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circSamd4 represses myogenic transcriptional activity of PUR proteins

Poonam R Pandey1, Jen-Hao Yang1, Dimitrios Tsitsipatis1

  • 1Laboratory of Genetics and Genomics, National Institute on Aging Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.

Nucleic Acids Research
|January 26, 2020
PubMed

Insights

Circular RNAs (circRNAs) like circSamd4 play a crucial role in muscle development. circSamd4 enhances myogenesis by preventing repressive proteins from binding to myosin heavy chain (MHC) gene promoters.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Mammalian circular RNAs (circRNAs) are implicated in diverse biological functions through interactions with proteins and nucleic acids.
  • Myogenesis, the process of muscle cell differentiation, involves complex regulatory networks.
  • Differential expression of circRNAs during myogenesis suggests their potential roles in muscle development.

Purpose of the Study:

  • To investigate the role of circSamd4 during myogenesis.
  • To identify proteins interacting with circSamd4.
  • To elucidate the mechanism by which circSamd4 influences muscle differentiation.

Main Methods:

  • RNA sequencing to identify differentially expressed circRNAs during myogenesis.
  • Knockdown experiments to assess the functional impact of circSamd4.
  • Affinity pulldown followed by mass spectrometry to identify circSamd4-interacting proteins.
  • Chromatin immunoprecipitation (ChIP) assays to study protein-DNA interactions.

Main Results:

  • circSamd4 expression significantly increased during myogenesis in mouse C2C12 myoblasts.
  • Silencing circSamd4 impaired myogenesis and reduced myogenic marker expression in human and mouse myoblasts.
  • circSamd4 was found to associate with PURA and PURB, known repressors of myogenesis.
  • circSamd4 binding to PUR proteins prevented their association with the myosin heavy chain (MHC) gene promoter, thereby promoting MHC transcription.

Conclusions:

  • circSamd4 promotes myogenesis by sequestering PUR proteins, relieving their repression on MHC gene transcription.
  • circSamd4 acts as a crucial regulator of muscle differentiation.
  • The findings highlight a novel mechanism of gene regulation by circRNAs in mammalian development.

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