KAP1-associated transcriptional inhibitory complex regulates C2C12 myoblasts differentiation and mitochondrial biogenesis via miR-133a repression.

The differentiation of myoblasts plays a key role in the growth of biological individuals and the reconstruction of muscle tissue. Several microRNAs are significantly upregulated during the differentiation of myoblasts and their target genes have been explored. However, the molecular mechanisms underlying the transcriptional regulation of microRNAs remain elusive. In the present study, we found that the expression of miR-133a is increased during the differentiation of C2C12 myoblasts. miR-133a mimic is sufficient to induce the biogenesis of mitochondria and differentiation of C2C12 myoblasts whereas miR-133a inhibitor abolishes cell differentiation. Using CRISPR affinity purification in situ of regulatory elements (CAPTURE) technique, we further dissected the regulatory mechanisms of miR-133a expression and found that KAP1-associated transcription complex accounts for the suppression of miR-133a in C2C12 myoblasts. Knockdown of KAP1 increased the expression of miR-133a, which contributed to the biogenesis of mitochondria and differentiation of C2C12 myoblasts. To our knowledge, this is the first study using the CAPTURE technology to identify the regulatory factors of miR-133a during cell differentiation, which may provide new ideas for understanding the precision regulatory machinery of microRNAs during different biological processes.