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Frontiers in Molecular Neuroscience 2024Here, we investigated the role of the canonical Wnt signaling pathway transcriptional regulators at the neuromuscular junction. Upon applying a denervation paradigm, the...
Here, we investigated the role of the canonical Wnt signaling pathway transcriptional regulators at the neuromuscular junction. Upon applying a denervation paradigm, the transcription levels of , , , , , and were significantly downregulated. A significant decrease in canonical Wnt signaling activity was observed using the denervation paradigm in Axin2-lacZ reporter mice. Alterations in the transcriptional profile of the myogenic lineage in response to agrin (AGRN) suggested that TLE3 and TLE4, family members of groucho transducin-like enhancer of split 3 (TLE3), transcriptional repressors known to antagonize T cell factor/lymphoid enhancer factor (TCF)-mediated target gene activation, could be important regulators of canonical Wnt signaling activity at the postsynapse. Knockouts of these genes using CRISPR/Cas9 gene editing in primary skeletal muscle stem cells, called satellite cells, led to decreased AGRN-dependent acetylcholine receptor (CHRN) clustering and reduced synaptic gene transcription upon differentiation of these cells. Overall, our findings demonstrate that TLE3 and TLE4 participate in diminishing canonical Wnt signaling activity, supporting transcription of synaptic genes and CHRN clustering at the neuromuscular junction.
PubMed: 38600964
DOI: 10.3389/fnmol.2024.1360368 -
Drugs & Aging May 2024Statins medications negatively affect age-associated loss of muscle mass and strength, termed sarcopenia, and neuromuscular junction (NMJ) integrity. However, their...
PURPOSE
Statins medications negatively affect age-associated loss of muscle mass and strength, termed sarcopenia, and neuromuscular junction (NMJ) integrity. However, their association with the sarcopenia-related-quality-of-life (SarQoL) is unknown.
METHODS
In this cross-sectional, case control study, we recruited male nonusers (n = 75 and age 75.2 ± 5.9 years) and users (n = 77 and age 77.1 ± 6.2 years) of statins to evaluate SarQoL and handgrip strength (HGS). We also measured plasma C-terminal agrin fragment-22 (CAF22) as a marker of NMJ degradation.
RESULTS
Statin users had higher CAF22, and lower HGS, and cumulative SarQoL scores than non-users (all p < 0.05). Plasma CAF22 exhibited negative correlations with SarQoL scores for physical and mental health, locomotion, functionality, activities-of-daily-living, and cumulative SarQoL in statins users and non-users (all p < 0.05). Lastly, the cumulative SarQoL scores exhibited positive associations with HGS and gait speed in the study participants (all p < 0.05).
CONCLUSIONS
Collectively, statin usage was associated with NMJ degradation and reduced SarQoL. Statins should be cautiously prescribed in patients with sarcopenia with reduced QoL.
Topics: Humans; Sarcopenia; Male; Quality of Life; Aged; Cross-Sectional Studies; Hyperlipidemias; Case-Control Studies; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hand Strength; Aged, 80 and over; Hypolipidemic Agents; Agrin
PubMed: 38564165
DOI: 10.1007/s40266-024-01111-2 -
Journal of Neuroimmunology May 2024The article highlights upcoming potential treatments, which target different phases of inflammation and offer remyelinating strategies as well as direct and indirect... (Review)
Review
BACKGROUND
The article highlights upcoming potential treatments, which target different phases of inflammation and offer remyelinating strategies as well as direct and indirect neuroprotective and oligodendrocyte protective effects, providing a hopeful outlook for patients with primary and secondary progressive multiple sclerosis (PPMS and SPMS).
OBJECTIVES
The review aims to identify potential treatments and ongoing clinical trials for PPMS and SPMS, and compare their mechanisms of action, efficacy, and side effects with current treatments.
METHODS
We reviewed ongoing clinical trials for PPMS and SPMS on the NIH website, as well as articles from PubMed, Embase, and clinicaltrails.gov since 2010.
RESULTS
BTKIs like, tolebrutinib, and fenebrutinib are being explored as potential PMS treatments. Vidofludimus calcium, an orally available treatment, has shown a reduction of active and new MRI lesions. Other treatments like simvastatin, N-acetylcysteine (NAC), and alpha-lipoic acid are being explored for their antioxidant properties. AHSCT and mesenchymal stem cell therapy are experimental options for younger patients with high inflammatory activity.
CONCLUSIONS
SPMS and PPMS are being studied for new treatments and future trials should consider combination therapies targeting inflammation, demyelination, and neuronal death, as the pathogenesis of PMS involves complex factors.
Topics: Animals; Humans; Multiple Sclerosis, Chronic Progressive; Agammaglobulinaemia Tyrosine Kinase
PubMed: 38554666
DOI: 10.1016/j.jneuroim.2024.578315 -
Aging Cell Mar 2024Neuromuscular junction (NMJ) degeneration is one of pathological factors of sarcopenia. Low-magnitude high-frequency vibration (LMHFV) was reported effective in...
Neuromuscular junction (NMJ) degeneration is one of pathological factors of sarcopenia. Low-magnitude high-frequency vibration (LMHFV) was reported effective in alleviating the sarcopenia progress. However, no previous study has investigated treatment effects of LMHFV targeting NMJ degeneration in sarcopenia. We first compared morphological differences of NMJ between sarcopenic and non-sarcopenic subjects, as well as young and old C57BL/6 mice. We then systematically characterized the age-related degeneration of NMJ in SAMP8 against its control strain, SAMR1 mice, from 3 to 12 months old. We also investigated effects of LMHFV in SAMP8 on the maintenance of NMJ during the onset of sarcopenia with respect to the Agrin-LRP4-MuSK-Dok7 pathway and investigated the mechanism related to ERK1/2 signaling. We observed sarcopenic/old NMJ presented increased acetylcholine receptors (AChRs) cluster fragmentation and discontinuity than non-sarcopenic/young NMJ. In SAMP8, NMJ degeneration (morphologically at 6 months and functionally at 8 months) was observed associated with the sarcopenia onset (10 months). SAMR1 showed improved NMJ morphology and function compared with SAMP8 at 10 months. Skeletal muscle performance was improved at Month 4 post-LMHFV treatment. Vibration group presented improved NMJ function at Months 2 and 6 posttreatment, accompanied with alleviated morphological degeneration at Month 4 posttreatment. LMHFV increased Dok7 expression at Month 4 posttreatment. In vitro, LMHFV could promote AChRs clustering in myotubes by increasing Dok7 expression through suppressing ERK1/2 phosphorylation. In conclusion, NMJ degeneration was observed associated with the sarcopenia onset in SAMP8. LMHFV may attenuate NMJ degeneration and sarcopenia progression by increasing Dok7 expression through suppressing ERK1/2 phosphorylation.
PubMed: 38532712
DOI: 10.1111/acel.14156 -
Circulation Mar 2024
Topics: Humans; Heart; Myocardium; Extracellular Matrix; Regeneration; Myocytes, Cardiac
PubMed: 38527129
DOI: 10.1161/CIRCULATIONAHA.123.068078 -
Cell Death & Disease Mar 2024Sarcopenia, a progressive and prevalent neuromuscular disorder, is characterized by age-related muscle wasting and weakening. Despite its widespread occurrence, the...
Sarcopenia, a progressive and prevalent neuromuscular disorder, is characterized by age-related muscle wasting and weakening. Despite its widespread occurrence, the molecular underpinnings of this disease remain poorly understood. Herein, we report that levels of Agrin, an extracellular matrix (ECM) protein critical for neuromuscular formation, were decreased with age in the skeletal muscles of mice. The conditional loss of Agrin in myogenic progenitors and satellite cells (SCs) (Pax7 Cre:: Agrin flox/flox) causes premature muscle aging, manifesting a distinct sarcopenic phenotype in mice. Conversely, the elevation of a miniaturized form of Agrin in skeletal muscle through adenovirus-mediated gene transfer induces enhanced muscle capacity in aged mice. Mechanistic investigations suggest that Agrin-mediated improvement in muscle function occurs through the stimulation of Yap signaling and the concurrent upregulation of dystroglycan expression. Collectively, our findings underscore the pivotal role of Agrin in the aging process of skeletal muscles and propose Agrin as a potential therapeutic target for addressing sarcopenia.
Topics: Animals; Mice; Agrin; Muscle, Skeletal; Muscular Atrophy; Sarcopenia; Signal Transduction
PubMed: 38461287
DOI: 10.1038/s41419-024-06581-1 -
Skeletal Muscle Mar 2024Neurovascular cells have wide-ranging implications on skeletal muscle biology regulating myogenesis, maturation, and regeneration. Although several in vitro studies have...
BACKGROUND
Neurovascular cells have wide-ranging implications on skeletal muscle biology regulating myogenesis, maturation, and regeneration. Although several in vitro studies have investigated how motor neurons and endothelial cells interact with skeletal myocytes independently, there is limited knowledge about the combined effect of neural and vascular cells on muscle maturation and development.
METHODS
Here, we report a triculture system comprising human-induced pluripotent stem cell (iPSC)-derived skeletal myocytes, human iPSC-derived motor neurons, and primary human endothelial cells maintained under controlled media conditions. Briefly, iPSCs were differentiated to generate skeletal muscle progenitor cells (SMPCs). These SMPCs were seeded at a density of 5 × 10 cells/well in 12-well plates and allowed to differentiate for 7 days before adding iPSC-derived motor neurons at a concentration of 0.5 × 10 cells/well. The neuromuscular coculture was maintained for another 7 days in coculture media before addition of primary human umbilical vein endothelial cells (HUVEC) also at 0.5 × 10 cells/well. The triculture was maintained for another 7 days in triculture media comprising equal portions of muscle differentiation media, coculture media, and vascular media. Extensive morphological, genetic, and molecular characterization was performed to understand the combined and individual effects of neural and vascular cells on skeletal muscle maturation.
RESULTS
We observed that motor neurons independently promoted myofiber fusion, upregulated neuromuscular junction genes, and maintained a molecular niche supportive of muscle maturation. Endothelial cells independently did not support myofiber fusion and downregulated expression of LRP4 but did promote expression of type II specific myosin isoforms. However, neurovascular cells in combination exhibited additive increases in myofiber fusion and length, enhanced production of Agrin, along with upregulation of several key genes like MUSK, RAPSYN, DOK-7, and SLC2A4. Interestingly, more divergent effects were observed in expression of genes like MYH8, MYH1, MYH2, MYH4, and LRP4 and secretion of key molecular factors like amphiregulin and IGFBP-4.
CONCLUSIONS
Neurovascular cells when cultured in combination with skeletal myocytes promoted myocyte fusion with concomitant increase in expression of various neuromuscular genes. This triculture system may be used to gain a deeper understanding of the effects of the neurovascular niche on skeletal muscle biology and pathophysiology.
Topics: Humans; Induced Pluripotent Stem Cells; Endothelial Cells; Cells, Cultured; Muscle Fibers, Skeletal; Motor Neurons; Cell Differentiation
PubMed: 38454511
DOI: 10.1186/s13395-024-00336-4 -
BMC Sports Science, Medicine &... Feb 2024Sarcopenia is an age-related progressive loss of muscle mass and strength that can be modulated by resistance training. This study aimed to investigate the effects of...
BACKGROUND
Sarcopenia is an age-related progressive loss of muscle mass and strength that can be modulated by resistance training. This study aimed to investigate the effects of TRX Suspension Training (TST) on serum levels of neuromuscular and growth factors and functional indices in elderly men with sarcopenia, an age-related condition characterized by progressive muscle mass and strength loss.
METHODS
Nineteen sarcopenic elderly men (age = 74.87 ± 4.58 years) were randomly assigned into two groups, the TST group (n = 10) and the control group (n = 9). Serum concentrations of regulatory muscle markers, anthropometric and body composition indices, and functional tests were evaluated at baseline and after 8 weeks. The training protocol consisted of eight weeks of TRX exercises, with three weekly sessions.
RESULTS
After 8 weeks of training, growth factors such as Follistatin (FST) (P = 0.001), 22 kDa C-terminal agrin fragment (CAF) (P = 0.031), and growth differentiation factor 15 (GDF15) (P = 0.049) increased significantly in the training group in comparison to the control group and Myostatin (MSTN) (P = 0.002) had a significant decrease. However, there was no significant difference in ASMM/m2 (P = 0.527), SMM/m2 (P = 0.621), or Body fat mass (P = 0.433) within or between groups. In addition, the TRX Suspension Training had a significant effect on the functional tests and improved gait speed (P = 0.037), chair stand (P = 0.016), and TUG (P = 0.016) as well as Handgrip strength (P = 0.035).
CONCLUSION
Our findings highlight the efficacy of TRX Suspension Training in enhancing the serum levels of muscle growth factors and functional capacities among elderly individuals with sarcopenia. Therefore, considering the ongoing COVID-19 pandemic, this protocol can prove beneficial for this demographic group.
TRIAL REGISTRY
Iranian Registry of Clinical Trials identifier: IRCT20230727058944N1, prospectively registered 20-09-2023, https://en.irct.ir/trial/71635.
PubMed: 38409184
DOI: 10.1186/s13102-024-00849-x -
Molecular Cancer Therapeutics Jun 2024Mucin-16 (MUC16) is a target for antibody-mediated immunotherapy in pancreatic ductal adenocarcinoma (PDAC) among other malignancies. The MUC16-specific monoclonal...
Mucin-16 (MUC16) is a target for antibody-mediated immunotherapy in pancreatic ductal adenocarcinoma (PDAC) among other malignancies. The MUC16-specific monoclonal antibody AR9.6 has shown promise for PDAC immunotherapy and imaging. Here, we report the structural and biological characterization of the humanized AR9.6 antibody (huAR9.6). The structure of huAR9.6 was determined in complex with a MUC16 SEA (Sea urchin sperm, Enterokinase, Agrin) domain. Binding of huAR9.6 to recombinant, shed, and cell-surface MUC16 was characterized, and anti-PDAC activity was evaluated in vitro and in vivo. HuAR9.6 bound a discontinuous, SEA domain epitope with an overall affinity of 88 nmol/L. Binding affinity depended on the specific SEA domain(s) present, and glycosylation modestly enhanced affinity driven by favorable entropy and enthalpy and via distinct transition state thermodynamic pathways. Treatment with huAR9.6 reduced the in vitro growth, migration, invasion, and clonogenicity of MUC16-positive PDAC cells and patient-derived organoids (PDO). HuAR9.6 blocked MUC16-mediated ErbB and AKT activation in PDAC cells, PDOs, and patient-derived xenografts and induced antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. More importantly, huAR9.6 treatment caused substantial PDAC regression in subcutaneous and orthotopic tumor models. The mechanism of action of huAR9.6 may depend on dense avid binding to homologous SEA domains on MUC16. The results of this study validate the translational therapeutic potential of huAR9.6 against MUC16-positive PDACs.
Topics: Humans; Animals; Mice; Pancreatic Neoplasms; CA-125 Antigen; Antibodies, Monoclonal, Humanized; Xenograft Model Antitumor Assays; Cell Line, Tumor; Membrane Proteins; Cell Proliferation; Carcinoma, Pancreatic Ductal; Female
PubMed: 38394685
DOI: 10.1158/1535-7163.MCT-23-0868 -
Stem Cells Translational Medicine May 2024Regenerative cell therapy to replenish the missing neurons and glia in the aganglionic segment of Hirschsprung disease represents a promising treatment option. However,...
Regenerative cell therapy to replenish the missing neurons and glia in the aganglionic segment of Hirschsprung disease represents a promising treatment option. However, the success of cell therapies for this condition are hindered by poor migration of the transplanted cells. This limitation is in part due to a markedly less permissive extracellular environment in the postnatal gut than that of the embryo. Coordinated interactions between enteric neural crest-derived cells (ENCDCs) and their local environment drive migration along the embryonic gut during development of the enteric nervous system. Modifying transplanted cells, or the postnatal extracellular environment, to better recapitulate embryonic ENCDC migration could be leveraged to improve the engraftment and coverage of stem cell transplants. We compared the transcriptomes of ENCDCs from the embryonic intestine to that of postnatal-derived neurospheres and identified 89 extracellular matrix (ECM)-associated genes that are differentially expressed. Agrin, a heparin sulfate proteoglycan with a known inhibitory effect on ENCDC migration, was highly over-expressed by postnatal-derived neurospheres. Using a function-blocking antibody and a shRNA-expressing lentivirus, we show that inhibiting agrin promotes ENCDC migration in vitro and following cell transplantation ex vivo and in vivo. This enhanced migration is associated with an increased proportion of GFAP + cells, whose migration is especially enhanced.
Topics: Animals; Cell Movement; Neural Stem Cells; Mice; Agrin; Enteric Nervous System; Colon; Neural Crest; Hirschsprung Disease; Stem Cell Transplantation
PubMed: 38387006
DOI: 10.1093/stcltm/szae013