Lineage Tracing Reveals a Subset of Reserve Muscle Stem Cells Capable of Clonal Expansion under Stress

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The JAK2/STAT3 Signal Pathway Regulates the Expression of Genes Related to Skeletal Muscle Development and Energy Metabolism in Mice and Mouse Skeletal Muscle Cells

The gene encoding a β-galactosidase from Entevobacter cloacae GAO was cloned and expressed in Escherichia coli. The nucleotide sequence of the insert of a positive clone had an open reading frame of 3084 bp that encoded a polypeptide of 1028 amino acid residues with a calculated molecular mass of 116,677 daltons. The amino acid sequence of β-galactosidase deduced from the nucleotide sequence, especially the sequence around the putative active site and of the fourteen regions, showed significant homology to β-galactosidases of other microorganisms, E. coli, Klebsiella pneumoniae, Lactobacillus bulgaricus, and Clostridium acetobutylicum.     

Aging Disrupts Muscle Stem Cell Function by Impairing Matricellular WISP1 Secretion from Fibro-Adipogenic Progenitors

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Metabolic Maturation during Muscle Stem Cell Differentiation Is Achieved by miR-1/133a-Mediated Inhibition of the Dlk1-Dio3 Mega Gene Cluster

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Muscle Stem Cells Give Rise to Rhabdomyosarcomas in a Severe Mouse Model of Duchenne Muscular Dystrophy

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Lactate Contributes to Glyceroneogenesis and Glyconeogenesis in Skeletal Muscle by Reversal of Pyruvate Kinase

Phosphoenolpyruvate (PEP) generated from pyruvate is required for de novo synthesis of glycerol and glycogen in skeletal muscle. One possible pathway involves synthesis of PEP from the citric acid cycle intermediates via PEP carboxykinase, whereas another could involve reversal of pyruvate kinase (PK). Earlier studies have reported that reverse flux through PK can contribute carbon precursors for glycogen synthesis in muscle, but the physiological importance of this pathway remains uncertain especially in the setting of high plasma glucose. In addition, although PEP is a common intermediate for both glyconeogenesis and glyceroneogenesis, the importance of reverse PK in de novo glycerol synthesis has not been examined. Here we studied the contribution of reverse PK to synthesis of glycogen and the glycerol moiety of acylglycerols in skeletal muscle of animals with high plasma glucose. Rats received a single intraperitoneal bolus of glucose, glycerol, and lactate under a fed or fasted state. Only one of the three substrates was ¹³C-labeled in each experiment. After 3 h of normal awake activity, the animals were sacrificed, and the contribution from each substrate to glycogen and the glycerol moiety of acylglycerols was evaluated. The fraction of ¹³C labeling in glycogen and the glycerol moiety exceeded the possible contribution from either plasma glucose or muscle oxaloacetate. The reverse PK served as a common route for both glyconeogenesis and glyceroneogenesis in the skeletal muscle of rats with high plasma glucose. The activity of pyruvate carboxylase was low in muscle, and no PEP carboxykinase activity was detected.     

Wnt3a诱导小鼠胚胎干细胞向心肌细胞分化的研究

目的：研究Wnt3a在诱导小鼠胚胎干细胞心肌细胞分化中的作用和原理。方法：设计不同浓度,不同成分的Wnt3a条件培养基对小鼠胚胎干细胞诱导分化,对分化细胞进行形态学鉴定,通过免疫细胞化学检测心肌肌钙蛋白-T（cTnT）的表达,通过RT．PCR检测肌球蛋白重链（ot．MHC）和肌球蛋白轻链（MLC．2v）的表达。结果：Wnt3a诱导小鼠胚胎干细胞分化为心肌样细胞,分化细胞具有自动收缩性,免疫细胞化学检测心肌肌钙蛋白．T（cTllT）表达阳性,RT．PCR检测肌球蛋白重链（d—MHC）和肌球蛋白轻链（MLC-2v）表达阳性。经典Wnt信号途径的抑制剂Frizzled一8／Fc,能够抑制Wnt3a的诱导分化作用。结论：Wnt3a通过经典Wnt信号途径诱导小鼠胚胎干细胞向心肌细胞分化。     

Visualization of G3BP Stress Granules Dynamics in Live Primary Cells

SGs can be visualized in cells by immunostaining of specific protein components or polyA+ mRNAs. SGs are highly dynamic and the study of their assembly and fate is important to understand the cellular response to stress. The deficiency in key factors of SGs like G3BP (RasGAP SH3 domain Binding Protein) leads to developmental defects in mice and alterations of the Central Nervous System. To study the dynamics of SGs in cells from an organism, one can culture primary cells and follow the localization of a transfected tagged component of SGs. We describe time-lapse experiment to observe G3BP1-containing SGs in Mouse Embryonic Fibroblasts (MEFs). This technique can also be used to study G3BP-containing SGs in live neurons, which is crucial as it was recently shown that these SGs are formed at the onset of neurodegenerative diseases like Alzheimer''s disease. This approach can be adapted to any other cellular body and granule protein component, and performed with transgenic animals, allowing the live study of granules dynamics for example in the absence of a specific factor of these granules.     

Transplantation of Induced Pluripotent Stem Cell-derived Mesoangioblast-like Myogenic Progenitors in Mouse Models of Muscle Regeneration

Patient-derived iPSCs could be an invaluable source of cells for future autologous cell therapy protocols. iPSC-derived myogenic stem/progenitor cells similar to pericyte-derived mesoangioblasts (iPSC-derived mesoangioblast-like stem/progenitor cells: IDEMs) can be established from iPSCs generated from patients affected by different forms of muscular dystrophy. Patient-specific IDEMs can be genetically corrected with different strategies (e.g. lentiviral vectors, human artificial chromosomes) and enhanced in their myogenic differentiation potential upon overexpression of the myogenesis regulator MyoD. This myogenic potential is then assessed in vitro with specific differentiation assays and analyzed by immunofluorescence. The regenerative potential of IDEMs is further evaluated in vivo, upon intramuscular and intra-arterial transplantation in two representative mouse models displaying acute and chronic muscle regeneration. The contribution of IDEMs to the host skeletal muscle is then confirmed by different functional tests in transplanted mice. In particular, the amelioration of the motor capacity of the animals is studied with treadmill tests. Cell engraftment and differentiation are then assessed by a number of histological and immunofluorescence assays on transplanted muscles. Overall, this paper describes the assays and tools currently utilized to evaluate the differentiation capacity of IDEMs, focusing on the transplantation methods and subsequent outcome measures to analyze the efficacy of cell transplantation.     

Differential Regulation of NOTCH2 and NOTCH3 Contribute to Their Unique Functions in Vascular Smooth Muscle Cells

Notch signaling is a key regulator of vascular smooth muscle cell (VSMC) phenotypes, including differentiation, proliferation, and cell survival. However, the exact contribution of the individual Notch receptors has not been thoroughly delineated. In this study, we identify unique roles for NOTCH2 and NOTCH3 in regulating proliferation and cell survival in cultured VSMCs. Our results indicate that NOTCH2 inhibits PDGF-B-dependent proliferation and its expression is decreased by PDGF-B. In contrast, NOTCH3 promotes proliferation and receptor expression is increased by PDGF-B. Additionally, data show that NOTCH3, but not NOTCH2 protects VSMCs from apoptosis and apoptosis mediators degrade NOTCH3 protein. We identified three pro-survival genes specifically regulated by NOTCH3 in cultured VSMCs and in mouse aortas. This regulation is mediated through MAP kinase signaling, which we demonstrate can be activated by NOTCH3, but not NOTCH2. Overall, this study highlights discrete roles for NOTCH2 and NOTCH3 in VSMCs and connects these roles to specific upstream regulators that control their expression.     

Sustained co-cultivation with human placenta-derived MSCs enhances ALK5/Smad3 signaling in human breast epithelial cells,leading to EMT and differentiation

The interaction between mammary epithelial cells and their surrounding microenvironment are important in the development of the mammary gland. Thus, mesenchymal stem cells (MSCs), which retain pluripotency for various mesenchymal lineages, may provide a permissive environment for the morphologic alteration and differentiation of mammary epithelial cells. To this end, we investigated whether the interactions between mammary epithelial cells and human placenta-derived MSCs (hPMSC) affect the morphology, proliferation, and differentiation of epithelial cells in a co-culture system. We show that after co-culture with hPMSCs, human mammary epithelial cell lines (MCF-10F and HEMC) underwent significant morphologic alterations and a dramatic increase in ductal–alveolar branching, which was accompanied by a decrease or loss of the epithelial marker E-cadherin and a gain of the mesenchymal markers, α-SMA and vimentin. MCF-10F and HEMC proliferation was also inhibited in the presence of hPMSCs, and this retardation in growth was due to cell cycle arrest. Furthermore, in MCF-10F and HMEC cells, hPMSCs induced the production of lipid droplets, milk fat globule protein, and milk protein lactoferrin, which are markers of functional mammary differentiation. We also noticed an elevation in ALK5 and phosphorylated Smad3 protein levels upon hPMSC co-culture. Strikingly, the changes in morphology, proliferation, and differentiation were reversed by treatment with ALK5 or Smad3 knockdown in MCF-10F/hPMSC co-cultures. Collectively, our findings suggest that co-cultivation with hPMSCs leads to epithelial to mesenchymal transition (EMT) and differentiation of human breast epithelial cells through the ALK5/Smad3 signaling pathway.     

TRPC3-mediated Ca influx contributes to Rac1-mediated production of reactive oxygen species in MLP-deficient mouse hearts

Dilated cardiomyopathy (DCM) is a myocardial disorder that is characterized by dilation and dysfunction of the left ventricle (LV). Accumulating evidence has implicated aberrant Ca²⁺ signaling and oxidative stress in the progression of DCM, but the molecular details are unknown. In the present study, we report that inhibition of the transient receptor potential canonical 3 (TRPC3) channels partially prevents LV dilation and dysfunction in muscle LIM protein-deficient (MLP (−/−)) mice, a murine model of DCM. The expression level of TRPC3 and the activity of Ca²⁺/calmodulin-dependent kinase II (CaMKII) were increased in MLP (−/−) mouse hearts. Acitivity of Rac1, a small GTP-binding protein that participates in NADPH oxidase (Nox) activation, and the production of reactive oxygen species (ROS) were also increased in MLP (−/−) mouse hearts. Treatment with pyrazole-3, a TRPC3 selective inhibitor, strongly suppressed the increased activities of CaMKII and Rac1, as well as ROS production. In contrast, activation of TRPC3 by 1-oleoyl-2-acetyl-sn-glycerol (OAG), or by mechanical stretch, induced ROS production in rat neonatal cardiomyocytes. These results suggest that up-regulation of TRPC3 is responsible for the increase in CaMKII activity and the Nox-mediated ROS production in MLP (−/−) mouse cardiomyocytes, and that inhibition of TRPC3 is an effective therapeutic strategy to prevent the progression of DCM.     

MICAL2 is expressed in cancer associated neo-angiogenic capillary endothelia and it is required for endothelial cell viability,motility and VEGF response

The capacity of inducing angiogenesis is a recognized hallmark of cancer cells. The cancer microenvironment, characterized by hypoxia and inflammatory signals, promotes proliferation, migration and activation of quiescent endothelial cells (EC) from surrounding vascular network. Current anti-angiogenic drugs present side effects, temporary efficacy, and issues of primary resistance, thereby calling for the identification of new therapeutic targets.MICALs are a unique family of redox enzymes that destabilize F-actin in cytoskeletal dynamics. MICAL2 mediates Semaphorin3A-NRP2 response to VEGFR1 in rat ECs. MICAL2 also enters the p130Cas interactome in response to VEGF in HUVEC. Previously, we showed that MICAL2 is overexpressed in metastatic cancer. A small-molecule inhibitor of MICAL2 exists (CCG-1423).Here we report that 1) MICAL2 is expressed in neo-angiogenic ECs in human solid tumors (kidney and breast carcinoma, glioblastoma and cardiac myxoma, n = 67, were analyzed with immunohistochemistry) and in animal models of ischemia/inflammation neo-angiogenesis, but not in normal capillary bed; 2) MICAL2 protein pharmacological inhibition (CCG-1423) or gene KD reduce EC viability and functional performance; 3) MICAL2 KD disables ECs response to VEGF in vitro. Whole-genome gene expression profiling reveals MICAL2 involvement in angiogenesis and vascular development pathways.Based on these results, we propose that MICAL2 expression in ECs participates to inflammation-induced neo-angiogenesis and that MICAL2 inhibition should be tested in cancer- and noncancer-associated neo-angiogenesis, where chronic inflammation represents a relevant pathophysiological mechanism.     

Impact of advanced glycation end products (AGEs) signaling in coronary artery disease

Coronary artery disease remains the leading cause of mortality in adult diabetic population with however, a high predominance also in non-diabetic subjects. In search of common molecular mechanisms and metabolic by-products with potential pathogenic role, increased advanced glycation end products (AGEs) present a critical biomarker for CAD development in both cases. Interaction of AGEs with their transmembrane cell receptor, RAGE in endothelial and smooth muscle cells as well as in platelets, activates intracellular signaling that leads to endothelial injury, modulation of vascular smooth muscle cell function and altered platelet activity. Furthermore, tissue accumulation of AGEs affects current treatment approaches being involved in stent restenosis. The present review provides an update of AGE-induced molecular mechanisms involved in CAD pathophysiology while it discusses emerging therapeutic interventions targeting AGE reduction and AGE-RAGE signaling with beneficial clinical outcome.     

Pinealectomy or light exposure exacerbates biliary damage and liver fibrosis in cholestatic rats through decreased melatonin synthesis

Melatonin, a neuroendocrine hormone synthesized by the pineal gland and cholangiocytes, decreases biliary hyperplasia and liver fibrosis during cholestasis-induced biliary injury via melatonin-dependent autocrine signaling through increased biliary arylalkylamine N-acetyltransferase (AANAT) expression and melatonin secretion, downregulation of miR-200b and specific circadian clock genes. Melatonin synthesis is decreased by pinealectomy (PINX) or chronic exposure to light. We evaluated the effect of PINX or prolonged light exposure on melatonin-dependent modulation of biliary damage/ductular reaction/liver fibrosis. Studies were performed in male rats with/without BDL for 1 week with 12:12 h dark/light cycles, continuous light or after 1 week of PINX. The expression of AANAT and melatonin levels in serum and cholangiocyte supernatant were increased in BDL rats, while decreased in BDL rats following PINX or continuous light exposure. BDL-induced increase in serum chemistry, ductular reaction, liver fibrosis, inflammation, angiogenesis and ROS generation were significantly enhanced by PINX or light exposure. Concomitant with enhanced liver fibrosis, we observed increased biliary senescence and enhanced clock genes and miR-200b expression in total liver and cholangiocytes. In vitro, the expression of AANAT, clock genes and miR-200b was increased in PSC human cholangiocyte cell lines (hPSCL). The proliferation and activation of HHStecs (human hepatic stellate cell lines) were increased after stimulating with BDL cholangiocyte supernatant and further enhanced when stimulated with BDL rats following PINX or continuous light exposure cholangiocyte supernatant via intracellular ROS generation. Conclusion: Melatonin plays an important role in the protection of liver against cholestasis-induced damage and ductular reaction.