Ret finger protein inhibits muscle differentiation by modulating serum response factor and enhancer of polycomb1

Abstract

Skeletal myogenesis is precisely regulated by multiple transcription factors. Previously, we demonstrated that enhancer of polycomb 1 (Epc1) induces skeletal muscle differentiation by potentiating serum response factor (SRF)-dependent muscle gene activation. Here, we report that an interacting partner of Epc1, ret finger protein (RFP), blocks skeletal muscle differentiation. Our findings show that RFP was highly expressed in skeletal muscles and was downregulated during myoblast differentiation. Forced expression of RFP delayed myoblast differentiation, whereas knockdown enhanced it. Epc1-induced enhancements of SRF-dependent multinucleation, transactivation of the skeletal a-actin promoter, binding of SRF to the serum response element, and muscle-specific gene induction were blocked by RFP. RFP interfered with the physical interaction between Epc1 and SRF. Muscles from rfp knockout mice (Rfp À/À ) mice were bigger than those from wild-type mice, and the expression of SRF-dependent muscle-specific genes was upregulated. Myotube formation and myoblast differentiation were enhanced in Rfp À/À mice. Taken together, our findings highlight RFP as a novel regulator of muscle differentiation that acts by modulating the expression of SRFdependent skeletal muscle-specific genes. Skeletal muscle is critical for the generation of active force, the maintenance of posture, and body shape. Muscle regeneration from myoblasts is important for the repair and maintenance of skeletal muscles after muscle injury or dystrophy. Myogenesis from the precursor cells to the skeletal muscle lineage consists of multiple steps, and each of these steps is tightly organized by extrinsic and intrinsic signaling pathways. Thus, not only for understanding the regeneration of injured skeletal muscles, but also for furthering therapeutic approaches to muscle atrophy, a hot issue in current research is how the proliferation and differentiation of myoblasts are regulated. To ultimately provide important clues for therapeutics, a comprehensive understanding of how various signaling mechanisms collaborate to regulate the gene expression and epigenetic programs for myoblast differentiation is needed.The TRIM (tripartite motif) protein family (also known as the RBCC protein family) has the common structures of three zinc-binding domains, a RING, a B-box type 1, and a B-box type 2, followed by a coiled-coil region.

High-resolution Episcopic Microscopy (HREM) - Simple and Robust Protocols for Processing and Visualizing Organic Materials

“…HREM is a highly robust microscopic method that is ideal for visualizing a broad spectrum of organic materials used in biomedicine and industry 18 21 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 . It can be employed as an exclusive imaging modality, as currently used by the Mechanisms of Developmental Disorders (DMDD) program 41 42 43 44 , or as an integrative part of multimodal imaging pipelines 45 .…”

Sumoylation of histone deacetylase 1 regulates MyoD signaling during myogenesis

“…These procedures have been previously described. 21 , 22 , 23 The primer sequences for quantitative real-time PCR will be provided upon request. The real-time PCR amplification products were confirmed by sequencing.…”

Horizontal gene transfer from macrophages to ischemic muscles upon delivery of naked DNA with Pluronic block copolymers

“…To obtain terminally differentiated skeletal myotubes (MTs), C2C12 MBs were plated in 96-well plates (50,000 cells/well) in complete media (CM) containing Dulbecco’s minimal essential media (DMEM) and 10% fetal bovine serum (FBS). After 24 h or ~100% confluence, CM was replaced with 200 µl/well differentiation media (DM) containing DMEM and 2% horse serum (HS) to facilitate fusion of MBs (18). DM was changed every 12 h thereafter until day 5–10 when healthy long differentiated MTs were formed.…”