Effects of mechanical trauma on the differentiation and ArfGAP3 expression of C2C12 myoblast and mouse levator ani muscle.
International urogynecology journal
INTRODUCTION AND HYPOTHESIS:Severe mechanical injury or inadequate repair of the levator ani muscle (LAM) is a key contributor to the development of pelvic floor dysfunction (PFD). We explored the effects of mechanical stress on myoblasts and LAM at the cellular and animal level and the possible mechanism of PFD induced by mechanical trauma. METHODS:A C2C12 cell mechanical injury model was established with a four-point bending device, and a LAM injury mouse model was established via vaginal distention and distal traction, a common way of simulating the birth injury. The cells were divided into control, 1333 μ strain for 4-h cyclic mechanical strain (CMS), 1333 μ strain for 8-h CMS, and 5333 μ strain for 4-h CMS groups. Mice were divided into control and injury groups. After treatment, mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) levels, indicators of oxidative damage, cell apoptosis, muscle and cell morphology, cell differentiation, and expression of adenosine diphosphate (ADP)-ribosylation factor GTPase activating protein 3 (ArfGAP3) were detected. RESULTS:5333 μ strain for 4-h CMS loading could induce myoblast injury with a reduction of ΔΨm, increased ROS levels, aggravation of oxidative damage-associated proteins NADPH oxidase 2 (NOX2) and xanthine oxidase (XO), and an increased apoptosis rate of C2C12 cells. At the same time, the injury CMS loading can promote the differentiation of myoblasts and increase the expression of ArfGAP3, a factor regulating intracellular transport. Mechanical trauma could also lead to the oxidative damage of LAM, indicated by 8-hydroxy-2'-deoxyguanosine(8-OHdG), NOX2 and XO protein accumulation, and increase the expression of ArfGAP3 in LAM. CONCLUSIONS:Oxidative stress caused by mechanical trauma induces dysfunction and damage repairing of LAM and C2C12 myoblast, and ArfGAP3 may promote the repairing process.
10.1007/s00192-019-04212-4
β-Catenin regulates hepatic mitochondrial function and energy balance in mice.
Lehwald Nadja,Tao Guo-Zhong,Jang Kyu Yun,Papandreou Ioanna,Liu Bowen,Liu Bo,Pysz Marybeth A,Willmann Jürgen K,Knoefel Wolfram T,Denko Nicholas C,Sylvester Karl G
Gastroenterology
BACKGROUND & AIMS:Wnt signaling regulates hepatic function and nutrient homeostasis. However, little is known about the roles of β-catenin in cellular respiration or mitochondria of hepatocytes. METHODS:We investigated β-catenin's role in the metabolic function of hepatocytes under homeostatic conditions and in response to metabolic stress using mice with hepatocyte-specific deletion of β-catenin and their wild-type littermates, given either saline (sham) or ethanol (as a model of binge drinking and acute ethanol intoxication). RESULTS:Under homeostatic conditions, β-catenin-deficient hepatocytes demonstrated mitochondrial dysfunctions that included impairments to the tricarboxylic acid cycle and oxidative phosphorylation (OXPHOS) and decreased production of adenosine triphosphate (ATP). There was no evidence for redox imbalance or oxidative cellular injury in the absence of metabolic stress. In mice with β-catenin-deficient hepatocytes, ethanol intoxication led to significant redox imbalance in the hepatocytes and further deterioration in mitochondrial function that included reduced OXPHOS, fatty acid oxidation (FAO), and ATP production. Ethanol feeding significantly increased liver steatosis and oxidative damage, compared with wild-type mice, and disrupted the ratio of nicotinamide adenine dinucleotide. β-catenin-deficient hepatocytes also had showed disrupted signaling of Sirt1/peroxisome proliferator-activated receptor-α signaling. CONCLUSIONS:β-catenin has an important role in the maintenance of mitochondrial homeostasis, regulating ATP production via the tricarboxylic acid cycle, OXPHOS, and fatty acid oxidation; β-catenin function in these systems is compromised under conditions of nutrient oxidative stress. Reagents that alter Wnt-β-catenin signaling might be developed as a useful new therapeutic strategy for treatment of liver disease.
10.1053/j.gastro.2012.05.048
Wnt signaling in skeletal muscle dynamics: myogenesis, neuromuscular synapse and fibrosis.
Cisternas Pedro,Henriquez Juan P,Brandan Enrique,Inestrosa Nibaldo C
Molecular neurobiology
The signaling pathways activated by Wnt ligands are related to a wide range of critical cell functions, such as cell division, migration, and synaptogenesis. Here, we summarize compelling evidence on the role of Wnt signaling on several features of skeletal muscle physiology. We briefly review the role of Wnt pathways on the formation of muscle fibers during prenatal and postnatal myogenesis, highlighting its role on the activation of stem cells of the adult muscles. We also discuss how Wnt signaling regulates the precise formation of neuromuscular synapses, by modulating the differentiation of presynaptic and postsynaptic components, particularly regarding the clustering of acetylcholine receptors on the muscle membrane. In addition, based on previous evidence showing that Wnt pathways are linked to several diseases, such as Alzheimer's and cancer, we address recent studies indicating that Wnt signaling plays a key role in skeletal muscle fibrosis, a disease characterized by an increase in the extracellular matrix components leading to failure in muscle regeneration, tissue disorganization and loss of muscle activity. In this context, we also discuss the possible cross-talk between the Wnt/β-catenin pathway with two other critical profibrotic pathways, transforming growth factor β and connective tissue growth factor, which are potent stimulators of the accumulation of connective tissue, an effect characteristic of the fibrotic condition. As it has emerged in other pathological conditions, we suggests that muscle fibrosis may be a consequence of alterations of Wnt signaling activity.
10.1007/s12035-013-8540-5
[Effect of electroacupuncture on urodynamics and expression of Wnt-1, β-catenin, and Ngn1 in the spinal cord in rats with bladder detrusor hyperreflexia due to supersacral spinal cord transection].
Deng Yue-Ning,Zhou Da-An,Xu Xiao-Mei,Liu Lei,Nie Xiao-Jiao,Ma Xian-de,Liu Shu-Quan,Lü Xin
Zhen ci yan jiu = Acupuncture research
OBJECTIVE:To investigate the effect of electroacupuncture (EA) at "Dazhui" (GV14) and "Ciliao" (BL32) on rats with bladder detrusor hyperreflexia (DH) after supersacral spinal cord transection, as well as the mechanism of EA in improving the urinary function by regulating the expression of Wnt-1, β-catenin and Neurogenin 1(Ngn1). METHODS:A total of 48 female Sprague-Dawley rats were randomly divided into sham-operation group, model control group, EA group, and EA control group, with 12 rats in each group. T10 spinal cord transection (SCT) was performed by surgery. The Basso, Beattie and Bresnahan (BBB) score was used to evaluate the motor function of SCT rat, and the Crede technique was used to assist urination. After the urine volume became stable, the urodynamic test was used to determine whether a rat model of DH was successfully established. The rats in the EA group were given EA at GV14 and BL32, and those in the EA control group were given EA (10 Hz/50 Hz, 20 min) at the acupuncture points at 1 cm next to GV14 and BL32 at both sides alternatively. EA was performed once a day for one week. Urodynamic parameters were used to evaluate urinary function. Western blot and immunohistochemistry were used to measure the expression of Wnt-1 and β-catenin in the spinal cord, and immunofluorescence assay was used to measure the expression of Ngn1 in the spinal cord. RESULTS:The BBB score of the model control group significantly decreased compared with that of the sham-operation group(<0.01), and the EA group was significantly higher than the model control group and the EA control group. Compared with the sham-operation group, the model control group had significant increases in bladder base pressure, maximum pressure, and leak point pressure (<0.01) and significant reductions in maximum bladder capacity and compliance (<0.01). Compared with the model control group, the EA group had significant reductions in bladder base pressure, maximum pressure, and leak point pressure (<0.01) and significant increases in maximum bladder capacity and compliance (<0.01, <0.05). Compared with the EA group, the EA control group had significant increases in bladder base pressure, maximum pressure, and leak point pressure (<0.01) and significant reductions in maximum bladder capacity and compliance (<0.01, <0.05). Compared with the sham-operation group, the model control group had significant increases in the protein expression of Wnt-1 and β-catenin (<0.05, <0.01) and a signi-ficant reduction in the protein expression of Ngn1 in the spinal cord (<0.01). Compared with the model control group, the EA group had significant increases in the protein expression of Wnt-1, β-catenin and Ngn1 in the spinal cord (<0.01). Compared with the EA group, the EA control group had significant reductions in the protein expression of Wnt-1, β-catenin, and Ngn1 in the spinal cord (<0.01). CONCLUSION:EA at GV14 and BL32 can significantly improve urinary function in rats with bladder DH due to SCT, partially by activating the Wnt/β-catenin signaling pathway and promoting the protein expression of Wnt-1, β-catenin and Ngn1.
10.13702/j.1000-0607.190129
CACNA1H downregulation induces skeletal muscle atrophy involving endoplasmic reticulum stress activation and autophagy flux blockade.
Li Suting,Hao Menglei,Li Bingshu,Chen Mao,Chen Jue,Tang Jianming,Hong Shasha,Min Jie,Hu Ming,Hong Li
Cell death & disease
Multiple vaginal delivery (MVD) is an important factor for pelvic floor muscle (PFM) function decline and pelvic floor dysfunction (PFD). PFD is common in middle-aged and elderly women, but its pathogenesis is not clear. In this study, we found that the expression of CACNA1H was lower in the PFM of old mice after MVD compared with old or adult mice. In in-vitro studies, we found that treatment with the T-type Ca channel (T-channel) inhibitor NNC-55 or downregulation of the CACNA1H gene by siRNA intervention promoted myotube atrophy and apoptosis. Mechanistically, we revealed that NNC-55 increased the expression of GRP78 and DDIT3 in myotubes, indicating endoplasmic reticulum stress (ERS) activation, and that the IRE1 and PERK pathways might be involved in this effect. NNC-55 induced the formation of autophagosomes but inhibited autophagy flux. Moreover, rapamycin, an autophagy activator, did not rescue myotube atrophy or apoptosis induced by NNC-55, and the autophagy inhibitors 3-MA and HCQ accelerated this damage. Further studies showed that the ERS inhibitors 4-PBA and TUDAC relieved NNC-55-induced damage and autophagy flux blockade. Finally, we found multisite muscle atrophy and decreased muscle function in Cacna1h (TH-null) mice, as well as increased autophagy inhibition and apoptotic signals in the PFM of old WT mice after MVD and TH-null mice. Taken together, our results suggest that MVD-associated PFD is partially attributed to CACNA1H downregulation-induced PFM atrophy and that ERS is a potential therapeutic target for this disease.
10.1038/s41419-020-2484-2
Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review.
International urogynecology journal
INTRODUCTION AND HYPOTHESIS:Mouse knockout (KO) models of pelvic organ prolapse (POP) have contributed mechanistic evidence for the role of connective tissue defects, specifically impaired elastic matrix remodeling. Our objective was to summarize what mouse KO models for POP are available and what have we learned from these mouse models about the pathophysiological mechanisms of POP development. METHODS:We conducted a systematic review and reported narrative findings according to PRISMA guidelines. Two independent reviewers searched PubMed, Scopus and Embase for relevant manuscripts and conference abstracts for the time frame of January 1, 2000, to March 31, 2021. Conference abstracts were limited to the past 5 years. RESULTS:The search strategy resulted in 294 total titles. We ultimately included 25 articles and an additional 11 conference abstracts. Five KO models have been studied: Loxl1, Fbln5, Fbln3, Hoxa11 and Upii-sv40t. Loxl1 and Fbln5 KO models have provided the most reliable and predictable POP phenotype. Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging. These mouse KO models have been used for a wide variety of investigations including genetic pathways involved in development of POP, biomechanical properties of the pelvic floor, elastic fiber deposition, POP therapies and the pathophysiology associated with mesh complications. CONCLUSIONS:Mouse KO models have proved to be a valuable tool in the study of specific genes and their role in the development and progression of POP. They may be useful to study POP treatments and POP complications.
10.1007/s00192-021-05066-5
The effects of microenergy acoustic pulses on animal model of obesity-associated stress urinary incontinence. Part 2: In situ activation of pelvic floor and urethral striated muscle progenitor cells.
Kang Ning,Peng Dongyi,Wang Bohan,Ruan Yajun,Zhou Jun,Reed-Maldonado Amanda B,Banie Lia,Wang Guifang,Xing Nianzeng,Tang Yuxin,Lin Guiting,Lue Tom F
Neurourology and urodynamics
AIM:To investigate the possibility and mechanism of microenergy acoustic pulses (MAP) for activating tissue resident stem/progenitor cells within pelvic and urethral muscle and possible mechanism. METHODS:The female Zucker Lean and Zucker Fatty rats were randomly divided into four groups: ZL control, ZLMAP, ZF control, and ZFMAP. MAP was applied at 0.033 mJ/mm , 3 Hz for 500 pulses, and the urethra and pelvic floor muscles of each rat was then harvested for cell isolation and flow cytometry assay. Freshly isolated cells were analyzed by flow cytometry for Pax-7, Int-7α, H3P, and EdU expression. Meanwhile, pelvic floor muscle-derived stem cells (MDSCs) were harvested through magnetic-activated cell sorting, MAP was then applied to MDSCs to assess the mechanism of stem cell activation. RESULTS:Obesity reduced EdU-label-retaining cells and satellite cells in both pelvic floor muscle and urethra, while MAP activated those cells and enhanced cell proliferation, which promoted regeneration of striated muscle cells of the pelvic floor and urethral sphincter. Activation of focal adhesion kinase (FAK)/AMP-activated protein kinase (AMPK) /Wnt/β-catenin signaling pathways by MAP is the potential mechanism. CONCLUSIONS:MAP treatment activated tissue resident stem cells within pelvic floor and urethral muscle in situ via activating FAK-AMPK and Wnt/β-catenin signaling pathway.
10.1002/nau.24152
Gpcpd1-GPC metabolic pathway is dysfunctional in aging and its deficiency severely perturbs glucose metabolism.
Nature aging
Skeletal muscle plays a central role in the regulation of systemic metabolism during lifespan. With aging, this function is perturbed, initiating multiple chronic diseases. Our knowledge of mechanisms responsible for this decline is limited. Glycerophosphocholine phosphodiesterase 1 (Gpcpd1) is a highly abundant muscle enzyme that hydrolyzes glycerophosphocholine (GPC). The physiological functions of Gpcpd1 remain largely unknown. Here we show, in mice, that the Gpcpd1-GPC metabolic pathway is perturbed in aged muscles. Further, muscle-specific, but not liver- or fat-specific, inactivation of Gpcpd1 resulted in severely impaired glucose metabolism. Western-type diets markedly worsened this condition. Mechanistically, Gpcpd1 muscle deficiency resulted in accumulation of GPC, causing an 'aged-like' transcriptomic signature and impaired insulin signaling in young Gpcpd1-deficient muscles. Finally, we report that the muscle GPC levels are markedly altered in both aged humans and patients with type 2 diabetes, displaying a high positive correlation between GPC levels and chronological age. Our findings reveal that the muscle GPCPD1-GPC metabolic pathway has an important role in the regulation of glucose homeostasis and that it is impaired during aging, which may contribute to glucose intolerance in aging.
10.1038/s43587-023-00551-6
Protective role of pretreatment with Anisodamine against sepsis-induced diaphragm atrophy via inhibiting JAK2/STAT3 pathway.
International immunopharmacology
There is an increasing tendency for sepsis patients to suffer from diaphragm atrophy as well as mortality. Therefore, reducing diaphragm atrophy could benefit sepsis patients' prognoses. Studies have shown that Anisodamine (Anis) can exert antioxidant effects when blows occur. However, the role of Anisodamine in diaphragm atrophy in sepsis patients has not been reported. Therefore, this study investigated the antioxidant effect of Anisodamine in sepsis-induced diaphragm atrophy and its mechanism. We used cecal ligation aspiration (CLP) to establish a mouse septic mode and stimulated the C2C12 myotube model with lipopolysaccharide (LPS). After treatment with Anisodamine, we measured the mice's bodyweight, diaphragm weight, fiber cross-sectional area and the diameter of C2C12 myotubes. The malondialdehyde (MDA) levels in the diaphragm were detected using the oxidative stress kit. The expression of MuRF1, Atrogin1 and JAK2/STAT3 signaling pathway components in the diaphragm and C2C12 myotubes was measured by RT-qPCR and Western blot. The mean fluorescence intensity of ROS in C2C12 myotubes was measured by flow cytometry. Meanwhile, we also measured the levels of Drp1 and Cytochrome C (Cyt-C) in vivo and in vitro by Western blot. Our study revealed that Anisodamine alleviated the reduction in diaphragmatic mass and the loss of diaphragmatic fiber cross-sectional area and attenuated the atrophy of the C2C12 myotubes by inhibiting the expression of E3 ubiquitin ligases. In addition, we observed that Anisodamine inhibited the JAK2/STAT3 signaling pathway and protects mitochondrial function. In conclusion, Anisodamine alleviates sepsis-induced diaphragm atrophy, and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway.
10.1016/j.intimp.2024.112133
Endurance Training Inhibits the JAK2/STAT3 Pathway to Alleviate Sarcopenia.
Physiological research
Aging leads to a decrease in muscle function, mass, and strength in skeletal muscle of animals and humans. The transcriptome identified activation of the JAK/STAT pathway, a pathway that is associated with skeletal muscle atrophy, and endurance training has a significant effect on improving sarcopenia; however, the exact mechanism still requires further study. We investigated the effect of endurance training on sarcopenia. Six-month-old male SAMR1 mice were used as a young control group (group C), and the same month-old male SAMP8 mice were divided into an exercise group (group E) and a model group (group M). A 3-month running exercise intervention was performed on group E, and the other two groups were kept normally. Aging caused significant signs of sarcopenia in the SAMP8 mice, and endurance training effectively improved muscle function, muscle mass, and muscle strength in the SAMP8 mice. The expression of JAK2/STAT3 pathway factor was decreased in group E compared with group M, and the expression of SOCS3, the target gene of STAT3, and NR1D1, an atrophy-related factor, was significantly increased. Endurance training significantly improved the phenotypes associated with sarcopenia, and the JAK2/STAT3 pathway is a possible mechanism for the improvement of sarcopenia by endurance training, while NR1D1 may be its potential target. Keywords: Sarcopenia, Endurance training, Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3), Nuclear receptor subfamily 1, group D member 1 (Nr1d1).
JAK2/STAT3 as a new potential target to manage neurodegenerative diseases: An interactive review.
European journal of pharmacology
Neurodegenerative diseases (NDDs) are a collection of incapacitating disorders in which neuroinflammation and neuronal apoptosis are major pathological consequences due to oxidative stress. Neuroinflammation manifests in the impacted cerebral areas as a result of pro-inflammatory cytokines stimulating the Janus Kinase2 (JAK2)/Signal Transducers and Activators of Transcription3 (STAT3) pathway via neuronal cells. The pro-inflammatory cytokines bind to their respective receptor in the neuronal cells and allow activation of JAK2. Activated JAK2 phosphorylates tyrosines on the intracellular domains of the receptor which recruit the STAT3 transcription factor. The neuroinflammation issues are exacerbated by the active JAK2/STAT3 signaling pathway in conjunction with additional transcription factors like nuclear factor kappa B (NF-κB), and the mammalian target of rapamycin (mTOR). Neuronal apoptosis is a natural process made worse by persistent neuroinflammation and immunological responses via caspase-3 activation. The dysregulation of micro-RNA (miR) expression has been observed in the consequences of neuroinflammation and neuronal apoptosis. Neuroinflammation and neuronal apoptosis-associated gene amplification may be caused by dysregulated miR-mediated aberrant phosphorylation of JAK2/STAT3 signaling pathway components. Therefore, JAK2/STAT3 is an attractive therapeutic target for NDDs. Numerous synthetic and natural small molecules as JAK2/STAT3 inhibitors have therapeutic advances against a wide range of diseases, and many are now in human clinical studies. This review explored the interactive role of the JAK2/STAT3 signaling system with key pathological factors during the reinforcement of NDDs. Also, the clinical trial data provides reasoning evidence about the possible use of JAK2/STAT3 inhibitors to abate neuroinflammation and neuronal apoptosis in NDDs.
10.1016/j.ejphar.2024.176490
CaMKIIβ deregulation contributes to neuromuscular junction destabilization in Myotonic Dystrophy type I.
Skeletal muscle
BACKGROUND:Myotonic Dystrophy type I (DM1) is the most common muscular dystrophy in adults. Previous reports have highlighted that neuromuscular junctions (NMJs) deteriorate in skeletal muscle from DM1 patients and mouse models thereof. However, the underlying pathomechanisms and their contribution to muscle dysfunction remain unknown. METHODS:We compared changes in NMJs and activity-dependent signalling pathways in HSA and Mbnl1 mice, two established mouse models of DM1. RESULTS:Muscle from DM1 mouse models showed major deregulation of calcium/calmodulin-dependent protein kinases II (CaMKIIs), which are key activity sensors regulating synaptic gene expression and acetylcholine receptor (AChR) recycling at the NMJ. Both mouse models exhibited increased fragmentation of the endplate, which preceded muscle degeneration. Endplate fragmentation was not accompanied by changes in AChR turnover at the NMJ. However, the expression of synaptic genes was up-regulated in mutant innervated muscle, together with an abnormal accumulation of histone deacetylase 4 (HDAC4), a known target of CaMKII. Interestingly, denervation-induced increase in synaptic gene expression and AChR turnover was hampered in DM1 muscle. Importantly, CaMKIIβ/βM overexpression normalized endplate fragmentation and synaptic gene expression in innervated Mbnl1 muscle, but it did not restore denervation-induced synaptic gene up-regulation. CONCLUSIONS:Our results indicate that CaMKIIβ-dependent and -independent mechanisms perturb synaptic gene regulation and muscle response to denervation in DM1 mouse models. Changes in these signalling pathways may contribute to NMJ destabilization and muscle dysfunction in DM1 patients.
10.1186/s13395-024-00345-3
Differentiation stage-specific inhibition of the Raf-MEK-ERK pathway by Akt.
Rommel C,Clarke B A,Zimmermann S,Nuñez L,Rossman R,Reid K,Moelling K,Yancopoulos G D,Glass D J
Science (New York, N.Y.)
Extracellular signals often result in simultaneous activation of both the Raf-MEK-ERK and PI3K-Akt pathways (where ERK is extracellular-regulated kinase, MEK is mitogen-activated protein kinase or ERK kinase, and PI3K is phosphatidylinositol 3-kinase). However, these two signaling pathways were shown to exert opposing effects on muscle cell hypertrophy. Furthermore, the PI3K-Akt pathway was shown to inhibit the Raf-MEK-ERK pathway; this cross-regulation depended on the differentiation state of the cell: Akt activation inhibited the Raf-MEK-ERK pathway in differentiated myotubes, but not in their myoblast precursors. The stage-specific inhibitory action of Akt correlated with its stage-specific ability to form a complex with Raf, suggesting the existence of differentially expressed mediators of an inhibitory Akt-Raf complex.
10.1126/science.286.5445.1738
The MuSK-BMP pathway maintains myofiber size in slow muscle through regulation of Akt-mTOR signaling.
Skeletal muscle
Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling. MuSK is expressed at all neuromuscular junctions and is also present extrasynaptically in the mouse soleus, whose predominantly oxidative fiber composition is akin to that of human muscle. To investigate the role of the MuSK-BMP pathway in vivo, we generated mice lacking the BMP-binding MuSK Ig3 domain. These ∆Ig3-MuSK mice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice, myofibers are smaller in the slow soleus, but not in the fast tibialis anterior (TA). Transcriptomic analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1-Akt-mTOR pathway components. Biochemical analysis showed that Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
10.1186/s13395-023-00329-9
The reciprocal regulation between mitochondrial-associated membranes and Notch signaling in skeletal muscle atrophy.
eLife
Skeletal muscle atrophy and the inhibition of muscle regeneration are known to occur as a natural consequence of aging, yet the underlying mechanisms that lead to these processes in atrophic myofibers remain largely unclear. Our research has revealed that the maintenance of proper mitochondrial-associated endoplasmic reticulum membranes (MAM) is vital for preventing skeletal muscle atrophy in microgravity environments. We discovered that the deletion of the mitochondrial fusion protein Mitofusin2 (MFN2), which serves as a tether for MAM, in human induced pluripotent stem (iPS) cells or the reduction of MAM in differentiated myotubes caused by microgravity interfered with myogenic differentiation process and an increased susceptibility to muscle atrophy, as well as the activation of the Notch signaling pathway. The atrophic phenotype of differentiated myotubes in microgravity and the regenerative capacity of Mfn2-deficient muscle stem cells in dystrophic mice were both ameliorated by treatment with the gamma-secretase inhibitor DAPT. Our findings demonstrate how the orchestration of mitochondrial morphology in differentiated myotubes and regenerating muscle stem cells plays a crucial role in regulating Notch signaling through the interaction of MAM.
10.7554/eLife.89381
Regenerating Urethral Striated Muscle by CRISPRi/dCas9-KRAB-Mediated Myostatin Silencing for Obesity-Associated Stress Urinary Incontinence.
The CRISPR journal
Overweight females are prone to obesity-associated stress urinary incontinence (OA-SUI), and there are no definitive medical therapies for this common urologic condition. This study was designed to test the hypothesis that regenerative therapy to restore urethral striated muscle (stM) and pelvic floor muscles might represent a valuable therapeutic approach. For the experiment, single-guide RNAs targeting myostatin () were used for CRISPRi/dCas9-Kruppel associated box (KRAB)-mediated gene silencing. For the experiment, a total of 14 female lean ZUC-Lepr 186 and 14 fatty ZUC-Lepr 185 rats were used as control and CRISPRi-MSTN treated groups, respectively. The results indicated that lentivirus-mediated expression of MSTN CRISPRi/dCas9-KRAB caused sustained downregulation of MSTN in rat L6 myoblast cells and significantly enhanced myogenesis . , the urethral sphincter injection of lentiviral-MSTN sgRNA and lentiviral-dCas9-KRAB significantly increased the leak point pressure, the thickness of the stM layer, the ratio of stM to smooth muscle, and the number of neuromuscular junctions. Downregulation of with CRISPRi/dCas9-KRAB-mediated gene silencing significantly enhanced myogenesis and It also improved urethral continence in the OA-SUI rat model.
10.1089/crispr.2020.0077
MicroRNA-302b mitigates renal fibrosis via inhibiting TGF-β/Smad pathway activation.
Sun Mengkui,Zhou Wei,Yao Fei,Song Jianming,Xu Yanan,Deng Zhimei,Diao Hongwang,Li Shoulin
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
Renal fibrosis is one of the most significant pathological changes after ureteral obstruction. Transforming growth factor-β (TGF-β) signaling pathway plays essential roles in kidney fibrosis regulation. The aims of the present study were to investigate effects of microRNA-302b (miR-302b) on renal fibrosis, and interaction between miR-302b and TGF-β signaling pathway in murine unilateral ureteral obstruction (UUO) model. Microarray dataset GSE42716 was downloaded by retrieving Gene Expression Omnibus database. In accordance with bioinformatics analysis results, miR-302b was significantly down-regulated in UUO mouse kidney tissue and TGF-β1-treated HK-2 cells. Masson's trichrome staining showed that miR-302b mimics decreased renal fibrosis induced by UUO. The increased mRNA expression of collagen I and α-smooth muscle actin (α-SMA) and decreased expression of E-cadherin were reversed by miR-302b mimics. In addition, miR-302b up-regulation also inhibited TGF-β1-induced epithelial mesenchymal transition (EMT) of HK-2 cells by restoring E-cadherin expression and decreasing α-SMA expression. miR-302b mimics suppressed both luciferase activity and protein expression of TGF-βR2. However, miR-302b inhibitor increased TGF-βR2 luciferase activity and protein expression. Meanwhile, miR-302b mimics inhibited TGF-βR2 mRNA expression and decreased Smad2 and Smad3 phosphorylation in vivo and in vitro. Furthermore, over-expression of TGF-βR2 restored the miR-302b-induced decrease of collagen I and α-SMA expression. In conclusion, this study demonstrated that miR-302b attenuated renal fibrosis by targeting TGF-βR2 to suppress TGF-β/Smad signaling activation. Our findings showed that elevating renal miR-302b levels may be a novel therapeutic strategy for preventing renal fibrosis.
10.1590/1414-431X20209206