Imperatorin ameliorates kidney injury in diabetic mice by regulating the TGF-ß/Smad2/3 signaling axis, epithelial-to-mesenchymal transition, and renal inflammation.

Diabetic nephropathy (DN) is a serious concern in patients with diabetes mellitus. Prolonged hyperglycemia induces oxidative damage, chronic inflammation, and build-up of extracellular matrix (ECM) components in the renal cells, leading to kidney structural and functional changes. Imperatorin (IMP) is a naturally occurring furanocoumarin derivative with proven antioxidative and anti-inflammatory properties. We investigated whether IMP could improve DN and employed high glucose (HG)-induced HK-2 cells and high-fat diet-fed streptozotocin (HFD/STZ)-generated DN experimental model in C57BL/6 mice. In vitro, IMP effectively reduced the HG-activated reactive oxygen species generation, disturbance in the mitochondrial membrane potential (MMP) and epithelial-to-mesenchymal transition (EMT)-related markers, and the transforming growth factor (TGF)-ß and collagen 1 expression in HK-2 cells. In vivo, we found an elevation of serum creatinine, kidney histology alterations, and collagen build-up in the kidneys of the DN control group. Also, we found an altered expression of EMT-related markers, upregulation of the TGF-ß/Smad2/3 axis, and elevated pro-inflammatory molecules, TNF-α, IL-1ß, IL-18 and phospho-NF-kB (p65) in the DN control group. IMP treatment did not significantly reduce the blood glucose level compared to the DN control group. However, IMP treatment effectively improved renal damage by ameliorating kidney histological changes and serum renal injury markers. IMP treatment restored renal antioxidants and exhibited anti-inflammatory effects in the kidneys. Moreover, the abnormal manifestation of EMT-related attributes and elevated levels of TGF-ß, phospho-Smad2/3, and collagen 1 were also normalized in the IMP treatment group. Our findings highlight that IMP may be a potential candidate for treating DN.

Stachydrine inhibits TGF-ß1-induced epithelial-mesenchymal transition in hepatocellular carcinoma cells through the TGF-ß/Smad and PI3K/Akt/mTOR signaling pathways.

Stachydrine is a bioactive alkaloid that has been found to exert tumor-suppressive potential. However, the effect of stachydrine on hepatocellular carcinoma (HCC) has not been previously investigated. In the present study, we investigated the effect of transforming growth factor-ß1 (TGF-ß1)-induced epithelial-mesenchymal transition (EMT) in HepG2 cells. Our results showed that stachydrine significantly suppressed TGF-ß1-induced HepG2 cell migration and invasion in a dose-dependent manner. Stachydrine prevented TGF-ß1-induced EMT in HepG2 cells, as proved by the increased expression level of E-cadherin and decreased expression levels of N-cadherin and vimentin. In addition, stachydrine attenuated TGF-ß1-induced upregulation of TGF-ß receptor I (TßRI) in both protein and mRNA levels. Further mechanism investigations proved that stachydrine prevented TGF-ß1-induced activation of Smad2/3 and phosphoinositol-3-kinase (PI3K)/Akt/mTOR signaling pathways in HepG2 cells. In conclusion, these findings demonstrated that stachydrine prevented TGF-ß1-induced EMT in HCC cells through Smad2/3 and PI3K/Akt/mTOR signaling pathways. Thus, stachydrine might be a potential therapeutic agent for the treatment of HCC.

Inhibitory Effect of the LY2109761 on the Development of Human Keloid Fibroblasts.

Keloids are scars characterized by abnormal proliferation of fibroblasts and overproduction of extracellular matrix components including collagen. We previously showed that LY2109761, a transforming growth factor- (TGF-) ß receptor inhibitor, suppressed the secretion of matrix components and slowed the proliferation of fibroblasts derived from human hypertrophic scar tissue. However, the exact mechanism underlying this effect remains unclear. Here, we replicated the above results in keloid-derived fibroblasts and show that LY2109761 promoted apoptosis, decreased the phosphorylation of Smad2 and Smad3, and suppressed TGF-ß1. These results suggest that the development and pathogenesis of keloids are positively regulated by the Smad2/3 signaling pathway and the upregulation of TGF-ß1 receptors. LY2109761 and other inhibitors of these processes may therefore serve as therapeutic targets to limit excessive scarring after injury.

Qingda granule attenuates cardiac fibrosis via suppression of the TGF-ß1/Smad2/3 signaling pathway in vitro and in vivo.

Cardiac fibrosis plays an important role in hypertension-related contractile dysfunction and heart failure. Qingda granule (QDG), derived from the Qingxuan Jiangya decoction, has been used clinically for more than 60 years to treat hypertension. However, the effect of QDG on hypertensive cardiac fibrosis remains largely unknown. The objective of this study was to investigate the effect of QDG on cardiac fibrosis and explore the underlying mechanism in vivo and in vitro. For in vivo experiments, 30 male spontaneously hypertensive rats were randomly divided into groups that received no QDG or one of three doses (0.45, 0.9 or 1.8 g/kg/day). Positive-control animals received valsartan (VAL, 7.2 mg/kg/day). Treatments were administered by gavage for 10 weeks. All three doses of QDG and VAL led to significantly lower blood pressure than in SHR animals. Besides, all three doses of QDG and VAL attenuated pathological changes in SHR animals. However, only intermediate, high concentrations of QDG and VAL led to significantly lower left ventricle ejection fraction and left ventricle fractional shortening than in SHR animals. Therefore, the minimum and effective QDG dose (intermediate concentration of QDG) was selected for subsequent animal experiments in this study. Our results showed that intermediate concentration of QDG also significantly mitigated the increases in levels of α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), collagen III, transforming growth factor-ß1 (TGF-ß1) and in the ratio of phospho-Smad2/3 to total Smad2/3 protein in cardiac tissue, based on immunohistochemistry, Western blotting, and Masson staining. For in vitro experiments, primary cardiac fibroblasts were stimulated with 100 nM angiotensin II in the presence or absence of QDG. And we tested different concentrations of QDG (3.125, 6.25, 12.5, 25, 50 µg/mL) in the cell viability experiment. Our results showed that 3.125, 6.25 and 12.5 µg/mL of QDG treatment for 24 h didn't affect the cell viability of cardiac fibroblasts. Consistently, QDG at 6.25 or 12.5 µg/mL significantly reduced cell viability and down-regulated α-SMA in primary cardiac fibroblasts were stimulated with 100 nM angiotensin II. Therefore, QDG at 12.5 µg/mL was chosen for the following cell experiment. Our results showed that QDG at 12.5 µg/mL alleviated the increase of PCNA, collagen Ⅲ, TGF-ß1 expression, and the ratio of phospho-Smad2/3 to total Smad2/3 protein. Our studies in vitro and in vivo suggest that QDG reduces blood pressure and cardiac fibrosis as well as protecting cardiac function, and that it exerts these effects in part by suppressing TGF-ß1/Smad2/3 signaling.

Quercetin regulates fibrogenic responses of endometrial stromal cell by upregulating miR-145 and inhibiting the TGF-ß1/Smad2/Smad3 pathway.

OBJECTIVES: Aim of this study is to explore whether quercetin can inhibit the enlarged fibrogenic responses of endometrial stromal cells by increasing the level of microRNA-145 (miR-145) and mediating the TGFß1/Smad2/Smad3 signaling pathway, and to discuss the mechanism of signal transduction, further to provide experimental basis for revealing the pathophysiological mechanism and seeking new strategies for effective prevention and treatment of endometrial fibrosis. METHODS: The expression levels of miR-145 and TGF-ß receptor 2 (TGFBR2) were detected by RT-qPCR analysis. Expressions of α-smooth muscle actin (α-SMA) and vimentin were examined by immunofluorescence staining. Cell viability was measured by MTT assay. The protein expression of collagen type 1 alpha 1 (Col1a1), α-SMA, fibronectin (FN), TGFBR2, transforming growth factor (TGF-ß1), Smad2/3, phospho-Smad2/3 (p-Smad2/3) were detected by western blot analysis. The interaction between miR-145 and TGFBR2 was confirmed by dual-luciferase reporter gene assay. RESULTS: The expression level of miR-145 was decreased, whereas TGFBR2 was increased in intrauterine adhesion tissue. The expression levels of COL1A1, α-SMA, FN, TGFBR2, and p-Smad2/3 were increased, whereas miR-145 and cell proliferation were decreased in human endometrial stromal cells (hESCs) in response to TGF-ß1 stimulation in a time and dose-dependent manner, which could be reversed by quercetin. Furthermore, quercetin regulates cell fibrogenic responses of endometrial stromal cells via miR-145/TGF-ß1/Smad2/Smad3 pathway. CONCLUSIONS: These findings indicated that quercetin have a significant anti-fibrotic effect and could upregulate miR-145 and inhibit activation of TGF-ß1/Smad2/Smad3 pathway to regulate TGF-ß1 induced fibrogenic responses of endometrial stromal cells, which may serve as a potential therapeutic agent for endometrial fibrosis.

All-trans-retinoic acid inhibits mink hair follicle growth via inhibiting proliferation and inducing apoptosis of dermal papilla cells through TGF-ß2/Smad2/3 pathway.

Dermal papilla cells (DPCs), an important component of hair follicles, its proliferation and apoptosis directly regulate and maintain the growth of hair follicles. All-trans-retinoic acid (ATRA) plays a critical role in hair growth. In this study, the effects of ATRA on cultured mink hair follicle growth were studied by administration of different concentrations of ATRA for 12 days in vitro. In addition, the proliferation and apoptosis of DPCs were measured after treating with ATRA. The mRNA and protein levels of hair follicle growth associated factor transforming growth factor-ß2 (TGF-ß2) and the phosphorylation levels of Smad2/3 were determined. Moreover, TGF-ß type I and type II receptor inhibitor LY2109761 and specific inhibitor of Smad3 (SIS3) were administered to investigate the underlying molecular mechanism. The results showed that ATRA inhibited hair follicle growth, promoted TGF-ß2 expression and activated phosphorylation of Smad2/3. In addition, ATRA inhibited cell proliferation by arresting the cell cycle at G1 phase and induced apoptosis of DPCs by enhancing the ratio of Bax/Bcl-2 and promoted the cleavage of caspase-3. Furthermore, LY2109761 or SIS3 partially reversed the decreased cell viability, increased apoptosis that were induced by ATRA. In conclusion, ATRA could inhibit hair follicle growth via inhibiting proliferation and inducing apoptosis of DPCs partially through the TGF-ß2/Smad2/3 pathway.

Positive Effects of a Young Systemic Environment and High Growth Differentiation Factor 11 Levels on Chondrocyte Proliferation and Cartilage Matrix Synthesis in Old Mice.

OBJECTIVE: To investigate the effects of a young systemic environment and growth differentiation factor 11 (GDF-11) on aging cartilage. METHODS: A heterochronic parabiosis model (2-month-old mouse and 12-month-old mouse [Y/O]), an isochronic parabiosis model (12-month-old mouse and 12-month-old mouse [O/O]), and 12-month-old mice alone (O) were evaluated. Knee joints and chondrocytes from old mice were examined by radiography, histology, cell proliferation assays, immunohistochemistry, Western blotting, and quantitative reverse transcriptase-polymerase chain reaction 16 weeks after parabiosis surgery. GDF-11 was injected into 12-month-old mouse joints daily for 16 weeks. Cartilage degeneration, cell proliferation, and osteoarthritis-related gene expression were evaluated. RESULTS: Osteoarthritis Research Society International scores in old mice were significantly lower in the Y/O group than in the O/O and O groups (both P < 0.05). The percentage of 5-ethynyl-2'-deoxyuridine-positive chondrocytes in old mice was significantly higher in the Y/O group than in the other groups (P < 0.05). Type II collagen (CII) and SOX9 messenger RNA levels differed in cartilage from old mice in the Y/O group compared to the O/O and O groups (both P < 0.05). RUNX-2, CX, and matrix metalloproteinase 13 levels were significantly lower in cartilage from old mice in the Y/O group compared to the O/O and O groups (both P < 0.05). Similar results were obtained for protein expression levels and after GDF-11 treatment in vitro and in vivo. Phosphorylated Smad2/3 (pSmad2/3) levels were higher in the recombinant GDF-11-treated group than in the control group. CONCLUSION: A young systemic environment promotes chondrocyte proliferation and cartilage matrix synthesis in old mice. GDF-11, a "young factor," contributes to these effects through the up-regulation of pSmad2/3.

Cordyceps polysaccharide ameliorates airway inflammation in an ovalbumin-induced mouse model of asthma via TGF-ß1/Smad signaling pathway.

Allergic asthma is a chronic inflammatory disease characterized by airflow obstruction, airway hyperresponsiveness (AHR), airway inflammation, and mucus overproduction. Cordyceps polysaccharide (CPS) is one of the main bioactive compounds of Cordyceps militarisis, a traditional Chinese medicine. In this study, we established a mouse model of asthma using ovalbumin (OVA) challenge and evaluated the potential regulatory effect of CPS (25, 50, and 100 mg/kg) on asthmatic mice. These results showed that the asthmatic mice treated with CPS suppressed the secretion of eotaxin, IL-4, IL-5, IL-13, and IFN-γ in the blood and bronchoalveolar lavage fluid (BALF), and decreased serum IgE levels compared to the vehicle-treated mice. CPS also alleviated inflammatory cell infiltration, goblet cell hyperplasia, and the increases of inflammatory cells in the mouse model of asthma. In addition, OVA-induced AHR was inhibited by CPS treatment. Further analyses of protein expression revealed that CPS inhibited the activation of transforming growth factor ß1 (TGF-ß1)/Smad pathway in mice with asthma. These findings indicated that CPS might serve as a potential therapeutic agent for the management of allergic asthma.

Hypoxia and transforming growth factor ß1 regulation of long non-coding RNA transcriptomes in human pulmonary fibroblasts.

One of the key characteristics of idiopathic pulmonary fibrosis (IPF) is accumulation of excess fibrous tissue in the lung, which leads to hypoxic conditions. Transforming growth factor (TGF) ß is a major mediator that promotes the differentiation of fibroblasts to myofibroblasts. However, how hypoxia and TGFß together contribute the pathogenesis of IPF is poorly understood. Long non-coding RNAs (lncRNAs) have regulatory effects on certain genes and are involved in many diseases. In this study, we determined the effects of hypoxia and/or TGFß on mRNA and lncRNA transcriptomes in pulmonary fibroblasts. Hypoxia and TGFß1 synergistically increased myofibroblast marker expression. RNA sequencing revealed that hypoxia and TGFß1 treatment resulted in significant changes in 669 lncRNAs and 2,676 mRNAs compared to 150 lncRNAs and 858 mRNAs in TGFß1 alone group and 222 lncRNAs and 785 mRNAs in hypoxia alone group. TGFß1 induced the protein expression of HIF-1α, but not HIF-2α. On the other hand, hypoxia enhanced the TGFß1-induced phosphorylation of Smad3, suggesting a cross-talk between these two signaling pathways. In all, 10 selected lncRNAs (five-up and five-down) in RNA sequencing data were validated using real-time PCR. Two lncRNAs were primarily located in cytoplasm, three in nuclei and five in both nuclei and cytoplasm. The silencing of HIF-1α and Smad3, but not Smad2 and HIF-2α rescued the downregulation of FENDRR by hypoxia and TGFß1. In conclusion, hypoxia and TGFß1 synergistically regulate mRNAs and lncRNAs involved in several cellular processes, which may contribute to the pathogenesis of IPF.

Arsenic trioxide inhibits the differentiation of fibroblasts to myofibroblasts through nuclear factor erythroid 2-like 2 (NFE2L2) protein and the Smad2/3 pathway.

BACKGROUND: Tissue contraction and the extracellular matrix deposition are part of the pathogenesis of hypertrophic scars. The transcriptional factor NFE2L2 inhibits fibroblast differentiation in idiopathic pulmonary fibrosis and promotes myofibroblast dedifferentiation. Our previous study showed that the transcription factor NFE2L2 was strongly induced on treatment with arsenic trioxide (ATO). OBJECTIVE: The present study sought to investigate the effect of ATO on myofibroblast formation to determine its potential role in hypertrophic scar treatment. METHODS: Small interfering RNA against NFE2L2 was used on treatment with ATO in human skin myofibroblasts. The expression levels of fibrosis markers were assessed by reverse transcription polymerase chain reaction, western blot, and immunofluorescence staining. The transforming growth factor-ß1 (TGF-ß1)/Smad2/3 signaling was detected by western blot. A rabbit ear model was used to evaluate the antifibrotic role of ATO. RESULTS: At the cellular level, ATO abolished fibroblast differentiation in response to TGF-ß1. ATO reduced TGF-ß1-induced reactive oxygen species accumulation through increased expression of the antioxidant gene HO-1 in fibroblasts. In addition, ATO promoted the nuclear translocation of NFE2L2 and inhibited the phosphorylation of Smad2/3. In the rabbit ear model, ATO prevented the progression of hypertrophic scar formation. CONCLUSIONS: This study provides the first evidence implying that ATO inhibits the formation of myofibroblasts in vivo and in vitro and provides a possible treatment for hypertrophic scars.

Rapamycin activates TGF receptor independently of its ligand: implications for endothelial dysfunction.

Rapamycin, the macrolide immunosuppressant and active pharmaceutic in drug-eluting stents (DES), has a well-recognized antiproliferative action that involves inhibition of the mTOR pathway after binding to the cytosolic protein FKBP12. TGF receptor-type I (TGFRI) spontaneous activation is inhibited by the association with FKBP12. We hypothesized that rapamycin, in addition to inhibition of mTOR signaling, activates TGFRI independent of TGFß. Human umbilical vein endothelial cells (HUVECs) were treated with rapamycin (10 nmol/l) and/or TGFß RI kinase inhibitor (TGFRIi, 100 nmol/l) for 24 h. Rapamycin induced SMAD phosphorylation (SMAD1, SMAD2, and SMAD5) and PAI-1 up-regulation, which was specifically abrogated by SMAD2 knockdown. TGFRIi efficiently blocked phosphorylation of SMAD2, but not SMAD1/5. Interestingly, the inhibitor did not alter cell proliferation arrest induced by rapamycin. Active TGFß secretion was not affected by the treatment. Neutralizing TGFß experiments did not influence SMAD2 phosphorylation or PAI-1 expression indicating that activation of this pathway is independent of the ligand. In addition, rapamycin induction of endothelial-to-mesenchymal transition (EndMT) was potentiated by IL-1ß and efficiently blocked by TGFRIi. In vivo, the prothrombogenic effects of rapamycin and up-regulation of PAI-1 in murine carotid arteries were reduced by TGFRIi treatment. In conclusion, we provide evidence that rapamycin activates TGF receptor independent of its ligand TGFß, in concert with promotion of PAI-1 expression and changes in endothelial phenotype. These undesirable effects, the prothrombogenic state, and activation of EndMT are SMAD2-dependent and independent of the therapeutic rapamycin-induced cell proliferation arrest.

GDF11 Attenuates Development of Type 2 Diabetes via Improvement of Islet ß-Cell Function and Survival.

Growth differentiation factor 11 (GDF11) has been implicated in the regulation of islet development and a variety of aging conditions, but little is known about the physiological functions of GDF11 in adult pancreatic islets. Here, we showed that systematic replenishment of GDF11 not only preserved insulin secretion but also improved the survival and morphology of ß-cells and improved glucose metabolism in both nongenetic and genetic mouse models of type 2 diabetes (T2D). Conversely, anti-GDF11 monoclonal antibody treatment caused ß-cell failure and lethal T2D. In vitro treatment of isolated murine islets and MIN6 cells with recombinant GDF11 attenuated glucotoxicity-induced ß-cell dysfunction and apoptosis. Mechanistically, the GDF11-mediated protective effects could be attributed to the activation of transforming growth factor-ß/Smad2 and phosphatidylinositol-4,5-bisphosphate 3-kinase-AKT-FoxO1 signaling. These findings suggest that GDF11 repletion may improve ß-cell function and mass and thus may lead to a new therapeutic approach for T2D.

Synergistic effect of vitamin D and low concentration of transforming growth factor beta 1, a potential role in dermal wound healing.

Dermal wound healing, in which transforming growth factor beta 1 (TGFß1) plays an important role, is a complex process. Previous studies suggest that vitamin D has a potential regulatory role in TGFß1 induced activation in bone formation, and there is cross-talk between their signaling pathways, but research on their effects in other types of wound healing is limited. The authors therefore wanted to explore the role of vitamin D and its interaction with low concentration of TGFß1 in dermal fibroblast-mediated wound healing through an in vitro study. Human dermal fibroblasts were treated with vitamin D, TGFß1, both, or vehicle, and then the wound healing functions of dermal fibroblasts were measured. To further explore possible mechanisms explaining the synergistic effect of vitamin D and TGFß1, targeted gene silencing of the vitamin D receptor was performed. Compared to either factor alone, treatment of fibroblasts with both vitamin D and low concentration of TGFß1 increased gene expression of TGFß1, connective tissue growth factor, and fibronectin 1, and enhanced fibroblast migration, myofibroblast formation, and collagen production. Vitamin D receptor gene silencing blocked this synergistic effect of vitamin D and TGFß1 on both collagen production and myofibroblast differentiation. Thus a synergistic effect of vitamin D and low TGFß1 concentration was found in dermal fibroblast-mediated wound healing in vitro. This study suggests that supplementation of vitamin D may be an important step to improve wound healing and regeneration in patients with a vitamin D deficiency.

Restriction of spontaneous and prednisolone-induced leptin production to dedifferentiated state in human hip OA chondrocytes: role of Smad1 and ß-catenin activation.

OBJECTIVE: The aetiology of OA is not fully understood although several adipokines such as leptin are known mediators of disease progression. Since leptin levels were increased in synovial fluid compared to serum in OA patients, it was suggested that joint cells themselves could produce leptin. However, exact mechanisms underlying leptin production by chondrocytes are poorly understood. Nevertheless, prednisolone, although displaying powerful anti-inflammatory properties has been recently reported to be potent stimulator of leptin and its receptor in OA synovial fibroblasts. Therefore, we investigated, in vitro, spontaneous and prednisolone-induced leptin production in OA chondrocytes, focusing on transforming growth factor-ß (TGFß) and Wnt/ß-catenin pathways. DESIGN: We used an in vitro dedifferentiation model, comparing human freshly isolated hip OA chondrocytes cultivated in monolayer during 1 day (type II, COL2A1 +; type X, COL10A1 + and type I collagen, COL1A1 -) or 14 days (COL2A1 -; COL10A1 - and COL1A1+). RESULTS: Leptin expression was not detected in day1 OA chondrocytes whereas day14 OA chondrocytes produced leptin, significantly increased with prednisolone. Activin receptor-like kinase 1 (ALK1)/ALK5 ratio was shifted during dedifferentiation, from high ALK5 and phospho (p)-Smad2 expression at day1 to high ALK1, endoglin and p-Smad1/5 expression at day14. Moreover, inactive glycogen synthase kinase 3 (GSK3) and active ß-catenin were only found in dedifferentiated OA chondrocytes. Smad1 and ß-catenin but not endoglin stable lentiviral silencing led to a significant decrease in leptin production by dedifferentiated OA chondrocytes. CONCLUSIONS: Only dedifferentiated OA chondrocytes produced leptin. Prednisolone markedly enhanced leptin production, which involved Smad1 and ß-catenin activation.

Growth Differentiation Factor-8 Decreases StAR Expression Through ALK5-Mediated Smad3 and ERK1/2 Signaling Pathways in Luteinized Human Granulosa Cells.

Growth differentiation factor-8 (GDF-8) has been recently shown to be expressed in human granulosa cells, and the mature form of GDF-8 protein can be detected in the follicular fluid. However, the biological function and significance of this growth factor in the human ovary remains to be determined. Here, we investigated the effects of GDF-8 on steroidogenic enzyme expression and the potential mechanisms of action in luteinized human granulosa cells. We demonstrated that treatment with GDF-8 did not affect the mRNA levels of P450 side-chain cleavage enzyme and 3ß-hydroxysteroid dehydrogenase, whereas it significantly down-regulated steroidogenic acute regulatory protein (StAR) expression and decreased progesterone production. The suppressive effect of GDF-8 on StAR expression was abolished by the inhibition of the TGF-ß type I receptor. In addition, treatment with GDF-8 activated both Smad2/3 and ERK1/2 signaling pathways. Furthermore, knockdown of activin receptor-like kinase 5 reversed the effects of GDF-8 on Smad2/3 phosphorylation and StAR expression. The inhibition of Smad3 or ERK1/2 signaling pathways attenuated the GDF-8-induced down-regulation of StAR and production of progesterone. Interestingly, the concentrations of GDF-8 were negatively correlated with those of progesterone in human follicular fluid. These results indicate a novel autocrine function of GDF-8 to down-regulate StAR expression and decrease progesterone production in luteinized human granulosa cells, most likely through activin receptor-like kinase 5-mediated Smad3 and ERK1/2 signaling pathways. Our findings suggest that granulosa cells might play a critical role in the regulation of progesterone production to prevent premature luteinization during the final stage of folliculogenesis.

Apigenin induces dermal collagen synthesis via smad2/3 signaling pathway.

Decrease in fibroblast-produced collagen has been proven to be the pivotal cause of skin aging, but there is no satisfactory drug which directly increases dermal thickness and collage density. Here we found that a flavonoid natural product, apigenin, could significantly increase collagen synthesis. NIH/3T3 and primary human dermal fibroblasts (HDFs) were incubated with various concentrations of apigenin, with dimethyl sulfoxide (DMSO) serving as the negative control. Real-time reverse-transcription polymerase chain reaction (PCR), Western Blot, and Toluidine blue staining demonstrated that apigenin stimulated type-I and type-III collagen synthesis of fibroblasts on the mRNA and protein levels. Meanwhile, apigenin did not induce expression of alpha smooth muscle actin (α-SMA) in vitro and in vivo, a fibrotic marker in living tissues. Then the production of collagen was confirmed by Masson's trichrome stain, Picrosirius red stain and immunohistochemistry in mouse models. We also clarified that this compound induced collagen synthesis by activating smad2/3 signaling pathway. Taken together, without obvious influence on fibroblasts' apoptosis and viability, apigenin could promote the type-I and type-III collagen synthesis of dermal fibroblasts in vitro and in vivo, thus suggesting that apigenin may serve as a potential agent for esthetic and reconstructive skin rejuvenation.

Effect of HGF on the apoptosis of rat corpus cavernosum smooth muscle cells induced by TGFß1.

Corpus cavernosum smooth muscle cells (CCSMCs) are important functional cells for penile erection. We evaluated the effect of transforming growth factor ß1 (TGFß1) and hepatocyte growth factor (HGF) on the viability and apoptosis of CCSMCs in vitro. CCSMCs from healthy male Sprague Dawley rats were randomly divided into four groups: a negative control group, a TGFß1 group, a HGF group and a HGF+ TGFß1 group. Differences in cell viability and apoptosis among groups were observed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and flow cytometry. Western blot was used to detect the change of apoptosis-related proteins. The level of reactive oxygen species (ROS) was detected by colorimetry. In the TGFß1 group, the MTT values were obviously decreased at 12 h, 24 h, 48 h-0.320, 0.383 and 0.432 respectively. However, compared with the normal group, the apoptosis index was markedly increased, reaching 26.86% at the 48-h time point. After TGFß1 treatment, the levels of cleaved caspase-3 and p-Smad2 were increased in the cells, but the levels of Bcl-xL, Bcl-2 and p-Akt were significantly lower. However, HGF co-treatment partially reversed these changes and could decrease the intracellular ROS level while increasing the Akt phosphorylation level. These results indicate that TGFß1 might induce apoptosis of CCSMCs in vitro and that HGF could interfere with the above process through downregulation of apoptosis signalling and oxidative stress reaction.

TGF-ß is a potent inducer of Nerve Growth Factor in articular cartilage via the ALK5-Smad2/3 pathway. Potential role in OA related pain?

OBJECTIVE: Pain is the main problem for patients with osteoarthritis (OA). Pain is linked to inflammation, but in OA a subset of patients suffers from pain without inflammation, indicating an alternative source of pain. Nerve Growth Factor (NGF) inhibition is very efficient in blocking pain during OA, but the source of NGF is unclear. We hypothesize that damaged cartilage in OA releases Transforming Growth Factor-ß (TGF-ß), which in turn stimulates chondrocytes to produce NGF. DESIGN: Murine and human chondrocyte cell lines, primary bovine and human chondrocytes, and cartilage explants from bovine metacarpal joints and human OA joints were stimulated with TGF-ß1 and/or Interleukin-1 (IL-1)ß. We analyzed NGF expression on mRNA level with QPCR and stained human OA cartilage for NGF immunohistochemically. Cultures were additionally pre-incubated with inhibitors for TAK1, Smad2/3 or Smad1/5/8 signaling to identify the TGF-ß pathway inducing NGF. RESULTS: NGF expression was consistently induced in higher levels by TGF-ß than IL-1 in all of our experiments: murine, bovine and human origin, in cell lines, primary chondrocytes and explants cultures. TAK1 inhibition consistently reduced TGF-ß-induced NGF whereas it fully blocked IL-1ß-induced NGF expression. In contrast, ALK5-Smad2/3 inhibition fully blocked TGF-ß-induced NGF expression. Despite the large variation in basal NGF in human OA samples (mRNA and histology), TGF-ß exposure led to a consistent high level of NGF induction. CONCLUSION: We show for the first time that TGF-ß induces NGF expression in chondrocytes, in a ALK5-Smad2/3 dependent manner. This reveals a potential alternative non-inflammatory source of pain in OA.

Daidzein stimulates collagen synthesis by activating the TGF-ß/smad signal pathway.

BACKGROUND/OBJECTIVES: The objective of this study was to investigate the effects of daidzein on collagen metabolism and its underlying mechanism in cultured skin fibroblast and nude mouse skin. METHODS: Skin fibroblasts were exposed to different concentrations of daidzein (0.5-50 µg/mL) for 24 h or 48 h, respectively. Female nude mice were treated topically with 200 µg/mL daidzein once a day for 6 weeks. Cell viability and cell cycle were determined by MTT and flow cytometer. The transcriptional activity of collagen type I was evaluated and the expression of procollagen, matrix metalloproteinase-1 (MMP1) and MMP2 were measured by real-time polymerase chain reaction. A Western blot analysis was applied to detect the levels of phosphorylated-Smad2 and Smad3. RESULTS: In the daidzein-treated cells the expression of type I procollagen increased markedly while the expressions of MMP1, and MMP2 was significantly inhibited. Additionally, the mouse skin showed more collagen deposition after daidzein treatment. The levels of transforming growth factor (TGF)-ß, phosphorylated-smad2 and smad3 were also higher in the daidzein treated skin fibroblasts than in the controls. CONCLUSIONS: The results showed that daidzein treatment can increase skin collagen synthesis and inhibit collagen degradation in vitro and in vivo. It seems that TGF-ß/smad signalling pathways play an important role in daidzein-induced collagen accumulation.