
Funder
Publisher
NUI Galway