Transforming growth factor-Β1 deficiency in b cells decrease atherosclerosis in ApoE-/- mice

In addition to many important roles for Cdk5 in brain development and synaptic function, we reported previously that Cdk5 regulates inflammatory pain signaling, partly through phosphorylation of transient receptor potential vanilloid 1 (TRPV1), an important Na(+)/Ca(2+) channel expressed in primary nociceptive afferent nerves. Because TGF-β regulates inflammatory processes and its receptor is expressed in TRPV1-positive afferents, we studied the cross-talk between these two pathways in sensory neurons during experimental peripheral inflammation. We demonstrate that TGF-β1 increases transcription and protein levels of the Cdk5 co-activator p35 through ERK1/2, resulting in an increase in Cdk5 activity in rat B104 neuroblastoma cells. Additionally, TGF-β1 enhances the capsaicin-induced Ca(2+) influx in cultured primary neurons from dorsal root ganglia (DRG). Importantly, Cdk5 activity was reduced in the trigeminal ganglia and DRG of 14-day-old TGF-β1 knock-out mice, resulting in reduced Cdk5-dependent phosphorylation of TRPV1. The decreased Cdk5 activity is associated with attenuated thermal hyperalgesia in TGF-β1 receptor conditional knock-out mice, where TGF-β signaling is significantly reduced in trigeminal ganglia and DRG. Collectively, our results indicate that active cross-talk between the TGF-β and Cdk5 pathways contributes to inflammatory pain signaling.

Transforming growth factor beta (TGF-beta) and related growth factors are essential regulators of embryogenesis and tissue homeostasis. The signaling pathways mediated by their receptors and Smad proteins are precisely modulated by various means. Xenopus BAMBI (bone morphogenic protein (BMP) and activin membrane-bound inhibitor) has been shown to function as a general negative regulator of TGF-beta/BMP/activin signaling. Here, we provide evidence that human BAMBI (hBAMBI), like its Xenopus homolog, inhibits TGF-beta- and BMP-mediated transcriptional responses as well as TGF-beta-induced R-Smad phosphorylation and cell growth arrest, whereas knockdown of endogenous BAMBI enhances the TGF-beta-induced reporter expression. Mechanistically, in addition to interfering with the complex formation between the type I and type II receptors, hBAMBI cooperates with Smad7 to inhibit TGF-beta signaling. hBAMBI forms a ternary complex with Smad7 and the TGF-beta type I receptor ALK5/TbetaRI and inhibits the interaction between ALK5/TbetaRI and Smad3, thus impairing Smad3 activation. These findings provide a novel insight to understand the molecular mechanism underlying the inhibitory effect of BAMBI on TGF-beta signaling.

Background:Wnt and transforming growth factor-β (TGF-β) signaling pathways are known to be involved in the pathogenesis of androgenetic alopecia (AGA). However, the way that Wnt and TGF-β signaling is altered in patients with AGA and whether there exists a crosstalk between them in pathogenetic process of AGA remain unclear.Objectives:To investigate the expression of Wnt and TGF-β signaling and the crosstalk between these 2 signaling pathways in AGA.Methods:Fifteen male patients with AGA were recruited for our research. Fifteen scalp specimens of the balding were collected from frontal areas, and 9 nonbalding were collected from occipital areas. We analyzed the expression and activation of downstream Wnt and TGF-β signaling molecules in both balding and nonbalding hair follicles isolated from scalp specimens. Furthermore, we evaluated the activation of Wnt and TGF-β signaling after either of them was blocked with the inhibitor in balding and nonbalding dermal papilla (DP) cells.Results:Compared with the nonbalding counterparts, the mRNA level of Wnt10a and LEF1 was decreased. But TβRI and TβRII, and the protein expression of TGF-β1 was elevated in balding hair follicles. To investigate the crosstalk between Wnt and TGF-β signaling, we used SB431542 to inhibit the TGF-β signaling in balding DP cells and found that SB431542 significantly attenuated the phosphorylation of Smad2 and Akt. However, the mRNA level of Wnt10a, LEF1, and the nuclear translocation of β-catenin was increased. On the other hand, we suppressed the Wnt signaling by XAV939 in nonbalding DP cells, which displayed that the level of β-catenin and LEF1 was significantly inhibited; however, the level of active TGF-β1 and the phosphorylation of Smad2 and Akt were up-regulated.Conclusions:These data indicate that crosstalk between Wnt/β-catenin and TGF-β signaling pathways may exist as one of the important mechanisms contributing to AGA.

The G protein-coupled receptor proteinase-activated receptor 2 (PAR2) has been implicated in various aspects of cellular physiology including inflammation, obesity and cancer. In cancer, it usually acts as a driver of cancer progression in various tumor types by promoting invasion and metastasis in response to activation by serine proteinases. Recently, we discovered another mode through which PAR2 may enhance tumorigenesis: crosstalk with transforming growth factor-β (TGF-β) signaling to promote TGF-β1-induced cell migration/invasion and invasion-associated gene expression in ductal pancreatic adenocarcinoma (PDAC) cells. In this chapter, we review what is known about the cellular TGF-β responses and signaling pathways affected by PAR2 expression, the signaling activities of PAR2 required for promoting TGF-β signaling, and the potential molecular mechanism(s) that underlie(s) the TGF-β signaling–promoting effect. Since PAR2 is activated through various serine proteinases and biased agonists, it may couple TGF-β signaling to a diverse range of other physiological processes that may or may not predispose cells to cancer development such as local inflammation, systemic coagulation and pathogen infection.

Transforming growth factor-β (TGF-β) signaling pathway serves a pivotal role in the pathogenesis of colorectal cancer (CRC). However, the specific molecular mechanisms by which the TGF-β signaling pathway regulates CRC are still not fully understood. In the present study, metabolomics and transcriptomics were used to screen for key metabolites and regulatory genes most related to the regulation of the TGF-β signaling pathway in CRC. Additionally, reverse transcription-quantitative PCR, western blotting and Transwell assays were performed to assess the process of epithelial-mesenchymal transition (EMT). Metabolomics analysis indicated that TGF-β1 has an impact on purine metabolism, leading to an increase in the purine metabolite inosine. The increase of inosine is essential for facilitating EMT and cell migration in CRC cells. Furthermore, the integrated analysis of metabolomics and transcriptomics data revealed that TGF-β1 induces the expression of laccase domain-containing 1 (LACC1), an enzyme involved in the regulation of inosine. Knockdown of LACC1 resulted in a reduction of TGF-β1-induced alterations in inosine levels, EMT and cell migration in CRC cells. The results of the present study suggest that the TGF-β signaling pathway is involved in the regulation of purine metabolism in CRC through the modulation of LACC1 expression. Furthermore, LACC1 appears to influence EMT and cell migration by elevating the levels of the purine metabolite inosine.

To explore the molecular connections between redox-dependent apoptosis signal-regulating kinase 1 (ASK1) and transforming growth factor-β (TGF-β) signaling pathways and to examine the physiological processes in which coordinated regulation of these two signaling pathways plays a critical role. We provide evidence that the ASK1 and TGF-β signaling pathways are interconnected by a multiprotein complex harboring murine protein serine-threonine kinase 38 (MPK38), ASK1, Sma- and Mad-related proteins (SMADs), zinc-finger-like protein 9 (ZPR9), and thioredoxin (TRX) and demonstrate that the activation of either ASK1 or TGF-β activity is sufficient to activate both the redox-dependent ASK1 and TGF-β signaling pathways. Physiologically, the restoration of the downregulated activation levels of ASK1 and TGF-β signaling in genetically and diet-induced obese mice by adenoviral delivery of SMAD3 or ZPR9 results in the amelioration of adiposity, hyperglycemia, hyperlipidemia, and impaired ketogenesis. Our data suggest that the multiprotein complex linking ASK1 and TGF-β signaling pathways may be a potential target for redox-mediated metabolic complications.

The transforming growth factor-β (TGF-β) signaling plays a critical role in the development and tissue homeostasis in metazoans, and deregulation of TGF-β signaling leads to many pathological conditions. Mounting evidence suggests that TGF-β signaling can actively alter metabolism in diverse cell types. Furthermore, metabolic pathways, beyond simply regarded as biochemical reactions, are closely intertwined with signal transduction. Here, we discuss the role of TGF-β in glucose, lipid, amino acid, redox and polyamine metabolism with an emphasis on how TGF-β can act as a metabolic modulator and how metabolic changes can influence TGF-β signaling. We also describe how interplay between TGF-β signaling and cell metabolism regulates cellular homeostasis as well as the progression of multiple diseases, including cancer.

BackgroundNicotinamide phosphoribosyltransferase (NAMPT) and the transforming growth factor-β (TGF-β) signaling pathway play important roles in colorectal tumorigenesis and progress. However, the underlying regulatory mechanisms between NAMPT and TGF-β signaling in colorectal cancer (CRC) remain poorly understood.MethodsPublic data were extracted from the Oncomine database and the PrognoScan database to investigate the mRNA expression and the prognostic value of NAMPT, respectively, in CRC. Western blot tests were performed to detect Smad2, Smad3, p-Smad2, p-Smad3, Smad4 expression in CRC cells transfected with human NAMPT-siRNA or NAMPT-overexpressing plasmid. TGF-β1 concentrations in culture supernatants were assayed using ELISA kits. The effect of TGF-β1 on NAMPT expression was evaluated by quantitative real-time PCR and Western blot. The dual-luciferase reporter assay was employed to confirm the binding of miR-1-3p to NAMPT 3ʹ-UTR. Subsequently, NAMPT levels in HCT116 cells transfected with the mimics and inhibitors of miR-1-3p were detected by quantitative real-time PCR and Western blot.ResultsNAMPT was overexpressed in human CRC and was correlated with short overall survival. NAMPT increased the protein expression levels of components in the TGF-β signaling pathway including Smad2, Smad3, and Smad4. Moreover, NAMPT promoted TGF-β1 secretion. Intriguingly, the TGF-β1 treatment down-regulated NAMPT expression at mRNA and protein levels in CRC cells which were partly through the up-regulation of miR-1-3p that directly bound to the NAMPT 3ʹ-UTR. These outcomes demonstrated that NAMPT was a downstream target of miR-1-3p and there was a negative association between NAMPT and miR-1-3p in CRC.ConclusionThere is a negative feedback loop between NAMPT and the TGF-β signaling pathway in CRC cells, providing new insight into the mechanism underlying the regulatory pathways in CRC.

On and off: proteasome and TGF-β signaling

Purpose: Hypertrophic cardiomyopathy (HCM) is considered one of the most common genetic heart disorders with a prevalence of about 1 in 500 people, with 35% of those affected being attributed to mutations within the gene encoding cardiac myosin-binding protein C (cMyBP-C). Cardiac stress, as well as cMyBP-C mutations, can trigger production of a 40kDa truncated fragment derived from the amino terminus of cMyBP-C. Genetic expression of this 40kDa fragment in mouse cardiomyocytes ( Mybp3 40kDa ) leads to HCM, fibrosis and heart failure, mimicking human disease progression. The transforming growth factor-β (TGFβ) signaling pathway has been implicated in a variety of fibrotic processes. The goal of this study is to define the role of TGFβ signaling in distinct cell populations, the cardiomyocyte and fibroblast, in the cMyBP-C HCM/HF model. Methods and results: Masson’s Trichrome staining, PCR arrays, immunohistochemistry and western blots were performed to characterize the fibrotic progression in Mybp3 40kDa transgenic mice. Cardiac fibrosis was initially detected 4 weeks after transgene expression. Extensive interstitial fibrosis and severe atrial fibrosis were detected at 16 weeks. Both canonical and non-canonical TGFβ pathways were active during fibrotic progression. To specifically block TGFβ signaling in Mybp3 40kDa transgenic mice, compound mutant mice were generated, in which the tgfbr1 or tgfbr2 alleles were ablated, either in cardiomyocytes or in activated fibroblasts (myofibroblasts) by αMHC-Cre or Periostin-MerCreMer-Cre respectively. Blockage of TGFβ signaling in either cardiomyocytes or myofibroblasts alleviated cardiac fibrosis. Furthermore, treatment with the non-canonical TGFβ signaling inhibitor MMI-0100 also alleviated cardiac fibrosis and increased the life span of the Mybp3 40kDa transgenic mice. Conclusions: TGFβ signaling is activated in the Mybp3 40kD HCM/HF model. Genetic or pharmaceutical inhibition of TGFβ signaling inhibited fibrosis and increased the life span in this model.

The Notch and transforming growth factor-β (TGF-β) signaling pathways play critical roles in the control of cell fate during metazoan development. However, mechanisms of cross-talk and signal integration between the two systems are unknown. Here, we demonstrate a functional synergism between Notch and TGF-β signaling in the regulation of Hes-1, a direct target of the Notch pathway. Activation of TGF-β signaling up-regulated Hes-1 expression in vitro and in vivo. This effect was abrogated in myogenic cells by a dominant-negative form of CSL, an essential DNA-binding component of the Notch pathway. TGF-β regulated transcription from the Hes-1 promoter in a Notch-dependent manner, and the intracellular domain of Notch1 (NICD) cooperated synergistically with Smad3, an intracellular transducer of TGF-β signals, to induce the activation of synthetic promoters containing multimerized CSL- or Smad3-binding sites. NICD and Smad3 were shown to interact directly, both in vitro and in cells, in a ligand-dependent manner, and Smad3 could be recruited to CSL-binding sites on DNA in the presence of CSL and NICD. These findings indicate that Notch and TGF-β signals are integrated by direct protein–protein interactions between the signal-transducing intracellular elements from both pathways.

Physical cues, such as extracellular matrix stiffness, direct cell differentiation and support tissue-specific function. Perturbation of these cues underlies diverse pathologies, including osteoarthritis, cardiovascular disease and cancer. However, the molecular mechanisms that establish tissue-specific material properties and link them to healthy tissue function are unknown. We show that Runx2, a key lineage-specific transcription factor, regulates the material properties of bone matrix through the same transforming growth factor-β (TGFβ)-responsive pathway that controls osteoblast differentiation. Deregulated TGFβ or Runx2 function compromises the distinctly hard cochlear bone matrix and causes hearing loss, as seen in human cleidocranial dysplasia. In Runx2+/⁻ mice, inhibition of TGFβ signalling rescues both the material properties of the defective matrix, and hearing. This study elucidates the unknown cause of hearing loss in cleidocranial dysplasia, and demonstrates that a molecular pathway controlling cell differentiation also defines material properties of extracellular matrix. Furthermore, our results suggest that the careful regulation of these properties is essential for healthy tissue function.

Cholangiocyte Endothelin 1 and Transforming Growth Factor β1 Production in Rat Experimental Hepatopulmonary Syndrome

Mesenchymal-cell proliferation is the main process in shelf outgrowth. Both all-trans-retinoic acid (atRA) and transforming growth factor-β3 (TGF-β3) play an important role in mouse embryonic palate mesenchymal (MEPM) cell proliferation. In the present study, we investigated the crosstalk between RA and TGF-β signaling in MEPM-cell proliferation. We found that atRA inhibited MEPM-cell proliferation by downregulating TGF-β/Smad signaling and that TGF-β3 treatment was able to antagonize RA signaling. Transforming growth-interacting factor (TGIF) is a transcriptional repressor that suppresses both TGF-β- and retinoid-driven gene transcription. Furthermore, we investigated the role of TGIF in the interaction between both TGF-β and RA signaling in MEPM-cell proliferation. The results showed that both atRA and TGF-β3 significantly increased the expression level of TGIF, and TGIF mediated the negative interaction between TGF-β and RA signaling pathways, which depended on TGIF binding to Smad2 or RARβ (RA receptor beta). Moreover, after deletion of TGIF, both the effects of atRA on TGF-β-dependent protein expression and the effects of TGF-β on RA-dependent protein expression were lost. So we conclude that there is a negative functional interplay of RA and TGF-β signaling mediated by TGIF to modulate MEPM-cell proliferation.

Gli1 activation and protection against hepatic encephalopathy is suppressed by circulating transforming growth factor β1 in mice