Differentiation-dependent telomeric long non-coding transcription in a model of skeletal myogenesis

Telomeres comprise the distal ends of eukaryotic chromosomes, serve to maintain genomic integrity and are extended by the ribonucleoprotein telomerase. Recent evidence indicates that telomeres are transcribed to generate long non-coding RNAs (lncRNAs) and that these transcripts (TERRA) may inhibit telomerase activity. In this study we assessed telomerase activity and telomeric lncRNA expression in a mouse model of skeletal myogenesis. Using the C2C12 cell line we demonstrated decreased telomerase activity during differentiation into terminally-differentiated skeletal myotubes. Despite existing in a post-mitotic state, residual telomerase activity remained in C2C12 myotubes, indicating a role independent of telomere extension. Telomeric transcripts were detected in both myoblasts and myotubes, with reduced expression during differentiation correlating with reduced telomerase expression. Our data indicate that in a mouse model of skeletal myogenesis TERRA expression does not reduce telomerase activity, suggesting that their relationship is more complex than originally perceived; the role of telomeric derived lncRNAs in relation to telomerase activity may be cell-type specific. These findings raise the possibility for novel non-telomerase regulatory function for TERRA-lncRNAs during skeletal myogenesis.