The clinical treatment of joint contracture due to immobilization remains difficult. The pathological changes of muscle tissue caused by immobilization-induced joint contracture include disuse skeletal muscle atrophy and skeletal muscle tissue fibrosis. The proteolytic pathways involved in disuse muscle atrophy include the ubiquitin-proteasome-dependent pathway, caspase system pathway, matrix metalloproteinase pathway, Ca-dependent pathway and autophagy-lysosomal pathway. The important biological processes involved in skeletal muscle fibrosis include intermuscular connective tissue thickening caused by transforming growth factor-β1 and an anaerobic environment within the skeletal muscle leading to the induction of hypoxia-inducible factor-1α. This article reviews the progress made in understanding the pathological processes involved in immobilization-induced muscle contracture and the currently available treatments. Understanding the mechanisms involved in immobilization-induced contracture of muscle tissue should facilitate the development of more effective treatment measures for the different mechanisms in the future.
Atrophy ; Autophagy ; Calcium ; metabolism ; Caspases ; metabolism ; Connective Tissue ; metabolism ; pathology ; Contracture ; etiology ; metabolism ; pathology ; therapy ; Fibrosis ; Humans ; Immobilization ; adverse effects ; Joints ; Lysosomes ; metabolism ; Matrix Metalloproteinases ; metabolism ; Muscle, Skeletal ; metabolism ; pathology ; Proteasome Endopeptidase Complex ; metabolism ; Proteolysis ; Signal Transduction ; physiology ; Transforming Growth Factor beta1 ; metabolism ; Ubiquitin ; metabolism

To investigate the role of glucose transporter 1 (GLUT1) and sodium-glucose cotransporter 1 (SGLT1) in high glucose dialysate-induced peritoneal fibrosis.Thirty six male SD rats were randomly divided into 6 groups (6 in each):normal control group, sham operation group, peritoneal dialysis group (PD group), PD+phloretin group (PD+T group), PD+phlorizin group (PD+Z group), PD+phloretin+phlorizin group (PD+T+Z group). Rat model of uraemia was established using 5/6 nephrotomy, and 2.5% dextrose peritoneal dialysis solution was used in peritoneal dialysis. Peritoneal equilibration test was performed 24 h after dialysis to evaluate transport function of peritoneum in rats; HE staining was used to observe the morphology of peritoneal tissue; and immunohistochemistry was used to detect the expression of GLUT1, SGLT1, TGF-β1 and connective tissue growth factor (CTGF) in peritoneum. Human peritoneal microvascular endothelial cells (HPECs) were divided into 5 groups:normal control group, peritoneal dialysis group (PD group), PD+phloretin group (PD+T group), PD+phlorezin group (PD+Z group), and PD+phloretin+phlorezin group (PD+T+Z group). Real time PCR and Western blotting were used to detect mRNA and protein expressions of GLUT1, SGLT1, TGF-β1, CTGF in peritoneal membrane and HPECs., compared with sham operation group, rats in PD group had thickened peritoneum, higher ultrafiltration volume, and the mRNA and protein expressions of GLUT1, SGLT1, CTGF, TGF-β1 were significantly increased (all<0.05); compared with PD group, thickened peritoneum was attenuated, and the mRNA and protein expressions of GLUT1, SGLT1, CTGF, TGF-β1 were significantly decreased in PD+T, PD+Z and PD+T+Z groups (all<0.05). Pearson's correlation analysis showed that the expressions of GLUT1, SGLT1 in peritoneum were positively correlated with the expressions of TGF-β1 and CTGF (all<0.05)., the mRNA and protein expressions of GLUT1, SGLT1, TGF-β1, CTGF were significantly increased in HPECs of peritoneal dialysis group (all<0.05), and those in PD+T, PD+Z, and PD+T+Z groups were decreased (all<0.05). Pearson's correlation analysis showed that the expressions of GLUT1, SGLT1 in HPECs were positively correlated with the expressions of TGF-β1 and CTGF (all<0.05).High glucose peritoneal dialysis fluid may promote peritoneal fibrosis by upregulating the expressions of GLUT1 and SGLT1.
Animals ; Cells, Cultured ; Connective Tissue Growth Factor ; analysis ; drug effects ; Dialysis Solutions ; adverse effects ; chemistry ; pharmacology ; Gene Expression Regulation ; drug effects ; Glucose ; adverse effects ; pharmacology ; Glucose Transporter Type 1 ; analysis ; drug effects ; physiology ; Hemodiafiltration ; adverse effects ; methods ; Humans ; Male ; Peritoneal Dialysis ; adverse effects ; methods ; Peritoneal Fibrosis ; chemically induced ; genetics ; physiopathology ; Peritoneum ; chemistry ; drug effects ; pathology ; Phloretin ; Phlorhizin ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Sodium-Glucose Transporter 1 ; analysis ; drug effects ; physiology ; Transforming Growth Factor beta1 ; analysis ; drug effects ; Uremia ; chemically induced

Mammalian pancreatic β-cells play a pivotal role in development and glucose homeostasis through the production and secretion of insulin. Functional failure or decrease in β-cell number leads to type 2 diabetes (T2D). Despite the physiological importance of β-cells, the viability of β-cells is often challenged mainly due to its poor ability to adapt to their changing microenvironment. One of the factors that negatively affect β-cell viability is high concentration of free fatty acids (FFAs) such as palmitate. In this work, we demonstrated that Yes-associated protein (Yap1) is activated when β-cells are treated with palmitate. Our loss- and gain-of-function analyses using rodent insulinoma cell lines revealed that Yap1 suppresses palmitate-induced apoptosis in β-cells without regulating their proliferation. We also found that upon palmitate treatment, re-arrangement of F-actin mediates Yap1 activation. Palmitate treatment increases expression of one of the Yap1 target genes, connective tissue growth factor (CTGF). Our gain-of-function analysis with CTGF suggests CTGF may be the downstream factor of Yap1 in the protective mechanism against FFA-induced apoptosis.
Actins ; metabolism ; Adaptor Proteins, Signal Transducing ; antagonists & inhibitors ; genetics ; metabolism ; Animals ; Apoptosis ; drug effects ; physiology ; Bridged Bicyclo Compounds, Heterocyclic ; pharmacology ; Cell Line, Tumor ; Connective Tissue Growth Factor ; genetics ; metabolism ; pharmacology ; Cytochalasin D ; pharmacology ; Fatty Acids, Nonesterified ; pharmacology ; HEK293 Cells ; Humans ; Immunohistochemistry ; Insulin-Secreting Cells ; cytology ; drug effects ; metabolism ; Mice ; Microscopy, Fluorescence ; Palmitic Acid ; pharmacology ; Phosphoproteins ; antagonists & inhibitors ; genetics ; metabolism ; RNA Interference ; RNA, Small Interfering ; metabolism ; Rats ; Recombinant Proteins ; genetics ; metabolism ; pharmacology ; Thiazolidines ; pharmacology

Liver fibrosis is a common pathological process for chronic liver injury caused by multiple etiological factors and an inevitable phase leading to liver cirrhosis. According to the previous studies, hesperidin (HDN) shows a very good protective effect on CCl4-induced chemical hepatic fibrosis in rats. In this experiment, based on the findings of the previous studies, a platelet-derived growth factor (PDGF)-induced HSC-T6 model was established to observe the inhibitory effect of HDN on HSC-T6 proliferation. The ELISA method was adopted to detect the content of collagen I in HSC-T6 supernatant. Transforming growth factor (TGF)-beta1, Smad2, Smad3, Smad7 and connective tissue growth factor (CTGF) mRNA expressions were measured by RT-PCR; TGF-beta1 and CT-GF protein expressions in HSC-T6 were determined by Western blot, in order to study HDN's effect on TGF-beta1 signaling pathway in HSC and its potential action mechanism. The results demonstrated that HDN could notably improve HSC-T6 proliferation, Collagen I growth and TGF-beta1, Smad2, Smad3 and CTGF mRNA.expressions. After being intervened with HDN, it could notably inhibit HSC-T6 proliferation and Collagen I growth, reduce TGF-beta1, Smad2, Smad3 and CTGF mRNA and TGF-beta1, CTGF protein expressions and increase Smad7 mRNA expression. HDN's antihepatic fibrosis effect may be related to the inhibition of HSC proliferation and activation by modulating TGF-beta/Smad signaling pathway.
Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Connective Tissue Growth Factor ; physiology ; Hesperidin ; pharmacology ; Platelet-Derived Growth Factor ; pharmacology ; Rats ; Signal Transduction ; drug effects ; Smad Proteins ; physiology ; Transforming Growth Factor beta1 ; physiology

BACKGROUNDSmall noncoding microRNAs regulate gene expression in cardiac development and disease and have been implicated in the aging process and in the regulation of extracellular matrix proteins. However, their role in age-related cardiac remodeling and atrial fibrillation (AF) was not well understood. The present study was designed to decipher molecular mechanisms underlying age-related atrial structural remodeling and AF.

METHODSThree groups of dogs were studied: adult and aged dogs in sinus rhythm and with persistent AF induced by rapid atrial pacing. The expressions of microRNAs were measured by quantitative real-time polymerase chain reaction. Pathohistological and ultrastructural changes were tested by light and electron microscopy. Apoptosis index of myocytes was detected by TUNEL.

RESULTSSamples of atrial tissue showed the abnormal pathohistological and ultrastructural changes, the accelerated fibrosis, and apoptosis with aging and/or in AF dogs. Compared to the adult group, the expressions of microRNAs-21 and -29 were significantly increased, whereas the expressions of microRNAs-1 and -133 showed obvious downregulation tendency in the aged group. Compared to the aged group, the expressions of microRNAs-1, -21, and -29 was significantly increased in the old group in AF; contrastingly, the expressions of microRNA-133 showed obvious downregulation tendency.

CONCLUSIONThese multiple aberrantly expressed microRNAs may be responsible for modulating the transition from adaptation to pathological atrial remodeling with aging and/or in AF.

Age Factors ; Animals ; Apoptosis ; Atrial Fibrillation ; etiology ; Atrial Remodeling ; Connective Tissue Growth Factor ; physiology ; Dogs ; Electrocardiography ; Fibrosis ; In Situ Nick-End Labeling ; MicroRNAs ; analysis ; physiology ; Myocardium ; pathology ; ultrastructure

BACKGROUNDWe have previously found that connective tissue growth factor (CTGF) is highly expressed in a rat model of liver cancer. Here, we examined expression of CTGF in human hepatocellular carcinoma (HCC) cells and its effect on cell growth.

METHODSReal-time PCR was used to observe expression of CTGF in human HCC cell lines HepG2, SMMC-7721, MHCC-97H and LO2. siRNA for the CTGF gene was designed, synthesized and cloned into a Plk0.1-GFP-SP6 vector to construct a lentivirus-mediated shRNA/CTGF. CTGF mRNA and protein expression in HepG2 cells treated by CTGF-specific shRNA was evaluated by real-time PCR and Western blotting. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to evaluate the growth effect, and a colony formation assay was used for observing clonogenic growth. In vivo, tumor cell proliferation was evaluated in a nude mouse model of xenotransplantation. Statistical significance was determined by t test for comparison between two groups, or analysis of variance (ANOVA) for multiple groups.

RESULTSImmunohistochemical staining of CTGF was seen in 35 of 40 HCC samples (87.5%). CTGF was overexpressed 5-fold in 20 HCC tissues, compared with surrounding non-tumor liver tissue. CTGF mRNA level was 5 - 8-fold higher in HepG2, SMMC-7721 and MHCC-97H than in LO2 cells. This indicated that the inhibition rate of cell growth was 43% after knockdown of CTGF expression (P < 0.05). Soft agar colony formation assay showed that siRNA mediated knockdown of CTGF inhibited colony formation in soft agar of HepG2 cells (P < 0.05). The volume of tumors from CTGF-shRNA-expressing cells only accounted for 35% of the tumors from the scrambled control-infected HepG2 cells (P < 0.05).

CONCLUSIONSCTGF was overexpressed in human HCC cells and downregulation of CTGF inhibited HCC growth in vitro and in vivo. Knockdown of CTGF may be a potential therapeutic strategy for treatment of HCC.

Animals ; Carcinoma, Hepatocellular ; genetics ; metabolism ; therapy ; Cell Line, Tumor ; Cell Proliferation ; Connective Tissue Growth Factor ; genetics ; metabolism ; Gene Expression Regulation, Neoplastic ; genetics ; physiology ; Hep G2 Cells ; Humans ; Liver Neoplasms ; genetics ; metabolism ; therapy ; Male ; Mice ; Mice, Nude ; RNA, Small Interfering ; genetics ; Xenograft Model Antitumor Assays

BACKGROUNDEnhanced and prolonged expression of connective tissue growth factor (CTGF) is associated with kidney fibrosis. Parathyroid hormone (PTH) is involved in the genesis of disturbed calcium/phosphate metabolism and ostitis fibrosa in renal failure. PTH activated mitogen-activated protein kinase (MAPK) signaling pathway is present in renal tubular cells. The aim of this study was to identify the mechanism how the signal is transduced to result in extracellular signal-regulated protein kinase (ERK) activation, leading to upregulation of CTGF.

METHODSThe levels of CTGF mRNA and protein in human kidney proximal tubular cells (HK-2) treated with PTH in the presence or absence of the MAPK inhibitor PD98059 were analyzed by quantitative real-time polymerase chain reaction (RT-PCR) and immunoblotting assay. The activation of the CTGF promoter in HK-2 cells was determined by the dual-luciferase assay. The effects of the protein kinase A (PKA) activator 8-Br-cAMP and protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) on MAPK phosphorylation, and the effects of the PKA inhibitor H89 and PKC inhibitor calphostin C on MAPK phosphorylation and CTGF expression were detected by immunoblotting assay.

RESULTSPD98059 inhibited the PTH stimulated expression of CTGF, which strongly suggested that the MAPK signaling pathway plays an important role in the PTH-induced CTGF upregulation in renal tubular cells. A PKA activator as well as PKC activators induced MAPK phosphorylation, and both PKA and PKC inhibitors antagonized PTH-induced MAPK phosphorylation and CTGF expression.

CONCLUSIONCTGF expression is upregulated by PTH through a PKC/PKA-ERK-dependent pathway.

Cells, Cultured ; Connective Tissue Growth Factor ; genetics ; physiology ; Cyclic AMP-Dependent Protein Kinases ; physiology ; Extracellular Signal-Regulated MAP Kinases ; physiology ; Fibrosis ; Flavonoids ; pharmacology ; Humans ; Kidney Tubules, Proximal ; metabolism ; pathology ; MAP Kinase Signaling System ; Mitogen-Activated Protein Kinases ; physiology ; Parathyroid Hormone ; pharmacology ; Phosphorylation ; Protein Kinase C ; physiology

Total aralosides of Aralia elata (Miq) Seem (TASAES) from Chinese traditional herb Longya Aralia chinensis L was found to improve cardiac function. The present study was to determine the protective effects of TASAES on diabetic cardiomyopathy, and the possible mechanisms. Therefore, a single dose of streptozotocin was used to induce diabetes in Wister rats. Diabetic rats were immediately treated with low, medium and high doses of TASAES at 4.9, 9.8 mg/kg and 19.6 mg/kg body weight by gavage, respectively, for eight weeks. Cardiac function was evaluated by in situ hemodynamic measurements, and patch clamp for the L-type Ca2+ channel current (ICa2+-L) and transient outward K+ channel current (Ito). Histopathological changes were observed under light and electron microscope. The expression of pro-fibrotic factor, connective tissue growth factor (CTGF) was monitored using immunohistochemistry staining. Compared with diabetic group, medium and high doses, but not low dose, of TASAES showed a significant protection against diabetes-induced cardiac dysfunction, shown by increased absolute value of left ventricular systolic pressure (LVSP) and maximum rates of pressure development (+/-dp/dt(max)), and enhanced amplitude of ICa2+-L (P < 0.05). Histological staining indicated a significant inhibition of diabetes-caused pathological changes and up-regulation of CTGF expression (P < 0.05). The results suggest that TASAES prevents diabetes-induced cardiac dysfunction and pathological damage through up-regulating ICa2+-L in cardiac cells and decreasing CTGF expression.
Animals ; Aralia/*chemistry ; Calcium Channels, L-Type/physiology ; Cardiomyopathies/*drug therapy/etiology/physiopathology ; Connective Tissue Growth Factor/metabolism ; Diabetes Mellitus, Experimental/*complications ; Drugs, Chinese Herbal/*chemistry ; Heart/drug effects/physiopathology ; Hemodynamics ; Male ; Myocardium/pathology ; *Oleanolic Acid/analogs & derivatives/therapeutic use ; Patch-Clamp Techniques ; Potassium Channels/physiology ; Rats ; Rats, Wistar ; Saponins/*therapeutic use ; Treatment Outcome

Animals ; Arginine Vasopressin ; physiology ; Connective Tissue Growth Factor ; physiology ; Glomerular Mesangium ; pathology ; Humans ; Integrin alpha1beta1 ; physiology ; Kidney Diseases ; etiology ; Proto-Oncogene Protein c-ets-1 ; physiology

OBJECTIVETo investigate whether aristolochic acid can be transported into human kidney proximal tubular cell (HKC) and its potential mechanism.

METHODSIntracellular aristolochic acid was measured by liquid chromatography-tandem mass spectrometry. The release of lactate dehydrogenase (LDH) induced by aristolochic acid in the presence of organic anion transporter inhibitor (probenecid) or organic cation transporter inhibitor (tetraethylammonium) was evaluated. The effects of probenecid on aristolochic acid induced connective tissue growth factor (CTGF) mRNA and protein expression were also examined by real time polymerase chain reaction and Western blot, respectively.

RESULTSAristolochic acid was detected in the suspension of the denatured HKC after incubation with aristolochic acid sodium salt. The release of LDH from HKC, which was induced by 60 mg/L aristolochic acid sodium salt, was significantly inhibited by 1 mmol/L probenecid (P < 0.01), but not by 1 mmol/L tetraethylammonium. The increased CTGF mRNA and protein expression in HKC stimulated by 40 mg/L aristolochic acid sodium salt was significantly down-regulated by 1 mmol/L probenecid (P < 0.05), with an inhibition rate of 16% and 21%, respectively.

CONCLUSIONAristolochic acid can be transported into HKC by organic anion transport system, and then exerts its biological effects.

Aristolochic Acids ; metabolism ; Connective Tissue Growth Factor ; metabolism ; Epithelial Cells ; metabolism ; Humans ; Kidney ; physiology ; Organic Anion Transporters ; metabolism