Smad1/5 signal transduction regulates the ameloblastic differentiation of induced pluripotent stem cells

Abstract Induced pluripotent stem (iPS) cells could be induced into ameloblast-like cells by ameloblasts serum-free conditioned medium (ASF-CM), and bone morphogenetic proteins (BMPs) might be essential during the regulation of this process. The present study investigates the signal transduction that regulates the ameloblastic differentiation of iPS cells induced by ASF-CM. Mouse iPS cells were characterized and then cultured for 14 days in epithelial cell medium (control) or ASF-CM. Bone morphogenetic protein receptor II (BMPR-II) siRNA, inhibitor of Smad1/5 phosphorylation activated by activin receptor-like kinase (ALK) receptors, and inhibitors of mitogen-activated protein kinases (MAPKs) phosphorylation were used to treat the iPS cells in combination with ASF-CM. Real-time PCR, western blotting, and immunofluorescent staining were used to evaluate the expressions of ameloblast markers ameloblastin, enamelin, and cytokeratin-14. BMPR-II gene and protein levels increased markedly in ASF-CM-treated iPS cells compared with the controls, while the mRNA levels of Bmpr-Ia and Bmpr-Ib were similar between the ASF-CM and control groups. ASF-CM stimulation significantly increased the gene and protein expression of ameloblastin, enamelin and cytokeratin-14, and phosphorylated SMAD1/5, p38 MAPK, and ERK1/2 MAPK compared with the controls. Knockdown of BMPR-II and inhibition of Smad1/5 phosphorylation both could significantly reverse the increased expression of ameloblastin, enamelin, and cytokeratin-14 induced by ASF-CM, while neither inhibition of p38 nor ERK1/2 phosphorylation had significant reversing effects. We conclude that smad1/5 signaling transduction, activated by ALK receptors, regulates the ameloblastic differentiation of iPS cells induced by ameloblast-conditioned medium.

Smad1/5 signal transduction regulates the ameloblastic differentiation of induced pluripotent stem cells

Abstract Induced pluripotent stem (iPS) cells could be induced into ameloblast-like cells by ameloblasts serum-free conditioned medium (ASF-CM), and bone morphogenetic proteins (BMPs) might be essential during the regulation of this process. The present study investigates the signal transduction that regulates the ameloblastic differentiation of iPS cells induced by ASF-CM. Mouse iPS cells were characterized and then cultured for 14 days in epithelial cell medium (control) or ASF-CM. Bone morphogenetic protein receptor II (BMPR-II) siRNA, inhibitor of Smad1/5 phosphorylation activated by activin receptor-like kinase (ALK) receptors, and inhibitors of mitogen-activated protein kinases (MAPKs) phosphorylation were used to treat the iPS cells in combination with ASF-CM. Real-time PCR, western blotting, and immunofluorescent staining were used to evaluate the expressions of ameloblast markers ameloblastin, enamelin, and cytokeratin-14. BMPR-II gene and protein levels increased markedly in ASF-CM-treated iPS cells compared with the controls, while the mRNA levels of Bmpr-Ia and Bmpr-Ib were similar between the ASF-CM and control groups. ASF-CM stimulation significantly increased the gene and protein expression of ameloblastin, enamelin and cytokeratin-14, and phosphorylated SMAD1/5, p38 MAPK, and ERK1/2 MAPK compared with the controls. Knockdown of BMPR-II and inhibition of Smad1/5 phosphorylation both could significantly reverse the increased expression of ameloblastin, enamelin, and cytokeratin-14 induced by ASF-CM, while neither inhibition of p38 nor ERK1/2 phosphorylation had significant reversing effects. We conclude that smad1/5 signaling transduction, activated by ALK receptors, regulates the ameloblastic differentiation of iPS cells induced by ameloblast-conditioned medium.

Activin Receptor-Like Kinase 5 Inhibitor Attenuates Fibrosis in Fibroblasts Derived from Peyronie's Plaque

PURPOSE: Transforming growth factor-beta1 (TGF-beta1) is the key fibrogenic cytokine associated with Peyronie's disease (PD). The aim of this study was to determine the antifibrotic effect of 3-((5-(6-Methylpyridin-2-yl)-4-(quinoxalin-6-yl)-1H-imidazol-2-yl) methyl)benzamide (IN-1130), a small-molecule inhibitor of the TGF-beta type I receptor activin receptor-like kinase 5 (ALK5), in fibroblasts isolated from human PD plaque. MATERIALS AND METHODS: Plaque tissue from a patient with PD was used for primary fibroblast culture, and we then characterized primary cultured cells. Fibroblasts were pretreated with IN-1130 (10 microM) and then stimulated with TGF-beta1 protein (10 ng/ml). We determined the inhibitory effect of IN-1130 on TGF-beta1-induced phosphorylation of Smad2 and Smad3 or the nuclear translocation of Smad proteins in fibroblasts. Western blot analyses for plasminogen activator inhibitor-1, fibronectin, collagen I, and collagen IV were performed to evaluate effect of IN-1130 on the production of extracellular matrix proteins. RESULTS: The treatment of fibroblasts with TGF-beta1 significantly increased phosphorylation of Smad2 and Smad3 and induced translocation of Smad proteins from the cytoplasm to the nucleus. Pretreatment with IN-1130 substantially inhibited TGF-beta1-induced phosphorylation of Smad2 and Smad3 and nuclear accumulation of Smad proteins. The TGF-beta1-induced production of extracellular matrix proteins was also significantly inhibited by treatment with IN-1130 and returned to basal levels. CONCLUSIONS: Overexpression of TGF-beta and activation of Smad transcriptional factors are known to play a crucial role in the pathogenesis of PD. Thus, inhibition of the TGF-beta signaling pathway by ALK5 inhibitor may represent a promising therapeutic strategy for treating PD.

Transforming Growth Factor-beta Type I Receptor Inhibitor Induces Functional and Morphologic Recovery in a Rat Model of Erectile Dysfunction and Cavernous Fibrosis / 대한남성과학회지

PURPOSE: To examine the effectiveness of small-molecule inhibitor of transforming growth factor-beta (TGF-beta) type I receptor, an activin receptor-like kinase 5 (ALK5), on erectile dysfunction (ED) in a rat model of cavernous fibrosis, in which fibrosis was induced by intracavernous injection of adenovirus expressing TGF-beta1 (Ad-TGF-beta1). MATERIALS AND METHODS: Four-month-old Sprague-Dawley rats were divided into four groups (n=10 per group): age-matched controls without treatment, age-matched controls receiving intracavernous injection of LacZ adenovirus, and cavernous fibrosis rats receiving an intracavernous injection of saline or ALK5 inhibitor (5 mg/kg). ALK5 inhibitor or saline was administered on day 5 after injection of Ad-TGF-beta1. On day 30, erectile function was assessed by electrical stimulation of the cavernous nerve and the penis was then harvested for histologic studies (n=6 per group) and for the measurement of the hydroxyproline level (n=4 per group). RESULTS: Ad-TGF-beta1-induced cavernous fibrosis rats treated with saline showed a significant decrease in cavernous smooth muscle and endothelial content, and an increase in collagen deposition, which resulted in profound deterioration of all erectile function parameters, such as the ratios of maximal intracavernous pressure (ICP), total ICP, and slope to mean arterial pressure. ALK5 inhibitor significantly restored erectile function in a rat model of cavernous fibrosis by increasing cavernous smooth muscle and endothelial content, and by blocking cavernous fibrosis. CONCLUSIONS: The results suggest that inhibition of the TGF-beta pathway is a promising therapeutic strategy for the treatment of ED related to cavernous fibrosis from various causes.

Activin A Stimulates Mouse APCs to Express BAFF via ALK4-Smad3 Pathway

BACKGROUND: B cell-activating factor belonging to the TNF family (BAFF) is primarily expressed by macrophages and dendritic cells, and stimulates B cell proliferation, differentiation, survival, and Ig production. In the present study, we explored the effect of activin A on BAFF expression by APCs. METHODS: To investigate the effect of activin A on BAFF expression by mouse APCs, we measured the level of BAFF expression at the transcriptional and protein levels using RT-PCR and ELISA. RESULTS: Activin A markedly enhanced BAFF expression in mouse macrophages and dendritic cells at both the transcriptional and protein levels. SB431542, an activin receptor-like kinase 4 (ALK4) inhibitor, completely abrogated activin A-induced BAFF transcription. Furthermore, overexpression of DN-Smad3 abolished activin-induced BAFF expression at the transcriptional and protein levels. CONCLUSION: These results demonstrate that activin A can enhance BAFF expression through ALK4-Smad3 pathway.

Activin and activin receptors in related gynecologic and obstetric diseases / 中南大学学报(医学版)

Activin is a member of the transforming growth factor-beta (TGF-beta) superfamily that result from the assembly of disulphide-linked betaA and betaB subunits. Activin receptors are transmembrane proteins and activin fulfils the biological function through the signal transduction of the receptor system. In recent years, many studies have suggested that activins have wide biological activities. It is the basic medium in regulating histiocytic function and plays a role in maintaining the normal function of cells. Moreover, abnormal expression of activin in the tissues of many gynecologic and obstetric diseases, such as epithelial ovarian tumor, endometrial carcinoma, pre-eclampsia, polycystic ovary syndrome, endometriosis and so on affects the development of these diseases.

Effect of IN-1130, a Novel Transforming Growth Factor-beta Type I Receptor Kinase (ALK5) Inhibitor, on a Rat Model of Peyronie's Disease Induced by Repeated Intratunical Injections of Fibrin / 대한남성과학회지

PURPOSE: Transforming growth factor-beta1 (TGF-beta1) has been known to be involved in the pathogenesis of Peyronie's disease (PD). In the present study, we investigated the therapeutic effect of IN-1130, a novel small molecule inhibitor of activin receptor-like kinase (ALK)5, a type I receptor of TGF-beta, in an animal model of PD induced by fibrin. MATERIALS AND METHODS: Four-month-old male Sprague-Dawley rats were divided into three groups (n=4 per group): group 1, age-matched control; group 2, PD rats without treatment; group 3, PD rats receiving an intratunical injection of IN-1130 (on day 20, 5 mg/kg in 0.1 ml saline) into the lesion. PD was induced in rats through repeated injections of fibrin (50 microliter each of human fibrin and thrombin solutions, days 0, 3, and 6, respectively) into the tunica albuginea. Penile curvature was evaluated by use of an artificialerection test on day 30. The penis was then harvested and stained with Masson trichrome, hematoxylin- eosin, and antibody to vimentin and phospho-Smad2. RESULTS: PD rats receiving repeated intratunical injections of fibrin revealed an infiltration of inflammatory cells, including lymphocytes, plasma cells, and fibroblasts, and an increase in transnuclear expression of phospho-Smad2 in the fibrotic plaque. However, repeated intratunical injections of fibrin did not induce penile curvature. IN-1130 induced significant regression of fibrotic plaque through reduced infiltration of inflammatory cells and reduced transnuclear expression of phospho-Smad2. CONCLUSIONS: Inhibition of TGF-beta pathway through the use of ALK5 inhibitors may be a curative local treatment modality for PD.