Proprotein convertase furin inhibits matrix metalloproteinase 13 in a TGFß-dependent manner and limits osteoarthritis in mice.

Cartilage loss in osteoarthritis (OA) results from altered local production of growth factors and metalloproteases (MMPs). Furin, an enzyme involved in the protein maturation of MMPs, might regulate chondrocyte function. Here, we tested the effect of furin on chondrocyte catabolism and the development of OA. In primary chondrocytes, furin reduced the expression of MMP-13, which was reversed by treatment with the furin inhibitor α1-PDX. Furin also promoted the activation of Smad3 signaling, whereas activin receptor-like kinase 5 (ALK5) knockdown mitigated the effects of furin on MMP-13 expression. Mice underwent destabilization of the medial meniscus (DMM) to induce OA, then received furin (1 U/mice), α1-PDX (14 µg/mice) or vehicle. In mice with DMM, the OA score was lower with furin than vehicle treatment (6.42 ± 0.75 vs 9.16 ± 0.6, p < 0.01), and the number of MMP-13(+) chondrocytes was lower (4.96 ± 0.60% vs 20.96 ± 8.49%, p < 0.05). Moreover, furin prevented the increase in ALK1/ALK5 ratio in cartilage induced by OA. Conversely, α1-PDX had no effect on OA cartilage structure. These results support a protective role for furin in OA by maintaining ALK5 receptor levels and reducing MMP-13 expression. Therefore, furin might be a potential target mediating the development of OA.

Reduced expression of activin receptor-like kinase 7 in breast cancer is associated with tumor progression.

To explore the clinical implication of activin receptor-like kinase 7 (ALK7) expression in breast cancer, we evaluated its protein level in six kinds of human breast tissue samples, including adjacent normal tissues, adenosis, breast fibroadenoma, ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and lymph node metastases (LNM). Immunohistochemical analyses showed that ALK7 was more frequently and much more intensely expressed in adjacent normal tissues, adenosis, and fibroadenoma tissues than in malignant tissues (DCIS, IDC, and LNM). Furthermore, the ALK7 expression in primary tumors and the corresponding LNM was evaluated in parallel samples from 60 patients with IDC. Results showed that the ALK7 expression status in primary tumors and LNM was concordant in 53 patients (88%), suggesting that ALK7 expression was retained in LNM. Moreover, our results suggested that ALK7 expression inversely correlated with the tumor grade (P=0.009) and clinical stage (P=0.004) in IDC significantly. Finally, the effect of activin-ALK7 pathway on the breast cancer cell growth was elucidated, and results revealed that overexpression of ALK7 could restore the inhibitory effect of activin B on the growth of ALK7-negative breast cancer cell line, ZR-75-30. These findings provide the evidence that the reduction or lack of ALK7 expression may account for the loss of its ligand sensitivity of breast cancer cells, thereby leading to breast tumor progression.

Effects of curcumin on peroxisome proliferator-activated receptor gamma expression and nuclear translocation/redistribution in culture-activated rat hepatic stellate cells.

BACKGROUND: The function of peroxisome proliferator-activated receptor gamma (PPARgamma) in hepatic fibrogenesis remains largely unknown. Curcumin is a natural substance extracted form Curcuma Longa Linn and has a variety of pharmacological effects. In this study, the effects of curcumin on the proliferation, activation and apoptosis of rat hepatic stellate cells (HSCs) through PPARgamma signaling were investigated. METHODS: HSCs were isolated from the normal Sprague Dawley rats through in situ perfusion of the liver with Pronase E and density-gradient centrifugation with Nycodenz. Cells were treated with curcumin, troglitazone, salvianolic acid B or GW9662. The effect on HSCs proliferation was determined by MTT colorimetry. Total RNA was extracted by TRizol reagent and gene levels were determined by semi-quantitative RT-PCR. Total cellular and nuclear protein were isolated and separated by 10% sodium dodecy lsulfate polyacrylamide gel electrophoresis. Protein levels were determined by Western blot. Cell apoptosis was detected by Hoechst 33258 staining. PPARgamma subcellular distribution was detected by immunofluorescent staining. The activities of MMP-2 and 9 were measured by Gelatin zymograph assay. RESULTS: Curcumin suppressed HSCs proliferation in a dose-dependent manner. As HSCs underwent gradual activation with culture prolongation the PPARgamma nuclear expression level decreased. Curcumin up-regulated PPARgamma expression and significantly inhibited the production of alpha-SMA and collagen I. PPARgamma is expressed in the cytoplasm and nucleus and is evenly distributed in HSCs, but accumulated in the nucleus of HSCs and disappeared from cytoplasm after curcumin treatment. Hoechst 33258 staining showed that curcumin induced the apoptosis of culture-activated HSCs and significantly increased pro-apoptotic Bax expression and reduced anti-apoptotic Bcl-2 expression. Cyclin D1 gene, activated NFkappaB p65 protein and TGFbetaR-I protein expression were down-regulated significantly by curcumin. The activities of MMP-2 and MMP-9 were enhanced significantly by curcumin. CONCLUSIONS: Curcumin can inhibit the proliferation and activation of HSCs, induce the apoptosis of activated HSCs and enhance the activities of MMP-2 and MMP-9. The effects of curcumin are mediated through activating the PPARgamma signal transduction pathway and associated with PPARgamma nuclear translocation/redistribution.

Expression of activin and inhibin subunits, receptors and binding proteins in human pheochromocytomas: a study based on mRNA analysis and immunohistochemistry.

OBJECTIVE: Pheochromocytomas are uncommon tumours arising from chromaffin cells of the adrenal medulla and related paraganglia. So far, one of the few reported markers to discriminate malignant from benign tumours is the betaB-subunit of inhibin and activin, members of the transforming growth factor (TGF)-beta superfamily of growth and differentiation factors. DESIGN: We investigated the expression of the mRNAs coding for activin and inhibin subunits, their receptors and binding proteins by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and studied the presence of the inhibin betaB-subunit in human pheochromocytomas by immunohistochemistry. PATIENTS: Samples from resected pheochromocytomas of patients operated between 1973 and 2003 were used for experiments. RESULTS: The immunohistochemical investigations revealed that staining of the inhibin betaB-subunit was positive in 12 of 36 (33%) benign and 5 of 34 (15%) malignant pheochromocytomas (P > 0.05). Therefore, it was not possible to discriminate between benign and malignant tumours solely on the basis of inhibin betaB-subunit immunohistochemistry. Quantitative real-time RT-PCR in nine benign and four malignant tumours showed expression of inhibin alpha-, betaA- and betaB-subunits, the activin receptors Alk-4, ActRIIA, and ActRIIB, and the inhibin- and activin-binding proteins betaglycan and follistatin in all samples. No correlations were detected between individually coupled expression of mRNAs of these activin- and inhibin-related genes in the 13 pheochromocytomas. Only inhibin betaA-subunit expression was different in malignant compared to benign pheochromocytomas (P = 0.020). CONCLUSIONS: No clear role for activin and inhibin was found in discriminating between benign and malignant pheochromocytomas.

Runx2 expression is associated with pathologic new bone formation around radicular cysts: an immunohistochemical demonstration.

BACKGROUND: Radicular cysts are the most common cysts in human jaw bones. These lesions induce bone remodeling of the surrounding alveolar bones, which was termed 'condensing osteitis', and was suggested to be related to cells of the osteoblastic lineage. The Runx2 (core-binding protein [cbfa]1/polyoma enhancer-binding protein [pebp]2alphaA) was shown to be a DNA-binding transcriptional molecule expressed in osteoprogenitor cells. METHODS: We confirmed the specificity of anti-Runx2 antiserum, using Western blotting analysis. We investigated the expression and localization of Runx2 in 32 radicular cyst cases with bone tissue fragments, immunohistochemically. RESULTS: Signals for Runx2 were seen in 18 cases (56.3%) of radicular cysts with bone formation. These signals were immunolocalized in the nuclei of the spindle-shaped osteoprogenitor cells in the cyst walls, whereas only a few signals were seen in the cuboidal osteoblastic cells near the fibrous bones. Signals for type I collagen were immunolocalized in the dense collagen fibers in the cyst walls and in the matrix of the fibrous bone around the radicular cysts, whereas no signals were seen on the inner portions with inflammatory cell infiltration of the cyst walls. Very weak signals for transforming growth factor (TGF)-beta1 were infrequently seen in the osteoblasts of the fibrous bone, whereas signals for TGF-beta2 were observed in young osteocytes in the fibrous bones, in B-cell lymphocytes infiltrating into the inner portions, and on the cellular membranes of the lining epithelium. CONCLUSIONS: The nuclear expression of Runx2 in spindle-shaped cells in the outer portions may play an essential role in the induction of fibrous bone tissue around radicular cysts. TGF-beta2 may play a role in the production of type I collagen, which acts as a template for pathologic new bone formation, in radicular cysts.

Hereditary hemorrhagic telangiectasia, a vascular dysplasia affecting the TGF-beta signaling pathway.

Hereditary hemorrhagic telangiectasia (HHT) is caused by mutations in endoglin (ENG; HHT1) or ACVRL1/ALK1 (HHT2) genes and is an autosomal dominant vascular dysplasia. Clinically, HHT is characterized by epistaxis, telangiectases and arteriovenous malformations in some internal organs such as the lung, brain or liver. Endoglin and ALK1 proteins are specific endothelial receptors of the transforming growth factor (TGF)-beta superfamily that are essential for vascular integrity. Genetic studies in mice and humans have revealed the pivotal role of TGF-beta signaling during angiogenesis. Through binding to the TGF-beta type II receptor, TGF-beta can activate two distinct type I receptors (ALK1 and ALK5) in endothelial cells, each one leading to opposite effects on endothelial cell proliferation and migration. The recent isolation and characterization of circulating endothelial cells from HHT patients has revealed a decreased endoglin expression, impaired ALK1- and ALK5-dependent TGF-beta signaling, disorganized cytoskeleton and the failure to form cord-like structures which may lead to the fragility of small vessels with bleeding characteristic of HHT vascular dysplasia or to disrupted and abnormal angiogenesis after injuries and may explain the clinical symptoms associated with this disease.

Characterization of TGF-beta-regulated interleukin-8 expression in human prostate cancer cells.

BACKGROUND: Interleukin (IL)-8 and transforming growth factor (TGF)-beta1 are overexpressed in advanced prostate cancer. The purpose of this study was to investigate TGF-beta1-regulated IL-8 expression in prostate cancer cells. METHODS: TGF-beta receptor expression was evaluated by real-time reverse-transcription PCR (RT-PCR) and Western blotting. TGF-beta1-regulated IL-8 expression was determined by real-time RT-PCR, enzyme-linked immunoabsorbance assay (ELISA), nuclear run-on, and IL-8 promoter reporter assay. RESULTS: PC-3MM2 cells expressed type I and type II TGF-beta receptors (TbetaRI and TbetaRII). LNCaP cells expressed significantly lower level of TbetaRII. Constitutive expression of IL-8 was detected in PC-3MM2 cells and LNCaP cells engineered with TbetaRII (LNCaP-TbetaRII). TGF-beta1 stimulated IL-8 expression in dose- and time-dependent manners, which was blocked by cycloheximide (CHX) and actinomycin D (ActD). The nuclear run-on and IL-8 luciferase reporter assays show that TGF-beta1 activated IL-8 gene transcription. CONCLUSIONS: TGF-beta1 signaling regulates IL-8 expression in prostate cancer cells and may contribute to the overexpression of IL-8 in human prostate cancer.

Molecular evidence that growth of dominant follicles involves a reduction in follicle-stimulating hormone dependence and an increase in luteinizing hormone dependence in cattle.

The bovine dominant follicle (DF) model was used to identify molecular mechanisms potentially involved in initial growth of DF during the low FSH milieu of ovarian follicular waves. Follicular fluid and RNA from granulosa and theca cells were harvested from 10 individual DF obtained between 2 and 5.5 days after emergence of the first follicular wave of the estrous cycle. Follicular fluid was subjected to RIA to determine estradiol (E) and progesterone (P) concentrations and RNA to cDNA microarray analysis and (or) quantitative real-time PCR. Results showed that DF growth was associated with a decrease in intrafollicular E:P ratio and in mRNA for the FSH receptor, estrogen receptor 2 (ER beta), inhibin alpha, activin A receptor type I, and a proliferation (cyclin D2) and two proapoptotic factors (apoptosis regulatory protein Siva, Fas [TNFRSF6]-associated via death domain) in granulosa cells. In contrast, mRNAs for the LH receptor in granulosa cells and for two antiapoptotic factors (TGFB1-induced antiapoptotic factor 1, LAG1 longevity assurance homolog 4 [Saccharomyces cerevisiae]) and one proapoptotic factor (tumor necrosis factor [ligand] superfamily, member 8) were increased in theca cells. We conclude that the bovine DF provides a unique model to identify novel genes potentially involved in survival and apoptosis of follicular cells and, importantly, to determine the FSH-, estradiol-, and LH-target genes regulating its growth and function. Results provide new molecular evidence for the hypothesis that DF experience a reduction in FSH dependence but acquire increased LH dependence as they grow during the low FSH milieu of follicular waves.

Differential expression of mRNAs encoding the putative inhibin co-receptor (betaglycan) and activin type-I and type-II receptors in preovulatory and prehierarchical follicles of the laying hen ovary.

Ovarian follicle development is primarily regulated by an interplay between the pituitary gonadotrophins, LH and FSH, and ovary-derived steroids. Increasing evidence implicates regulatory roles of transforming growth factor-beta (TGFbeta) superfamily members, including inhibins and activins. The aim of this study was to identify the expression of mRNAs encoding key receptors of the inhibin/activin system in ovarian follicles ranging from 4 mm in diameter to the dominant F1 follicle (approximately 40 mm). Ovaries were collected (n = 16) from mid-sequence hens maintained on a long-day photoschedule (16 h of light:8 h of darkness). All follicles removed were dissected into individual granulosa and thecal layers. RNA was extracted and cDNA synthesized. Real-time quantitative PCR was used to quantify the expression of mRNA encoding betaglycan, activin receptor (ActR) subtypes (type-I, -IIA and -IIB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH); receptor expression data were normalized to GAPDH expression. Detectable levels of ActRI, -IIA and -IIB and the inhibin co-receptor (betaglycan) expression were found in all granulosa and thecal layers analysed. Granulosa ActRI mRNA peaked (P < 0.05) in 8-9.9 mm follicles, whereas ActRIIA rose significantly from 6-7.9 mm to 8-9.9 mm, before falling to F3/2; levels then rose sharply (3-fold) to F1 levels. Granulosa betaglycan mRNA expression rose 3-fold from 4-5.9 mm to 8-9.9 mm, before falling 4-fold to F3/2; levels then rose sharply (4-fold) to F1 levels. ActRIIB levels did not vary significantly during follicular development. Thecal ActRI mRNA expression was similar from 4-7.9 mm then decreased significantly to a nadir at the F4 position, before increasing 2-fold to the F1 (P < 0.05). Although thecal ActRIIB and -IIA expression did not vary significantly from 4 mm to F3, ActRIIB expression increased significantly (2-fold) from F3 to F1 and ActRIIA increased 2-fold from F2 to F1 (P < 0.05). Thecal betaglycan fell to a nadir at F6 after follicle selection; levels then increased significantly to F2, before falling approximately 50% in the F1. In all follicles studied expression of betaglycan and ActRI (granulosa: r = 0.65, P < 0.001, n = 144/group; theca: r = 0.49, P < 0.001, n = 144/group) was well correlated. No significant correlations were identified between betaglycan and ActRIIA or -IIB. Considering all follicles analysed, granulosa mRNA expression of betaglycan, ActRI, ActRIIA and ActRIIB were all significantly lower than in corresponding thecal tissue (betaglycan, 11.4-fold; ActRIIB, 5.1-fold; ActRI, 3.8-fold; ActRIIA, 2.8-fold). The co-localization of type-I and -II activin receptors and betaglycan on granulosa and thecal cells are consistent with a local auto/paracrine role of inhibins and activins in modulating ovarian follicle development, selection and progression in the domestic fowl.

Ovarian dysfunction in peripubertal hyperinsulinemia.

OBJECTIVE: Increasing evidence suggests that hyperinsulinemia plays an important role in the pathogenesis of polycystic ovary syndrome (PCOS). However, the timing for the onset of hyperinsulinemia is not clear. The objective of this study was to examine the effect of peripubertal hyperinsulinemia on the maturing female reproductive axis. METHODS: Hyperinsulinemia was induced in 28-day-old peripubertal female rats by infusing insulin (0.04 IU/d) via subcutaneously implanted Alzet minipumps (Model #2004; Durect Corp, Cupertino, CA; constant flow rate 0.25 muL/h) for 4 weeks. Control animals were administered normal saline. Estrus cyclicity was monitored regularly. Upon termination of the experimental period, the animals were killed, trunk blood and pituitaries were collected for hormone assays, and ovaries were collected for histological and immunocytochemical studies. RESULTS: In contrast to the control animals, hyperinsulinemic animals had (1) erratic estrus cycles, with prolonged (2 to 3 days) metestrus-diestrus or diestrus-proestrus stages; (2) significantly (P <.05) decreased levels of serum progesterone, and significantly (P <.05) increased levels of serum testosterone and dehydroepiandrostene sulfate; (3) prematurely luteinized ovarian follicles with prominent thecal and interfollicular stromal proliferation; and (4) markedly reduced expression of growth differentiation factor-9 (GDF-9) and activin receptors (ActR) I and IB in the ovaries. CONCLUSION: Peripubertal hyperinsulinemia in rats causes hormonal and ovarian changes similar to those in women with PCOS. Based on these novel findings, we speculate that peripubertal hyperinsulinemia may be a risk factor for the development of PCOS later in life.

Proteomic identification of activin receptor-like kinase-1 as a differentially expressed protein during hyaloid vascular system regression.

The hyaloid vascular system (HVS) is a transient network of capillaries that nourishes the embryonic lens and the primary vitreous of the developing eye. We used proteomic analysis and immunohistochemical staining to identify activin receptor-like kinase-1 (ALK1), a type I receptor for transforming growth factor-beta1, during the HVS regression phase. In addition, we overexpressed ALK1 in corneas implanted with bFGF (basic fibroblast growth factor) pellets and observed that ALK1 overexpression resulted in inhibition of bFGF-induced corneal neovascularization in vivo. Our data suggest that ALK1 may play a role in HVS regression during ocular development.

Stromal remodeling and SPARC (secreted protein acid rich in cysteine) expression in invasive ductal carcinomas of the breast.

In the present study, we analyzed tumor associated stromal remodeling with special respect to SPARC (secreted protein acid rich in cysteine) expression. 25 invasive ductal carcinomas of the breast and corresponding tumor-free breast tissue were studied immunohistochemically (CD34, alpha-SMA, SPARC and TGFbeta-R1). Tumor associated stroma was characterized by a loss of CD34 expression, paralleled by a gain in alpha-SMA. While SPARC expression was virtually absent from normal stromal cells in the tumor stroma, strong cytoplasmic SPARC reactivity was found in the majority of stromal cells. The TGFbeta-R1 also showed stronger expression in the tumor stroma compared to that of the normal breast. Stromal response to antecedent core needle biopsy was similar to that observed in the tumor stroma. We conclude that SPARC overexpression is a constant and functionally important feature of invasive ductal carcinomas, since SPARC mediates stromal de-adhesion crucial for local tumor invasion and systemic spread, respectively. When considering changes of the stromal phenotype (normal: CD34+alpha-SMA-SPARC- vs. carcinoma: CD34-alpha-SMA+SPARC+) as a tool in distinguishing benign from malignant breast lesion one has to keep in mind that the phenotype of granulation tissue in areas of antecedent biopsy resembles that of tumor stroma.

The expression of matrix metalloproteinases-9, transforming growth factor-beta1 and transforming growth factor-beta receptor I in human atherosclerotic plaque and their relationship with plaque stability.

BACKGROUND: Transforming growth factor-beta (TGF-beta) and matrix metalloproteinases-9 (MMP-9) have been implicated in the pathogenesis of human atherosclerosis but their relationship during lesion progression are poorly understood. The objective of this study was to investigate the expression of MMP-9, TGF-beta1 and TGF-beta receptor I (TbetaR-I) in human atherosclerotic plaque and their relationship and plaque stability. METHODS: Specimens of human coronary artery atherosclerotic plaques were obtained from 41 patients undergoing coronary endarterectomy, and were paraffin embedded, sectioned at 4 microm intervals then stained with haematoxylin and eosin. They were divided into stable (with no or only little lipid core) and unstable plaque groups (with lipid core size > 40%): the immunohistochemical staining were performed for MMP-9, TGF-beta1 and TbetaR-I. RESULTS: The expression of MMP-9 in the unstable plaques was much higher than in the stable ones, but the expression of TGF-beta1 was higher in the stable plaques. There was no similar significant difference for TbetaR-I. Correlation analysis showed that there was a negative correlation between the expression of MMP-9 and TGF-beta1 (r = -0.332, P = 0.034 for average areal density; r = -0.373, P = 0.016 for average optical density). CONCLUSIONS: There were close relationships between MMP-9, TGF-beta1 and plaque stability. Enhanced production of MMP-9 may participate in the formation of unstable plaque, while TGF-beta1 maybe an important stabilizing factor in preventing transition into an unstable plaque phenotype.

[Effect of helicobacter pylori on gastric mucosal cell proliferation in gastritis].

OBJECTIVE: To study the effect of helicobacter pylori on gastric mucosal cell proliferation in gastritis. METHODS: Fifty-six gastritis patients with or without Helicobacter pylori infection (Hp+ 27; Hp- 29) were selected. The expression of proliferation cell nuclear antigen (PCNA), epidermal growth factor receptor (EGFR), transforming growth factor beta receptor type I and type II(TGFbetaRI, TGFbetaRII) in gastric mucosa were examined by immunohistochemical method. RESULTS: The PCNA and EGFR were significantly higher in Hp positive chronic gastritis patients than in Hp negative ones(P<0.05); The TGFbetaRI(P=0.16) and TGFbetaRII(P=0.97) were lower. CONCLUSION: Hp infection promotes over proliferation of gastric mucosal cells.

In situ expression of connective tissue growth factor in human crescentic glomerulonephritis.

Connective tissue growth factor (CTGF) has recently been recognized as an important profibrotic factor and is up-regulated in various renal diseases with fibrosis. The present study describes the sequential localization of CTGF mRNA and its association with transforming growth factor (TGF)-beta1 in human crescentic glomerulonephritis (CRGN). Furthermore, we examined the phenotype of CTGF-expressing cells using serial section analysis. Kidney biopsy specimens from 18 CRGN patients were examined using in situ hybridization and immunohistochemistry. CTGF mRNA was expressed in the podocytes and parietal epithelial cells (PECs) in unaffected glomeruli. In addition, it was strongly expressed in the cellular and fibrocellular crescents, particularly in pseudotubule structures. Serial sections revealed that the majority of CTGF mRNA-positive cells in the crescents co-expressed the epithelial marker cytokeratin, but not a marker for macrophages. Moreover, TGF-beta1, its receptor TGF-beta receptor-I, and extracellular matrix molecules (collagen type I and fibronectin) were co-localized with CTGF mRNA-positive crescents. Our results suggest that CTGF is involved in extracellular matrix production in PECs and that it is one of the mediators promoting the scarring process in glomerular crescents.

Immunolocalization of Alk8 during replacement tooth development in zebrafish.

The novel type I transforming growth factor-beta (TGF-beta) family member receptor Alk8 was previously identified in a degenerate RT-PCR screen for zebrafish type I and II TGF-beta family member receptors. Functional analyses revealed that Alk8 acts through Bmp signaling pathways in early embryonic dorsoventral patterning, in neural crest cell specification, and in patterning and differentiation of neural crest cell-derived pharyngeal arch cartilages. In addition, Alk8 forms active signaling complexes with TGF-beta1 and the TGF-beta RII receptor, suggesting that Alk8 mediates cross talk between Bmp and TGF-beta subfamily members. In this study, immunohistochemical analysis was performed on zebrafish aged 2 days postfertilization to 1 year, revealing immunolocalization of Alk8 to tissues of the tooth-bearing ceratobranchial 5 (cb5) arch including dental epithelial and mesenchymal tooth tissues of developing primary and replacement teeth, mucous-producing crypt epithelium, keratinized bite plate, and developing taste buds. These results suggest roles for Alk8 in patterning tooth-bearing pharyngeal epithelium, in the initiation of tooth development, in odontoblast and ameloblast differentiation, and in osteoblast maturation. The ability for zebrafish to continuously form teeth throughout their lives allows for the comparison of Alk8 expression in both primary and replacement tooth development, revealing identical Alk8 expression profiles. This study advances our current understanding of the functions of Alk8, particularly with respect to primary and replacement tooth formation, reveals additional roles for Alk8 in dental epithelial patterning and in odontoblast, ameloblast and osteoblast differentiation, and demonstrates the utility of the zebrafish as a model for primary and replacement tooth development.

Molecular and functional analysis identifies ALK-1 as the predominant cause of pulmonary hypertension related to hereditary haemorrhagic telangiectasia.

BACKGROUND: Mutations of the transforming growth factor beta (TGFbeta) receptor components ENDOGLIN and ALK-1 cause the autosomal dominant vascular disorder hereditary haemorrhagic telangiectasia (HHT). Heterozygous mutations of the type II receptor BMPR2 underlie familial primary pulmonary hypertension. OBJECTIVE: To investigate kindreds presenting with both pulmonary hypertension and HHT. METHODS: Probands and families were identified by specialist pulmonary hypertension centres in five countries. DNA sequence analysis of ALK-1, ENDOGLIN, and BMPR2 was undertaken. Cellular localisation was investigated by heterologous overexpression of mutant constructs in both BAEC and HeLa cells. The impact of a novel sequence variant was assessed through comparative analysis and computer modelling. RESULTS: Molecular analysis of 11 probands identified eight missense mutations of ALK-1, one of which was observed in two families. Mutations were located within exons 5 to 10 of the ALK-1 gene. The majority of ALK-1 mutant constructs appeared to be retained within the cell cytoplasm, in the endoplasmic reticulum. A novel GS domain mutation, when overexpressed, reached the cell surface but is predicted to disrupt conformational changes owing to loss of a critical hydrogen bond. Two novel missense mutations were identified in ENDOGLIN. CONCLUSIONS: The association of pulmonary arterial hypertension and HHT identifies an important disease complication and appears most common among subjects with defects in ALK-1 receptor signalling. Future studies should focus on detailed molecular analysis of the common cellular pathways disrupted by mutations of ALK-1 and BMPR2 that cause inherited pulmonary vascular disease.

[Effects of transforming growth factor beta1 on the proliferation and type I collagen expression at different differential rat hepatic stellate cells].

OBJECTIVES: To investigate the biological responses of cultured hepatic stellate cells (HSC) at different differentiated stages on exotic transforming growth factor (TGF-beta1). METHODS: HSC was isolated from rat and primarily cultured in uncoated disc for 1 d, 4 d and 7 d, when the cells were at quiescent, intermediate activated and full activated stages respectively. The cells were incubated with 10 pmol/L to 500 pmol/L TGF-beta1 for 24 h, cell proliferation was measured with [3H] TdR incorporation, alpha-smooth muscle actin (alpha-SMA) and type I collagen protein were assayed with Western blot, and total protein secretion in the culture supernatant was analyzed by [3H] proline pulse and collagenase digestion. HSC was treated with 100 pmol/L TGF- beta1 for 15 min to 90 min, and type I pro-collagen mRNA level was assayed by Northern blot. RESULTS: TGF-beta1 remarkably inhibited d1 HSC proliferation, the percentage of [3H] TdR incorporation at 10 pmol/L to 500 pmol/L TGF-beta1 was 52.8% to 16.8% of the control, q value was 5.44 to 10.37 and P<0.01 vs control. But TGF-beta1 had no influence on d4 and d7 HSC. As the cells cultivation prolonged and activated, the basal levels of alpha-SMA, type I collagen and gene expression increased gradually. TGF-beta1 increased the above protein and gene expression. The basal and TGF-beta1 stimulated total protein secretion levels at d1-d7 HSC were 804+/-274 vs 1200+/-708; 2966+/-1701 vs 6160+/-1123, t=3.84, P<0.01; 2580+/-767 vs 4583+/-1467, t=2.96, P<0.05. While d4 HSC showed the strongest response of total protein secretion and alpha-SMA expression. CONCLUSIONS: TGF-beta1 remarkably inhibited quiescent HSC proliferation, and promoted HSC collagen production at both quiescent and activated HSC. Intermediate HSC had the strongest response to TGF-beta1, while activated HSC lost the response to TGF-beta1 inhibitory growth, and TGF-beta1 exerted divergent actions on HSC as the cells activated.

Activin A is an autocrine activator of rat pancreatic stellate cells: potential therapeutic role of follistatin for pancreatic fibrosis.

BACKGROUND AND AIM: The present study was conducted to examine the effect of activin A on activation of rat pancreatic stellate cells (PSCs). METHODS: PSCs were prepared from rat pancreas using collagenase digestion and centrifugation with Nycodenz gradient. Activation of PSCs was examined by determining smooth muscle actin expression with western blotting. The presence of activin A receptors in PSCs was investigated by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunocytochemistry. Expression of activin A and transforming growth factor beta (TGF-beta) mRNA was examined by RT-PCR. Activin A and TGF-beta peptide concentrations were examined with ELISA. Existence of activin A peptide in PSCs was investigated by immunocytochemistry. Collagen secretion was determined by Sirius red dye binding. RESULTS: Activin A receptors I and IIa were present in PSCs. PSCs expressed activin A mRNA and secreted activin A. Activin A enhanced PSC activation and collagen secretion in a dose dependent manner. TGF-beta and activin A increased each other's secretion and mRNA expression of PSCs. Follistatin decreased TGF-beta mRNA expression and TGF-beta secretion of PSCs, and inhibited both PSC activation and collagen secretion. CONCLUSION: Activin A is an autocrine activator of PSCs. Follistatin can inhibit PSC activation and collagen secretion by blocking autocrined activin A and decreasing TGF-beta expression and secretion of PSCs.