scholarly journals Interactions between p-Akt and Smad3 in injured muscles initiate myogenesis or fibrogenesis

2013 ◽  
Vol 305 (3) ◽  
pp. E367-E375 ◽  
Author(s):  
Yanjun Dong ◽  
Ronak Lakhia ◽  
Sandhya S. Thomas ◽  
Yanlan Dong ◽  
Xiaonan H. Wang ◽  
...  
Keyword(s):  
Satellite Cells ◽  
Nuclear Translocation ◽  
Wild Type Mouse ◽  
Muscle Fibrosis ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Igf I ◽  
Smad3 Phosphorylation ◽  
Tgf Β1 ◽  
Igf Signaling

In catabolic conditions such as aging and diabetes, IGF signaling is impaired and fibrosis develops in skeletal muscles. To examine whether impaired IGF signaling initiates muscle fibrosis, we generated IGF-IR+/− heterozygous mice by crossing loxP-floxed IGF-IR (exon 3) mice with MyoD-cre mice. IGF-IR+/− mice were studied because we were unable to obtain homozygous IGF-IR-KO mice. In IGF-IR+/− mice, both growth and expression of myogenic genes (MyoD and myogenin; markers of satellite cell proliferation and differentiation, respectively) were depressed. Likewise, in injured muscles of IGF-IR+/− mice, there was impaired regeneration, depressed expression of MyoD and myogenin, and increased expression of TGF-β1, α-SMA, collagen I, and fibrosis. To uncover mechanisms stimulating fibrosis, we isolated satellite cells from muscles of IGF-IR+/− mice and found reduced proliferation and differentiation plus increased TGF-β1 production. In C2C12 myoblasts (a model of satellite cells), IGF-I treatment inhibited TGF-β1-stimulated Smad3 phosphorylation, its nuclear translocation, and expression of fibronectin. Using immunoprecipitation assay, we found an interaction between p-Akt or Akt with Smad3 in wild-type mouse muscles and in C2C12 myoblasts; importantly, IGF-I increased p-Akt and Smad3 interaction, whereas TGF-β1 decreased it. Therefore, in muscles of IGF-IR+/− mice, the reduction in IGF-IR reduces p-Akt, allowing for dissociation and nuclear translocation of Smad3 to enhance the TGF-β1 signaling pathway, leading to fibrosis. Thus, strategies to improve IGF signaling could prevent fibrosis in catabolic conditions with impaired IGF signaling.

IGFBP-3 activates TGF-β receptors and directly inhibits growth in human intestinal smooth muscle cells

2004 ◽  
Vol 287 (4) ◽  
pp. G795-G802 ◽  
Author(s):  
John F. Kuemmerle ◽  
Karnam S. Murthy ◽  
Jennifer G. Bowers
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Nuclear Translocation ◽  
Thymidine Incorporation ◽  
Muscle Cells ◽  
Serine Phosphorylation ◽  
Intestinal Smooth Muscle ◽  
Igf I ◽  
Tgf Β1 ◽  
Igfbp 3

We have shown that human intestinal smooth muscle cells produce IGF-I and IGF binding protein-3 (IGFBP-3). Endogenous IGF-I acts in autocrine fashion to stimulate growth of these cells. IGFBP-3 inhibits the binding of IGF-I to its receptor and thereby inhibits IGF-I-stimulated growth. In several carcinoma cell lines and some normal cells, IGFBP-3 regulates growth independently of IGF-I. Two mechanisms for this effect have been identified: IGFBP-3 can directly activate transforming growth factor-β (TGF-β) receptors or it can undergo direct nuclear translocation. The aim of the present study was to determine whether IGFBP-3 acts independently of IGF-I and to characterize the mechanisms mediating this effect in human intestinal smooth muscle cells. The direct effects of IGFBP-3 were determined in the presence of an IGF-I receptor antagonist to eliminate its IGF-I-dependent effects. Affinity labeling of TGF-β receptors (TGF-βRI, TGF-βRII, and TGF-βRV) with 125I-labeled TGF-β1 showed that IGFBP-3 displaced binding to TGF-βRII and TGF-βRV in a concentration-dependent fashion. IGFBP-3 stimulated TGF-βRII-dependent serine phosphorylation (activation) of both TGF-βRI and of its primary substrate, Smad2(Ser465/467). IGFBP-3 also caused IGF-I-independent inhibition of basal [3H]thymidine incorporation. The effects of IGFBP-3 on Smad2 phosphorylation and on smooth muscle cell proliferation were independent of TGF-β1 and were abolished by transfection of Smad2 siRNA. Immunoneutralization of IGFBP-3 increased basal [3H]thymidine incorporation, implying that endogenous IGFBP-3 inhibits proliferation. We conclude that endogenous IGFBP-3 directly inhibits proliferation of human intestinal smooth muscle cells by activation of TGF-βRI and Smad2, an effect that is independent of its effect on IGF-I-stimulated growth.

scholarly journals Thermal stress affects proliferation and differentiation of turkey satellite cells through the mTOR/S6K pathway in a growth-dependent manner

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262576
Author(s):  
Jiahui Xu ◽  
Gale M. Strasburg ◽  
Kent M. Reed ◽  
Sandra G. Velleman
Keyword(s):  
Thermal Stress ◽  
Satellite Cells ◽  
Muscle Growth ◽  
Control Line ◽  
Dependent Manner ◽  
S6 Kinase ◽  
Downstream Effector ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Irreversible Effects

Satellite cells (SCs) are stem cells responsible for post-hatch muscle growth through hypertrophy and in birds are sensitive to thermal stress during the first week after hatch. The mechanistic target of rapamycin (mTOR) signaling pathway, which is highly responsive to thermal stress in differentiating turkey pectoralis major (p. major) muscle SCs, regulates protein synthesis and the activities of SCs through a downstream effector, S6 kinase (S6K). The objectives of this study were: 1) to determine the effect of heat (43°C) and cold (33°C) stress on activity of the mTOR/S6K pathway in SCs isolated from the p. major muscle of one-week-old faster-growing modern commercial (NC) turkeys compared to those from slower-growing Randombred Control Line 2 (RBC2) turkeys, and 2) to assess the effect of mTOR knockdown on the proliferation, differentiation, and expression of myogenic regulatory factors of the SCs. Heat stress increased phosphorylation of both mTOR and S6K in both turkey lines, with greater increases observed in the RBC2 line. With cold stress, greater reductions in mTOR and S6K phosphorylation were observed in the NC line. Early knockdown of mTOR decreased proliferation, differentiation, and expression of myoblast determination protein 1 and myogenin in both lines independent of temperature, with the RBC2 line showing greater reductions in proliferation and differentiation than the NC line at 38° and 43°C. Proliferating SCs are more dependent on mTOR/S6K-mediated regulation than differentiating SCs. Thus, thermal stress can affect breast muscle hypertrophic potential by changing satellite cell proliferation and differentiation, in part, through the mTOR/S6K pathway in a growth-dependent manner. These changes may result in irreversible effects on the development and growth of the turkey p. major muscle.

scholarly journals Store-operated calcium entry suppressed the TGF-β1/Smad3 signaling pathway in glomerular mesangial cells

2017 ◽  
Vol 313 (3) ◽  
pp. F729-F739 ◽  
Author(s):  
Sarika Chaudhari ◽  
Weizu Li ◽  
Yanxia Wang ◽  
Hui Jiang ◽  
Yuhong Ma ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Transforming Growth Factor ◽  
Nuclear Translocation ◽  
Mesangial Cells ◽  
Underlying Mechanism ◽  
Glomerular Mesangial Cells ◽  
Critical Pathway ◽  
Smad3 Phosphorylation ◽  
Tgf Β1

Our previous study demonstrated that the abundance of extracellular matrix proteins was suppressed by store-operated Ca2+entry (SOCE) in mesangial cells (MCs). The present study was conducted to investigate the underlying mechanism focused on the transforming growth factor-β1 (TGF-β1)/Smad3 pathway, a critical pathway for ECM expansion in diabetic kidneys. We hypothesized that SOCE suppressed ECM protein expression by inhibiting this pathway in MCs. In cultured human MCs, we observed that TGF-β1 (5 ng/ml for 15 h) significantly increased Smad3 phosphorylation, as evaluated by immunoblot. However, this response was markedly inhibited by thapsigargin (1 µM), a classical activator of store-operated Ca2+channels. Consistently, both immunocytochemistry and immunoblot showed that TGF-β1 significantly increased nuclear translocation of Smad3, which was prevented by pretreatment with thapsigargin. Importantly, the thapsigargin effect was reversed by lanthanum (La3+; 5 µM) and GSK-7975A (10 µM), both of which are selective blockers of store-operated Ca2+channels. Furthermore, knockdown of Orai1, the pore-forming subunit of the store-operated Ca2+channels, significantly augmented TGF-β1-induced Smad3 phosphorylation. Overexpression of Orai1 augmented the inhibitory effect of thapsigargin on TGF-β1-induced phosphorylation of Smad3. In agreement with the data from cultured MCs, in vivo knockdown of Orai1 specific to MCs using a targeted nanoparticle small interfering RNA delivery system resulted in a marked increase in abundance of phosphorylated Smad3 and in nuclear translocation of Smad3 in the glomerulus of mice. Taken together, our results indicate that SOCE in MCs negatively regulates the TGF-β1/Smad3 signaling pathway.

The negative effect of GH/IGF-1 excess on NAD- and NADP-dependent blood lymphocytes dehydrogenases activity in acromegaly

2016 ◽  
Vol 62 (5) ◽  
pp. 59-60
Author(s):  
Margarita A. Dudina ◽  
Sergey A. Dogadin ◽  
Аndrey A. Savchenko
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Blood Lymphocytes ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Igf I ◽  
Negative Effect ◽  
Active Acromegaly ◽  
Dehydrogenases Activity ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Potent Effector

Background. Acromegaly is a rare serious condition characterized by chronic hypersecretion of growth hormone (GH) from a pituitary adenoma and induces the synthesis of insulin-like growth factor I (IGF-1). The idea of the crucial GH importance not only in the control of cell proliferation and differentiation, but, also, in the regulation of immune cells metabolism allows to think that chronic excess GH/IGF-I in acromegaly is the potent effector distortion of the immune response mechanisms. Aim. To study the NAD(P)-dependent dehydrogenases level in blood lymphocytes and their interaction with GH/IGF-1 concentration in patients with active acromegaly.Methods. The level of NAD(P)-dependent dehydrogenases in blood lymphocytes was studied in a group of 88 patients with active acromegaly, mean age 51.0±12.5 years. The NAD(P)-dependent dehydrogenases activity was determined by biochemiluminescence method. The concentrations of GH and IGF-1 were measured by ELISA.Results. Studying the activity of mitochondrial NAD(P)-dependent dehydrogenases found a decrease in all NAD-dependent oxidoreductase: NADIDH, NADGDH, and MDH (P<0.01), which allows to state the low level flow in the tricarboxylic acid cycle. In active acromegaly were revealed the decreasing activity of all studied oxidoreductases: glucose-6-phosphate dehydrogenase (P<0.01), NAD–lactate dehydrogenase (LDH) (P<0.001), NADH–LDH (P<0.001), NAD–malate dehydrogenase (MDH) (P<0.001), NADH–MDH (P<0.001), NADP–MDH (P<0.001), NAD–glutamate dehydrogenases (GDH) and NADH–GDH (P<0.001), NADP–GDH and NADPH–GDH (P<0.001), NAD–isocitrate dehydrogenases (IDH) and NADP–IDH (P<0.01 and P<0.001 respectively), and, also, glutathione reductase (P<0.001). Our data observed that decreasing activity of NADP–GDH positively correlated with the basal GH level (r=+0.23, P=0.04) and NADP–MDH activity with IGF-1 level (r=+0.30, P=0.008). The low NADH–MDH activity negatively correlated to the basal GH concentration (r=−0.23, P=0.04).Conclusion. The chronic excess of GH/IGF-1 causes a significant depletion of metabolic lymphocytes reserves and may play an important role in several systems malignancies of acromegaly patients. This pathway continues to attract interest as a potentially useful target for therapeutic design of acromegaly.

scholarly journals Myc stimulates B lymphocyte differentiation and amplifies calcium signaling

2007 ◽  
Vol 179 (4) ◽  
pp. 717-731 ◽  
Author(s):  
Tania Habib ◽  
Heon Park ◽  
Mark Tsang ◽  
Ignacio Moreno de Alborán ◽  
Andrea Nicks ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Cell ◽  
Target Genes ◽  
B Lymphocyte ◽  
Nuclear Translocation ◽  
Efflux Pump ◽  
Double Knockout ◽  
Activated T Cells ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation

Deregulated expression of the Myc family of transcription factors (c-, N-, and L-myc) contributes to the development of many cancers by a mechanism believed to involve the stimulation of cell proliferation and inhibition of differentiation. However, using B cell–specific c-/N-myc double-knockout mice and Eμ-myc transgenic mice bred onto genetic backgrounds (recombinase-activating gene 2−/− and Btk−/− Tec−/−) whereby B cell development is arrested, we show that Myc is necessary to stimulate both proliferation and differentiation in primary B cells. Moreover, Myc expression results in sustained increases in intracellular Ca2+ ([Ca2+]i), which is required for Myc to stimulate B cell proliferation and differentiation. The increase in [Ca2+]i correlates with constitutive nuclear factor of activated T cells (NFAT) nuclear translocation, reduced Ca2+ efflux, and decreased expression of the plasma membrane Ca2+–adenosine triphosphatase (PMCA) efflux pump. Our findings demonstrate a revised model whereby Myc promotes both proliferation and differentiation, in part by a remarkable mechanism whereby Myc amplifies Ca2+ signals, thereby enabling the concurrent expression of Myc- and Ca2+-regulated target genes.

Satellite cell proliferation and differentiation during postnatal growth of porcine skeletal muscle

2002 ◽  
Vol 282 (4) ◽  
pp. C899-C906 ◽  
Author(s):  
N. T Mesires ◽  
M. E. Doumit
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Nuclear Antigen ◽  
Positive Staining ◽  
Age Related ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Satellite Cell Proliferation

Age-related changes in satellite cell proliferation and differentiation during rapid growth of porcine skeletal muscle were examined. Satellite cells were isolated from hindlimb muscles of pigs at 1, 7, 14, and 21 wk of age (4 animals/age group). Satellite cells were separated from cellular debris by using Percoll gradient centrifugation and were adsorbed to glass coverslips for fluorescent immunostaining. Positive staining for neural cell adhesion molecule (NCAM) distinguished satellite cells from nonmyogenic cells. The proportion of NCAM-positive cells (satellite cells) in isolates decreased from 1 to 7 wk of age. Greater than 77% of NCAM-positive cells were proliferating cell nuclear antigen positive at all ages studied. Myogenin-positive satellite cells decreased from 30% at 1 wk to 14% at 7 wk of age and remained at constant levels thereafter. These data indicate that a high percentage of satellite cells remain proliferative during rapid postnatal muscle growth. The reduced proportion of myogenin-positive cells during growth may reflect a decrease in the proportion of differentiating satellite cells or accelerated incorporation of myogenin-positive cells into myofibers.

scholarly journals IGF-1 colocalizes with muscle satellite cells following acute exercise in humans

2014 ◽  
Vol 39 (4) ◽  
pp. 514-518 ◽  
Author(s):  
Amanda Grubb ◽  
Sophie Joanisse ◽  
Daniel R. Moore ◽  
Leeann M. Bellamy ◽  
Cameron J. Mitchell ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Stem Cell ◽  
Growth Factor ◽  
Satellite Cells ◽  
Acute Exercise ◽  
Stem Cell Proliferation ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Exercise In Humans

Insulin-like growth factor-1 (IGF-1) regulates stem cell proliferation and differentiation in vitro. The aim of this study was to quantify the change in satellite cell (SC) specific IGF-1 colocalization following exercise. We observed a significant increase (p < 0.05) in the percentage of SC with IGF-1 colocalization from baseline to 72 h after a bout of resistance exercise. This strongly supports a role for IGF-1 in human SC function following exercise.

scholarly journals Sequential expression of IGF-IB followed by active TGF-β1 induces synergistic pulmonary fibroproliferation in vivo

2012 ◽  
Vol 303 (9) ◽  
pp. L788-L798 ◽  
Author(s):  
Graciela Andonegui ◽  
Ai Ni ◽  
Caroline Léger ◽  
Margaret M. Kelly ◽  
Josée F. Wong ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Ex Vivo ◽  
Smooth Muscle Actin ◽  
Wild Type Mouse ◽  
Inflammatory Cells ◽  
Lung Parenchyma ◽  
Lavage Fluid ◽  
Igf I ◽  
Tgf Β1

Pulmonary fibrosis, the end stage of a variety of fibroproliferative lung diseases, is usually induced after repetitive or chronic lung injury or inflammation. The mechanisms of fibroproliferation are poorly understood. Insulin-like growth factor-I (IGF-I) is significantly elevated in patients with pulmonary fibrosis and fibroproliferative acute respiratory distress syndrome. However, we showed that IGF-I overexpression alone in wild-type mouse lungs does not cause fibroproliferation. We therefore questioned whether IGF-I, acting together with active TGF-β1, a known profibrotic cytokine, enhances pulmonary fibroproliferation caused by active TGF-β1. A unique sequential adenoviral transgene mouse model was used expressing AdEmpty/AdTGF-β1 or AdhIGF-IB/AdTGF-β1 transgenes. IGF-IB plus active TGF-β1 transgene expression synergistically increased collagen deposition in the lung parenchyma compared with active TGF-β1 expression alone. The enhanced fibrosis was accompanied by an increased recruitment of macrophages and lymphocytes into the bronchoalveolar lavage fluid (BALF) and inflammatory cells in the lungs. α-Smooth muscle actin expression, a marker of myofibroblast proliferation and differentiation, was also increased. Finally, fibroblasts exposed ex vivo to BALF isolated from AdhIGF-IB/AdTGF-β1-transduced mice showed synergistic collagen induction compared with BALF from AdEmpty/AdTGF-β1-transduced mice. This study provides the first direct evidence that IGF-I is able to synergistically enhance pulmonary fibroproliferation in cooperation with TGF-β1.

Biological activities of commercial bovine lactoferrin sources

2020 ◽  
Author(s):  
Bo Lönnerdal ◽  
Xiaogu Du ◽  
Rulan Jiang
Keyword(s):  
Cell Proliferation ◽  
Biological Activities ◽  
Intestinal Cell ◽  
Bovine Lactoferrin ◽  
Cell Proliferation And Differentiation ◽  
Sds Page ◽  
Proliferation And Differentiation ◽  
Intestinal Proliferation ◽  
Tgf Β1

Lactoferrin (Lf) samples from several manufacturers were evaluated in vitro. The purity and protein form of each Lf were examined by SDS-PAGE, Western blot, and proteomics analysis. Assays were conducted to evaluate uptake of Lfs and iron from Lfs by enterocytes as well as Lf bioactivities, including effects on intestinal cell proliferation and differentiation, IL-18 secretion, TGF-β1 transcription, and growth of enteropathogenic Escherichia coli (EPEC). Composition of the Lfs varied; some only contain a major Lf band (~80 kDa), and some also contain minor forms. All Lfs and iron from the Lfs were absorbed by Caco-2 cells with varying efficiencies. The bioactivities of the Lfs varied considerably, but there was no consistent trend. All Lfs promoted intestinal cell proliferation, secretion of IL-18, and transcription of TGF-β1. Some Lfs exhibited pro-differentiation effects on Caco-2 cells. Effects of pasteurization (62.5°C for 30 min, 72°C for 15 sec, or 121°C for 5 min) on integrity, uptake and bioactivities were examined using Dicofarm, Tatua, and native bovine Lfs. Results show that pasteurization did not affect protein integrity, but variously affected uptake of Lf, and its effects on intestinal proliferation, differentiation, and EPEC growth. To choose a Lf source for a clinical trial, assessment of bioactivities is recommended.

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