Regulatory Axis of miR-195/497 and HMGA1-Id3 Governs Muscle Cell Proliferation and Differentiation

Abstract

Myocytes withdraw from the cell cycle to differentiate during muscle development. Given the capacity of microRNAs (miRNAs) to regulate gene expression during development, we screened for miRNAs that were associated with muscle development. S-Poly(T) Plus analysis of 273 miRNAs in porcine longissimus dorsi muscles revealed 14 miRNAs that were strongly upregulated with age of postnatal muscle development in vivo, including miR-195 and miR-497. These two miRNAs were also strongly upregulated at late differentiation stages of mouse skeletal myoblast C2C12 cells, and demethylation treatment induced significant upregulation of miR-195/497. Manipulation of miR-195/497 expression resulted in dramatic changes in the proliferation and differentiation of C2C12 cells. We identified high-mobility group AT-hook 1 (Hmga1) mRNA as a highly conserved target of miR-195/497 in C2C12 myoblasts. Overexpression of miR-195/497 or Hmga1 silencing in C2C12 cells promoted myogenic differentiation. Moreover, we showed that miR-195/497 repressed Hmga1, which in turn downregulated one of the HMGA1 downstream targets Id3, whose inhibitory effect on myogenic differentiation is well established. Our study revealed a subset of potential development-associated miRNAs and suggests a novel regulatory axis for myogenesis in which miR-195/497 promote myogenic differentiation by repressing the HMGA1-Id3 pathway.

HMGA Genes and Proteins in Development and Evolution

“…Overexpression of miR-195/497 or Hmga1 silencing in C2C12 cells promotes myotube formation and myogenic differentiation. This suggests a novel regulatory axis for myogenesis in which miR-195/497 promote myogenic differentiation by repressing the HMGA1-ID3 pathway [83] ( Figure 3A). Furthermore, the ε isoform of PKC serine-threonine kinase (PKCε) also downregulates Hmga1 expression, consequently leading to an increased expression of myogenic differentiation genes in mouse.…”

MicroRNA-18a promotes proliferation and metastasis in hepatocellular carcinoma via targeting KLF4

“…MicroRNAs (miRNAs) are a type of short, non-coding and endogenous RNAs that inhibit the protein coding genes expression through partial complementary binding to the 3’-UTR of mRNAs [ 4 ]. Accumulating evidence suggests that the dysregulation of miRNAs is involved in the pathogenesis of multiple human diseases [ 5 – 7 ]. In cancer, Ectopic regulation of miRNA expression has been reported widely and proven to be associated with cancer progression in glioma, metastatic prostate cancer, hepatocellular carcinoma, and others [ 8 , 9 ].…”

Epigenetic Contribution of High-Mobility Group A Proteins to Stem Cell Properties

“…Among these miRs, we show the action of miR-1, miR-133, and miR-206 in Figure 6 . These miRs, also reported by Chen et al [ 122 ], are also involved in myogenesis together with miR-34b [ 123 ], miR-16 [ 124 ], and miR-195/497 [ 125 ]. The middle of Figure 6 shows the contribution of various miRs to the promotion of myogenic differentiation (left side, yellow) which results in the inhibition of myogenic proliferation (right side, blue).…”

“…Once factors in the microenvironment are produced in response to a request for regeneration, satellite stem cells are activated by the proliferation-inducing HMGA2/IGF2BP2, the cell cycle inducer cyclin D1, and an increase in H3K27me3. Many specific myogenic factors such as MyoD and Myf5 are expressed and growth starts [ 125 , 139 , 140 ]. Once an appropriate number of cells have been produced and the action of HMGA proteins is no longer necessary, their expression is repressed as specifically reported for HMGA1 [ 141 , 142 ], and differentiation proceeds to completion.…”