TGF-β1 and connexin-43 expression in neurogenic bladder from rats with sacral spinal cord injury

AIMS

Sacral spinal cord injury (SCI) could induce underactive bladder (UAB). Malfunction of connexin 43 (CX43) regulated by TGF-β1 might involve in urinary bladder dysfunction. We studied the changes of CX43 and TGF-β1/Smad3 signaling in detrusor of neurogenic bladder (NB) in sacral SCI rats.

METHODS

Sacral SCI was produced by hemisection (SSCH) or transection (SSCT) of spinal cord between L4 and L5 in female Wistar rats. BBB scores, residual urine volume and bladder weight as well as characteristic cystometric parameters at 6th week were used to confirm the successful establishment of NB. Western blotting and qRT-PCR were used to exam the protein and mRNA expression levels of CX43, CX45, TGF-β1, and Smad3 in detrusor.

RESULTS

BBB scores were significantly decreased, with the lowest in SSCT rats (P < 0.01). The residual urine volume, mean bladder weight, and cystometric parameters were increased, with the highest in SSCT rats. CX43 and phospho-CX43 protein levels were significantly decreased, but those of TGF-β1, Smad3, and phospho-Smad3 were significantly increased. It was the protein and mRNA levels of CX43 but not those of CX45 which were decreased in negative accordance with those of TGF-β1 and Smad3. Those changes were more significant in SSCT than in SSCH rats.

CONCLUSIONS

This study indicates that voiding dysfunction is related to the decreased CX43 function in detrusor from NB. TGF-β1/Smad3 signaling might be involved in the down-regulation of CX43 in SCI rats. Early regulation of CX43 might be beneficial to patients with voiding dysfunction.

Overexpressed miR-145 inhibits osteoclastogenesis in RANKL-induced bone marrow-derived macrophages and ovariectomized mice by regulation of Smad3

BACKGROUND

MicroRNAs (miRs) play an important role in osteoclastogenesis. However, no study has investigated the underlying molecular mechanisms of miR-145 in this process. The purpose of the present study was to investigate the role of miR-145 and its post-transcriptional mechanism in the progression of osteoclast differentiation.

METHODS

Macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor-kB ligand (RANKL) were used to induce osteoclastogenesis originated from bone marrow-derived macrophages (BMMs). Female C57BL/6J mice were divided into sham, OVX, OVX + NC-agomir and OVX + miR-145-agomir groups. Tartrate-resistant acid phosphatase (TRAP) staining was performed to identify osteoclasts in-vitro and in-vivo. The mRNA and protein levels in osteoclast and tibia were assayed by qRT-PCR and western blotting, respectively.

RESULTS

miR-145 expression was inhibited in RANKL-induced osteoclastogenesis, whereas overexpression of miR-145 attenuated it. We further found that Smad3 is a direct target gene of miR-145 by binding with its 3'-UTR. Overexpression of miR-145 significantly suppressed Smad3 mRNA and protein expression. In-vivo, miR-145 agomir treatment inhibited osteoclast activity in OVX mice by inhibiting Smad3 expression.

CONCLUSION

We provide the evidence that over-expression of miR-145 could inhibit osteoclast differentiation, at least partially, by decreasing Smad3 expression.

Fluoride Regulate Osteoblastic Transforming Growth Factor-β1 Signaling by Mediating Recycling of the Type I Receptor ALK5

This study aimed to preliminary investigate the role of activin receptor-like kinase (ALK) 5 as one of TGF-βR1 subtypes in bone turnover and osteoblastic differentiation induced by fluoride. We analyzed bone mineral density and the expression of genes related with transforming growth factor-β1(TGF-β1) signaling and bone turnover in rats treated by different concentrations of fluoride with or without SB431542 in vivo. Moreover, MTT assay, alkaline phosphatase staining, RT-PCR, immunocytochemical analysis and western blot analysis were used to detect the influence on bone marrow stem cells (BMSC) after stimulating by varying concentration of fluoride with or without SB431542 in vitro. The in vivo study showed SB431542 treatment affected bone density and gene expression of rats, which indicated TGF-β1 and ALK5 might take part in fluoride-induced bone turnover and bone formation. The in vitro study showed low concentration of fluoride improved BMSC cells viability, alkaline phosphatase activity, and osteocalcin protein expression which were inhibited by high concentration of fluoride. The gene expression of Runx2 and ALK5 in cells increased after low concentration fluoride treatment which was also inhibited by high concentration of fluoride. Fluoride treatment inhibited gene and protein expression of Samd3 (except 1 mgF-/L). Compared with fluoride treatment alone, cells differentiation was inhibited with SB431542 treatment. Moreover, the expression of Runx2, ALK5 and Smad3 were influenced by SB431542 treatment. In conclusion, this preliminary study indicated that fluoride regulated osteoblastic TGFβ1 signaling in bone turnover and cells differentiation via ALK5.

Lactobacillus acidophilus attenuates Salmonella-induced intestinal inflammation via TGF-β signaling

BACKGROUND

Salmonella is a common intestinal pathogen that causes acute and chronic inflammatory response. Probiotics reduce inflammatory cytokine production and serve as beneficial commensal microorganisms in the human gastrointestinal tract. TGF-β (transforming growth factor β)/SMAD and NF-κB signaling play important roles in inflammation in intestinal cells. However, the involvement of the signaling in regulating inflammation between Salmonella and probiotics is not fully understood.

METHODS

L. acidophilus and prebiotic inulin were used to treat human intestinal Caco-2 cells prior to infection with Salmonella. The cells were harvested to examine the cytokines and MIR21 expression with immunoblotting and real-time PCR. NF-κB and SMAD3/4 reporter vectors were transfected into cells to monitor inflammation and TGF-β1 signaling, respectively.

RESULTS

In this study, we showed that the probiotic L. acidophilus decreased Salmonella-induced NF-κB activation in human intestinal Caco-2 cells. Expression of the inflammatory cytokines, TNF-α and IL-8, in L. acidophilus-pretreated cells was also significantly lower than that in cells infected with Salmonella alone. Moreover, TGF-β1 and MIR21 expression was elevated in cells pretreated with L. acidophilus or synbiotic, a combination of inulin and L. acidophilus, compared to that in untreated cells or cells infected with S. typhimurium alone. By contrast, expression of SMAD7, a target of MIR21, was accordingly reduced in cells treated with L. acidophilus or synbiotics. Consistent with TGF-β1/MIR21 and SMAD7 expression, SMAD3/4 transcriptional activity was significantly higher in the cells treated with L. acidophilus or synbiotics. Furthermore, TGF-β1 antibody antagonized the SMAD3/4 and NF-κB transcriptional activity modulated by L. acidophilus in intestinal cells.

CONCLUSION

Our results suggest that the TGF-β1/MIR21 signaling pathway may be involved in the suppressive effects of L. acidophilus on inflammation caused by S. typhimurium in intestinal Caco-2 cells.

Lung metastasis of pancreatic carcinoma is regulated by TGFβ signaling

The molecular regulation of the lung metastasis of pancreatic carcinoma (PCC) is not completely understood. Here, we show that the levels of phosphorylated SMAD3, ZEB1, ZEB2, Snail1, and Snail2 were significantly higher in PCC with lung metastasis than in PCC without lung metastasis. Overexpression of TGFβ1 enhanced the invasiveness of PCC cells, while inhibition of TGFβ1 decreased the invasiveness of PCC cells, which appeared to be conducted by activated TGFβ receptor signaling-induced upregulation of ZEB1, ZEB2, Snail1, and Snail2, suggesting a process of epithelial-mesenchymal transition (EMT). Taken together, our study provides evidence that TGFβ receptor signaling-induced EMT may be responsible for the increased PCC invasiveness to enhance its lung metastasis.

Smad2 protects against TGF-β1/Smad3-mediated collagen synthesis in human hepatic stellate cells during hepatic fibrosis

With structural similarity but functional diversity, Smad2 and Smad3 interact with each other to mediate transforming growth factor-β (TGF-β)-triggered signaling transduction. However, in the hepatic fibrosis, the detailed roles of R-Smads, and interaction between Smad2 and Smad3 are still undefined. In this setting, we established a rat model of CCl4-induced hepatic fibrosis in vivo and TGF-β1-treated hepatic stellate cell model in vitro to detect whether Smad2 and Smad3 play distinct roles in mediating liver fibrogenesis. Results indicated that both phosphorylation of Smad2 and Smad3 were detected in the hepatic stellate cells of liver fibrotic tissues and cells. Furthermore, In vitro data demonstrated that knockdown of Smad2 in human hepatic stellate cells increased expression of collagen I (Col.I), tissue inhibitor of metalloproteinase-1 (TIMP-1) whereas decreasing expression of the matrix metalloproteinases-2(MMP-2) in presence of TGF-β1 compared with control group. In contrast, knockdown of Smad3 significantly reduced TGF-β1-induced Col.I production. These findings were further evident by the results that overexpression of Smad2 attenuated the expression of Col.I and TIMP-1, but enhanced MMP-2 whereas overexpression of Smad3 showed the opposite effect. Furthermore, Smad2 suppressed the phosphorylation and nuclear translocation of Smad3, which may protect against Smad3-mediated fibrotic response. Collectively, Smad2 may be a potential therapeutic target for the treatment of hepatic fibrosis.

Oxidative exposure impairs TGF-β pathway via reduction of type II receptor and SMAD3 in human skin fibroblasts

Exposure to oxidants results in cellular alterations that are implicated in aging and age-associated diseases. Here, we report that brief, low-level oxidative exposure leads to long-term elevation of cellular reactive oxygen species (ROS) levels and oxidative damage in human skin fibroblasts. Elevated ROS impairs the transforming growth factor-β (TGF-β) pathway, through reduction of type II TGF-β receptor (TβRII) and SMAD3 protein levels. This impairment results in reduced expression of connective tissue growth factor (CTGF/CCN2) and type I collagen, which are regulated by TGF-β. Restoration of TβRII and SMAD3 together, but not separately, reinstates TGF-β signaling and increases CTGF/CCN2 and type I collagen levels. Treatment with the anti-oxidant N-acetylcysteine reduces ROS elevation and normalizes TGF-β signaling and target gene expression. These data reveal a novel linkage between limited oxidant exposure and altered cellular redox homeostasis that results in impairment of TGF-β signaling. This linkage provides new insights regarding the mechanism by which aberrant redox homeostasis is coupled to decline of collagen production, a hallmark of human skin aging.

The expression of Pax6 variants is subject to posttranscriptional regulation in the developing mouse eyelid

Pax6 is a pivotal transcription factor that plays a role during early eye morphogenesis, but its expression and function in eyelid development remain unknown. In this study, the expression patterns of Pax6 mRNA and protein were examined in the developing mouse eyelid at embryonic days 14.5, 15.5, and 16.5. The function of Pax6 in eyelid development was determined by comparing it to that in the eyes-open-at-birth mutant mouse. In the normally developing eyelid, Pax6 and Pax6(5a) mRNA levels were low at E14.5, increased at E15.5, and then declined at E16.5, accompanied by a change in the Pax6/Pax6(5a) ratio. Pax6 protein was mainly located in the mesenchyme and conjunctiva. It was expressed at low levels in the epidermis at E14.5, severely reduced at E15.5, but re-expressed in the keratinocyte cells of the periderm at E16.5. In contrast, Pax6 and the Pax6/Pax6(5a) ratio were considerably higher with strong nuclear expression in the mutant at E15.5. Next, we examined the relationship of Pax6 to epidermal cell proliferation, migration, and the associated signalling pathways. The Pax6 protein in the developing eyelid was negatively correlated with epidermal cell proliferation but not migration, and it is in contrast to the activation of the EGFR-ERK pathway. Our in vivo data suggest that Pax6 expression and the Pax6/Pax6(5a) ratio are at relatively low levels in the eyelid, and acting as a transcription factor, Pax6 is required for the initiation of eyelid formation and for differential development of the keratinised cells in the closed eyelid. The Pax6 protein is likely to be controlled by the EGFR-ERK pathways. An abnormal increase in Pax6 expression and the Pax6/Pax6(5a) ratio due to alteration of the pathway activity could suppress epidermal cell proliferation leading to the eyes-open-at-birth defect. This study offers insight into the function of the Pax6 protein in eyelid development.

Qindan-capsule inhibits proliferation of adventitial fibroblasts and collagen synthesis

AIMS

Qindan-capsule (QC) is a prescription of traditional Chinese medicine for the treatment of hypertension. We investigated the effect and mechanism of QC-containing serum on proliferation of aortal adventitial fibroblasts (AFs) and composition of extracellular matrix (ECM). We also tested whether the Smad3 signaling pathway is activated in the progress.

MATERIALS AND METHODS

AFs were cultured by tissue explant in vitro. The proliferation of AFs induced by transforming growth factor beta1 (TGF-beta1) and affected by QC-containing serum with high or low dose was detected by MTT. The protein and mRNA expressions of Smad3 and Procollagen I were observed by Western blot and Real-time PCR respectively.

RESULTS

Western blot and Real-time PCR revealed that after being activated by TGF-beta1 for 24h, the expressions of Smad3, Pho-Smad3 and Procollagen I were all higher than those in the control group. But these functions were inhibited, to some extent in different doses, by QC-containing serum. So that the proliferation of AFs which was evaluated by MTT.

CONCLUSIONS

The results suggested QC-containing serum has significantly improved proliferation of AFs and composition of extracellular matrix. TGF-beta1/Smad3 signaling pathway may be involved in the mechanism.

[Effect of small interfering RNA-mediated Smad3 gene silencing on transforming growth factor-beta1-induced bi-directional effects on skin fibroblast proliferation]

OBJECTIVE

To study the role of Smad3 in transforming growth factor-beta1 (TGF-beta1)-induced bi-directional effects on skin fibroblast proliferation.

METHODS

The Smad3 small interfering (siRNA) plasmid was constructed using a pSUPER vector. The efficiency of cell transfection was detected by fluorescence microscopy, and the inhibitory effect of the plasmid was assessed by real-time quantitative RT-PCR and immunohistochemistry. The effect of the plasmid on the fibroblast proliferation and Smad3 binding activity was analyzed by BRDU ELISA and EMSA, respectively.

RESULTS

The transfection efficiency of the plasmid into the cells was 41.2%. The Smad3 siRNA plasmid produced efficient and specific inhibition of the expression of Smad3, and promoted the cell proliferation in a dose-dependent manner and abrogated the bi-directional effect of TGF-beta1 on the cell proliferation and Smad3 binding activity.

CONCLUSION

The siRNA targeting Smad3 gene can inhibit the protein expression and RNA transcription of Smad3, and TGF-beta1 exerts bi-directional regulation on fibroblast proliferation by modulating Smad3 activity.

Smad3 activates the Sox9-dependent transcription on chromatin

Transforming growth factor (TGF)-beta has an essential role for the Sry-type high-mobility-group box (Sox)-regulated chondrogenesis. Chondrogenic differentiation is also controlled by chromatin-mediated transcription. We have previously reported that TGF-beta-regulated Smad3 induces chondrogenesis through the activation of Sox9-dependent transcription. However, the cross-talk between TGF-beta signal and Sox9 on chromatin-mediated transcription has not been elucidated. In the present study, we investigated the activity of Smad3, Sox9, and coactivator p300 using an in vitro chromatin assembly model. Luciferase reporter assays revealed that Smad3 stimulated the Sox9-mediated transcription in a TGF-beta-dependent manner. Recombinant Sox9 associated with phosphorylated Smad3/4 and recognized the enhancer region of type II collagen gene. In vitro transcription and S1 nuclease assays showed that Smad3 and p300 cooperatively activated the Sox9-dependent transcription on chromatin template. The combination treatment of phosphorylated Smad3, Sox9, and p300 were necessary for the activation of chromatin-mediated transcription. These findings suggest that TGF-beta signal Smad3 plays a key role for chromatin remodeling to induce chondrogenesis via its association with Sox9.

Phosphorylated Smad2/3 immunoreactivity in sporadic and familial amyotrophic lateral sclerosis and its mouse model

Phosphorylated Smad2/3 (pSmad2/3), the central mediators of transforming growth factor (TGF)-beta signaling, were recently identified in tau-positive inclusions in certain neurodegenerative disorders. To clarify whether the localization of pSmad2/3 is altered in amyotrophic lateral sclerosis (ALS), we immunohistochemically examined spinal cords from sporadic ALS (SALS), from familial ALS (FALS) patients with the A4V mutation in their Cu/Zn superoxide dismutase (SOD1) gene, and from G93A mutant SOD1 transgenic (mSOD1 Tg) mice. In control spinal cords, pSmad2/3 immunoreactivity was observed exclusively in neuronal and glial nuclei. In SALS and FALS patients the nuclei showed increased immunoreactivity for pSmad2/3. Noticeably, round hyaline inclusions (RHIs) and skein-like inclusions of SALS patients were immunoreactive for pSmad2/3. Double immunofluorescence staining for pSmad2/3 and transactive response-DNA-binding protein (TDP)-43 revealed co-localization of these proteins within RHIs. In contrast, Bunina bodies in SALS and Lewy body-like hyaline inclusions (LBHIs) in FALS were devoid of labeling for pSmad2/3. Similarly, in the mSOD1 Tg mice pSmad2/3 immunoreactivity was increased in the nuclei, while LBHIs were not labeled. These findings suggest increased TGF-beta-Smad signaling in SALS, FALS, and mSOD1 Tg mice, as well as impaired TGF-beta signal transduction in RHI-bearing neurons of SALS patients, presumably at the step of pSmad2/3 translocation into the nucleus. The pathomechanisms, including the process of inclusion development, appears to be different between SALS and mSOD1-related FALS or Tg mice.

Smad3 is overexpressed in advanced human prostate cancer and necessary for progressive growth of prostate cancer cells in nude mice

PURPOSE

The purpose of this study was to investigate the potential role of Smad3, a key mediator of transforming growth factor-beta signaling, in progression of prostate cancer.

EXPERIMENTAL DESIGN

Expression of Smad proteins was determined in human prostate cancer tissue array and cell lines. Growth and metastasis of cells overexpressing dominant-negative Smad3 (Smad3D) were studied to determine its role in tumor progression in mice. Cell growth, apoptosis, and expression of angiogenic molecules in tumor lesions were studied to determine potential pathways that Smad3 promotes tumor progression.

RESULTS

Smad3 was overexpressed in human prostate cancer, which correlated with Gleason score and expression of proliferating cell nuclear antigen. Androgen-independent PC-3MM2 and DU145 cells expressed much higher levels of Smad3 than did androgen-dependent LNCaP, 22Rv1, and LAPC-4 cells. Overexpression of Smad3D in PC-3MM2 cells (PC-3MM2-Smad3D) had minimal direct effects on cell growth but attenuated effects of transforming growth factor-beta1 on gene expression and cell growth. Overexpression of Smad3D did not significantly alter tumor incidence but reduced tumor growth rate and metastasis incidence. Most cells in the control tumors, but not PC-3MM2-Smad3D tumors, were positively stained by an antibody to proliferating cell nuclear antigen. Microvessels and expression of angiogenic molecule interleukin-8 were significantly reduced in tumors from PC-3MM2-Smad3D cells. PC-3MM2-Smad3D tumors also expressed lower levels of vascular endothelial growth factor and platelet-derived growth factor.

CONCLUSIONS

These data suggest that Smad3, through regulating angiogenic molecule expression in tumor cells, is critical for progression of human prostate cancer.

Prognostic significance of TGFbeta-1 and pSmad2/3 in breast cancer patients with T1-2,N0 tumours

BACKGROUND

The transforming growth factor beta (TGFbeta) signaling pathway has been shown to exert divergent effects and to cross-talk with estrogen pathways in mammary gland tumorigenesis. TGF signaling in early stage breast cancer was investigated by examining the expression of TGFbeta-1 and the signaling mediators pSmad2/3 and Smad4. Their association with oestrogen and progesterone receptors, as well as with clinical and pathological features was also analyzed.

PATIENTS AND METHODS

Sixty-one tumor specimens from surgically treated patients with primary T12,N0 breast cancer were examined. The expression of TGFbeta-1, pSmad2 and Smad4 was assessed implementing immunohistochemical assays.

RESULTS

TGFbeta-I, pSmad2/3 and Smad4 were expressed in 50.9%, 74.0% and 61.0% of specimens, respectively. The degree of expression of the three molecules was significantly associated with each other. Loss of pSmad2/3 expression indicated a shorter disease-free survival in all patients, including those with oestrogen receptor-positive tumors. Patients not expressing TGFbeta-1 were 4.6 times more likely to experience distant recurrence.

CONCLUSION

Our results demonstrate that pSmad2/3 and TGFP-1 may be promising novel prognostic markers for T1.2,N0 breast carcinomas.

Effect of TGF-beta/Smad signaling pathway on lung myofibroblast differentiation

AIM

Myofibroblasts play important roles in the pathogenesis of lung fibrosis. Transforming growth factor (TGF)-beta 1 has been widely recognized as a key fibrogenic cytokine. The major signaling pathway of (TGF)-beta(1) is through cytoplasmic Smad proteins. Our study investigated the role of individual (TGF)-beta(1)/Smad signal proteins in mediating alpha-smooth muscle actin (alpha-SMA) gene expression, which is a well-known key marker of myofibroblast differentiation.

METHODS

We transiently cotransfected alpha-SMA promoter-luciferase fusion plasmid (p895-Luc) and Smad expression plasmids and measured Luc activity in (TGF)-beta(1)-treated human fetal lung fibroblasts. We induced Smad3 knockout mice lung fibrosis by bleomycin. alpha-SMA protein expression was assessed by Western blotting. Collagen protein was analyzed by measuring hydroxyprolin. Myofibroblast morphology was assessed by immunohistochemistry.

RESULTS

We found that the overexpression of Smad3, not Smad2 markedly increased (TGF)-beta(1)-induced alpha-SMA promoter activity and alpha-SMA protein expression in vitro, whereas the overexpression of dominant negative mutant Smad3 and Smad7 repressed (TGF)-beta(1)-induced alpha-SMA gene expression. Compared to wild-type mice, Smad3 knockout mice showed attenuated lung fibrosis after bleomycin treatment, manifested by lower collagen production and myofibroblast differentiation.

CONCLUSION

Our study suggested (TGF)-beta(1)/Smad3 is a major pathway which regulated the myofibroblast differentiation. This result indicates a potential significance for future attempts of attenuating the progression of human lung fibrosis by the inhibition of the Smad3 cascade.

Inhibition of SMAD2 expression prevents murine palatal fusion

Transforming growth factor (TGF)-beta 3 is known to regulate the disappearance of murine medial edge epithelium (MEE) during palatal fusion. Our previous studies showed that SMAD2, a TGF-beta signaling mediator, was expressed and phosphorylated primarily in the MEE and that SMAD2 phosphorylation in the MEE was temporospatially regulated by TGF-beta 3. The goal of this study was to examine the requirement for SMAD2 to complete the developmental events necessary for palatal fusion. SMAD2 expression was inhibited with Smad2 siRNA transfection into palatal tissues in vitro. The results showed that Smad2 siRNA transfection resulted in the maintenance of MEE cells in the palatal midline. Western blot and immunofluorescence analyses confirmed that the endogenous SMAD2 and phospho-SMAD2 levels were reduced following siRNA transfection. The SMAD3 level was not altered by the Smad2 siRNA transfection. The persistence of the MEE and the decreased SMAD2/phospho-SMAD2 levels were coincident with increased MEE cell proliferation. Addition of exogenous TGF-beta 3 increased p-SMAD2 level but not the total SMAD2 level. Therefore, exogenous TGF-beta 3 was not able to induce p-SMAD2 enough to rescue the palatal phenotype in the Smad2 siRNA group. The results indicated that the endogenous SMAD2 level is crucial in the regulation of disappearance of MEE during palatal fusion.

Effects of perindopril and valsartan on expression of transforming growth factor-beta-Smads in experimental hepatic fibrosis in rats

BACKGROUND

Previous studies have shown that the renin-angiotensin system (RAS) plays an important role in the pathogenesis of hepatic fibrosis, and blockers of the RAS may be active as an antifibrogenic goal. However, the potential role of RAS inhibition on expression transforming growth factor (TGF)-beta-Smads in hepatic fibrosis remains unknown. The aim of this study was to investigate the effect and mechanism of an angiotensin-converting enzyme inhibitor (perindopril) and an angiotensin II receptor blocker (valsartan) on TGF-beta1 and TGF receptor II (TRII) mRNA, Smad3 and Smad7 in fibrotic hepatic livers in rats.

METHODS

Sixty Wistar rats were randomly divided into four study groups (n = 15 for each group), including normal controls, hepatic fibrosis models, and two treated groups with either perindopril or valsartan, starting from the fourth week after being exposed to carbon tetrachloride (CCl(4)) for 4 weeks. The levels of TGF-beta and TRII mRNA in liver tissue were analyzed by RT-PCR. The expressions of TGF-beta1, Smad3 and Smad7 in liver tissues were evaluated by immunohistochemistry. The liver histopathology was examined by hematoxylin and eosin (HE) staining and by electron microscopy, respectively. The liver function and serum hyaluronic acid were also assayed by biochemistry and radioimmunoassay.

RESULTS

Compared with the hepatic fibrosis models, the levels of TGF-beta1, TRII mRNA and the expression Smad3 significantly decreased in the two treated groups, and the expression of Smad7 was significantly increased in the liver of rats treated with perindopril or valsartan (P < 0.05 or P < 0.01). The histological changes and ultrastructure of fibrotic liver, liver function and hyaluronic acid also remarkably improved in the treated rats.

CONCLUSIONS

The angiotensin-converting enzyme inhibitors perindopril and valsartan have a protective effect on liver injury and can ameliorate hepatic fibrosis in rats induced by CCl(4). The mechanisms may be associated with their effects of down-regulating TGF-beta1, TRII mRNA and smad3, and up-regulating Smad7.

Dietary fiber enhances a tumor suppressor signaling pathway in the gut

OBJECTIVE

To determine whether sodium butyrate (NaB), a major short-chain fatty acid produced in the human gut by bacterial fermentation of dietary fiber, enhances transforming growth factor (TGF)-beta signaling and potentiates its tumor suppressor activity in the gut.

SUMMARY BACKGROUND DATA

The molecular mechanisms by which dietary fiber decreases the risk of colon cancers are poorly characterized. TGF-beta is an important tumor suppressor in the gut and has many similar biologic activities as NaB. Therefore, we hypothesized that the chemo-preventive effects of NaB are mediated in part by enhancing TGF-beta signaling and its tumor suppressor function in the gut.

METHODS

The effects of NaB on Smad3 expression in rat intestinal epithelial (RIE-1) cells and 6 human colon cancer cell lines were examined. The effects of NaB on TGF-beta-induced Smad3 phosphorylation and plasminogen activator inhibitor-1 (PAI-1) and cyclooxygenase-2 (COX-2) gene expression were also examined in RIE-1 cells. Finally, the effects of NaB and TGF-beta on anchorage-independent growth were examined in Akt-transformed RIE-1 cells.

RESULTS

NaB induced Smad3 in RIE-1 cells and in 4 human colon cancer cell lines. NaB enhanced TGF-beta-induced Smad3 phosphorylation and potentiated TGF-beta-induced PAI-1 expression. NaB and TGF-beta synergistically inhibited anchorage-independent growth of Akt-transformed RIE-1 cells.

CONCLUSIONS

These results demonstrate that NaB induces Smad3 and potentiates TGF-beta signaling and its tumor suppressor activity in gut epithelial cells. Our data reveal a novel molecular mechanism that may explain in part the beneficial effects of dietary fiber in decreasing the risk of colon cancers.

Bifidobacterium breve enhances transforming growth factor beta1 signaling by regulating Smad7 expression in preterm infants

OBJECTIVES

Transforming growth factor (TGF) beta1 displays a broad spectrum of activities in mucosal regulation, including induction of oral tolerance, potent anti-inflammatory effects, mucosal IgA expression and effects on epithelial cell proliferation and differentiation. The present study examined the effect of probiotics on the immunologic system of preterm infants in relation to TGF-beta signaling.

METHODS

Subjects comprised 19 preterm infants divided into 2 groups: receiving Bifidobacterium breve supplementation (B. breve group) and without supplementation (controls). Blood samples were collected from both groups on days 0, 14 and 28 after birth. Serum cytokine levels were measured using enzyme-linked immunosorbent assay, and expression levels of the TGF-beta signaling molecule, Smad, were examined using semiquantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Serum TGF-beta1 level was elevated on day 14 and remained elevated on day 28 in the B. breve group. Level of messenger RNA expression was enhanced for Smad3 and reduced for Smad7 (antagonistic Smad) after B. breve administration relative to levels in controls on day 28.

CONCLUSIONS

These results demonstrated that the administration of B. breve to preterm infants can up-regulate TGF-beta1 signaling and may possibly be beneficial in attenuating inflammatory and allergic reactions in these infants.

Fetal and adult fibroblasts have similar TGF-beta-mediated, Smad-dependent signaling pathways

BACKGROUND

The scarless fetal skin-healing mechanism is mediated in part by the fibroblast and involves differential expression of transforming growth factor (TGF)-beta isoforms 1 and 3. The authors hypothesized that fetal and adult fibroblasts respond differently to TGF-beta isoform-specific stimulation, which may influence whether wounds scar. Connective tissue growth factor (CTGF), Smad3, and Smad7 are TGF-beta target genes. Expression of these targets was quantitated after TGF-beta1 and -beta3 stimulation of fetal and adult fibroblasts.

METHODS

Primary mouse fibroblast cultures at gestational day 16.5 (E17), 18.5 (E19), and 6 weeks (adult) were stimulated with TGF-beta1 or TGF-beta3. Quantitative polymerase chain reaction was performed for CTGF, Smad3, and Smad7 expression.

RESULTS

CTGF was reduced four-fold in E17 and E19 compared with adult fibroblasts (p < 0.005). After TGF-beta1 stimulation, CTGF expression increased more than 60-fold in both E17 and E19 (p < 0.01), which was three-fold greater than that in adult fibroblasts (p < 0.005). TGF-beta3 induced more than 70-fold, 50-fold, and 20-fold increases in CTGF expression in E17, E19, and adult fibroblasts, respectively (p < 0.01 for each). Both TGF-beta1 and -beta3 decreased Smad3 expression and increased Smad7 expression in each fibroblast type, suggesting that intact TGF-beta-mediated signaling pathways were present.

CONCLUSIONS

Fetal (E17 and E19) fibroblasts have lower CTGF expression compared with adult fibroblasts. However, fetal fibroblasts have larger increases in CTGF expression after TGF-beta1 or -beta3 stimulation. Fetal and adult mouse fibroblasts have similar TGF-beta1 and TGF-beta3 transcriptional regulation of Smad3 and Smad7. This suggests that scarless healing is likely not mediated by different Smad-dependent transcriptional responses to TGF-beta isoforms in the fetal E17 fibroblast.

Smad3 reduces susceptibility to hepatocarcinoma by sensitizing hepatocytes to apoptosis through downregulation of Bcl-2

In the liver, derangement of TGF-beta signaling is associated with an increased incidence of hepatocellular carcinoma (HCC), but the mechanism is not clear. We report here that forced expression of a major TGF-beta signaling transducer, Smad3, reduces susceptibility to HCC in a chemically induced murine model. This protection is conferred by Smad3's ability to promote apoptosis by repressing Bcl-2 transcription in vivo through a GC-rich element in the Bcl-2 promoter. We also show that the proapoptotic activity of Smad3 requires both input from TGF-beta signaling and activation of p38 MAPK, which occurs selectively in the liver tumor cells. Thus, Smad3 enables the tumor suppression function of TGF-beta by serving as a physiological mediator of TGF-beta-induced apoptosis.

PKCδ Is Necessary for Smad3 Expression and Transforming Growth Factor β–Induced Fibronectin Synthesis in Vascular Smooth Muscle Cells

Objective— The purpose of these studies is to investigate the mechanism by which transforming growth factor (TGF)β1 regulates the synthesis of the extracellular matrix protein fibronectin (FN).

Methods and Results— TGFβ1 elicited a time-dependent induction of FN protein and mRNA in A10 rat aortic smooth muscle cells (SMCs). Ectopic expression of Smad3 in A10 cells stimulated both basal and TGFβ1-induced FN expression, whereas expression of Smad7 eliminated the TGFβ response. Because TGFβ activated PKCδ in SMCs, we tested the role of PKCδ in regulation of FN expression. Inhibition of PKCδ activity by rottlerin or dominant-negative adenovirus (AdPKCδ DN) blocked TGFβ1’s induction of FN, whereas overexpression of PKCδ enhanced TGFβ’s effect. Moreover, aortic SMCs isolated from PKCδ −/− mice exhibited diminished FN induction in response to TGFβ. Furthermore, we found that Smad3 protein and mRNA were markedly reduced in AdPKCδ DN-treated A10 cells and in PKCδ null cells. Finally, restoring Smad3 in rottlerin-treated A10 and PKCδ null cells rescues the ability of TGFβ to upregulate FN protein and mRNA expression.

Conclusion— Our data suggest that TGFβ-activated PKCδ is critical to maintain normal expression of Smad3, which in turn is required for the induction of fibronectin. PKCδ represents a promising target for treating the fibroproliferative response after arterial injury.

[Effect of dihydrotestosterone on the transcriptions and expressions of Smad3 and Smad4 in LNCaP cell line]

OBJECTIVE

To investigate the effect of dihydrotestosterone (DHT) on the gene transcriptions and expressions of Smad3 and Smad4 in androgen dependent prostate cancer cell line LNCaP, and whether this effect can be suppressed by the androgen receptor inhibitor flutamide.

METHODS

The androgen dependent prostate cancer cell line LNCaP was cultured in RPMI 1640 medium and treated with different concentrations of DHT(2, 10, 50 nmol/L) and flutamide (100 nmol/L). Quantitative reverse transcription PCR (RT-PCR) was used to detect the mRNAs of Smad3 and Smad4. The expressions of Smad3 and Smad4 protein were detected by Western blot assay.

RESULTS

Compared with the control group without any DHT or flutamide, higher concentration(10, 50 nmol/L) of DHT enhanced the transcription of Smad3 mRNA (P <0.05). Serial concentrations of DHT increased the expression of Smad3 protein(P < 0.05). Flutamide inhibited the up-regulation of both Smad3 mRNA transcription and expression significantly (P <0.05). 10 nmol/L DHT significantly suppressed the transcription of Smad4 (P <0.05). There was considerable suppressions of Smad4 expression at the presence of DHT in different concentrations (P < 0.05). And the degree of this suppression was more significant than that of DHT on Smad4 mRNA transcription. Flutamide inhibited the suppressive effects of DHT on both Smad4 mRNA transcription and expression.

CONCLUSION

DHT can enhance the transcription and expression of Smad3, while it decreases the transcription and expression of Smad4 in LNCaP cell line. There is a possible crosstalk between the AR signal and TGF-beta signal passways at the level of Smads.

[The influence of dermal template on the expressions of signal transduction protein Smad 3 and transforming growth factor beta1 and its receptor during wound healing process in patients with deep burns]

OBJECTIVE

To investigate the influence of dermal template on the expressions of signal transduction protein Smad 3 and transforming growth factor beta1 and its receptor during wound healing process in patients with deep burns.

METHODS

Twenty burn patients with excision of full thickness burn in the extremities were enrolled in the study and divided into two groups, i.e. template interfering group (E, n = 20, grafting of dermal template [allogeneic acellular dermal matrix] with razor thin autoskin) and control group (C, n = 20, grafting of razor thin autoskin only). The contralateral side served as the self-control. Tissue samples from the burn wounds were harvested at 1, 2, 3 and 4 post-operative weeks (POW) for immunohistochemistry staining. The positive expression rates of TGF-beta1, TbetaRI, TbetaRII and Smad3 proteins were determined by image analysis system.

RESULTS

The positive expressions of TGFbeta1, TbetaRI, TbetaRII and signal transduction protein Smad 3 in the tissue samples in both groups could be identified during 1 approximately 4 POW, and they diminished thereafter with the process of wound healing. The expression rate of TGF-beta1 in E group was (13.08 +/- 4.65)% at 1 POW and (9.03 +/- 1.89)% at 4 POW. The positive expression rate of above indices in E group was obviously lower than that in C group in corresponding time points (P < 0.05).

CONCLUSION

The expression levels of TGFbeta1, TbetaRI, TbetaRII and Smad 3 protein in deep burn wounds could be lowered by mixed grafting of dermal template with razor thin autoskin, which might be beneficial in ameliorating of scar hyperplasia in the burn wound.

Influence of exogenous TGFbeta1 on the expression of smad2 and smad3 in rat bone marrow-derived mesenchymal stem cells

The expression of Smad2 and Smad3 and the influence of exogenous transforming growth factorbeta1 (TGFbeta1) on them in rat bone marrow-derived mesenchymal stem cells (MSCs) cultured in vitro were investigated. The effects of different concentrations of TGFbeta1 on cell proliferation and ALP activity were detected by MTT and PNPP in MSCs respectively. The expression of Smad2 and Smad3 and the influence of exogenous TGFbeta1, on them were also examined by immunocytochemistry and Western blot assays. The exogenous TGFbeta1 induced a dose-dependent decrease in cell proliferation and a dose-dependent increase in ALP activity, which plateaued at 5 ng/ml. Smad2 and Smad3 proteins were detected only in the cytoplasm in the absence of TGFbeta1, and TGFbeta1, could stimulate the translocation of them from the cytoplasm to the nucleus. The total amount of Smad2 protein remained unchanged before and after TGFbeta1 treatment (P > 0.05). The expression levels of Smad3 remained unchanged after 3 h and 6 h treatment (P > 0.05), but decreased markedly after 24 h treatment (P <0.05). It was concluded that TGFbeta1 is a latent osteoinductive factor involved in osteoblastic differentiation. Both Samd2 and Smad3 mediate TGFbeta1 signaling as downstream mediators in MSCs. The biological output of TGFbeta1 triggering the osteoblastic differentiation could be entirely determined by Smad3 in MSCs.

[Effects of perindopril and valsartan on the expression of TGF beta 1 and TGF beta receptor II mRNA, Smad3 and Smad7 in experimental hepatic fibrotic rats]

OBJECTIVE

To investigate the therapeutic effects of perindopril, an angiotensin-converting enzyme inhibitor, and valsartan, an angiotensin II receptor blocker on TGFbeta1 and TGFbeta receptor II mRNA, Smad3 and Smad7 on rat liver fibrosis.

METHODS

60 Wistar rats were randomly divided into four groups (each group, n=15). Group 1 rats were not treated and served as healthy controls. The rats of groups 2,3,and 4 were injected with CCl(4) which induced liver fibrosis. After four weeks, group 3 rats started a treatment of perindopril, and group 4 rats with valsartan. All rats were sacrificed at the eighth week and their blood and livers were collected for analysis. The effects of perindopril and valsartan were evaluated by the levels of transforming growth factor-beta1 (TGFb1), and TGF receptor (TGFb1RII) mRNA in liver tissues by RT-PCR, the expressions and sites of TGFb1, Smad3 and Smad7 in liver tissue by immunohistochemical staining. The liver histopathology was also examined with HE staining, and the hydroxyproline in the liver and serum hyaluronic acid (HA) were examined using biochemsitry and RIA.

RESULTS

Compared with the control group, the levels of TGFb1, TGFb1RII mRNA and the expression Smad3 were significantly decreased in the two treated groups, and the expression of Smad7 was also remarkably increased in the livers of rats treated with perindopril or valsartan. The histological changes of fibrosis, the hydroxyproline in the livers and HA were also improved in the treated rats.

CONCLUSION

Perindopril and valsartan have a protective effect on liver injury and can inhibit hepatic fibrosis induced by CCl(4) in rats. Their mechanisms may be associated with their effects of down-regulating TGFb1, TGFb1RII mRNA and smad3, and up-regulating Smad7 which then resulted in suppressing the activation of hepatic stellate cells.

Activation of the Smad Pathway in Glomeruli from a Spontaneously Diabetic Rat Model, OLETF Rats

BACKGROUND/AIMS

Transforming growth factor-beta (TGF-beta) mediates the excess accumulation of extracellular matrix in the diabetic kidney. Smad family proteins have been identified as signal transducers for the TGF-beta superfamily. We sought to characterize the role of Smad proteins in mediating TGF-beta responses in the development of diabetic nephropathy.

METHODS

We evaluated the time course of TGF-beta1 fibronectin, Smad2 and Smad3 protein expression and Smad3 activation in glomeruli from spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats, using immunohistochemistry and Western blot analysis.

RESULTS

The glomeruli of diabetic OLETF rats showed not only accelerated activation of Smad3, but also enhanced protein expression of Smad2 and Smad3, which occurred in parallel to the increased expression of TGF-beta and fibronectin compared with glomeruli of control, Long-Evans Tokushima Otsuka (LETO) rats at 30 weeks of age. No differences were found in TGF-beta1 fibronectin, Smad2 and Smad3 protein expression and Smad3 activation in glomeruli between the two strains at 12 weeks of age when OLETF rats were not diabetic.

CONCLUSIONS

The enhancement of Smad protein expression and activation may be involved in the TGF-beta signaling cascade that plays an important role in the development of diabetic nephropathy through progressive expansion of the mesangial matrix.