Heart failure (HF) prognosis depends on various regulatory factors; microRNA-128 (miR-128) is identified as a regulator of cardiac fibrosis, contributing to HF. MyoD family inhibitor (MDFI), which is reported to be related with Wnt/β-catenin pathway, is supposed to be regulated by miR-128. This study investigates the interaction between miR-128 and MDFI in cardiomyocyte development and elucidates its role in heart injury. Gene expression profiling assessed miR-128\'s effect on MDFI expression in HF using qPCR and Western blot analysis. Luciferase assays studied the direct interaction between miR-128 and MDFI. MTT, transwell, and immunohistochemistry evaluated the effects of miR-128 and MDFI on myocardial cells in mice HF. Genescan and luciferase assays validated the interaction between miR-128 and MDFI sequences. miR-128 mimics significantly reduced MDFI expression at mRNA and protein levels with decrease rate of 55%. Overexpression of miR-128 promoted apoptosis with the increase rate 65% and attenuated cardiomyocyte proliferation, while MDFI upregulation significantly enhanced proliferation. Elevated miR-128 levels upregulated Wnt1 and β-catenin expression, whereas increased MDFI levels inhibited these expressions. Histological analysis with haematoxylin and eosin staining revealed that miR-128 absorption reduced MDFI expression, hindering cell proliferation and cardiac repair, with echocardiography showing corresponding improvements in cardiac function. Our findings suggest miR-128 interacts with MDFI, playing a crucial role in HF management by modulating the Wnt1/β-catenin pathway. Suppression of miR-128 could promote cardiomyocyte proliferation, highlighting the potential value of the miR-128/MDFI interplay in HF treatment.

BACKGROUND: Numerous studies have shown that somite development is a necessary stage of myogenesis chondrogenesis and osteogenesis. Our previous study has established a stable presomitic mesoderm progenitor cell line (UiPSM) in vitro. Naturally, we wanted to explore whether UiPSM cell can develop bone and myogenic differentiation.
RESULTS: Selective culture conditions yielded PAX3 and PAX7 positive skeletal muscle precursors from UiPSM cells. The skeletal muscle precursors undergo in vitro maturation resulting in myotube formation. MYOD effectively promoted the maturity of the skeletal myocytes in a short time. We found that UiPSM and MYOD mediated UiPSM cell-derived skeletal myocytes were viable after transplantation into the tibialis anterior muscle of MITRG mice, as assessed by bioluminescence imaging and scRNA-seq. Lack of teratoma formation and evidence of long-term myocytes engraftment suggests considerable potential for future therapeutic applications. Moreover, UiPSM cells can differentiate into osteoblast and chondroblast cells in vitro.
CONCLUSIONS: UiPSM differentiation has potential as a developmental model for musculoskeletal development research and treatment of musculoskeletal disorders.

During embryogenesis, basic fibroblast growth factor (bFGF) is released from neural tube and myotome to promote myogenic fate in the somite, and is routinely used for the culture of adult skeletal muscle (SKM) stem cells (MuSC, called satellite cells). However, the mechanism employed by bFGF to promote SKM lineage and MuSC proliferation has not been analyzed in detail. Furthermore, the question of if the post-translational modification (PTM) of bFGF is important to its stemness-promoting effect has not been answered. In this study, GST-bFGF was expressed and purified from E.coli, which lacks the PTM system in eukaryotes. We found that both GST-bFGF and commercially available bFGF activated the Akt-Erk pathway and had strong cell proliferation effect on C2C12 myoblasts and MuSC. GST-bFGF reversibly compromised the myogenesis of C2C12 myoblasts and MuSC, and it increased the expression of Myf5, Pax3/7, and Cyclin D1 but strongly repressed that of MyoD, suggesting the maintenance of myogenic stemness amid repressed MyoD expression. The proliferation effect of GST-bFGF was conserved in C2C12 over-expressed with MyoD (C2C12-tTA-MyoD), implying its independence of the down-regulation of MyoD. In addition, the repressive effect of GST-bFGF on myogenic differentiation was almost totally rescued by the over-expression of MyoD. Together, these evidences suggest that (1) GST-bFGF and bFGF have similar effects on myogenic cell proliferation and differentiation, and (2) GST-bFGF can promote MuSC stemness and proliferation by differentially regulating MRFs and Pax3/7, (3) MyoD repression by GST-bFGF is reversible and independent of the proliferation effect, and (4) GST-bFGF can be a good substitute for bFGF in sustaining MuSC stemness and proliferation.

Cellular therapy holds immense promise to remuscularize the damaged myocardium but is practically hindered by limited allogeneic sources of cardiac-committed cells that engraft stably in the recipient heart after transplantation. Here, we demonstrate that the pericardial tissue harbors myogenic stem cells (pSCs) that are activated in response to inflammatory signaling after myocardial infarction (MI). The pSCs derived from the MI rats (MI-pSCs) show in vivo and in vitro cardiac commitment characterized by cardiac-specific Tnnt2 expression and formation of rhythmic contraction in culture. Bulk RNA-seq analysis reveals significant upregulation of a panel of genes related to cardiac/myogenic differentiation, paracrine factors, and extracellular matrix in the activated pSCs compared to the control pSCs (Sham-pSCs). Notably, we define MyoD as a key factor that governs the process of cardiac commitment, as siRNA-mediated MyoD gene silencing results in a significant reduction of myogenic potential. Injection of the cardiac-committed cells into the infarcted rat heart leads to long-term survival and stable engraftment in the recipient myocardium. Therefore, these findings point to pericardial myogenic progenitors as an attractive candidate for cardiac cell-based therapy to remuscularize the damaged myocardium.

The principles of myogenesis play crucial roles in the production of cultured meat, and identifying protein stimulators associated with myogenesis holds great potential to enhance the efficiency of this process. In this study, we used surface plasmon resonance (SPR)-based screening of a natural product library to discover ligands for Pax7 and MyoD, key regulators of satellite cells (SCs), and performed cell-based assays on Hanwoo SCs (HWSCs) to identify substances that promote cell proliferation and/or differentiation. Through an SPR analysis, we found that six chemicals, including one Pax7+/MyoD- chemical, four Pax7+/MyoD+ chemicals, and one Pax7-/MyoD+ chemical, bound to Pax7 and/or MyoD proteins. Among four Pax7+/MyoD+ chemicals, parthenolide (0.5 and 1 µM) and rutin (100 and 200 µM) stimulated cell proliferation in the medium with 10% FBS similar to the medium with 20% FBS, without affecting differentiation. Adenosine, a Pax7-/MyoD+ chemical, accelerated differentiation. These chemicals could be potential additives to reduce the reliance of FBS required for HWSC proliferation and differentiation in cultured meat production.

Exercise training can stimulate the formation of fatty-acid-oxidizing slow-twitch skeletal muscle fibers, which are inversely correlated with obesity, but the molecular mechanism underlying this transformation requires further elucidation. Here, we report that the downregulation of the mitochondrial disulfide relay carrier CHCHD4 by exercise training decreases the import of TP53-regulated inhibitor of apoptosis 1 (TRIAP1) into mitochondria, which can reduce cardiolipin levels and promote VDAC oligomerization in skeletal muscle. VDAC oligomerization, known to facilitate mtDNA release, can activate cGAS-STING/NFKB innate immune signaling and downregulate MyoD in skeletal muscle, thereby promoting the formation of oxidative slow-twitch fibers. In mice, CHCHD4 haploinsufficiency is sufficient to activate this pathway, leading to increased oxidative muscle fibers and decreased fat accumulation with aging. The identification of a specific mediator regulating muscle fiber transformation provides an opportunity to understand further the molecular underpinnings of complex metabolic conditions such as obesity and could have therapeutic implications.

Long non-coding RNAs (lncRNAs) are involved in the process of muscle cell differentiation and play an important role. Previous studies have shown that lncRNA-MEG3 promotes the differentiation of porcine skeletal muscle satellite cells (PSCs), but the regulatory mechanism of MEG3 interaction with target protein has not been well studied. We demonstrated that MEG3 can bind dihydrolipoamide succinyltransferase (DLST) by RNA pull down and RIP-qPCR. Subsequently, knockdown and overexpression experiments showed that DLST promotes PSCs differentiation. Rescue experiments showed that the expression of DLST protein was significantly increased with MEG3 overexpression and decreased with MEG3 knockdown, while its mRNA expression was not changed. Furthermore, we have successfully predicted and validated that the transcription factor myogenic differentiation (MYOD) binds to the MEG3 core promoter though utilizing chromatin immunoprecipitation (CHIP) and luciferase reporter assays. The results indicated that MYOD acts as a transcription factor of MEG3 to promote MEG3 transcription. Knockdown of MEG3 in vivo indicated that MEG3 is involved in skeletal muscle regeneration. It is concluded that MYOD acts as a transcription factor to induce MEG3 expression. MEG3 acts as a molecular scaffold to bind and promote DLST protein expression. This paper provides a new molecular mechanism for MEG3 to promote the differentiation of PSCs.

Herein, we review a unique and versatile lineage composed of Myo/Nog cells that may be beneficial or detrimental depending on their environment and nature of the pathological stimuli they are exposed to. While we will focus on the lens, related Myo/Nog cell behaviors and functions in other tissues are integrated into the narrative of our research that spans over three decades, examines multiple species and progresses from early stages of embryonic development to aging adults. Myo/Nog cells were discovered in the embryonic epiblast by their co-expression of the skeletal muscle-specific transcription factor MyoD, the bone morphogenetic protein inhibitor Noggin and brain-specific angiogenesis inhibitor 1. They were tracked from the epiblast into the developing lens, revealing heterogeneity of cell types within this structure. Depletion of Myo/Nog cells in the epiblast results in eye malformations arising from the absence of Noggin. In the adult lens, Myo/Nog cells are the source of myofibroblasts whose contractions produce wrinkles in the capsule. Eliminating this population within the rabbit lens during cataract surgery reduces posterior capsule opacification to below clinically significant levels. Parallels are drawn between the therapeutic potential of targeting Myo/Nog cells to prevent fibrotic disease in the lens and other ocular tissues.

Labeo rohita is a widely cultivated tropical freshwater carp and found in rivers of South Asian region. A new cell line, designated LRM, has been developed from the muscle tissue of L. rohita. Muscle cells were subcultured up to 38 passages in a Leibovitz\'s-15 (L-15) supplemented with 10% FBS (Fetal Bovine Serum) and 10 ng/ml bFGF. The LRM cells exhibited fibroblastic morphology with a doubling time of 28 h, and a plating efficiency of 17%. A maximum growth rate was observed for LRM cells at 28 °C, 10% FBS and 10 ng/ml bFGF. A cytochrome C oxidase subunit I (COI) gene sequence was used to authenticate the developed cell line. Chromosome analysis revealed 50 diploid chromosomes. The fibroblastic characteristics of the of the LRM cells was confirmed by immunocytochemistry. The expression of MyoD gene in LRM cells was analyzed by quantitative PCR in comparison with passages 3, 18 and 32. The expression of MyoD was higher at passage 18 compared to the passages 3 and 32. The LRM cells attached properly onto the 2D scaffold and the expression of the F-actin filament protein was confirmed by phalloidin staining followed by counter staining with DAPI to observe the distribution of the muscle cell nuclei and the cytoskeleton protein. A revival rate of 70-80% was achieved when the LRM cells were cryopreserved at - 196 °C using liquid nitrogen. This study would further contribute to understanding the in vitro myogenesis and progress toward cultivated fish meat production.

The purpose of this study was to investigate the time-dependent alteration in whether concurrent aerobic exercise and bone marrow stromal cell (BMSC) engraftment could regulate myogenic differentiation-related signaling pathway in the soleus up to 35 days after sciatic nerve injury (SNI). The rats were divided as follows: the normal control (CON, n=5), sedentary group (SED, n=20), treadmill exercise group (TEX, n=20), BMSC transplantation group (BMSC, n=20), TEX+BMSC transplantation group (TEX+BMSC, n=20) 7, 14, 21, and 35 days after SNI. SNI was applied into the thigh and treadmill exercise was comprised of walking at a speed of 4 to 8 m/min for 30 min once a day. Harvested BMSC at a density of 5×106 in 50-μL phosphate-buff-ered saline was injected into the injury site. Phosphorylated (p) extracellular signal-regulated kinase 1/2 expression was dramatically upregulated in BMSC and BMSC+EX groups from 21 days after SNI compared to those in the SED group. P-ribosomal s6 kinase (RSK) was sharply increased 14 days later, and then rapidly downregulated from day 21, whereas TEX, BMSC and TEX+ BMSC groups significantly kept up expression levels of p-RSK until 35 days post injury than SED group. TEX+BMSC group significantly increased activation of protein kinase B-mammalian target of rapamycin in the soleus from day 14 and myoblast determination protein 1-myogen-in pathways was activated in TEX+BMSC group from day 21. Present findings provide information that combined intervention of aerobic exercise and BMSC transplantation might be a reliable therapeutic strategy for overcoming the morphological and functional problems in denervated soleus muscle.