Dual-specificity phosphatases 13 and 27 as key switches in muscle stem cell transition from proliferation to differentiation.

Muscle regeneration depends on muscle stem cell (MuSC) activity. Myogenic regulatory factors, including myoblast determination protein 1 (MyoD), regulate the fate transition of MuSCs. However, the direct target of MYOD in the process is not completely clear. Using previously established MyoD knock-in (MyoD-KI) mice, we revealed that MyoD targets dual-specificity phosphatase (Dusp) 13 and Dusp27. In Dusp13:Dusp27 double knock-out (DKO) mice, the ability for muscle regeneration after injury was reduced. Moreover, single-cell RNA sequencing of MyoD-high expressing MuSCs from MyoD-KI mice revealed that Dusp13 and Dusp27 are expressed only in specific populations within MyoD-high MuSCs, which also express Myogenin. Overexpressing Dusp13 in MuSCs causes premature muscle differentiation. Thus, we propose a model where DUSP13 and DUSP27 contribute to the fate transition of MuSCs from proliferation to differentiation during myogenesis.

The role of miR-128 and MDFI in cardiac hypertrophy and heart failure: Mechanistic.

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/ß-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 ß-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/ß-catenin pathway. Suppression of miR-128 could promote cardiomyocyte proliferation, highlighting the potential value of the miR-128/MDFI interplay in HF treatment.

Spindle cell rhabdomyosarcomas: With TFCP2 rearrangements, and novel EWSR1::ZBTB41 and PLOD2::RBM6 gene fusions. A study of five cases and review of the literature.

AIMS: Spindle-cell/sclerosing rhabdomyosarcomas (SS-RMS) are clinically and genetically heterogeneous. They include three well-defined molecular subtypes, of which those with EWSR1/FUS::TFCP2 rearrangements were described only recently. This study aimed to evaluate five new cases of SS-RMS and to perform a clinicopathological and statistical analysis of all TFCP2-rearranged SS-RMS described in the English literature to more comprehensively characterize this rare tumour type. METHODS AND RESULTS: Cases were retrospectively selected and studied by immunohistochemistry, fluorescence in situ hybridization with EWSR1/FUS and TFCP2 break-apart probes, next-generation sequencing (Archer FusionPlex Sarcoma kit and TruSight RNA Pan-Cancer Panel). The PubMed database was searched for relevant peer-reviewed English reports. Five cases of SS-RMS were found. Three cases were TFCP2 rearranged SS-RMS, having FUSex6::TFCP2ex2 gene fusion in two cases and triple gene fusion EWSR1ex5::TFCP2ex2, VAX2ex2::ALKex2 and VAX2intron2::ALKex2 in one case. Two cases showed rhabdomyoblastic differentiation and spindle-round cell/sclerosing morphology, but were characterized by novel genetic fusions including EWSR1ex8::ZBTB41ex7 and PLOD2ex8::RBM6ex7, respectively. In the statistical analysis of all published cases, CDKN2A or ALK alterations, the use of standard chemotherapy and age at presentation in the range of 18-24 years were negatively correlated to overall survival. CONCLUSION: EWSR1/FUS::TFCP2-rearranged SS-RMS is a rare rhabdomyosarcoma subtype, affecting predominantly young adults with average age at presentation 34 years (median 29.5 years; age range 7-86 years), with a predilection for craniofacial bones, rapid clinical course with frequent bone and lung metastases, and poor prognosis (3-year overall survival rate 28%).

Post-transcriptional regulation of myogenic transcription factors during muscle development and pathogenesis.

The transcriptional regulation of skeletal muscle (SKM) development (myogenesis) has been documented for over 3 decades and served as a paradigm for tissue-specific cell type determination and differentiation. Myogenic stem cells (MuSC) in embryos and adult SKM are regulated by the transcription factors Pax3 and Pax7 for their stem cell characteristics, while their lineage determination and terminal differentiation are both dictated by the myogenic regulatory factors (MRF) that comprise Mrf4, Myf5, Myogenin, and MyoD. The myocyte enhancer factor Mef2c is activated by MRF during terminal differentiation and collaborates with them to promote myoblast fusion and differentiation. Recent studies have found critical regulation of these myogenic transcription factors at mRNA level, including subcellular localization, stability, and translational regulation. Therefore, the regulation of Pax3/7, MRFs and Mef2c mRNAs by RNA-binding factors and non-coding RNAs (ncRNA), including microRNAs and long non-coding RNAs (lncRNA), will be the focus of this review and the impact of this regulation on myogenesis will be further addressed. Interestingly, the stem cell characteristics of MuSC has been found to be critically regulated by ncRNAs, implying the involvement of ncRNAs in SKM homeostasis and regeneration. Current studies have further identified that some ncRNAs are implicated in the etiology of some SKM diseases and can serve as valuable tools/indicators for prediction of prognosis. The roles of ncRNAs in the MuSC biology and SKM disease etiology will also be discussed in this review.

Cardiac Transcription Factors and Regulatory Networks.

Cardiac development is a fine-tuned process governed by complex transcriptional networks, in which transcription factors (TFs) interact with other regulatory layers. In this chapter, we introduce the core cardiac TFs including Gata, Hand, Nkx2, Mef2, Srf, and Tbx. These factors regulate each other's expression and can also act in a combinatorial manner on their downstream targets. Their disruption leads to various cardiac phenotypes in mice, and mutations in humans have been associated with congenital heart defects. In the second part of the chapter, we discuss different levels of regulation including cis-regulatory elements, chromatin structure, and microRNAs, which can interact with transcription factors, modulate their function, or are downstream targets. Finally, examples of disturbances of the cardiac regulatory network leading to congenital heart diseases in human are provided.

MyoD Over-Expression Rescues GST-bFGF Repressed Myogenesis.

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.

Inflammatory Cytokine-Induced Muscle Atrophy and Weakness Can Be Ameliorated by an Inhibition of TGF-ß-Activated Kinase-1.

Chronic inflammation causes muscle wasting. Because most inflammatory cytokine signals are mediated via TGF-ß-activated kinase-1 (TAK1) activation, inflammatory cytokine-induced muscle wasting may be ameliorated by the inhibition of TAK1 activity. The present study was undertaken to clarify whether TAK1 inhibition can ameliorate inflammation-induced muscle wasting. SKG/Jcl mice as an autoimmune arthritis animal model were treated with a small amount of mannan as an adjuvant to enhance the production of TNF-α and IL-1ß. The increase in these inflammatory cytokines caused a reduction in muscle mass and strength along with an induction of arthritis in SKG/Jcl mice. Those changes in muscle fibers were mediated via the phosphorylation of TAK1, which activated the downstream signaling cascade via NF-κB, p38 MAPK, and ERK pathways, resulting in an increase in myostatin expression. Myostatin then reduced the expression of muscle proteins not only via a reduction in MyoD1 expression but also via an enhancement of Atrogin-1 and Murf1 expression. TAK1 inhibitor, LL-Z1640-2, prevented all the cytokine-induced changes in muscle wasting. Thus, TAK1 inhibition can be a new therapeutic target of not only joint destruction but also muscle wasting induced by inflammatory cytokines.

Effect of Infrared and Green Photomodulation Exposure on the Number of Active Myosatellite Cells in Regenerating Muscles.

Reparative properties of infrared laser exposure are well known, but the effects of green laser light are little studied. We analyzed the effects of short (60 sec) and longer (180 sec) exposure to infrared (980 nm) and green (520 nm) laser on the number of activated myosatellite cells in the regenerating m. gastrocnemius of Wistar rats after infliction of an incision wound. Histological preparations were used for morphometric evaluation of myosatellite cells with MyoD+ nuclei. Increased numbers of MyoD+ nuclei were observed on days 3 and 7 after 60-sec exposure to infrared and green laser.

Generation of musculoskeletal cells from human urine epithelium-derived presomitic mesoderm cells.

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.

Gene structure, expression and function analysis of the MyoD gene in the Pacific white shrimp Litopenaeus vannamei.

The Pacific white shrimp Litopenaeus vannamei is a representative species of decapod crustacean and an economically important marine aquaculture species worldwide. However, research on the genes involved in muscle growth and development in shrimp is still lacking. MyoD is recognized as a crucial regulator of myogenesis and plays an essential role in muscle growth and differentiation in various animals. Nonetheless, little information is available concerning the function of this gene among crustaceans. In this study, we identified a sequence of the MyoD gene (LvMyoD) with a conserved bHLH domain in the L. vannamei genome. Phylogenetic analysis revealed that both the overall protein sequence and specific functional sites of LvMyoD are highly conserved with those of other crustacean species and that they are evolutionarily closely related to vertebrate MyoD and Myf5. LvMyoD expression is initially high during early muscle development in shrimp and gradually decreases after 40 days post-larval development. In adults, the muscle-specific expression of LvMyoD was confirmed through RT-qPCR analysis. Knockdown of LvMyoD inhibited the growth of the shrimp in body length and weight. Histological observation and transcriptome sequencing of muscle samples after RNA interference (RNAi) revealed nuclear agglutination and looseness in muscle fibers. Additionally, we observed significant effects on the expression of genes involved in heat shock proteins, myosins, actins, protein synthesis, and glucose metabolism. These findings suggest that LvMyoD plays a critical role in regulating muscle protein synthesis and muscle cell differentiation. Overall, this study highlights the involvement of LvMyoD in myogenesis and muscle growth, suggesting that it is a potentially important regulatory target for shrimp breeding efforts.

Intraoral Inflammatory Leiomyosarcoma: A Case Report and Literature Review.

Inflammatory leiomyosarcoma (ILMS) is a rare malignant soft tissue neoplasm with smooth muscle differentiation, prominent inflammatory infiltration, and near-haploidization. It is extremely rare in the head and neck region, and no intraoral cases have been reported. The lesion was initially diagnosed as a malignant spindle cell neoplasm at the referring laboratory. Microscopic examination of blocks of excised fragmented lesion revealed a cellular neoplasm composed of plump, spindle-shaped cells with blunt-ended and elongated nuclei and eosinophilic fibrillary cytoplasm arranged in a fascicular, herringbone to haphazard pattern. The tumor cells were interspersed with mixed inflammatory infiltration and were diffusely positive to desmin, SMA, H Caldesmon, and MYOD1. The diagnosis came as Inflammatory leiomyosarcoma. This case is the first reported case of ILMS involving the oral cavity. Even though this lesion is very rare, this neoplasm should be included in the differential diagnosis of a spindle cell lesion with marked lymphohistiocytic infiltration.

Cardiac commitment driven by MyoD expression in pericardial stem cells.

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.

Progressive Irreversible Proprioceptive Piezo2 Channelopathy-Induced Lost Forced Peripheral Oscillatory Synchronization to the Hippocampal Oscillator May Explain the Onset of Amyotrophic Lateral Sclerosis Pathomechanism.

Amyotrophic lateral sclerosis (ALS) is a mysterious lethal multisystem neurodegenerative disease that gradually leads to the progressive loss of motor neurons. A recent non-contact dying-back injury mechanism theory for ALS proposed that the primary damage is an acquired irreversible intrafusal proprioceptive terminal Piezo2 channelopathy with underlying genetic and environmental risk factors. Underpinning this is the theory that excessively prolonged proprioceptive mechanotransduction under allostasis may induce dysfunctionality in mitochondria, leading to Piezo2 channelopathy. This microinjury is suggested to provide one gateway from physiology to pathophysiology. The chronic, but not irreversible, form of this Piezo2 channelopathy is implicated in many diseases with unknown etiology. Dry eye disease is one of them where replenishing synthetic proteoglycans promote nerve regeneration. Syndecans, especially syndecan-3, are proposed as the first critical link in this hierarchical ordered depletory pathomechanism as proton-collecting/distributing antennas; hence, they may play a role in ALS pathomechanism onset. Even more importantly, the shedding or charge-altering variants of Syndecan-3 may contribute to the Piezo2 channelopathy-induced disruption of the Piezo2-initiated proton-based ultrafast long-range signaling through VGLUT1 and VGLUT2. Thus, these alterations may not only cause disruption to ultrafast signaling to the hippocampus in conscious proprioception, but could disrupt the ultrafast proprioceptive signaling feedback to the motoneurons. Correspondingly, an inert Piezo2-initiated proton-based ultrafast signaled proprioceptive skeletal system is coming to light that is suggested to be progressively lost in ALS. In addition, the lost functional link of the MyoD family of inhibitor proteins, as auxiliary subunits of Piezo2, may not only contribute to the theorized acquired Piezo2 channelopathy, but may explain how these microinjured ion channels evolve to be principal transcription activators.

MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells by binding ITGB4/LAMB3 to activate the AKT signaling pathway.

Colorectal cancer (CRC) is one of the most lethal cancers. Single-cell RNA sequencing (scRNA-seq) and protein-protein interactions (PPIs) have enabled the systematic study of CRC. In our research, the activation of the AKT pathway in CRC was analyzed by KEGG using single-cell sequencing data from the GSE144735 dataset. The correlation and PPIs of MDFI and ITGB4/LAMB3 were examined. The results were verified in the TCGA and CCLE and further tested by coimmunoprecipitation experiments. The effect of MDFI on the AKT pathway via ITGB4/LAMB3 was validated by knockdown and lentiviral overexpression experiments. The effect of MDFI on oxaliplatin/fluorouracil sensitivity was probed by colony formation assay and CCK8 assay. We discovered that MDFI was positively associated with ITGB4/LAMB3. In addition, MDFI was negatively associated with oxaliplatin/fluorouracil sensitivity. MDFI upregulated the AKT pathway by directly interacting with LAMB3 and ITGB4 in CRC cells, and enhanced the proliferation of CRC cells via the AKT pathway. Finally, MDFI reduced the sensitivity of CRC cells to oxaliplatin and fluorouracil. In conclusion, MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells, partially through the activation of the AKT signaling pathway by the binding to ITGB4/LAMB3. Our findings provide a possible molecular target for CRC therapy.

CHCHD4-TRIAP1 regulation of innate immune signaling mediates skeletal muscle adaptation to exercise.

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.

Discovery of Novel Stimulators of Pax7 and/or MyoD: Enhancing the Efficacy of Cultured Meat Production through Culture Media Enrichment.

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.

Effect of Thymoquinone on skeletal muscle regeneration via assessment of Pax-7 and Myo-D expression in the DMBA-treated hamster pouch / Efeito da Timoquinona na regeneração muscular esquelética através da avaliação da expressão das proteínas Pax-7 e Myo-D em bolsa jugal de hamsters tratados com DMBA

Objective: Pax-7 and Myo-D regulate satellite cells' activation and differentiation, thus muscle regeneration following damage. This research aimed to investigate the effect of Thymoquinone (TQ) on skeletal muscle regeneration following 7,12-dimethylbenz-(a)-anthracene (DMBA)-induced injury in the hamster buccal pouch via immunohistochemical assessment of Pax-7 and Myo-D expression. Material and Methods: 65 male golden Syrian hamsters were divided into 3 groups: Group 1: (n=5) received no treatment. Group 2: (n=20) served as a positive control. The left buccal pouches were painted with the carcinogen 3/week/ 6weeks. Group 3: (n=40) were subdivided into two equal sub-groups as follows: Group 3a: (n=20) were given one i.p. TQ injection. Group 3b: (n=20) were given two i.p. TQ injections. Five animals from each group (2 and 3) were euthanized at 24, 48 hrs, one, and two weeks after the last injection. A blood sample (2 ml) was withdrawn for assessment of TNF-α levels in serum. Serial sections of the pouches were examined histologically (H&E), and immunohistochemically (IHC) for the detection of Pax-7 and Myo-D proteins. Results: double i.p injections of TQ resulted in a significant elevation in the level of TNF-α from the second-day post-injection with a progressive formation of the muscle fibers (MFs) and mononuclear cells (MNCs) around the deeper blood vessels. At 14 days, no statistically significant difference was found between this group and group '2', while the difference remained significant compared to groups '1' and '3a'. The muscle fibers were more mature and compact. IHC results showed positive expression of the perivascular mononuclear cells (MNCs) to both Pax-7 and Myo-D with positive reactivity of the peripheral nuclei of muscle fibers to Pax-7 compared to the negative reaction in the positive control group. Conclusion: early and two TQ injections had a promising effect on the induction of striated muscle regeneration, mainly by non-myogenic stem cells (AU)

Objetivo: Pax-7 e Myo-D regulam a ativação e diferenciação de células satélites durante a regeneração muscular pós-trauma. Assim, objetivamos investigar o efeito da timoquinona (TQ) na regeneração muscular esquelética após injúria causada por 7,12 dimetilbenzantraceno (DMBA) em bolsa jugal de hamsters, através da análise imuno-histoquímica de Pax-7 e Myo-D. Material e Métodos: 65 hamsters-sírios machos foram divididos em 3 grupos: Grupo 1: (n=5) controle negativo, sem tratamento. Grupo 2: (n=20) controle positivo. A bolsa jugal do lado esquerdo recebeu aplicação do DMBA por 3 e 6 semanas. Grupo 3: (n=40) receberam aplicação de DMBA e foram então subdivididos em: Grupo 3a: (n=20) que recebeu 1 injeção intraperitoneal (ip) de TQ e Grupo 3b: (n=20) que recebeu duas injeções ip de TQ. Cinco animais dos grupos 2 e 3 foram eutanasiados em 24 horas, 48 horas, 7 dias e 14 dias após a administração de DMBA e da última injeção de TQ. Amostras de sangue (2 ml) foram coletadas para avaliação dos níveis séricos de TNF-α. Cortes seriados da bolsa jugal dos animais foram analisados histologicamente (H&E), e através de imunohistoquimica (IHC) para avaliação das proteínas Pax-7 e Myo-D. Resultados: duas injeções ip de TQ aumentaram os níveis séricos TNF-α à partir do segundo dia pós-administração com formação progressiva de fibras musculares (MFs) e células mononucleares (MNCs) ao redor dos vasos sanguíneos. No dia 14, não houve diferença estatística entre o grupo 3b e o grupo 2, enquanto a diferença permaneceu entre o grupo 1 e 3a. As MFs apresentavam-se mais maduras e compactas. A IHC mostrou expressão de Pax-7 e Myo-D nas MNCs ao redor dos vasos, e houve expressão nuclear de Pax-7 nas MFs no grupo 2. Conclusão: ambos regimes de administração do TQ, 1 ou 2 aplicações ip, apresentaram efeito promissor na indução da regeneração muscular esquelética, principalmente nas células não-miogênicas.(AU)

Differential expression patterns of myogenic regulatory factors in the postnatal longissimus dorsi muscle of Jeju Native Pig and Berkshire breeds along with their co-expression with Pax7

BACKGROUND: Myogenic regulatory factors (MRFs) such as MyoD, Myf6 and Myf5 play a vital role in the growth and development of muscles. Jeju Native Pig (JNP) is the top ranker in Korea amongst the indigenous livestock reared for meat purpose. Few studies covering transcript abundance of the MRFs and related to their co-expression with Pax7 in JNP have been conducted. Despite having better quality pork, JNP does not have a comparative growth rate with respect to western breeds. Therefore, the present study was designed with the objective to study the relative transcript levels of MRFs in the postnatal myogenesis of longissimus dorsi muscles in JNP and Berkshire breeds. RESULTS: Relative transcript levels were analyzed by qRT-PCR and blot expression analysis through Western blotting. Immunocytochemistry was performed to analyze their expressions at cellular levels. ToppCluster aided in the analysis of gene ontology of biological processes. The quantitative transcript levels of MyoD and Pax7 were significantly (P < 0.05) higher in Berkshire than in JNP. Myotube formation was observed under the co-expression of MyoD and Pax7. ToppCluster helped in the understanding of the linking of biological processes of the MRFs with the different signaling pathways. MyBPH had significantly (P < 0.05) high transcript levels during the chosen age groups in JNP than Berkshire. CONCLUSIONS: The current study can be helpful in understanding the genetic basis for myogenesis in postnatal stage. Moreover, it can act as stepping stone for the identification of marker genes related to body growth and meat quality in JNP.

Lack of dystrophin influences muscle inflammation but not myogenic regulatory factors after eccentric exercise in mdx mice

Abstract Aim: To investigate the consequences of chronic eccentric exercise in histopathology, inflammatory, and myogenic regulatory factors response in gastrocnemius muscle of X-chromosome-linked muscular dystrophy (mdx) mice. Method: Male mdx and control mice (C57BL/10 lineage) were distributed in the following groups: Sedentary Control (SC), Trained Control (TC), Sedentary Mdx (S-Mdx), and Trained Mdx (T-Mdx). Trained animals were subjected to downhill running for 7 weeks. Gastrocnemius was submitted to histopathological analysis and immunoexpression of Cyclooxygenase-2 (COX-2) and myogenic regulatory factors (myoD and myogenin). Results: The exercise influenced inflammation response as demonstrated by the increased COX-2 immunoexpression in T-Mdx. Interestingly, Myogenic regulatory factors revealed that the lack of dystrophin has not been influenced myoD and the increase of myogenin occurred due to exercise and was not aggravated by the absence of dystrophin. Conclusion: In conclusion, an eccentric exercise in gastrocnemius of mdx mice was characterized by an intense inflammatory process without myogenic response. These findings suggest that special attention should be given to inflammatory aspects related to COX-2 associated with a decrease of myoD expression, as biomarkers in motor rehabilitation programs.

Rheumatoid arthritis-increased gene expressions in muscle atrophy are restored back to control as a response to acute resistance exercise / Estímulo agudo de musculação promove regulação de genes alterados pela atrofi a muscular

This study had as objective to analyze the acute eff ects of resistance exercise (RE) on the mRNA levels of the following genes (MyoD, myogenin, IGF-1, atrogin-1, MuRF-1, and myostatin) in rheumatoid arthritis (experimental arthritis). Therefore, 26 females rats were randomly allocated into four groups, control (CT, n=7), exercise (Ex, n=6), rheumatoid arthritis (RA, n=6) and RA with exercise (RAEx, n=7). Met-BSA was injected into the tibiotarsal joint in the RA and RAEx groups. After 15 days from injection, the animals were submitted to an acute bout of RE and six hours post protocol the animals were euthanized. We evaluated the joint thickness, infl ammation score, cross-sectional area (CSA) of gastrocnemius muscle fi bers and mRNA expression of the IGF-1, MyoD, myogenin, myostatin, MuRF-1, atrogin-1 and GAPDH. It was observed that the joint thickness and score strongly increased in arthritic rats (p <0.001) while the CSA decreased (p ≤ 0.05). Increased mRNA levels of IGF-1 (2.0 fold), myostatin (4.5 fold), atrogin-1 (2.5 fold), MyoD (3.7-fold) and myogenin (5 fold) were observed in muscle of arthritic rats. The mRNA expression of myostatin, atrogin-1, MyoD and myogenin decreased in the RAEx group. In this way, we can conclude that experimental arthritis-increased gene expressions in muscle atrophy myostatin, atrogin-1, MyoD and myogenin) are restored back to control as a response to acute RE....(AU)

O presente estudo teve como objetivo analisar o efeito agudo do Exercício com pesos sobre os níves de mRNA de genes envolvidos no anabolismo ou catabolismo muscular em um modelo experimental de Artrite Reumatóide. Para tanto, 26 ratas fêmeas foram randomicamente alocadas em quatro grupos, controle (CT, n=7), Exercício (Ex, n=6), Artrite Reumatóide (AR, n=6) e Artrite Reumatóide com exercício (AREx, n=7). Uma substância contendo Albumina bovina metilada foi injetada na articulação tíbio-tarsal nos grupos AR e AREx para indução da Artrite Reumatóide. Após 15 dias da injeção, os animais foram submetidos a um estímulo agudo de treinamento com pesos e 6 horas após o exercício os animais foram eutanasiados. Nós avaliamos a espessura da articulação, escore de infl amação, a área de secção transversa (AST) das fi bras do músculo Gastrocnêmio e a mRNA de IGF-1, MyoD, Myogenina (genes envolvidos no anabolismo muscular), e MuRF-1, atrogina-1 (genes envolvidos no catabolismo muscular), além do gene controle , GAPDH. Foi observado que a espessura articular e o escore de infl amação aumentaram fortemente nas ratas induzidas a Artrite Reumatóide (p <0,001), enquanto a AST reduziu (p ≤ 0,05). Um aumento nos níveis de mRNA de IGF-1 (2,0 vezes), miostatina (4,5 vezes), atrogina-1 (2,5 vezes), MyoD (3,7 vezes) e miogenina (5 vezes) foi observado no músculo das ratas induzidas a Artrite Reumatóide. mRNA de miostatina, atrogina-1, MyoD e miogenina reduziu no grupo RAEx. Desta forma, podemos concluir, que o modelo experimental de Artrite Reumatóide induziu um aumento da expressão de genes durante a atrofi a muscular (myostatin, atrogin-1, MyoD and myogenin) e que estas alterações foram reguladas pelo Exercício com peso....(AU)