Small non-coding
microRNAs (
miRNAs) are involved in the regulation of mRNA stability. Their features, including high stability and secretion to biofluids, make them attractive as potential
biomarkers for diverse pathologies. This is the first study reporting
miRNA as potential
biomarkers for
oculopharyngeal muscular dystrophy (OPMD), an adult-onset
myopathy. We hypothesized that
miRNA that is differentially expressed in affected muscles from OPMD patients is secreted to biofluids and those
miRNAs could be used as
biomarkers for OPMD. We first identified candidate
miRNAs from OPMD-affected muscles and from muscles from an OPMD mouse model using
RNA sequencing. We then compared the OPMD-deregulated
miRNAs to the literature and, subsequently, we selected a few candidates for expression studies in serum and saliva biofluids using qRT-PCR. We identified 126
miRNAs OPMD-deregulated in human muscles, but 36 deregulated
miRNAs in mice only (pFDR < 0.05). Only 15 OPMD-deregulated
miRNAs overlapped between the in humans and mouse studies. The majority of the OPMD-deregulated
miRNAs showed opposite deregulation direction compared with known
muscular dystrophies miRNAs (myoMirs), which are associated. In contrast, similar dysregulation direction was found for 13
miRNAs that are common between OPMD and aging muscles. A significant age-association (p < 0.05) was found for 17 OPMD-deregulated
miRNAs (13.4%), whereas in controls, only six
miRNAs (1.4%) showed a significant age-association, suggesting that
miRNA expression in OPMD is highly age-associated.
miRNA expression in biofluids revealed that OPMD-associated deregulation in saliva was similar to that in muscles, but not in serum. The same as in muscle,
miRNA expression levels in saliva were also found to be associated with age (p < 0.05). Moreover, the majority of OPMD-
miRNAs were found to be associated with
dysphagia as an initial symptom. We suggest that levels of specific
miRNAs in saliva can mark muscle degeneration in general and
dysphagia in OPMD.