A nuclear factor 1 binding site mediates the transcriptional activation of a type I collagen promoter by transforming growth factor-beta

Rosemary extract and rosmarinic acid accelerate elastic fiber formation by increasing the expression of elastic fiber components in dermal fibroblasts

Ultraviolet (UV)-induced skin photoaging is caused by qualitative and quantitative degradation of dermal extracellular matrix components such as collagen and elastic fibers. Elastic fibers are important for maintaining cutaneous elasticity, despite their small amount in the skin. Previously, microfibril-associated protein 4 (MFAP-4), which is downregulated in photoaging dermis, has been found to be essential for elastic fiber formation by interaction with both fibrillin-1 and elastin, which are core components of elastic fiber. In addition, enhanced cutaneous MFAP-4 expression in a human skin-xenografted murine photoaging model protects against UV-induced photodamage accompanied by the prevention of elastic fiber degradation and aggravated elasticity. We therefore hypothesized that the upregulation of MFAP-4 in dermal fibroblasts may more efficiently accelerate elastic fiber formation. We screened botanical extracts for MFAP-4 expression-promoting activity in normal human dermal fibroblasts (NHDFs). We found that rosemary extract markedly promotes early microfibril formation and mature elastic fiber formation along with a significant upregulation of not only MFAP-4 but also fibrillin-1 and elastin in NHDFs. Furthermore, rosmarinic acid, which is abundant in rosemary extract, accelerated elastic fiber formation via upregulation of transforming growth factor β-1. This was achieved by the induction of cAMP response element-binding protein phosphorylation, demonstrating that rosmarinic acid represents one of the active ingredients in rosemary extract. Based on the findings in this study, we conclude that rosemary extract and rosmarinic acid represent promising materials that exert a preventive or ameliorative effect on skin photoaging by accelerating elastic fiber formation.

Carbon dioxide-induced decrease in extracellular pH enhances the production of extracellular matrix components by upregulating TGF-β1 expression via CREB activation in human dermal fibroblasts

Mild acidification caused by transcutaneous administration of carbon dioxide (CO2 ) has been reported to improve some epidermal skin impairments, such as desquamation and inflammation; however, its effects on dermal tissue remain unclear. Here, we examined the effect and mechanism of mild acidity on extracellular matrix (ECM) protein production in normal human dermal fibroblasts (NHDFs). To achieve this, the skin permeability of CO2 and its effect on intradermal pH were evaluated by treating reconstructed human skin equivalents (HSEs) with a CO2 -containing formulation. Additionally, NHDFs were cultured in a pH-adjusted medium (pH 6.5). CO2 successfully permeated HSEs and reduced the intradermal pH. Decreased extracellular pH activated CREB, upregulated TGF-β1 expression, promoted the production of elastic and collagen fibres, and increased hyaluronan concentration in NHDFs. Additionally, the low pH-induced increase in TGF-β1 expression was attenuated via the RNAi-mediated suppression of the expression of CREB1 and proton-sensing G protein-coupled receptors (GPCRs), including GPR4 and GPR65. Moreover, low pH-induced CREB activation was suppressed by the inhibition of the cAMP/PKA and PLC/PKC signalling pathways. Taken together, a CO2 -induced decrease in intradermal pH may promote ECM production in NHDFs via the upregulation of TGF-β1 expression, which was mediated by the activation of the GPCR signalling pathway and CREB, indicating that CO2 could be used to treat ultraviolet radiation-induced photoaging, intrinsic ageing and ECM deterioration.

Cyclopamine targeting hedgehog modulates nuclear control of the osteoblast activity

It is known that cellular events underlying the processes of bone maintenance, remodeling, and repair have their basis in the embryonic production of bone. Shh signaling is widely described developing important morphogenetic control in bone by modifying the activity of osteoblast. Furthermore, identifying whether it is associated with the modulation of nuclear control is very important to be the basis for further applications. Experimentally, osteoblasts were exposed with cyclopamine (CICLOP) considering up to 1 day and 7 days, here considered an acute and chronic responses respectively. Firstly, we have validated the osteogenic model in vitro by exposing the osteoblasts to classical differentiating solution up to 7 days to allow the analysis of alkaline phosphatase and mineralization. Conversely, our data shows that differentiating osteoblasts present higher activity of inflammasome-related genes, while Shh signaling members were lower, suggesting a negative feedback between them. Thereafter, to better know about the role of Shh signaling on this manner, functional assays using CICLOP (5 μM) were performed and the data validates the previously hypothesis that Shh represses inflammasome related genes activities. Altogether, our data supports the anti-inflammatory effect of Shh signaling by suppressing Tnfα, Tgfβ and inflammasome related genes during osteoblast differentiation, and this comprehension might support the understanding the molecular and cellular mechanisms related in bone regeneration by reporting molecular-related osteoblast differentiation.

Gene Regulation during Carapacial Ridge Development of Mauremys reevesii: The Development of Carapacial Ridge, Ribs and Scutes

The unique topological structure of a turtle shell, including the special ribs-scapula relationship, is an evolutionarily novelty of amniotes. The carapacial ridge is a key embryonic tissue for inducing turtle carapace morphologenesis. However, the gene expression profiles and molecular regulatory mechanisms that occur during carapacial ridge development, including the regulation mechanism of rib axis arrest, the development mechanism of the carapacial ridge, and the differentiation between soft-shell turtles and hard-shell turtles, are not fully understood. In this study, we obtained genome-wide gene expression profiles during the carapacial ridge development of Mauremys reevesii using RNA-sequencing by using carapacial ridge tissues from stage 14, 15 and 16 turtle embryos. In addition, a differentially expressed genes (DEGs) analysis and a gene set enrichment analysis (GSEA) of three comparison groups were performed. Furthermore, a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was used to analyze the pathway enrichment of the differentially expressed genes of the three comparative groups. The result displayed that the Wnt signaling pathway was substantially enriched in the CrTK14 vs. the CrTK15 comparison group, while the Hedgehog signaling pathway was significantly enriched in the CrTK15 vs. the CrTK16 group. Moreover, the regulatory network of the Wnt signaling pathway showed that Wnt signaling pathways might interact with Fgfs, Bmps, and Shh to form a regulatory network to regulate the carapacial ridge development. Next, WGCNA was used to cluster and analyze the expression genes during the carapacial ridge development of M. reevesii and P. sinensis. Further, a KEGG functional enrichment analysis of the carapacial ridge correlation gene modules was performed. Interesting, these results indicated that the Wnt signaling pathway and the MAPK signaling pathway were significantly enriched in the gene modules that were highly correlated with the stage 14 and stage 15 carapacial ridge samples of the two species. The Hedgehog signaling pathway was significantly enriched in the modules that were strongly correlated with the stage 16 carapacial ridge samples of M. reevesii, however, the PI3K-Akt signaling and the TGF-β signaling pathways were significantly enriched in the modules that were strongly correlated with the stage 16 carapacial ridge samples of P. sinensis. Furthermore, we found that those modules that were strongly correlated with the stage 14 carapacial ridge samples of M. reevesii and P. sinensis contained Wnts and Lef1. While the navajo white 3 module which was strongly correlated with the stage 16 carapacial ridge samples of M. reevesii contained Shh and Ptchs. The dark green module strongly correlated with the stage 16 carapacial ridge samples of P. sinensis which contained Col1a1, Col1a2, and Itga8. Consequently, this study systematically revealed the signaling pathways and genes that regulate the carapacial ridge development of M. reevesii and P. sinensis, which provides new insights for revealing the molecular mechanism that is underlying the turtle's body structure.

TGF-β1 upregulates Sar1a expression and induces procollagen-I secretion in hypertrophic scarring fibroblasts

Hypertrophic scarring (HTS) is a common fibroproliferative disorder that typically follows thermal and other injuries involving the deep dermis. The underlying pathogenic mechanisms are regulated by transforming growth factor-β (TGF-β); however, the exact mechanisms in HTS have not been elucidated. We conducted this study to explore the cellular signaling mechanisms for expression of Sar1a, a coat protein complex II-associated small GTPase, in HTS fibroblasts (HTSF). We found that Sar1a was upregulated in HTSF as compared to that in normal fibroblasts. Furthermore, stimulation of TGF-β1 increased the expression of Sar1a in HTSF, and small interfering RNA for Sar1a suppressed procollagen-I (PC-I) secretion. Next we investigated the signaling mechanism from TGF-β1 to Sar1a expression and its association with PC-I secretion. In the presence of TGF-β-activated kinase 1 (TAK1), c-Jun N-terminal kinase, or p38 inhibitors, the effect of TGF-β1 on Sar1a expression and PC-I secretion significantly decreased; however, it had no effect on collagen-1A (Col-1A) expression. Further, the inhibitors of Smad3 or extracellular signal-regulated kinases inhibited TGF-β1-induced Col-1A expression but had no effect on PC-I secretion and Sar1a expression. Taken together, our results suggested that TGF-β1 induces Sar1a expression through TAK1 signaling and this signaling event regulates PC-I secretion in HTSF.

Platelet-derived β2m regulates age related monocyte/macrophage functions

Platelets have central roles in both immune responses and development. Stimulated platelets express leukocyte adhesion molecules and release numerous immune modulatory factors that recruit and activate leukocytes, both at the sites of activation and distantly. Monocytes are innate immune cells with dynamic immune modulatory functions that change during the aging process, a phenomenon termed “inflammaging”. We have previously shown that platelets are a major source of plasma beta-2 microglobulin (β2M) and that β2M induced a monocyte pro-inflammatory phenotype. Plasma β2M increases with age and is a pro-aging factor. We hypothesized that platelet derived β2M regulates monocyte phenotypes in the context of aging. Using wild-type (WT) and platelet specific β2M knockout mice (Plt-β2M^-/-) mice, we found that plasma β2M increased with age and correlated with increased circulating Ly6C^Hi monocytes. However, aged Plt-β2M^-/- mice had significantly fewer Ly6C^Hi monocytes compared to WT mice. Quantitative real-time PCR of circulating monocytes showed that WT mouse monocytes were more “pro-inflammatory” with age, while Plt-β2M^-/- derived monocytes adopted a “pro-reparative” phenotype. Older Plt-β2M^-/- mice had a significant decline in heart function compared to age matched WT mice, as well as increased cardiac fibrosis and pro-fibrotic markers. These data suggest that platelet-derived β2M regulates age associated monocyte polarization, and a loss of platelet derived β2M shifted monocytes and macrophages to a pro-reparative phenotype and increased pro-fibrotic cardiac responses. Platelet regulation of monocyte phenotypes via β2M may maintain a balance between inflammatory and reparative signals that affects age related physiologic outcomes.

LRP1 (Low-Density Lipoprotein Receptor-Related Protein 1) Regulates Smooth Muscle Contractility by Modulating Ca2+ Signaling and Expression of Cytoskeleton-Related Proteins

Objective- Mutations affecting contractile-related proteins in the ECM (extracellular matrix), microfibrils, or vascular smooth muscle cells can predispose the aorta to aneurysms. We reported previously that the LRP1 (low-density lipoprotein receptor-related protein 1) maintains vessel wall integrity, and smLRP1-/- mice exhibited aortic dilatation. The current study focused on defining the mechanisms by which LRP1 regulates vessel wall function and integrity. Approach and Results- Isometric contraction assays demonstrated that vasoreactivity of LRP1-deficient aortic rings was significantly attenuated when stimulated with vasoconstrictors, including phenylephrine, thromboxane receptor agonist U-46619, increased potassium, and L-type Ca2+ channel ligand FPL-64176. Quantitative proteomics revealed proteins involved in actin polymerization and contraction were significantly downregulated in aortas of smLRP1-/- mice. However, studies with calyculin A indicated that although aortic muscle from smLRP1-/- mice can contract in response to calyculin A, a role for LRP1 in regulating the contractile machinery is not revealed. Furthermore, intracellular calcium imaging experiments identified defects in calcium release in response to a RyR (ryanodine receptor) agonist in smLRP1-/- aortic rings and cultured vascular smooth muscle cells. Conclusions- These results identify a critical role for LRP1 in modulating vascular smooth muscle cell contraction by regulating calcium signaling events that potentially protect against aneurysm development.

A COL1A1 Promoter-Controlled Expression of TGF-β Soluble Receptor Inhibits Hepatic Fibrosis Without Triggering Autoimmune Responses

BACKGROUND

Soluble TGF-β1 type II receptor (sTβRII) via TGF-β1 inhibition could inhibit hepatic fibrosis, but over-dosage triggers autoimmune responses.

AIM

To test whether the use of a TGF-β1-responsive collagen I promoter COL1A1, via generating a feedback loop to TGF-β1 level, could offer accurate control on sTβRII expression.

METHODS

Recombinant adenoviruses with COL1A1 (Ad-COL-sTβRII/Luc) or CMV promoter (Ad-CMV-sTβRII/Luc) were constructed and characterized. Inhibition of TGF-β activity was determined both in vitro and in vivo. Total and bioactive TGF-β, hepatic fibrosis scale, α-SMA, collagen levels, and liver function were determined.

RESULTS

COL1A1, but not CMV, responded to TGF-β1 in vitro. Both in vitro and in vivo, Ad-COL-sTβRII could significantly, but not completely inhibit TGF-β1 activity while Ad-CMV-sTβRII almost completely inhibited TGF-β1 activity. As evidenced by fibrosis scale, α-SMA, and collagen levels in liver tissue, Ad-COL-sTβRII and Ad-CMV-sTβRII had comparable efficacies in treating hepatic fibrosis. Ad-COL-sTβRII was better than Ad-CMV-sTβRII in liver function restore. Ad-CMV-sTβRII, but not Ad-COL-sTβRII, induced high level of anti-dsDNA and anti-Sm antibodies in rats.

CONCLUSIONS

COL1A1 can precisely control sTβRII expression to inhibit excessive bioactive TGF-β level and thus inhibit hepatic fibrosis but without inducing autoimmune responses.

Drug-Induced Lung Toxicity

The number of blood-borne chemotherapeutic agents implicated in drug-induced lung toxicity continues to increase, although problems in detection remain. The initiation of drug-induced lung injury can have an immunologic or nonimmunologic basis. If endothelial cells are injured, interstitial pulmonary edema may result. Regardless of the source of injury, the progression of drug-induced lung toxicity is often quite similar, involving (1) parenchymal damage, (2) recruitment of inflammatory cells, and (3) progression of the inflammatory process. If the inflammatory reponse is sufficiently severe and disperse, increased collagen can be deposited in interstitial and intra-alveolar areas. The resulting attenuation of gas exchange can induce dyspnea and possibly death. Recent research suggests mediation of the fibrogenic process via cytokines such as transforming growth factor-β and tumor necrosis factor. Preliminary results demonstrating amelioration of cytokine mediated lung-induced fibrosis in animal models with appropriate antibodies suggest a possible future modality of therapy. Certain amphiphilic drugs are capable of eliciting a more specific form of lung toxicity. This class of drugs can interfere with phospholipid metabolism in pulmonary macrophages. In these cases, phospholipidosis results from phospholipid accumulation. The physiologic sequelae in human phospholipidosis is still uncertain.

Identification of target proteins involved in cochlear otosclerosis

HYPOTHESIS

Investigation of differential protein expression will provide clues to pathophysiology in otosclerosis.

BACKGROUND

Otosclerosis is a bone remodeling disorder limited to the endochondral layer of the otic capsule within the temporal bone. Some authors have suggested an inflammatory etiology for otosclerosis resulting from persistent measles virus infection involving the otic capsule. Despite numerous genetic studies, implication of candidate genes in the otosclerotic process remains elusive. We employed liquid chromatography-mass spectrometry (LC-MS) analysis on formalin-fixed celloidin-embedded temporal bone tissues for postmortem investigation of otosclerosis.

METHODS

Proteomic analysis was performed using human temporal bones from a patient with severe otosclerosis and a control temporal bone. Sections were dissected under microscopy to remove otosclerotic lesions and normal otic capsule for proteomic analysis. Tandem 2D chromatography mass spectrometry was employed. Data analysis and peptide matching to FASTA human databases was done using SEQUEST and proteome discoverer software.

RESULTS

TGFβ1 was identified in otosclerosis but not in the normal control temporal bone specimen. Aside from TGFβ1, many proteins and predicted cDNA-encoded proteins were observed, with implications in cell death and/or proliferation pathways, suggesting a possible role in otosclerotic bone remodeling. Immunostaining using TGFβ1 monoclonal revealed marked staining of the spongiotic otosclerotic lesions.

CONCLUSIONS

Mechanisms involved in cochlear extension of otosclerosis are still unclear, but the implication of TGFβ1 is supported by the present proteomic data and immunostaining results. The established role of TGFβ1 in the chondrogenesis process supports the theory of a reaction targeting the globulae interossei within the otic capsule.

Distinct effects of losartan and atenolol on vascular stiffness in Marfan syndrome

We conducted a randomized, double-blind trial of losartan (100 mg QD) versus atenolol (50 mg QD) for 6 months in adults with Marfan syndrome. Carotid-femoral pulse wave velocity (PWV), central augmentation index (AIx), aortic diameter and left ventricular (LV) function were assessed with arterial tonometry and echocardiography. Thirty-four subjects (18 female; median age 35 years, IQR 27, 45) were randomized. Central systolic and diastolic blood pressure decreased comparably with atenolol and losartan (p = 0.64 and 0.31, respectively); heart rate decreased with atenolol (p = 0.02), but not with losartan. PWV decreased in patients treated with atenolol (-1.15 ± 1.68 m/s; p = 0.01), but not in those treated with losartan (-0.22 ± 0.59 m/s; p = 0.15; between-group difference p = 0.04). In contrast, AIx decreased in the losartan group (-9.6 ± 8.6%; p < 0.001) but not in the atenolol group (0.9 ± 6.2%, p = 0.57; between-group difference p < 0.001). There was no significant change in aortic diameters or LV ejection fraction in either treatment group. In adults with Marfan syndrome, 6 months of treatment with atenolol improves PWV, whereas losartan reduces the AIx. By improving vascular stiffness via distinct mechanisms of action, there is physiologic value to considering the use of both medications in individuals with Marfan syndrome.

Coronary adventitial cells are linked to perivascular cardiac fibrosis via TGFβ1 signaling in the mdx mouse model of Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), progressive accumulation of cardiac fibrosis promotes heart failure. While the cellular origins of fibrosis in DMD hearts remain enigmatic, fibrotic tissue conspicuously forms near the coronary adventitia. Therefore, we sought to characterize the role of coronary adventitial cells in the formation of perivascular fibrosis. Utilizing the mdx model of DMD, we have identified a population of Sca1+, PDGFRα+, CD31-, and CD45- coronary adventitial cells responsible for perivascular fibrosis. Histopathology of dystrophic hearts revealed that Sca1+ cells extend from the adventitia and occupy regions of perivascular fibrosis. The number of Sca1+ adventitial cells increased two-fold in fibrotic mdx hearts vs. age matched wild-type hearts. Moreover, relative to Sca1-, PDGFRα+, CD31-, and CD45- cells and endothelial cells, Sca1+ adventitial cells FACS-sorted from mdx hearts expressed the highest level of Collagen1α1 and 3α1, Connective tissue growth factor, and Tgfβr1 transcripts. Surprisingly, mdx endothelial cells expressed the greatest level of the Tgfβ1 ligand. Utilizing Collagen1α1-GFP reporter mice, we confirmed that the majority of Sca1+ adventitial cells expressed type I collagen, an abundant component of cardiac fibrosis, in both wt (71%±4.1) and mdx (77%±3.5) hearts. In contrast, GFP+ interstitial fibroblasts were PDGFRα+ but negative for Sca1. Treatment of cultured Collagen1α1-GFP+ adventitial cells with TGFβ1 resulted in increased collagen synthesis, whereas pharmacological inhibition of TGFβR1 signaling reduced the fibrotic response. Therefore, perivascular cardiac fibrosis by coronary adventitial cells may be mediated by TGFβ1 signaling. Our results implicate coronary endothelial cells in mediating cardiac fibrosis via transmural TGFβ signaling, and suggest that the coronary adventitia is a promising target for developing novel anti-fibrotic therapies.

Cellular distribution and gene expression profile during flexor tendon graft repair: A novel tissue engineering approach(*)

To understand scar and adhesion formation during postsurgical period of intrasynovial tendon graft healing, a murine model of flexor digitorum longus tendon graft repair was developed, by utilizing flexor digitorum longus tendon allograft from donor Rosa26/+ mouse, and the healing process at days 3, 7, 14, 21, 28, and 35 post surgery of host wild-type mouse was followed. Using X-gal staining, β-galactosidase positive cells of allograft origin were detectable in tissue sections of grafted tendon post surgery. Graft healing was assessed for the cellular density, scar and adhesion formation, and their interaction with surrounding tissue. From histological analysis, it was evident that the healing of intrasynovial flexor digitorum longus tendon graft takes place in an interactive environment of donor graft, host tendon, and host surrounding tissue. A total of 32 genes, analyzed by RNA analysis, expressed during healing process. Particularly, Alk1, Postn, Tnc, Tppp3, and Mkx will be further investigated for therapeutical value in reducing scars and adhesions.

Benazepril inhibited the NF-κB and TGF-β networking on LV hypertrophy in rats

PURPOSE

Benazepril, an angiotensin-converting enzyme (ACE) inhibitor, has been used to treat hypertension, congestive heart failure, and chronic renal failure. However, its biological activity and mechanism of action in inflammation are not fully identified. The present study was designed to determine the in vivo anti-inflammatory effects of benazepril on LV hypertrophy in rats.

METHODS

LV hypertrophy was produced in rats by abdominal aortic coarctation. They were then divided into the following groups: sham operation; LV hypertrophy; LV hypertrophy+benazepril (1mg/kg in a gavage, once a day for 4 weeks). Both morphological assays (hemodynamic and hemorheological measurement; LV hypertrophy assessment), and molecular assays (protein levels of Collagen type I/III, TNF-α and VCAM-1; TGF-β gene expression; NF-κB or Smad activation; intracellular ROS production) were performed.

RESULTS

The following effects were observed in rats treated with benazepril: (1) marked improvements in hemodynamic and hemorheological parameters; (2) significant reductions in LV hypertrophy, dilatation and fibrosis; (3) significantly attenuated protein levels of Collagen type I/III, TGF-β, TNF-α and VCAM-1, NF-κB or Smad activation, as well as intracellular ROS production.

CONCLUSIONS

These results suggest that the anti-inflammatory properties of benazepril may be ascribed to their down-regulation of both NF-κB and TGF-β signaling pathways by acting on the intracellular ROS production in rats with LV hypertrophy, thus supporting the use of benazepril as an anti-inflammatory agent.

Cellular and molecular factors in flexor tendon repair and adhesions: a histological and gene expression analysis

Flexor tendon healing is mediated by cell proliferation, migration, and extracellular matrix synthesis that contribute to the formation of scar tissue and adhesion. The biological mechanisms of flexor tendon adhesion formation have been linked to transforming growth factor β (TGF-β). To elucidate the cellular and molecular events in this pathology, we implanted live flexor digitorum longus grafts from the reporter mouse Rosa26(LacZ/+) in wild-type recipients, and used histological β-galactosidase (β-gal) staining to evaluate the intrinsic versus extrinsic cellular origins of scar, and reverse transcription-polymerase chain reaction to measure gene expression of TGF-β and its receptors, extracellular matrix proteins, and matrix metalloproteinases (MMPs) and their regulators. Over the course of healing, graft cellularity and β-gal activity progressively increased, and β-gal-positive cells migrated out of the Rosa26(LacZ/+) graft. In addition, there was an evidence of influx of host cells (β-gal-negative) into the gliding space and the graft, suggesting that both graft and host cells contribute to adhesions. Interestingly, we observed a biphasic pattern in which Tgfb1 expression was the highest in the early phases of healing and gradually decreased thereafter, whereas Tgfb3 increased and remained upregulated later. The expression of TGF-β receptors was also upregulated throughout the healing phases. In addition, type III collagen and fibronectin were upregulated during the proliferative phase of healing, confirming that murine flexor tendon heals by scar tissue. Furthermore, gene expression of MMPs showed a differential pattern in which inflammatory MMPs were the highest early and matrix MMPs increased over time. These findings offer important insights into the complex cellular and molecular factors during flexor tendon healing.

UVA irradiation following treatment with topical 8-methoxypsoralen improves bleomycin-induced scleroderma in a mouse model, by reducing the collagen content and collagen gene expression levels in the skin

BACKGROUND

Recent studies have demonstrated that systemic or topical PUVA therapy, i.e., ultraviolet A (UVA) irradiation following treatment with 8-methoxypsoralen (8-MOP), is effective against the sclerotic skin lesions in systemic sclerosis. However, the mechanisms still remain unknown.

OBJECTIVE

To clarify the mechanisms of this therapy, we created a mouse model of bleomycin (BLM) injection-induced scleroderma and evaluated the effects of PUVA on the fibrotic lesions of scleroderma in this mouse model.

METHODS

BLM was injected subcutaneously once a day into the mice for 24 days. During the injection period, one group of mice was irradiated with UVA following local application of 8-MOP. Control groups were also set up, which were injected with phosphate-buffered saline, instead of BLM. Skin tissue samples examined histopathologically changes, measured of the content of hydroxyproline, and checked for the expression of genes encoding type I collagen, type III collagen, and transforming growth factor-β1 (TGF-β1).

RESULTS

The mouse models of scleroderma was found to show an increase in the density of the collagen fibers and thickening of the dermis and increased expressions of type I collagen, type III collagen, and TGF-β1. However, the combination of BLM treatment and topical PUVA treatment mice appeared reduced the dermal thickness and hydroxyproline content, down-regulation of expressions of the type I and type III collagen genes was observed while the expression of the TGF-β1 gene remained unchanged.

CONCLUSION

These results suggest that the effectiveness of topical PUVA therapy is attributable to the down-regulation of the expressions of the collagen genes by this treatment. The results additionally suggest that is not mediated by down-regulated expression of the TGF-β1.

Extracellular volume imaging by magnetic resonance imaging provides insights into overt and sub-clinical myocardial pathology

AIMS

Conventional late gadolinium enhancement (LGE) cardiac magnetic resonance can detect myocardial infarction and some forms of non-ischaemic myocardial fibrosis. However, quantitative imaging of extracellular volume fraction (ECV) may be able to detect subtle abnormalities such as diffuse fibrosis or post-infarct remodelling of remote myocardium. The aims were (1) to measure ECV in myocardial infarction and non-ischaemic myocardial fibrosis, (2) to determine whether ECV varies with age, and (3) to detect sub-clinical abnormalities in 'normal appearing' myocardium remote from regions of infarction.

METHODS AND RESULTS

Cardiac magnetic resonance ECV imaging was performed in 126 patients with T1 mapping before and after injection of gadolinium contrast. Conventional LGE images were acquired for the left ventricle. In patients with a prior myocardial infarction, the infarct region had an ECV of 51 ± 8% which did not overlap with the remote 'normal appearing' myocardium that had an ECV of 27 ± 3% (P < 0.001, n = 36). In patients with non-ischaemic cardiomyopathy, the ECV of atypical LGE was 37 ± 6%, whereas the 'normal appearing' myocardium had an ECV of 26 ± 3% (P < 0.001, n = 30). The ECV of 'normal appearing' myocardium increased with age (r = 0.28, P = 0.01, n = 60). The ECV of 'normal appearing' myocardium remote from myocardial infarctions increased as left ventricular ejection fraction decreased (r = -0.50, P = 0.02).

CONCLUSION

Extracellular volume fraction imaging can quantitatively characterize myocardial infarction, atypical diffuse fibrosis, and subtle myocardial abnormalities not clinically apparent on LGE images. Taken within the context of prior literature, these subtle ECV abnormalities are consistent with diffuse fibrosis related to age and changes remote from infarction.

Transforming growth factor-β and atherosclerosis: interwoven atherogenic and atheroprotective aspects

Age-related progression of cardiovascular disease is by far the largest health problem in the US and involves vascular damage, progressive vascular fibrosis and the accumulation of lipid-rich atherosclerotic lesions. Advanced lesions can restrict flow to key organs and can trigger occlusive thrombosis resulting in a stroke or myocardial infarction. Transforming growth factor-beta (TGF-β) is a major orchestrator of the fibroproliferative response to tissue damage. In the early stages of repair, TGF-β is released from platelets and activated from matrix reservoirs; it then stimulates the chemotaxis of repair cells, modulates immunity and inflammation and induces matrix production. At later stages, it negatively regulates fibrosis through its strong antiproliferative and apoptotic effects on fibrotic cells. In advanced lesions, TGF-β might be important in arterial calcification, commonly referred to as "hardening of the arteries". Because TGF-β can signal through multiple pathways, namely the SMADs, a MAPK pathway and the Rho/ROCK pathways, selective defects in TGF-β signaling can disrupt otherwise coordinated pathways of tissue regeneration. TGF-β is known to control cell proliferation, cell migration, matrix synthesis, wound contraction, calcification and the immune response, all being major components of the atherosclerotic process. However, many of the effects of TGF-β are essential to normal tissue repair and thus, TGF-β is often thought to be "atheroprotective". The present review attempts to parse systematically the known effects of TGF-β on both the major risk factors for atherosclerosis and to isolate the role of TGF-β in the many component pathways involved in atherogenesis.

Polymorphisms of beta-lactoglobulin promoter region in three Sicilian goat breeds

Several beta-lactoglobulin (BLG) polymorphisms have been described within the proximal promoter region and coding region of the caprine gene, although no genetic variants affecting the protein amino acid composition and/or expression level have been characterized so far. Binding sites for several transcription factors (TFs) are present in the BLG promoter region. The aims of this work were to sequence the full-length promoter region of three Sicilian goat breeds in order to identify polymorphisms, analyze the identified haplotypes, search for differences between breeds for the presence of polymorphisms in this gene region, search for putative TFs binding sites, and check if polymorphisms lay within the identified TFs binding sites. The promoter region of BLG gene in Sicilian goat breeds showed high level of polymorphism due to the presence of 36 single nucleotide polymorphisms (SNPs). Association between polymorphic sites was computed within the whole sample analyzed and 18 haplotypes were inferred. Binding sites for three milk protein binding factors (MPBFs) and four nuclear factor-I (NF-I) were found within BLG promoter region based on the ovine sequence. The identification of some SNPs within TFs binding sites allowed hypothesizing the loss of TFs. Further studies are in progress to evaluate the effect of these mutations on binding affinity of TFs, the functional interaction of the TFs with the goat BLG promoter, and the relationship of the polymorphisms with BLG gene expression and milk production and composition.

Nuclear factor I revealed as family of promoter binding transcription activators

Background

Multiplex experimental assays coupled to computational predictions are being increasingly employed for the simultaneous analysis of many specimens at the genome scale, which quickly generates very large amounts of data. However, inferring valuable biological information from the comparisons of very large genomic datasets still represents an enormous challenge.

Results

As a study model, we chose the NFI/CTF family of mammalian transcription factors and we compared the results obtained from a genome-wide study of its binding sites with chromatin structure assays, gene expression microarray data, and in silico binding site predictions. We found that NFI/CTF family members preferentially bind their DNA target sites when they are located around transcription start sites when compared to control datasets generated from the random subsampling of the complete set of NFI binding sites. NFI proteins preferably associate with the upstream regions of genes that are highly expressed and that are enriched in active chromatin modifications such as H3K4me3 and H3K36me3. We postulate that this is a causal association and that NFI proteins mainly act as activators of transcription. This was documented for one member of the family (NFI-C), which revealed as a more potent gene activator than repressor in global gene expression analysis. Interestingly, we also discovered the association of NFI with the tri-methylation of lysine 9 of histone H3, a chromatin marker previously associated with the protection against silencing of telomeric genes by NFI.

Conclusion

Taken together, we illustrate approaches that can be taken to analyze large genomic data, and provide evidence that NFI family members may act in conjunction with specific chromatin modifications to activate gene expression.

Transcriptional regulation of matrix metalloproteinase-1 and collagen 1A2 explains the anti-fibrotic effect exerted by proteasome inhibition in human dermal fibroblasts

Introduction

Extracellular matrix (ECM) turnover is controlled by the synthetic rate of matrix proteins, including type I collagen, and their enzymatic degradation by matrix metalloproteinases (MMPs). Fibrosis is characterized by an unbalanced accumulation of ECM leading to organ dysfunction as observed in systemic sclerosis. We previously reported that proteasome inhibition (PI) in vitro decreases type I collagen and enhances MMP-1 production by human fibroblasts, thus favoring an antifibrotic fibroblast phenotype. These effects were dominant over the pro-fibrotic phenotype induced by transforming growth factor (TGF)-β. Here we investigate the molecular events responsible for the anti-fibrotic phenotype induced in fibroblasts by the proteasome inhibitor bortezomib.

Methods

The steady-state mRNA levels of COL1A1, COL1A2, TIMP-1, MMP-1, and MMP-2 were assessed by quantitative PCR in human dermal fibroblasts cultured in the presence of TGF-β, bortezomib, or both. Transient fibroblast transfection was performed with wild-type and mutated COL1A1 and MMP-1 promoters. Chromatin immunoprecipitation, electrophoretic mobility shift assay (EMSA), and DNA pull-down assays were used to assess the binding of c-Jun, SP1, AP2, and Smad2 transcription factors. Immunoblotting and immunofluorescent microscopy were performed for identifying phosphorylated transcription factors and their cellular localization.

Results

Bortezomib decreased the steady-state mRNA levels of COL1A1 and COL1A2, and abrogated SP1 binding to the promoter of COL1A2 in both untreated and TGF-β-activated fibroblasts. Reduced COL1A2 expression was not due to altered TGF-β-induced Smad2 phosphorylation, nuclear translocation, or binding to the COL1A2 promoter. In contrast to collagen, bortezomib specifically increased the steady-state mRNA levels of MMP-1 and enhanced the binding of c-Jun to the promoter of MMP-1. Furthermore, disruption of the proximal AP-1-binding site in the promoter of MMP-1 severely impaired MMP-1 transcription in response to bortezomib.

Conclusions

By altering the binding of at least two transcription factors, c-Jun and SP1, proteasome inhibition results in increased production of MMP-1 and decreased synthesis of type I collagen in human dermal fibroblasts. Thus, the antifibrotic phenotype observed in fibroblasts submitted to proteasome inhibition results from profound modifications in the binding of key transcription factors. This provides a novel rationale for assessing the potential of drugs targeting the proteasome for their anti-fibrotic properties.

Biological basis of bone formation, remodeling, and repair-part I: biochemical signaling molecules

The bony biochemical environment is an active and dynamic system that permits and promotes cellular functions that lead to matrix production and ossification. Each component is capable of conveying important regulatory cues to nearby cells, thus effecting gene expression and changes at the cytostructural level. Here, we review the various signaling molecules that contribute to the active and dynamic nature of the biochemical system. These components include hormones, cytokines, and growth factors. We describe their role in regulating bone metabolism. Certain growth factors (i.e., TGF-beta, IGF-1, and VEGF) are described in greater detail because of their potential importance in developing successful tissue-engineering strategies.

Nuclear factor I-C links platelet-derived growth factor and transforming growth factor beta1 signaling to skin wound healing progression

Transforming growth factor beta (TGF-beta) and platelet-derived growth factor A (PDGFAlpha) play a central role in tissue morphogenesis and repair, but their interplay remain poorly understood. The nuclear factor I C (NFI-C) transcription factor has been implicated in TGF-beta signaling, extracellular matrix deposition, and skin appendage pathologies, but a potential role in skin morphogenesis or healing had not been assessed. To evaluate this possibility, we performed a global gene expression analysis in NFI-C(-/-) and wild-type embryonic primary murine fibroblasts. This indicated that NFI-C acts mostly to repress gene expression in response to TGF-beta1. Misregulated genes were prominently overrepresented by regulators of connective tissue inflammation and repair. In vivo skin healing revealed a faster inflammatory stage and wound closure in NFI-C(-/-) mice. Expression of PDGFA and PDGF-receptor alpha were increased in wounds of NFI-C(-/-) mice, explaining the early recruitment of macrophages and fibroblasts. Differentiation of fibroblasts to contractile myofibroblasts was also elevated, providing a rationale for faster wound closure. Taken together with the role of TGF-beta in myofibroblast differentiation, our results imply a central role of NFI-C in the interplay of the two signaling pathways and in regulation of the progression of tissue regeneration.

Cytokines

During physiological and pathological skeletal remodelling, immune cells and stromal fibroblasts near active bone-forming and bone-resorbing surfaces might modulate the functions of skeletal tissue cells. Osteoblasts, osteoclasts and their progenitor cells are the probable direct targets of these effector cells (e.g. lymphocytes and monocytes) which act through direct contact or the release of soluble ligands (e.g. interleukin 1 or tumour necrosis factor, lymphotoxins, transforming growth factors). These cytokines bind to specific cellular receptors, resulting in changes in the form and function of the target bone cells and variable activation of genes coding for extracellular matrix proteins and proteinases which are responsible for remodelling the matrix. The synthesis and release of eicosanoids such as prostaglandins (e.g. PGE2) are frequent associated events. PGE2, in turn, affects several functions of the skeletal tissue cells as well as the lymphocytes and monocytes in their environment. The mesenchymal cells may also be induced to release ligands such as colony-stimulating factors, other cellular products or hormones resulting in a system of feedback and amplification loops. The cellular responses are thus subject to multiple controls not only determined by these ligands acting on their respective receptors but also by the pathways of signal transduction and how they, in turn, are influenced by interactions with molecules within the cells.

TGF-beta and wound healing

Wound healing comprises an ordered sequence of events including cell migration and proliferation, synthesis of extracellular matrix, angiogenesis and remodelling. TGF-beta regulates many of these processes. Animal models are used to study healing of simple linear incision wounds and deeper dermal wounds under normal and impaired conditions. TGF-beta increases the rate of healing and the breaking strength of the repaired tissue. It also enhances angiogenesis and consequent blood flow to dermal wounds, partly by stimulating the local release of other growth factors. TGF-beta reverses the adverse affects of glucocorticoids on wound healing and thus may be useful in the treatment of chronic ulcers or wounds in patients whose normal responses have been impaired by therapy with steroids, radiation or other drugs.

Upregulation of lysyl oxidase and MMPs during cardiac remodeling in human dilated cardiomyopathy

OBJECTIVE

Dilated cardiomyopathy (DCM) represents a large subset of patients with congestive heart failure (HF), and myocardial fibrosis has been shown to be associated with this process. Lysyl oxidase (LOX), a key enzyme, plays a potential role in the biogenesis of connective tissue matrices by catalyzing crosslinks in collagen and elastin. However, the mechanisms involved in the remodeling process during HF are not clearly understood. The present work was aimed to determine the changes in collagen phenotypes, MMPs, TIMPs, and LOX, in DCM and non-failing human hearts. Moreover, the role of TGFbeta in the induction of type III collagen in cardiac fibroblast is determined.

METHOD

Protein and RNA expression were quantified by Western and RT-PCR analysis; collagen phenotypes were determined by SDS-PAGE.

RESULTS

Our data demonstrated that in all DCM hearts, the collagen concentration was significantly elevated compared to that of the NF hearts associated with an increase in Type I (18%) and Type III (33%) collagen. The content of MMP-2 and MMP-9 were increased significantly in all DCM hearts compared to NF hearts. Transcriptional level of LOX, TIMP 1, and 2 were significantly upregulated in DCM hearts. In addition, a significant increase in the transcript levels of cytokines, notably IFN, IL-6, TNF-alpha, and TGF-beta superfamily was observed in all DCM hearts. Addition of TGFbeta to cardiac fibroblasts caused a dose dependent increase in type III collagen.

CONCLUSION

Altogether, our data suggest an alteration of collagen, MMPs, various cytokines and particularly, LOX participates, in part, in the remodeling of the heart leading to cardiac dysfunction and HF.

Cloning and characterization of the rat lysyl oxidase gene promoter: identification of core promoter elements and functional nuclear factor I-binding sites

Lysyl oxidase (LO) stabilizes the extracellular matrix by cross-linking collagen and elastin. To assess the transcriptional regulation of LO, we cloned the 5'-flanking region with 3,979 bp of the rat LO gene. LO transcription started at multiple sites clustered at the region from -78 to -51 upstream of ATG. The downstream core promoter element functionally independent of the initiator predominantly activated the TATA-less LO gene. 5' Deletion assays illustrated a sequence of 804 bp upstream of ATG sufficient for eliciting the maximal promoter activity and the region -709/-598 exhibiting strongly enhancing effects on the reporter gene expression in transiently transfected RFL6 cells. DNase I footprinting assays showed a protected pattern existing in the fragment -612/-580, which contains a nuclear factor I (NFI)-binding site at the region -594/-580 confirmed by electrophoretic mobility supershift assays. Mutations on this acting site decreased both NFI binding affinity in gel shift assays and stimulation of SV40 promoter activities in cells transfected with the NFI-binding site-SV40 promoter chimeric construct. Furthermore, at least two functional NFI-binding sites, including another one located at -147/-133, were identified in the LO promoter region -804/-1. Only NFI-A and NFI-B were expressed in rat lung fibroblasts, and their interaction with the LO gene was sensitively modulated by exogenous stimuli such as cigarette smoke condensate. In conclusion, the isolated rat LO gene promoter contains functionally independent initiator and downstream core promoter elements, and the conserved NFI-binding sites play a critical role in the LO gene activation.

Liposomal gene transfer of keratinocyte growth factor improves wound healing by altering growth factor and collagen expression

BACKGROUND

Growth factors affect the complex cascade of wound healing; however, interaction between different growth factors during dermal and epidermal regeneration are still not entirely defined. In the present study, we thought to determine the interaction between keratinocyte growth factor (KGF) administered as liposomal cDNA with other dermal and epidermal growth factors and collagen synthesis in an acute wound.

MATERIALS AND METHODS

Rats received an acute wound and were divided into two groups to receive weekly subcutaneous injections of liposomes plus the Lac-Z gene (0.22 microg, vehicle), or liposomes plus the KGF cDNA (2.2 microg) and Lac-Z gene (0.22 microg). Histological and immunohistochemical techniques were used to determine growth factor, collagen expression, and dermal and epidermal structure.

RESULTS

KGF cDNA increased insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3), and fibroblast growth factor (FGF), decreased transforming growth factor-beta (TGF-beta), while it had no effect on platelet-derived growth factor (PDGF) levels in the wound. KGF cDNA significantly increased collagen Type IV at both the wound edge as well as the wound bed, while it had no effect on collagen Type I and III. KGF cDNA increased re-epithelialization, improved dermal regeneration, and increased neovascularization.

CONCLUSIONS

Exogenous administered KGF cDNA causes increases in IGF-I, IGF-BP3, FGF, and collagen IV and decreases TGF-beta concentration. KGF gene transfer accelerates wound healing without causing an increase in collagen I or III.

Losartan, an AT1 antagonist, prevents aortic aneurysm in a mouse model of Marfan syndrome

Aortic aneurysm and dissection are manifestations of Marfan syndrome (MFS), a disorder caused by mutations in the gene that encodes fibrillin-1. Selected manifestations of MFS reflect excessive signaling by the transforming growth factor-beta (TGF-beta) family of cytokines. We show that aortic aneurysm in a mouse model of MFS is associated with increased TGF-beta signaling and can be prevented by TGF-beta antagonists such as TGF-beta-neutralizing antibody or the angiotensin II type 1 receptor (AT1) blocker, losartan. AT1 antagonism also partially reversed noncardiovascular manifestations of MFS, including impaired alveolar septation. These data suggest that losartan, a drug already in clinical use for hypertension, merits investigation as a therapeutic strategy for patients with MFS and has the potential to prevent the major life-threatening manifestation of this disorder.

Inhibition of systemic sclerosis dermal fibroblast type I collagen production and gene expression by simvastatin

OBJECTIVE

To examine whether statins are capable of modulating collagen gene expression in cultured systemic sclerosis dermal fibroblasts.

METHODS

Cultured dermal fibroblasts from 3 patients with diffuse systemic sclerosis of recent onset were treated with 5 microM and 10 microM of simvastatin for 3 or 4 days. Morphologic features, cytotoxicity, and type I collagen production and messenger RNA (mRNA) levels in the fibroblasts were examined. The effects of mevalonate, geranylgeranyl pyrophosphate (GGPP), and farnesyl pyrophosphate (FPP), which are lipids downstream from the hydroxymethylglutaryl-coenzyme A block, were also examined. Transient transfections with COL1A1 promoter-reporter constructs and electrophoretic gel mobility shift assays were utilized to examine COL1A1 transcription and Sp1 and CCAAT-box binding factor (CBF) binding.

RESULTS

Simvastatin did not cause morphologic changes or cytotoxicity in the fibroblasts, even after 4 days of treatment. Type I collagen production and mRNA levels showed a potent and dose-related inhibition following 3 and 4 days of treatment. The inhibition of collagen gene expression by simvastatin was completely reversed by mevalonate and GGPP, but not by FPP. The statin effects occurred at the transcriptional level and involved the proximal COL1A1 promoter region encompassing -174 bp. A significant reduction in Sp1 and CBF binding activity was also found in simvastatin-treated cells.

CONCLUSION

Simvastatin is a powerful inhibitor of type I collagen gene expression in normal and systemic sclerosis fibroblasts. The pleiotropic protective effects of statins on various endothelial and immune cell functions in conjunction with their potent inhibitory effects on type I collagen gene expression suggest that statins may be effective therapeutic agents in systemic sclerosis.

Transforming growth factor-beta1–induced hypertrophy and matrix expression in human bladder smooth muscle cells

OBJECTIVES

To determine whether transforming growth factor beta (TGF-beta) could activate hyperplasia, hypertrophy, and altered collagen expression in human detrusor smooth muscle cells (SMCs).

METHODS

Human bladder SMCs were treated in vitro with TGF-beta1 and analyzed for changes in both proliferative and hypertrophic responses by cell number and volume measurements, as well as for alterations in extracellular matrix gene and protein expression by Northern blot and enzyme-linked immunosorbent assay.

RESULTS

Proliferation of bladder SMCs was refractory to TGF-beta1, whereas the cells became hypertrophic upon TGF-beta1 treatment. The interstitial collagens, types I and III, were increased significantly in TGF-beta1-treated cultures in a dose-dependent manner. These increases were blocked in the presence of TGF-beta1 neutralizing antibody and also when cultures were treated with the protein synthesis inhibitor cycloheximide, indicating that new protein synthesis is necessary for upregulation of the interstitial collagens. Messenger ribonucleic acid transcripts for both the COL1A1 and COL3A1 genes were elevated at 4, 6, and 24 hours in TGF-beta1-treated cultures, preceding the expression of the collagenous protein, showing that TGF-beta1 effects on bladder smooth muscle occur, at least in part, at the transcriptional level.

CONCLUSIONS

These results indicate that human bladder SMCs have the potential to mediate both a hypertrophic and fibrotic response upon TGF-beta1 stimulation.

nfi-I affects behavior and life-span in C. elegans but is not essential for DNA replication or survival

BACKGROUND

The Nuclear Factor I (one) (NFI) family of transcription/replication factors plays essential roles in mammalian gene expression and development and in adenovirus DNA replication. Because of its role in viral DNA replication NFI has long been suspected to function in host DNA synthesis. Determining the requirement for NFI proteins in mammalian DNA replication is complicated by the presence of 4 NFI genes in mice and humans. Loss of individual NFI genes in mice cause defects in brain, lung and tooth development, but the presence of 4 homologous NFI genes raises the issue of redundant roles for NFI genes in DNA replication. No NFI genes are present in bacteria, fungi or plants. However single NFI genes are present in several simple animals including Drosophila and C. elegans, making it possible to test for a requirement for NFI in multicellular eukaryotic DNA replication and development. Here we assess the functions of the single nfi-1 gene in C. elegans.

RESULTS

C. elegans NFI protein (CeNFI) binds specifically to the same NFI-binding site recognized by vertebrate NFIs. nfi-1 encodes alternatively-spliced, maternally-inherited transcripts that are expressed at the single cell stage, during embryogenesis, and in adult muscles, neurons and gut cells. Worms lacking nfi-1 survive but have defects in movement, pharyngeal pumping and egg-laying and have a reduced life-span. Expression of the muscle gene Ce titin is decreased in nfi-1 mutant worms.

CONCLUSION

NFI gene function is not needed for survival in C. elegans and thus NFI is likely not essential for DNA replication in multi-cellular eukaryotes. The multiple defects in motility, egg-laying, pharyngeal pumping, and reduced lifespan indicate that NFI is important for these processes. Reduction in Ce titin expression could affect muscle function in multiple tissues. The phenotype of nfi-1 null worms indicates that NFI functions in multiple developmental and behavioral systems in C. elegans, likely regulating genes that function in motility, egg-laying, pharyngeal pumping and lifespan maintenance.

Early response of alpha2(I) collagen to acetaldehyde in human hepatic stellate cells is TGF-beta independent

Acetaldehyde is fibrogenic and induces the expression of type I collagen genes in hepatic stellate cells. Some of these acetaldehyde-dependent events are mediated by H(2)O(2) and thus establish a direct connection between oxidative stress and collagen upregulation. We localized to the -378 to -183 region of the alpha2(I) collagen (COL1A2) promoter an acetaldehyde-responsive element (AcRE) functional in human hepatic stellate cells (HHSCs) and investigated molecular mechanisms whereby acetaldehyde stimulates and modulates its transcriptional activity. Because the AcRE co-localized with a previously described transforming growth factor beta (TGF-beta)1-responsive element, and both acetaldehyde and this cytokine induce their effects through H(2)O(2), we investigated whether all fibrogenic actions of acetaldehyde were mediated by this cytokine. Here we show that acetaldehyde-induced COL1A2 upregulation in HHSCs recognizes two distinct but overlapping early and late stages that last from 1 to 6 hours and from 6 to 24 hours, respectively. We present several lines of evidence to show that early acetaldehyde-mediated events are independent of TGF-beta1. These include significant time-course differences in the expression of COL1A2 and TGF-beta1 mRNAs and inability of neutralizing antibodies to TGF-beta1 to inhibit acetaldehyde-dependent collagen gene transcription and Smad 3 phosphorylation. We also show that although acetaldehyde-dependent upregulation of collagen was PI3K dependent, that of TGF-beta1 was PI3K independent. In conclusion, acetaldehyde-dependent mechanisms involved in COL1A2 upregulation are similar, but not identical, to those of TGF-beta1. We suggest that early acetaldehyde-dependent events induce the late expression of TGF-beta1 and create an H(2)O(2)-dependent autocrine loop that may sustain and amplify the fibrogenic response of this alcohol metabolite.

Increased Phosphorylation and Activation of Mitogen-Activated Protein Kinase p38 in Scleroderma Fibroblasts

Transforming growth factor-beta (TGF-beta) stimulates the transcription of the alpha2(I) collagen gene. The dermal fibroblast activation in systemic sclerosis (SSc) may be a result of stimulation by autocrine TGF-beta. In this study, we investigated whether p38 mitogen-activated protein kinase (MAPK) is involved in TGF-beta-induced transcriptional activation of the human alpha2(I) collagen gene in normal dermal fibroblasts and in upregulated extracellular matrix (ECM) expression in SSc fibroblasts. Type I collagen expression induced by TGF-beta was suppressed by the specific p38 MAPK inhibitors SB203580 or SB202190 in normal fibroblasts. TGF-beta induced phosphorylation and activation of p38 MAPK in normal dermal fibroblasts. Transient transfection of dominant-negative mutant p38 MAPK into normal fibroblasts abolished TGF-beta-induced promoter activity of the human alpha2(I) collagen gene in normal fibroblasts. Moreover, constitutive phosphorylation and activation of p38 MAPK was demonstrated in SSc fibroblasts, and the inhibition of p38 MAPK using specific p38 MAPK inhibitors or dominant-negative mutant p38 MAPK abolished the upregulated expression of type I collagen or fibronectin in SSc fibroblasts. These results strongly suggest the contribution of p38 MAPK signaling to the TGF-beta-mediated regulation of the human alpha2(I) collagen gene in normal dermal fibroblasts and constitutive upregulated expression of type I collagen and fibronectin in SSc fibroblasts.

Species-specific regulation of the alpha-2(I) procollagen gene by proximal promoter elements

Transcriptional regulation of the human alpha 2(I) procollagen proximal promoter involves the interaction of trans-acting factors at the inverted CCAAT box (G/CBE) located at position -80 and an adjacent GGAGGCCC-box at -70. Both these elements have previously been shown to be essential for activity of the human promoter. This study investigated nucleotide differences at three sites (-74, -72 and -71) between the human and mouse promoters that were sufficient to abolish trans-acting factor binding with the mouse sequence (GGAGACGT). Two distinct DNA-protein interactions were detected on the human -107/+54 promoter fragment while a single interaction was observed at the equivalent mouse promoter. One of these factors is the CCAAT-binding factor (CBF) and it's binding was observed on both the human and mouse promoters. Although the GGAGGCCC DNA-binding element was not detected on the mouse promoter, GGAGGCC-binding proteins were present in mouse nuclear extracts as observed by their interaction with the human promoter. Functional analysis of the human and mouse -343/+54 and -107/+54 promoter regions revealed significant differences between species; the human constructs having higher activity than the mouse. The differences in promoter activity between species may in part be a result of the nucleotide differences in the GGAGGCCC-box. Mutations in this region of the human -107/+54 promoter prevented DNA-protein interaction and lowered promoter activity. These results support the hypothesis that the GGAGGCCC-box in the human alpha 2(1) procollagen promoter has a regulatory function and that there exists a species-specific difference in transcription factor binding and regulation of the gene.

TGF-beta and TNF-alpha: antagonistic cytokines controlling type I collagen gene expression

The balance between production and degradation of type I collagen plays a critical role in the development and maintenance of organ and tissue integrity. It also represents the most crucial element governing the process of tissue repair. The synthesis of type I collagen gene is highly regulated by different cytokines at the transcriptional level. Especially, transforming growth factor beta (TGF-beta), a key player in the physiopathology of tissue repair, enhances type I collagen gene expression. In contrast, tumor necrosis factor alpha (TNF-alpha), whose matrix-remodelling function is opposite to that of TGF-beta, reduces type I collagen gene expression. This review focuses on transcriptional regulation of type I collagen by TGF-beta and TNF-alpha and on the molecular mechanisms that control the antagonistic activity of TNF-alpha against TGF-beta-driven type I collagen gene expression.

Effect of human platelet supernatant on proliferation and matrix synthesis of human articular chondrocytes in monolayer and three-dimensional alginate cultures

Articular cartilage is rich in collagen type II fibres and proteoglycans and is characterized by low cell density. Chondrocytes have specific nutritional requirements and therefore cannot be expanded in vitro without the risk of generating fibroblastoid cells expressing type I collagen. Therefore, various growth conditions were tested for cartilage tissue engineering. Human platelets are a rich source of many growth factors including transforming growth factor-beta and platelet-derived growth factor. To investigate the effect of human platelet supernatant (hPS) on chondrocyte proliferation and differentiation, human articular biopsies obtained from three healthy donors. Chondrocytes were isolated and expanded separately in monolayer cultures and seeded in alginate beads in the presence and absence of hPS of 1% or 10% v/v concentration. Transcript levels of genes encoding chondrogenic factors were determined by quantitative reverse transcriptase-polymerase chain reaction. The deposition of types I and II collagen as well as proteoglycan was detected by indirect immunocytochemistry. Addition of hPS activated chondrocyte proliferation in monolayer cultures but induced a dedifferentiation of chondrocytes towards a fibroblast-like phenotype. The expression levels of mRNAs encoding type II collagen, aggrecan and bone morphogenetic protein-2 were reduced in all samples tested. Seeding chondrocytes in alginate beads in the presence of hPS generated a cell population capable of type II collagen expression, even though hPS induced considerable type I collagen expression as well. Differences (1% vs. 10% group, 1% vs. control, 10% vs. control) in the quantitative gene expression of types I and II collagen or of aggrecan were statistically significant (p<0.001). We conclude that addition of hPS may accelerate chondrocyte expansion but can lead to their dedifferentiation.

Signals regulating tendon formation during chick embryonic development

Tendons are collagen-rich structures that link muscle to cartilage. By using quail-chick chimeras, it has been shown that tendon and cartilage cells originate from the same mesodermic compartment, which is distinct from that giving rise to muscle cells. Axial tendons originate from the sclerotomal compartment, and limb tendons originate from the lateral plate, whereas axial and limb muscles derive from dermomyotomes. Despite these different embryologic origins, muscle and tendon morphogenesis occurs in close spatial and temporal association. Facilitated by the distinct embryologic origin of myogenic and tendon cells, surgical studies in the avian embryo have highlighted interactions between tendons and muscles, during embryonic development. However, these interactions seem to differ between axial and limb levels. The molecular mechanisms underlying muscle and tendon interactions have been shown recently to involve different members of the fibroblast growth factor family. This review covers the available data on the early steps of tendon formation in the limb and along the primary axis. The relationship with muscle morphogenesis will be highlighted.

Augmented production of transforming growth factor-beta by cultured peripheral blood mononuclear cells from patients with systemic sclerosis

We sought to determine whether the spontaneous production of transforming growth factor-beta (TGF-beta) by peripheral blood mononuclear cells (PBMC) is increased in patients with systemic sclerosis (SSc). Culture supernatants of PBMC from SSc patients (n = 88) and healthy controls (n = 44) were analyzed by enzyme-linked immunosorbent assay. The production of active TGF-beta1 and total (active and latent) TGF-beta1 by PBMC from patients with limited cutaneous SSc (lSSc) and by PBMC from patients with diffuse cutaneous SSc (dSSc) was significantly elevated compared to the production by PBMC from normal controls. Production of active TGF-beta1 by dSSc PBMC was higher than that by lSSc PBMC, although not significantly. Patients with PBMC with increased active or total TGF-beta1 production showed significantly shorter disease duration than patients with PBMC with normal production levels. PBMC from patients without anticentromere antibody showed enhanced active TGF-beta1 production more frequently than those from patients with anticentromere antibody. PBMC from SSc patients more frequently showed enhanced total TGF-beta2 production than PBMC from normal controls. Among each leukocyte subset, spontaneous production of total TGF-beta1 was significantly higher in cultured peripheral monocytes/macrophages, but not in T cells, B cells, or NK cells, from patients than from normal controls. Thus, the enhanced production of TGF-beta by PBMC may contribute to the disease process in SSc

Relationship between the DNA binding domains of SMAD and NFI/CTF transcription factors defines a new superfamily of genes

Transcription factors of the SMAD family relay signals from cell surface receptors to the nucleus in response to TGF-beta related soluble factors. Members of the nuclear factor I/CAAT box binding family (NFI/CTF) have been implicated as regulators of diverse biological processes such as adenovirus replication and transcription of TGF-responsive genes. There are highly conserved DNA binding domains in SMAD and NFI/CTF transcription factors that allow sequence specific DNA binding for members of each family. However, no homology relationship has been established for the DNA binding domains present in these families. For a better understanding of the structure and evolution of SMAD genes, we carried out a sensitive PSI-BLAST database search. This revealed significant similarities between the DNA binding domains of SMADs and NFI/CTF transcription factors. Enhanced graphic matrix analysis and multiple sequence alignment of the amino acid sequences of the SMAD and NFI/CTF DNA binding domains also show that these two classes of domains share considerable structural similarity. These results strongly suggest that these two classes of factors share a homologous DNA binding domain presumably resulting from a common ancestry. In contrast, the C-terminal transcription modulation domains of both SMAD and NFI/CTF families do not show any sequence similarity. Based on the structural relationship of their DNA binding domains, we propose that the SMAD and NFI/CTF transcription factors belong to new superfamily of genes.

Isolation and Characterization of the Human Syncytin Gene Promoter1

Syncytin, a protein encoded by an envelope gene of a human endogenous retrovirus-W (HERV-W), plays a critical role in trophoblast differentiation. We isolated the 5'-flanking region of the syncytin gene from human genomic DNA by PCR and identified cis-acting elements on the promoter that are important for transcription. The major transcription initiation site identified by mung bean nuclease protection assays is 56 base pairs (bp) downstream from a putative CCAAT box. Deletion analysis of the 5'-flanking region of the syncytin gene indicated that the proximal 148 bp are essential for minimal promoter activity and that regions of the promoter from nt -1519 to -984 and nt -294 to -148 are required for maximal expression in normal trophoblast cells. DNase I footprint analysis of the region between nt -252 and +110 revealed three protected regions, FP1-FP3. Mutagenesis of a hepatocyte-specific nuclear protein-1 (HAPF1) binding site in FP1 and a TATA box in FP3 had no effects on basal promoter activity. However, mutation of the CCAAT motif and the octamer protein (Oct) binding site in FP2 decreased promoter activity by 88% and 76%, respectively. Mutation of the ecdysone receptor (EcR) response element in FP2, which may bind a nuclear hormone receptor, increased basal promoter activity by 2-fold. Gel shift and supershift assays indicated that CCAAT-binding factor (CBF) binds to the CCAAT motif and that Oct binds to the Oct binding site. Taken together, these findings indicate that the syncytin promoter is located in the 5' long terminal repeat (LTR) of the HERV-W gene and that binding sites for CBF and Oct in the proximal promoter are critical for transcriptional regulation of the gene in trophoblast cells.

Transcriptional activation of the type I collagen genes COL1A1 and COL1A2 in fibroblasts by interleukin-4: analysis of the functional collagen promoter sequences

Pneumonitis followed by lung fibrosis is a frequent complication of radiation therapy of chest tumors. A hallmark of these fibrotic lesions is the excessive production and accumulation of extracellular matrix proteins such as type I collagen. In addition to TGF-beta1, IL-4 has been recognized as a potent inducer of collagen gene synthesis in fibroblasts. In this study, we analyzed the regulation of the alpha1(I) procollagen (COL1A1) promoter and the alpha2(I) procollagen (COL1A2) promoter by IL-4 in normal human lung fibroblasts. We provide evidence that the IL-4-induced transcriptional activator STAT6 binds to various sequences within the COL1A1 and COL1A2 promoter. The regulatory function of these regions was tested by reporter gene analysis using 5' deletions of the COL1A1 and COL1A2 promoter fused to the luciferase gene. Interleukin-4 treatment of human fibroblasts transiently transfected with COL1A1 promoter deletion constructs resulted in luciferase activity exceeding that of untreated fibroblasts by 25%, while luciferase activity driven by the COL1A2 promoter was enhanced by about 70% upon IL-4 treatment. A combined action of SP1, NFkappaB, and STAT6 essentially contributes to the IL-4 mediated COL1A2 gene activation. An AP2 site adjacent to the reverse orientated STAT6 consensus motif TTC N(3/4) GCT is located within 205 bases from the transcription start site and seems to support the moderate IL-4-induced COL1A1 gene activation. Interferon-gamma downregulation of transcription is mainly seen with the COL1A1 promoter.

Regulation of Rat Bone Sialoprotein Gene Transcription by Enamel Matrix Derivative

BACKGROUND

Enamel matrix derivative (EMD) has recently been developed for use as a periodontal regenerative treatment. While EMD is believed to induce regeneration of periodontal tissue, the precise mechanism is not known. Bone sialoprotein (BSP), an early phenotypic marker of osteoblast differentiation, has been implicated in the nucleation of hydroxyapatite during bone formation. In this study, we examined the ability of EMD to regulate BSP gene transcription in osteoblast-like cells.

METHODS

To determine the molecular basis of the transcriptional regulation of BSP gene transcription by EMD, we conducted Northern hybridization, transient transfection analyses with chimeric constructs of the rat BSP gene promoter linked to a luciferase reporter gene, and gel mobility shift assays.

RESULTS

Using the osteoblastic cell line ROS 17/2.8, we determined that BSP mRNA levels increased approximately 2.8-fold by EMD. In transient transfection analyses, EMD (50 microg/ml, 12 hours) increased luciferase activities of pLUC4 (nt -425 to +60) and pLUC5 (nt -801 to +60), transfected into ROS 17/2.8 cells. Within the pLUC4 and 5, a homeodomain binding element (HOX) and a transforming growth factor (TGF)-beta activation element (TAE) are present. Gel mobility shift assays with radiolabeled HOX and TAE ds-oligonucleotides revealed increased binding of nuclear proteins from EMD stimulated ROS 17/2.8 cells.

CONCLUSION

These studies have, therefore, identified EMD response elements in the rat BSP gene promoter that may mediates the effects of EMD on BSP gene transcription.

Glutathione regulates transforming growth factor-beta-stimulated collagen production in fibroblasts

Transforming growth factor-beta (TGF-beta) is a potent fibrogenic cytokine. The molecular mechanism underlying TGF-beta fibrogenesis, however, has not been completely elucidated. In this study, we showed that TGF beta decreased the intracellular GSH content in murine embryo fibroblasts (NIH 3T3), which was followed by an increase in collagen I mRNA content and collagen protein production. Prevention of GSH depletion with N-acetylcysteine (NAC), GSH, or GSH ester abrogated TGF-beta-stimulated collagen production, whereas a decrease in intracellular GSH content with L-buthionine-S,R-sulfoximine, an inhibitor of de novo GSH synthesis, enhanced TGF-beta-stimulated collagen production. These results suggest that GSH depletion induced by TGF-beta may mediate TGF-beta-stimulated collagen production. In addition, we showed that TGF-beta stimulated superoxide production and increased release of H2O2 from the cells, whereas GSH ester decreased basal and TGF-beta + glucose oxidase-stimulated H2O2 release. H2O2, exogenously added or continuously generated by glucose oxidase, enhanced TGF-beta-stimulated collagen production, whereas suppression of superoxide production by diphenyliodonium, an NAD(P)H oxidase inhibitor, blocked TGF-beta-stimulated collagen production. These data further suggest that reactive oxygen species are involved in TGF-beta-stimulated collagen production and that the effect of GSH depletion on TGF-beta-stimulated collagen production may be mediated by facilitating reactive oxygen species signaling.

Evolutionary conservation of regulatory elements in vertebrate Hox gene clusters

Comparisons of DNA sequences among evolutionarily distantly related genomes permit identification of conserved functional regions in noncoding DNA. Hox genes are highly conserved in vertebrates, occur in clusters, and are uninterrupted by other genes. We aligned (PipMaker) the nucleotide sequences of the HoxA clusters of tilapia, pufferfish, striped bass, zebrafish, horn shark, human, and mouse, which are separated by approximately 500 million years of evolution. In support of our approach, several identified putative regulatory elements known to regulate the expression of Hox genes were recovered. The majority of the newly identified putative regulatory elements contain short fragments that are almost completely conserved and are identical to known binding sites for regulatory proteins (Transfac database). The regulatory intergenic regions located between the genes that are expressed most anteriorly in the embryo are longer and apparently more evolutionarily conserved than those at the other end of Hox clusters. Different presumed regulatory sequences are retained in either the Aalpha or Abeta duplicated Hox clusters in the fish lineages. This suggests that the conserved elements are involved in different gene regulatory networks and supports the duplication-deletion-complementation model of functional divergence of duplicated genes.

TGF-beta1-induced Smad 3 binding to the Smad 7 gene: knockout of Smad 7 gene transcription by sense phosphorothioate oligos, autoregulation, and effect on TGF-beta1 secretion: bleomycin acts through TGF-beta1

Bleomycin produces its fibrogenic effect, at least in part, by TGF-beta1 secretion. Treatment of IMR-90 human embryonic lung fibroblasts with bleomycin at 0.5 microg/ml results in a 1.6-fold increase of TGF-beta1 as determined by a specific ELISA assay for TGF-beta1 after acidification of the conditioned media. This elevation of TGF-beta1 secretion is furthermore enhanced in vivo by TGF-beta1 autoinduction of the TGF-beta1 gene. To demonstrate TGF-beta1 autoinduction, the fibroblasts were pretreated with 12.5 ng/ml TGF-beta1, washed extensively to remove any residual TGF-beta1, and then allowed to incubate for 24 h in AIM V synthetic serum-free media. The media when assayed using the ELISA assay contained a 1.6-fold increase of TGF-beta1. The distal promoter of the human TGF-beta1 gene contains a Smad 3 element (CAGGACA), which is homologous to the Smad 3 binding element motif (CAGA). The nuclear extracts of human embryonic lung fibroblasts treated for either 15 min or 24 h with TGF-beta1 did not demonstrate specificity of binding of a protein(s) to the homologous Smad 3 element as determined by cold wild-type oligodeoxynucleotide competition experiments. However, specific Smad 3 binding to the Smad 3 element (GTCTAGAC) found in proximal promoter of the Smad 7 gene was observed by cold oligo competition and supershift assays using a goat polyclonal Smad 3 antibody in the presence and absence of an N-terminal Smad 3 peptide. To determine the functionality of this Smad 3 binding to the Smad 3 element in the proximal promoter of the Smad 7 inhibitory gene to TGF-beta1 secretion, fibroblasts were transiently pretransfected with double-stranded phosphorothioate oligo "decoys" containing the Smad 7/Smad 3 element in the presence of plasmin to convert latent TGF-beta1 to active TGF-beta1. Under these conditions, which simulate the in vivo situation of 2.2-fold increase of total active TGF-beta1 was observed. Fibroblasts were also pretransfected with these double-stranded oligo "decoys," washed, then treated with TGF-beta1, washed and incubated in AIM V for an additional 24 h. In this latter experiment, a superinduction of TGF-beta1 secretion was observed. We propose that these oligo "decoys" bind Smad 3 preventing this initiation factor from binding to the Smad 7/Smad 3 element thereby decreasing the transcription of the Smad 7 gene. The decrease of the inhibitory Smad 7 would result in less binding of this Smad inhibitor to the Type I TGF-beta receptor and less antagonism of active TGF-beta1, more autoinduction of the TGF-beta1 gene, and more of the fibrogenic effects of TGF-beta1.