The node and the anterior visceral endoderm (AVE) are important organizing centers that pattern the mouse embryo by establishing the anterior-posterior (A-P), dorsal-ventral (D-V), and left-right (L-R) axes. Activin/nodal signaling through the Smad2 pathway has been implicated in AVE formation and in morphogenesis of the primitive streak, the anterior end of which gives rise to the node. The forkhead DNA-binding protein, FoxH1 (or Fast), functions as a Smad DNA-binding partner to regulate transcription in response to activin signaling.
View Article and Find Full Text PDFTarget controlled infusion systems have been developed to provide improved convenience and control during intravenous anaesthesia. The anaesthetist sets and adjust the target blood concentration and depth of anaesthesia--as required on clinical grounds. Infusion rates are altered automatically according to a validated pharmacokinetic model.
View Article and Find Full Text PDFUbiquitin-mediated proteolysis regulates the activity of diverse receptor systems. Here, we identify Smurf2, a C2-WW-HECT domain ubiquitin ligase and show that Smurf2 associates constitutively with Smad7. Smurf2 is nuclear, but binding to Smad7 induces export and recruitment to the activated TGF beta receptor, where it causes degradation of receptors and Smad7 via proteasomal and lysosomal pathways.
View Article and Find Full Text PDFNucleic Acids Res
February 2001
An emerging theme in transforming growth factor-ss (TGF-ss) signalling is the association of the Smad proteins with diverse groups of transcriptional regulatory proteins. Several Smad cofactors have been identified to date but the diversity of TGF-ss effects on gene transcription suggests that interactions with other co-regulators must occur. In these studies we addressed the possible interaction of Smad proteins with the myocyte enhancer-binding factor 2 (MEF2) transcriptional regulators.
View Article and Find Full Text PDFThrough the use of two animal models, the present study demonstrates the ability of phosphonylated surfaces to bind bone. In one model, surface-treated polypropylene (PP) and polyethylene (PE) were implanted in the medial cortex of the goat tibia. In the second model, surface-treated poly(ether-ether ketone) (PEEK) and carbon fiber-reinforced PEEK (CFR-PEEK) were implanted through both cortices of the goat mandible.
View Article and Find Full Text PDFSmad proteins are effector molecules that transmit signals from the receptors for the transforming growth factor beta (TGF-beta) superfamily to the nucleus; of the Smad proteins, Smad2 and Smad4 are essential components for mouse early embryogenesis. We demonstrated that Hgs, a FYVE domain protein, binds to Smad2 in its C-terminal half and cooperates with another FYVE domain protein, the Smad anchor for receptor activation (SARA), to stimulate activin receptor-mediated signaling through efficient recruitment of Smad2 to the receptor. Furthermore, a LacZ knock-in allele of the C-terminal half-deletion mutant of mouse Hgs was created by gene targeting.
View Article and Find Full Text PDFActivation of transforming growth factor-beta (TGF-beta) receptors triggers phosphorylation of Smad2 and Smad3. After binding to Smad4, the complex enters the nucleus and interacts with other transcription factors to activate gene transcription. Unlike other Smads, Smad7 inhibits phosphorylation of Smad2 and Smad3, and its transcription is induced by TGF-beta, suggesting a negative feedback loop.
View Article and Find Full Text PDFCardiopulmonary bypass used in open heart surgery is responsible for nearly 15% of adult respiratory distress syndrome. The condition has a high mortality rate and still today we do not have a specific therapy for it. The aim of this study was to reveal the factors that are responsible for the adult respiratory distress syndrome developing after open heart operations.
View Article and Find Full Text PDFThe Smad signalling pathway is critical for transmitting transforming growth factor-beta (TGF-beta) superfamily signals from the cell surface to the nucleus. In the nucleus, Smads regulate transcriptional responses by recruiting co-activators and co-repressors to a wide array of DNA-binding partners. Thus, Smads function as transcriptional co-modulators to regulate TGFbeta-dependent gene expression.
View Article and Find Full Text PDFTransforming growth factor-beta superfamily member signals are conveyed through cell-surface serine/threonine kinase receptors to the intracellular mediators known as Smads. Activation of Smads causes their translocation from the cytoplasm to the nucleus where they function to control gene expression. In this review we will focus on proteins that modulate Smad activity, including SARA, for Smad Anchor for Receptor Activation, which functions during the initiation of signalling and on components of the ubiquitin-proteasome pathway, such as Smurf1, which can negatively regulate Smad signalling.
View Article and Find Full Text PDFThe tumor suppressor gene Smad4 has been proposed to be a common mediator of transforming growth factor beta (TGFbeta)-related signaling pathways. We investigated the role of Smad4 in TGFbeta-related pathways by targeted disruption of its locus in murine cell lines. TGFbeta responses, including growth arrest, induction of the endogenous PAI-1 gene, and other extracellular matrix components, were normal in Smad4-deficient fibroblasts.
View Article and Find Full Text PDFBone morphogenetic protein (BMP)-2 and hepatocyte growth factor (HGF) exert antagonistic effects on renal collecting duct formation during embryogenesis. A current model proposes HGF inhibits BMP-2 signaling at the level of Smad1 in a common target cell. Here, we show that BMP-2 and HGF control collecting duct formation via parallel pathways.
View Article and Find Full Text PDFThe Smad proteins mediate transforming growth factor-beta (TGFbeta) signaling from the transmembrane serine-threonine receptor kinases to the nucleus. The Smad anchor for receptor activation (SARA) recruits Smad2 to the TGFbeta receptors for phosphorylation. The crystal structure of a Smad2 MH2 domain in complex with the Smad-binding domain (SBD) of SARA has been determined at 2.
View Article and Find Full Text PDFProtein kinase A (PKA) regulates morphogenetic responses to bone morphogenetic proteins (BMPs) during embryogenesis. However, the mechanisms by which PKA regulates BMP function are unknown. During kidney development, BMP-2 and high doses of BMP-7 inhibit branching morphogenesis, whereas low doses of BMP-7 are stimulatory (Piscione, T.
View Article and Find Full Text PDFThe TGF-beta superfamily of proteins regulates many different biological processes, including cell growth, differentiation and embryonic pattern formation. TGF-beta-like factors signal across cell membranes through complexes of transmembrane receptors known as type I and type II serine/threonine-kinase receptors, which in turn activate the SMAD signalling pathway. On the inside of the cell membrane, a receptor-regulated class of SMADs are phosphorylated by the type-I-receptor kinase.
View Article and Find Full Text PDFMyocyte enhancer factor 2 (MEF2) transcriptional regulatory proteins are key regulators of muscle-specific gene expression and also play a general role in the cellular response to growth factors, cytokines and environmental stressors. To identify signaling pathway components that might mediate these events, the potential role of MAP kinase and PKC signaling in the modulation of MEF2A phosphorylation and transcriptional activity were therefore studied. In transient transfection reporter assays, activated p38 MAP kinase potently increased MEF2A trans -activating potential, PKC[delta] and [epsiv] isotypes enhanced MEF2A transactivation to a lesser extent, while the ERK1/2 and JNK/SAPK pathways were without effect.
View Article and Find Full Text PDFThe identification of molecules that regulate human hematopoietic stem cells has focused mainly on cytokines, of which very few are known to act directly on stem cells. Recent studies in lower organisms and the mouse have suggested that bone morphogenetic proteins (BMPs) may play a critical role in the specification of hematopoietic tissue from the mesodermal germ layer. Here we report that BMPs regulate the proliferation and differentiation of highly purified primitive human hematopoietic cells from adult and neonatal sources.
View Article and Find Full Text PDFSmads are central mediators of signal transduction for the TGFbeta superfamily. However, the precise functions of Smad-mediated signaling pathways in early development are unclear. Here we demonstrate a requirement for Smad2 signaling in dorsoanterior axis formation during Xenopus development.
View Article and Find Full Text PDFThe authors have studied the possible risk factors and complications of low cardiac output (LCO) following open heart operations. A retrospective analysis of 537 consecutive open heart operations has been performed with regards to the patients past medical and perioperative data. For statistical analysis the authors have applied the Chi-square test, T-probe, Mann-Whitney-test and logistical regression analysis by means of the SPSS software.
View Article and Find Full Text PDFThe TGF-beta superfamily of growth and differentiation factors, including TGF-beta, Activins and bone morphogenetic proteins (BMPs) play critical roles in regulating the development of many organisms. These factors signal through a heteromeric complex of type I and II serine/threonine kinase receptors that phosphorylate members of the Smad family of transcription factors, thereby promoting their nuclear localization. Although components of TGF-beta/Activin signaling pathways are well defined in vertebrates, no such pathway has been clearly defined in invertebrates.
View Article and Find Full Text PDFEndoglin (CD105) is a transmembrane glycoprotein that binds transforming growth factor (TGF)-beta1 and -beta3, and coprecipitates with the Ser/Thr kinase signaling receptor complex by affinity labeling of endothelial and leukemic cells. The present study shows that in addition to TGF-beta1 and -beta3, endoglin interacts with activin-A, bone morphogenetic protein (BMP)-7, and BMP-2 but requires coexpression of the respective ligand binding kinase receptor for this association. Endoglin cannot bind ligands on its own and does not alter binding to the kinase receptors.
View Article and Find Full Text PDFSmads transmit signals from transmembrane ser/thr kinase receptors to the nucleus. We now identify SARA (for Smad anchor for receptor activation), a FYVE domain protein that interacts directly with Smad2 and Smad3. SARA functions to recruit Smad2 to the TGFbeta receptor by controlling the subcellular localization of Smad2 and by interacting with the TGFbeta receptor complex.
View Article and Find Full Text PDF