Serum response factor (SRF) is a master transcription factor of the actin cytoskeleton that binds to highly conserved CArG boxes located within the majority of smooth muscle cell (SMC)-restricted promoters/enhancers. Although most studies of SRF focus on skeletal muscle, cardiac muscle, and vascular SMCs, SRF research has recently expanded into the gastrointestinal (GI) system. Genome scale analyses of GI SMC transcriptome and CArG boxes (CArGome) have identified new SRF target genes. In addition to circular and longitudinal smooth muscle layers, SRF is also expressed in GI mucosa and cancers. In the GI tract, SRF is the central regulator of genes involved in apoptosis, dedifferentiation, proliferation, and migration of cells. Since SRF is the cell phenotypic modulator, it may play an essential role in the development of myopathy, hypertrophy, ulcers, gastric and colon cancers within the GI tract. Given the multi-functional role displayed by SRF in the digestive system, SRF has received more attention emerging as a potential therapeutic target. This review summarizes the findings in SRF research pertaining to the GI tract and provides valuable insight into future directions.
Actin Cytoskeleton ; Apoptosis ; Colonic Neoplasms ; Digestive System ; Gastrointestinal Diseases ; Gastrointestinal Tract ; Genome ; Hypertrophy ; MicroRNAs ; Mucous Membrane ; Muscle Cells ; Muscle, Skeletal ; Muscle, Smooth ; Muscular Diseases ; Myocardium ; Myocytes, Smooth Muscle ; Serum Response Factor* ; Stomach Ulcer ; Transcription Factors ; Transcriptome

BACKGROUND/AIMS: Smooth muscle cells (SMCs) characteristically express serum response factor (SRF), which regulates their development. The role of SRF in SMC plasticity in the pathophysiological conditions of gastrointestinal (GI) tract is less characterized. METHODS: We generated SMC-specific Srf knockout mice and characterized the prenatally lethal phenotype using ultrasound biomicroscopy and histological analysis. We used small bowel partial obstruction surgeries and primary cell culture using cell-specific enhanced green fluorescent protein (EGFP) mouse lines to study phenotypic and molecular changes of SMCs by immunofluorescence, Western blotting, and quantitative polymerase chain reaction. Finally we examined SRF change in human rectal prolapse tissue by immunofluorescence. RESULTS: Congenital SMC-specific Srf knockout mice died before birth and displayed severe GI and cardiac defects. Partial obstruction resulted in an overall increase in SRF protein expression. However, individual SMCs appeared to gradually lose SRF in the hypertrophic muscle. Cells expressing low levels of SRF also expressed low levels of platelet-derived growth factor receptor alpha (PDGFRalphalow) and Ki67. SMCs grown in culture recaptured the phenotypic switch from differentiated SMCs to proliferative PDGFRalphalow cells. The immediate and dramatic reduction of Srf and Myh11 mRNA expression confirmed the phenotypic change. Human rectal prolapse tissue also demonstrated significant loss of SRF expression. CONCLUSIONS: SRF expression in SMCs is essential for prenatal development of the GI tract and heart. Following partial obstruction, SMCs down-regulate SRF to transition into proliferative PDGFRalphalow cells that may represent a phenotype responsible for their plasticity. These findings demonstrate that SRF also plays a critical role in the remodeling process following GI injury.
Animals ; Blotting, Western ; Fluorescent Antibody Technique ; Gastrointestinal Tract ; Heart ; Humans ; Mice ; Mice, Knockout ; Microscopy, Acoustic ; Muscle Cells ; Muscle, Smooth* ; Myocytes, Smooth Muscle ; Parturition ; Phenotype* ; Plastics ; Polymerase Chain Reaction ; Primary Cell Culture ; Receptors, Platelet-Derived Growth Factor ; Rectal Prolapse ; RNA, Messenger ; Serum Response Factor*

OBJECTIVETo explore the inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts induced by angiotensin (Ang) II.

METHODSThe study was divided into 2 step: (1) MRC-5 human fetal lung fibroblasts was induced for 48 h at different dose of Ang II and at different time point by 100 nmol/L Ang II. Then the expression of collagen type I and α-smooth muscle actin (α-SMA) were mesaured by western blot. (2) MRC-5 human fetal lung fibroblasts were divided into 4 group: (1) control, (2) Ang II, (3) Ang II+Ac-SDKP, (4) Ang II+8-Me-cAMP (a specific activator of Epac). The α-SMA expression was observed by immnocytochemical stain. The protein expression of collagen type I, α-SMA, serum response factor (SRF), myocardin-related transcription factor (MRTF)-A, exchange protein directly activated by cAMP (Epac) 1, 2 were measured by Westen blot.

RESULTSMyofibroblast differentiation could be induced by Ang II from MRC-5 cells with a dose- and time-dependent manner. The up-regulation of SRF and MRTF-A were observed in MRC-5 cells induced by Ang II and accompanied with collagen I and α-SMA increased. Pre-treatment with 8-Me-cAMP or Ac-SDKP could attenuated all this changes induced by Ang II, and promoted the expression of Epac1.

CONCLUSIONAc-SDKP can inhibit the myofibroblast differentiation of MRC-5 cells induced by Ang II via Epac1 activating.

Actins ; Angiotensin II ; Cell Differentiation ; drug effects ; Collagen ; Collagen Type I ; Cyclic AMP ; analogs & derivatives ; Fetus ; cytology ; Fibroblasts ; cytology ; Guanine Nucleotide Exchange Factors ; Humans ; Lung ; cytology ; Myofibroblasts ; drug effects ; Oligopeptides ; pharmacology ; Serum Response Factor ; Trans-Activators

OBJECTIVETo investigate whether N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts by regulating Rho-associated coiled-coil forming protein kinase (ROCK) pathway mediated by transforming growth factor-β1 (TGF-β1).

METHODSPrimary culture of pulmonary fibroblasts was performed by trypsinization method. Four generations of pulmonary fibroblasts were divided into control group, TGF-β-induced differentiation group, Y-27632 treatment group, and Ac-SDKP treatment group. The intracellular distributions of ROCK, serum response factor (SRF), and α-smooth muscle actin (α-SMA) were observed by confocal laser scanning microscopy. The protein expression of ROCK, SFR, α-SMA, and type I and type III collagen in pulmonary fibroblasts was measured by Western blot. The mRNA expression of ROCK, SFR, and α-SMA was measured by real-time quantitative PCR.

RESULTSCompared with the control group, the pulmonary fibroblasts stimulated by TGF-β1 had a lot of α-SMA antibody-labeled myofilaments in parallel or cross arrangement, as observed by confocal laser scanning microscopy, and the mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen increased significantly after 6, 12, and 24 h of stimulation (P < 0.05). Compared with the TGF-β1-induced differentiation group, the Y-27632 treatment group and Ac-SDKP treatment group had significantly decreased mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen at the same time point (P < 0.05).

CONCLUSIONAc-SDKP can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts and the synthesis of collagen in rats by regulating the ROCK pathway mediated by TGF-β1. That may be one of the mechanisms by which Ac-SDKP acts against (silicotic) pulmonary fibrosis.

Actins ; metabolism ; Animals ; Animals, Newborn ; Cell Differentiation ; drug effects ; Cells, Cultured ; Collagen Type I ; metabolism ; Collagen Type III ; metabolism ; Fibroblasts ; cytology ; drug effects ; Lung ; cytology ; drug effects ; Myofibroblasts ; cytology ; drug effects ; Oligopeptides ; pharmacology ; Rats ; Rats, Wistar ; Serum Response Factor ; metabolism ; Transforming Growth Factor beta ; pharmacology ; rho-Associated Kinases ; metabolism

BACKGROUND: Serum response factor (SRF) is a transcriptional factor that plays an important role in cell growth and differentiation for several types of cells. The expression of SRF in cholangiocarcinoma (CC) and its potential role has not been examined. The aim of this study was to determine the relationship between the expression of SRF in CC and the clinicopathological parameters, as well as patient survival. METHODS: We analyzed the expression of SRF in 84 surgically resected cases of CC (33 cases of intrahepatic CC [ICC] and 51 cases of extrahepatic CC [ECC]) by using immunohistochemistry. RESULTS: The positive expression of SRF was detected in 48.8% of the cases of CC (42.4% in ICC, 52.9% in ECC). SRF was predominantly expressed in the CC cells with intense labeling in the nucleus. A SRF expression was significantly associated with the cell proliferation rate (Ki-67 labeling index, p=0.046) and poor patient survival (p=0.002). The tumor differentiation (p=0.038), the T category (p<0.001), lymph node and distant metastasis (p<0.001, p=0.009) and nerve and vessel invasion (p=0.010, p=0.012) were also found to be significantly associated with a poor CC prognosis. CONCLUSIONS: These results suggest that the SRF may play a role in the tumor cell proliferation of CC, and its expression in tumor cells can provide additional prognostic information.
Cell Proliferation ; Cholangiocarcinoma ; Glycosaminoglycans ; Humans ; Immunohistochemistry ; Liver ; Lymph Nodes ; Neoplasm Metastasis ; Prognosis ; Serum Response Factor

OBJECTIVETo investigate the effects of the Chinese herbal medicine of Longbixiao (LBX) Capsule on the expressions of TGF-beta1 and Smoothelin in human prostatic stromal cells cultured in vitro.

METHODSBlood serum medicated with LBX was incubated with the stromal cells isolated from men with benign prostatic hyperplasia (BPH) and cultured in vitro. The mRNA expression levels of TGF-beta1 and Smoothelin were detected by real-time RT-PCR and other relevant techniques.

RESULTSIn the high and low concentration groups, the gene relative expressions of TGF-beta1 were (0.158 +/- 0.020) and (0.169 +/- 0.020) , while those of Smoothelin were (0.035 +/- 0.007) and (0.036 +/- 0.007) respectively, both significantly decreased in comparison with the control group(P < 0.01).

CONCLUSIONLBX reduces the mRNA expressions of TGF-beta1 and Smoothelin in human prostatic stromal cells and can be used in the treatment of BPH.

Animals ; Capsules ; Cells, Cultured ; Cytoskeletal Proteins ; genetics ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Gene Expression ; drug effects ; Humans ; Male ; Muscle Proteins ; genetics ; Prostatic Hyperplasia ; pathology ; Rabbits ; Reverse Transcriptase Polymerase Chain Reaction ; Serum ; chemistry ; Stromal Cells ; drug effects ; metabolism ; pathology ; Transforming Growth Factor beta1 ; genetics

OBJECTIVETo investigate the influence of heat shock factor1 (HSF1) on gene expression of inflammatory mediators in RAW264.7 murine macrophage cells induced by burn serum.

METHODSSera were separated from blood of normal rats and rats with severe burns, and the recombinant vector pcDNA3. 1/HSF1 was constructed. RAW264.7 macrophages were divided into non-transfection group, vacant vector group (with burn and normal sera stimulation, respectively after vacant vector transfection) and recombinant vector group (with burn and normal sera stimulation, respectively after recombinant vector transfection). Some recombinant vector transfected macrophages without serum stimulation were prepared for the determination of HSF 1 expression with Western blotting. The mRNA expressions of TNF-alpha, HMGB 1 and IL-10 were determined with RT-PCR.

RESULTSThe cell line attained after recombinant vector transfection was comparatively stable,with partial activation of HSF 1. Burn sera markedly upregulated TNF-alpha, HMGB1 mRNA expression (0.910 +/- 0.100, 0.860 +/- 0.020, respectively), but downregulated IL-10 expression (0.430 +/- 0.010, respectively) in normal macrophages, while these genes maintained in a very low level in normal macrophages with normal serum stimulation . macrophages with recombinant vector transfection and burn serum stimulation could obviously inhibit the expression of TNF-alpha and HMGB 1, but enhance the IL-10 gene expression (0.130 +/- 0.100, 0.450 +/- 0.020 , 0.450 +/- 0.020, respectively )when compared with that with vacant vector transfection and burn serum stimulation (0.800 +/- 0.050, 0.880 +/- 0.030, 0.420 +/- 0.010, respectively).

CONCLUSIONHSF1 can inhibit the expression of some pro-inflammatory mediators in macrophages after a severe burns, indicating that appropriate upregulation of anti-inflammatory mediators might exert protective effects on the organism.

Animals ; Burns ; metabolism ; Cell Line ; DNA-Binding Proteins ; genetics ; Female ; Gene Expression ; HMGB1 Protein ; metabolism ; Heat Shock Transcription Factors ; Heat-Shock Response ; genetics ; Inflammation Mediators ; metabolism ; Interleukin-10 ; metabolism ; Macrophages ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Serum ; Transcription Factors ; genetics ; Transfection ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo study the therapeutic mechanisms of Danshen injection in intrahepatic cholestasis of pregnancy (ICP).

METHODThe experimental serum was collected from 6 patients with ICP before therapy when in hospital. Endothelial cells were isolated from human umbilical veins chosen among the 10 normal pregnancy according to Jaffe's method. Serum of 20% concentration of ICP and different concentration of Danshen injection were cocultured with human vascular endothelial cells (HUVECs) for 24 hours. MTT method was applied to measuring the vitality of HUVECs. The expression value of vascular endothelial growth factor (VEGF) of different groups was detected by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA) respectively.

RESULTCompared with ICP group, the value of MTT and VEGF in the Danshen injection therapeutic groups were increased with the increase of concentration and moreover, 8 g x L(-1) of Danshen injection was the optical concentration. By immunocytochemistry, the expression of VEGF in HUVECs in the Danshen injection therapeutic groups was also enhanced with the increase of concentration.

CONCLUSIONDanshen injection can protect HUVECs against the injury of ICP serum and promote the expression of VEGF. Danshen injection improves HUVECs by increasing the value of VEGF.

Cells, Cultured ; Cholestasis, Intrahepatic ; blood ; Coculture Techniques ; Cytoplasm ; metabolism ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; pharmacology ; Endothelial Cells ; cytology ; metabolism ; Female ; Humans ; Injections ; Plants, Medicinal ; chemistry ; Pregnancy ; Pregnancy Complications ; blood ; Protective Agents ; administration & dosage ; isolation & purification ; pharmacology ; Salvia miltiorrhiza ; chemistry ; Serum ; physiology ; Umbilical Veins ; cytology ; Vascular Endothelial Growth Factor A ; metabolism

The regulatory mechanisms for the proliferation and the particular invasive phenotypes of stomach cancers are not still fully understood. Up-regulations of hepatocytes growth factor (HGF), its receptor (c-Met), and urokinase-type plasminogen activator (uPA) are correlated with the development and metastasis of cancers. In order to investigate roles of HGF/c-Met signaling in tumor progression and metastasis in stomach cancers, we determined effects of a specific MEK1 inhibitor (PD098059) and a p38 kinase inhibitor (SB203580) on HGF-mediated cell proliferation and uPA expression in stomach cancer cell lines (NUGC-3 and MKN-28). HGF treatment induced the phosphorylations of ERK and p38 kinase in time- and dose- dependent manners. Pre-treatment with PD098059 reduced HGF-mediated cell proliferation and uPA secretion. In contrast, SB203580 pre-treatment enhanced cell proliferation and uPA secretion due to induction of ERK phosphorylation. Stable expression of dominant negative-MEK1 in NUGC-3 cells showed a decrease in HGF-mediated uPA secretion. These results suggest that interaction of a MEK/ERK and a p38 kinase might play an important role in proliferation and invasiveness of stomach cancer cells.
Cell Line, Tumor ; Cell Proliferation/drug effects ; Culture Media, Serum-Free ; Dose-Response Relationship, Drug ; Enzyme Activation/drug effects ; Enzyme Inhibitors/pharmacology ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Flavonoids/pharmacology ; Hepatocyte Growth Factor/*pharmacology ; Humans ; Imidazoles/pharmacology ; Kinetics ; MAP Kinase Kinase 1/metabolism ; Mitogen-Activated Protein Kinases/antagonists & inhibitors/*metabolism ; Neoplasm Metastasis ; Phosphorylation/drug effects ; Pyridines/pharmacology ; Research Support, Non-U.S. Gov't ; Stomach Neoplasms/*enzymology/*pathology ; Urinary Plasminogen Activator/*secretion ; p38 Mitogen-Activated Protein Kinases/metabolism

To investigate the role and mechanism of Rac1 protein in the process of the human umbilical vein endothelial cell (HUVEC) senescence, we used hypoxia as a model for modulating HUVECs entering replicative senescence in vitro. Premature senescence of HUVECs was evidenced by detecting the SA-beta-Gal activity and PAI-1 expression. Meanwhile, cell cycle distribution and cell proliferation rate were investigated by flow cytometry assay and BrdU staining. The results indicated that the HUVECs became enlarged and flattened, both SA-beta-Gal activity and PAI-1 expression increased obviously, while cell proliferation was inhibited and G(1) phase cell cycle arresting occurred when HUVECs were treated with continued hypoxia for 96 h. Accompanied with these changes, the expression of activated Rac1 increased obviously in cells after hypoxia. All these observations suggested that endothelial senescence could be induced by continued hypoxia and it might correlate with the activity of Rac1. To further define the relationship between Rac1 and HUVEC senescence, HUVECs were transiently infected with the constitutively active form of Rac1 (V12Rac1) or dominant negative form of Rac1 (N17Rac1) using retrovirus vector pLNCX-V12Rac1 or pLNCX-N17Rac1. We observed the changes of these three kinds of HUVECs (HUVECs, N17Rac1-HUVECs, V12Rac1-HUVECs) after hypoxia for 48 h and 96 h, the expression and localization of serum response factor (SRF), which is one of the downstream signal molecules of Rac1, were also investigated. The results obtained indicated that after continued hypoxia for 48 h, HUVECs infected by V12Rac1 showed obvious senescence accompanied with SA-beta-Gal activation, PAI-1 expression increase, G(1) phase arrest and cell proliferation inhibition which were similar to HUVECs after continued 96-hour hypoxia treatment, while the senescence of HUVECs infected by N17Rac1 was significantly inhibited even if the cells were exposed to hypoxia for more than 96 h. All the results identified that the activation of Rac1 might accelerate HUVEC senescence induced by hypoxia and that inactivation of Rac1 could partly block the cell senescence. To further investigate the mechanism of HUVEC senescence induced by Rac1, we detected the expression of total SRF (tSRF) and nuclear SRF (nSRF) in these three kinds of HUVECs by immunofluorescent analysis and Western blot assay after hypoxia. The results showed that the expression of nSRF decreased obviously and the nuclear translocation of SRF was inhibited in HUVECs infected by V12Rac1 compared with those in the normal HUVECs. In contrast, the expression of nSRF increased obviously in the HUVECs infected by N17Rac1. These results suggest that activation of Rac1 accelerates endothelial cell senescence and inhibition of Rac1 activity prevents HUVECs from entering senescence induced by hypoxia, while the nuclear translocation of SRF regulated by Rac1 might play an important role in the process of senescence.
Cell Hypoxia ; Cells, Cultured ; Cellular Senescence ; physiology ; Human Umbilical Vein Endothelial Cells ; cytology ; Humans ; Plasminogen Activator Inhibitor 1 ; genetics ; metabolism ; Serum Response Factor ; genetics ; metabolism ; beta-Galactosidase ; metabolism ; rac1 GTP-Binding Protein ; metabolism