Mouse Anti Rat myogenin Hybridoma [G6E]

Background: JARID2 is a non-catalytic member of the polycomb repressive complex 2 (PRC2), which is known to regulate developmental target genes in embryonic stem cells. Here, we provide mechanistic insight into the modulation of Wnt signaling by JARID2 during murine skeletal muscle differentiation. Results: We show that JARID2 is expressed in proliferating myoblasts, but downregulated upon muscle differentiation. Unexpectedly, depletion of JARID2 or the catalytic subunit of the PRC2 complex, EZH2, inhibited differentiation, suggesting that JARID2 and the PRC2 complex are required to initiate this process. Expression of the myogenic regulatory factors required to promote differentiation, MYOD and MYOG, was downregulated in the absence of JARID2, even though decreases in the methylation of histone H3 lysine 27 (H3K27(me3)) were observed on both promoters. We found that activation of the Wnt signaling pathway upregulated MYOD and restored differentiation. Activation of the Wnt pathway in JARID2 depleted cells caused beta-catenin to translocate to the nucleus, where it bound to and activated the Myod1 promoter. We show that the Wnt antagonist SFRP1 is highly upregulated in the absence of JARID2 and is a direct target of JARID2 and the PRC2 complex. Ectopic expression of SFRP1 blocked MYOD and late muscle gene expression and inhibited the translocation of beta-catenin to the nucleus. Finally, we show that JARID2 and SFRP1 are inversely correlated in melanoma, confirming that the JARID2-mediated repression of SFRP1 extends beyond skeletal muscle and has important implications in many cellular systems, including cancer. Conclusions: We show that JARID2 and the PRC2 complex regulate muscle differentiation by modulating Wnt signaling through the direct repression of Wnt antagonists.

Hyperplasia or hypoplasia of muscles gradually leads to strabismus. Myogenesis-related genes are involved in extraocular muscle development, including myogenic differentiation I (MYOD1), myogenin (MYOG), retinoblastoma 1 (RB1), cyclin-dependent kinase inhibitor 1A (P21), cyclin-dependent kinase inhibitor 1C (P57), insulin-like growth factor 1 (IGF1) and muscle creatine kinase (MCK). This study evaluated the expression of the above seven myogenesis-related genes by real-time quantitative RT-PCR in 18 resected extrocular muscles of patients with concomitant strabismus and 12 normal control muscle samples from one presumably healthy male 6 h after sudden mortality. We found that although there was a great divergence among the expression levels of 6 myogenesis-related regulatory factors, the relative expression patterns were similar in all the normal muscles, including the synergistic, antagonistic and yoke muscles. However, their expression levels in the 18 diseased extraocular muscles were abnormal; the expression levels of all the genes, with the exception of P57, were reduced in most of the diseased muscle tissues. These results imply that the abnormal expression of these myogenesis-related genes may contribute to concomitant strabismus.