MP401DIFFERENTIAL MICRORNA EXPRESSION IN SKELETAL MUSCLE OF HUMAN CKD PATIENTS AND HEALTHY CONTROLS

Abstract

Introduction and Aims: Patients with advanced Chronic Kidney Disease (CKD) experience significant muscle wasting that negatively impacts upon quality of life, morbidity and mortality; however the causes of this muscle wasting are poorly understood. Many factors could play a role, but one possible mechanism is through microRNAs (miRNAs). MiRNAs are short non-coding RNA molecules that regulate gene and protein expression and have been implicated in human disease. Moreover, they have also been shown to directly regulate protein synthesis and degradation pathways, making them possible candidates for a role in muscle wasting in CKD. Therefore we investigated the differential expression of miRNAs in skeletal muscle of human CKD patients and healthy controls to identify potential regulators of muscle wasting in this population. Methods: Whole miRNA transcriptome profiling was performed in Vastus Lateralis skeletal muscle samples from five patients with CKD stage 3b-5 and five healthy controls matched for age, sex and ethnicity using next generation sequencing. Total RNA was isolated from skeletal muscle. MiRNA libraries were prepared using the Illumina TruSeq Small RNA kit according to Illumina's protocol. Indexed libraries were sequenced on an Illumina Miseq sequencer. Demultiplexing, adaptor trimming and read alignment onto the genome and small RNA databases were performed using the Illumina Miseq small RNA workflow. Raw read counts were normalised to the total number of mapped reads associated with each sample. Significantly differentially expressed miRNA were determined using a t-test with a P&It0.05 as a cut-off. Results: A 16-miRNA signature specific to CKD was identified in which 3 miRNAs were significantly upregulated, hsa-miR-128, -182, -92a and 13 were significantly down regulated, let-7a, let-7e, hsa-miR-1,-98,-99a, -99b,-100,-144, -145, -191, -208, -486, -499. Conclusions: This study has identified 16 miRNAs that are differentially expressed in skeletal muscle of CKD patients and may play a role in muscle wasting. Of note are miR-1, -206, -486 and -499 which are classed as myomiRNAs as they are only expressed in skeletal or cardiac muscle. Furthermore, in line with these results, miR-1 has also been found to be down regulated in COPD. Interestingly, miR-206 promotes muscle repair and regeneration, suggesting that the upregulation we observed in skeletal muscle in CKD may represent a protective measure to reduce muscle damage and muscle wasting.