Bone Morphogenetic Protein-Modulator BMPER Regulates Endothelial Barrier Function

The endothelium serves as a selective barrier and controls the exchange of nutrients, hormones, and leukocytes between blood and tissues. Molecular mechanisms contributing to the pathogenesis of endothelial barrier dysfunction remain incompletely understood. Accumulating evidence implicates bone morphogenetic protein (BMP)-modulator BMPER as a key regulator in endothelial biology. Herein, we analyze the impact of BMPER in the control of endothelial barrier function. To assess the role of BMPER in vascular barrier function in mice, we measured the leakage of Evans blue dye from blood into interstitial lung tissue. BMPER^+/? mice exhibited a significantly higher degree of vascular leak compared with wild-type siblings. In accordance with our in vivo observation, siRNA-based BMPER knockdown in human umbilical endothelial cells increased endothelial permeability measured by FITC-dextran passage in transwell assays. Mechanistically, BMPER knockdown reduced the expression of VE-cadherin, a pivotal component of endothelial adherens junctions. Conversely, recombinant human BMPER protein upregulated VE-cadherin protein levels and improved endothelial barrier function in transwell assays. The effects of BMPER knockdown on VE-cadherin expression and endothelial permeability were induced by enhanced BMP activity. Supporting this notion, activation of BMP4-Smad-Id1 signaling reduced VE-cadherin levels and impaired endothelial barrier function in vitro. In vivo, Evans blue dye accumulation was higher in the lungs of BMP4-treated C57BL/6 mice compared to controls indicating that BMP4 increased vascular permeability. High levels of BMPER antagonized BMP4-Smad5-Id1 signaling and prevented BMP4-induced downregulation of VE-cadherin and endothelial leakage, suggesting that BMPER exerts anti-BMP effects and restores endothelial barrier function. Taken together, this data demonstrates that BMPER-modulated BMP pathway activity regulates VE-cadherin expression and vascular barrier function.     

Elevated TGFβ–Smad signalling in experimental Pkd1 models and human patients with polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited renal disease characterized by many fluid‐filled cysts and interstitial fibrosis in the kidneys, leading to chronic renal failure. During cystogenesis the renal tubules undergo extensive structural alterations that are accompanied by altered cellular signalling, directly and/or indirectly regulated by the PKD1 and PKD2 proteins. Since transforming growth factor (TGF)‐β signalling modulates cell proliferation, differentiation, apoptosis, adhesion and migration of various cell types, we studied the activation of this signalling pathway in Pkd1‐mutant mouse models at different stages of the disease. Therefore, we analysed expression of the TGFβ–Smad signalling pathway and its target genes in different Pkd1 mutant mouse models in various stages of polycystic disease. Nuclear accumulation of P‐Smad2 in cyst lining epithelial cells was not observed in the initiation phase but was observed at mild and more advanced stages of PKD. This coincides with mild fibrosis and increased mRNA levels of TGFβ target genes, such as fibronectin, collagen type I, plasminogen activator inhibitor 1 and matrix metalloproteinase‐2. At this stage many interstitial fibroblasts were found around cysts, which also showed nuclear localization for P‐Smad2. However, bone morphogenetic protein (BMP) signalling, which can antagonize TGFβ signalling, is not affected, since nuclear expression of P‐Smad1/5/8 and expression of the BMP target gene, inhibitor of DNA binding/differential‐1 (ID‐1) is not altered compared to wild‐type controls. Also, human kidneys with progressive ADPKD showed increased nuclear localization of P‐Smad2, while in general expression of P‐Smad1/5/8 was weak. These results exclude TGFβ signalling at the initiation of cystogenesis, but indicate an important role during cyst progression and in fibrogenesis of progressive ADPKD. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Essential role for Smad3 in angiotensin II‐induced tubular epithelial–mesenchymal transition

Angiotensin II (Ang II) is a key mediator of chronic kidney disease, in which epithelial–mesenchymal transition (EMT) is a critical process mediated by the TGFβ/Smad signalling pathway. The present study examined the specific role of Smads in Ang II‐induced EMT in vitro and in vivo. We found that Ang II signalled through the receptor of AT1, not AT2, to activate Smad2/3 and induce EMT in a normal rat tubular epithelial cell line (NRK52E). Activation of Smads by Ang II was attributed to degradation of an inhibitory Smad7, which was mediated by the AT1‐Smurf2‐dependent ubiquitin degradation mechanism because blockade of AT1 receptor or knockdown of Smurf2 inhibited Smad7 loss, thereby reducing Smad2/3 activation and EMT in response to Ang II. In contrast, over‐expression of Smad7 inhibited Ang II‐induced Smad2/3 activation and EMT in NRK52E cells and in a rat model of remnant kidney disease. Moreover, knockdown of Smad3, not Smad2, attenuated Ang II‐induced EMT. In conclusion, Ang II activates Smad signalling to induce EMT, which is mediated by a loss of Smad7 through the AT1‐Smurf2‐dependent ubiquitin degradation pathway. Smad3, but not Smad2, may be a mediator of EMT, while Smad7 may play a protective role in EMT in response to Ang II. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Smad-3 as a mediator of the fibrotic response

Introduction Smad‐3, a key cytoplasmic mediator of transforming growth factor‐β (TGF‐β) signalling, mediates many of its inflammatory and fibrotic effects in vivo ( Roberts et al. 2001 ). Smad‐3 null mice are protected against cutaneous injury induced by ionizing irradiation ( Flanders et al. 2002 ). Here, we report on our continuing studies on radioprotection as well as protection against tubulointerstitial fibrosis following unilateral ureteral obstruction (UUO) in Smad‐3 null mice. Methods For radioprotection studies, the flank skin of Smad‐3^+/+ wild‐type (WT) and Smad‐3^–/– knockout (KO) mice was exposed to 30 Gy of localized γ‐irradiation and analysed for histology and gene expression at various times post irradiation. In the UUO model, the right proximal ureter of WT and KO mice was ligated, and 1–2 weeks later kidneys were analysed for inflammation, fibrosis and gene expression. Results Six weeks after exposure to irradiation, skin from KO mice shows less epidermal acanthosis and influx of mast cells, macrophages and neutrophils than skin of WT mice. Paradoxically, at 6–8 h post irradiation, KO skin shows a significantly greater number of neutrophils. Irradiated KO skin also exhibits less immunoreactive TGF‐β, fewer myofibroblasts and less scarring than does WT. Smad‐3 null dermal fibroblasts do not respond to the chemotactic effects of TGF‐β and show less induction of fibrogenic cytokines when treated with irradiation plus TGF‐β compared to WT cells. Following UUO, normal kidney architecture is preserved in KO mice, while kidneys from WT mice are enlarged with an influx of mononuclear cells and increased expression of collagen and TGF‐β1. Additionally, renal tubules in obstructed kidneys of KO mice remain positive for E‐cadherin without expression of α‐smooth muscle actin, while the opposite expression pattern is seen in obstructed kidneys of WT mice. TGF‐β treatment of primary cultures of WT renal tubular epithelial cells results in a phenotypic change from a cobblestone pattern to a spindle‐shaped fibroblastic appearance, while KO cells treated with TGF‐β maintain their original appearance. Conclusion Smad‐3 plays an important role in mediating pathogenic inflammation and fibrosis in several model systems and is also essential for TGF‐β1‐induced epithelial–mesenchymal transition in renal tubular epithelial cells. Inhibitors of the Smad‐3 pathway may have clinical applications in the treatment of a number of fibrotic conditions.     

AMPKα2 reduces renal epithelial transdifferentiation and inflammation after injury through interaction with CK2β

TGFβ1/Smad, Wnt/β‐catenin and snail1 are preferentially activated in renal tubular epithelia after injury, leading to epithelial–mesenchymal transition (EMT). The stress response is coupled to EMT and kidney injury; however, the underlying mechanism of the stress response in EMT remains elusive. AMP‐activated protein kinase (AMPK) signalling is responsive to stress and regulates cell energy balance and differentiation. We found that knockdown of AMPKα, especially AMPKα2, enhanced EMT by up‐regulating β‐catenin and Smad3 in vitro. AMPKα2 deficiency enhanced EMT and fibrosis in a murine unilateral ureteral obstruction (UUO) model. AMPKα2 deficiency also increased the expression of chemokines KC and MCP‐1, along with enhanced infiltration of inflammatory cells into the kidney after UUO. CK2β interacted physically with AMPKα and enhanced AMPKα Thr172 phosphorylation and its catalytic activity. Thus, activated AMPKα signalling suppresses EMT and secretion of chemokines in renal tubular epithelia through interaction with CK2β to attenuate renal injury. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Temporal and spatial regulation of bone morphogenetic protein signaling in late lung development.

Bone morphogenetic proteins (BMPs) play important roles in early lung development. No study to date has addressed a role for BMP signaling in late lung development. We describe changes in the expression and localization of BMP receptors (Bmpr1a, Bmpr1b, and Bmpr2) and Smad (Smad1, Smad4, Smad5, and Smad8) intracellular signaling proteins during the saccular and alveolarization stages of late lung development. BMP signaling, assessed by Smad1/5 phosphorylation, nuclear translocation, and induction of id1, id2, and id3 gene expression, was evident throughout late lung development. Our data indicate that BMP signaling is active during late lung development, and points to roles for the BMP system in septal and vascular development, and in the homeostasis of the epithelial layer of large conducting airways in the mature lung.     

Regulation of bone morphogenetic protein signalling in human pulmonary vascular development

The bone morphogenetic protein (BMP) type II receptor (BMPR-II) is predominantly expressed on the vascular endothelium in the adult lung. Although mutations in BMPR-II are known to underlie many cases of familial pulmonary arterial hypertension (FPAH), little is known regarding the expression of BMPs and their signalling pathways during normal lung development or the impact of BMPR-II mutations on endothelial cell function. We determined the cellular localization and expression levels of BMP4, BMP receptors, and activation of downstream signalling via phospho-Smad1 in a developmental series of human embryonic and fetal lungs by immunohistochemistry. The expression of BMP4 and BMP receptors was temporally and spatially regulated during lung development. BMPR-II expression correlated with phosphorylation of tissue Smad1 and was highest during the late pseudoglandular and early canalicular stage of lung development, when vasculogenesis is intense. Phospho-Smad1 expression was associated with markers of proliferation in endothelial cells. In vitro studies confirmed that BMPs 2 and 4 induced phosphorylation of Smad1/5 and pulmonary artery endothelial cell (PAEC) migration and proliferation. Adenoviral transfection of PAECs with mutant kinase-deficient BMPR-II, or siRNA knockdown of BMPR-II, inhibited Smad signalling and the proliferative response to BMP4. Our findings support a critical role for BMPs in lung vasculogenesis. Dysfunctional BMP signalling in PAECs during development may lead to abnormal pulmonary vascular development and contribute to the pathogenesis of FPAH.     

Fibroblast growth factor 2 decreases bleomycin‐induced pulmonary fibrosis and inhibits fibroblast collagen production and myofibroblast differentiation

Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of pulmonary fibrosis. Mice lacking FGF2 have increased mortality and impaired epithelial recovery after bleomycin exposure, supporting a protective or reparative function following lung injury. To determine whether FGF2 overexpression reduces bleomycin‐induced injury, we developed an inducible genetic system to express FGF2 in type II pneumocytes. Double‐transgenic (DTG) mice with doxycycline‐inducible overexpression of human FGF2 (SPC‐rtTA;TRE‐hFGF2) or single‐transgenic controls were administered intratracheal bleomycin and fed doxycycline chow, starting at either day 0 or day 7. In addition, wild‐type mice received intratracheal or intravenous recombinant FGF2, starting at the time of bleomycin treatment. Compared to controls, doxycycline‐induced DTG mice had decreased pulmonary fibrosis 21 days after bleomycin, as assessed by gene expression and histology. This beneficial effect was seen when FGF2 overexpression was induced at day 0 or day 7 after bleomycin. FGF2 overexpression did not alter epithelial gene expression, bronchoalveolar lavage cellularity or total protein. In vitro studies using primary mouse and human lung fibroblasts showed that FGF2 strongly inhibited baseline and TGFβ1‐induced expression of alpha smooth muscle actin (αSMA), collagen, and connective tissue growth factor. While FGF2 did not suppress phosphorylation of Smad2 or Smad‐dependent gene expression, FGF2 inhibited TGFβ1‐induced stress fiber formation and serum response factor‐dependent gene expression. FGF2 inhibition of stress fiber formation and αSMA requires FGF receptor 1 (FGFR1) and downstream MEK/ERK, but not AKT signaling. In summary, overexpression of FGF2 protects against bleomycin‐induced pulmonary fibrosis in vivo and reverses TGFβ1‐induced collagen and αSMA expression and stress fiber formation in lung fibroblasts in vitro, without affecting either inflammation or epithelial gene expression. Our results suggest that in the lung, FGF2 is antifibrotic in part through decreased collagen expression and fibroblast to myofibroblast differentiation. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Nuclear translocation of β-catenin synchronized with loss of E-cadherin in oral epithelial dysplasia with a characteristic two-phase appearance

Alvarado C G, Maruyama S, Cheng J, Ida‐Yonemochi H, Kobayashi T, Yamazaki M, Takagi R & Saku T
(2011) Histopathology 59 , 283–291 Nuclear translocation of β‐catenin synchronized with loss of E‐cadherin in oral epithelial dysplasia with a characteristic two‐phase appearance Aims: One of the important histopathological characteristics of oral epithelial dysplasia is a two‐phase appearance of rete processes, comprising an upper layer of keratinized cells and a lower layer of basaloid cells, and thereby creating a sharp contrast between these two separate cell populations. The aim of this study was to determine the cellular adhesion status of the basaloid cells. Methods and results: Immunohistochemistry for β‐catenin, E‐cadherin and their related molecules was carried out in surgical specimens of two‐phase epithelial dysplasia of the oral mucosa. The lower‐half basaloid cells and the upper keratinized cells were microdissected separately, and extracted DNA samples were subjected to methylation‐specific polymerase chain reaction amplification for E‐cadherin. β‐Catenin was immunolocalized within the nuclei and cytoplasm of Ki67‐positive lower‐half basaloid cells, as well as on the cell membrane of upper parakeratotic cells. The basaloid cells of the lower‐half were also positive for matrix metalloproteinase‐7 and cyclin D1, β‐catenin target gene products, α‐dystroglycan, tenascin‐C, and perlecan, but not for E‐cadherin. The promoter region of the E‐cadherin gene was hypermethylated. Conclusions: The solid proliferation of lower‐half E‐cadherin‐free basaloid cells is enhanced by Wnt signalling cascades, as well as by the intraepithelial extracellular matrix or its bound growth factors.     

The proximal half of the Drosophila E‐cadherin extracellular region is dispensable for many cadherin‐dependent events but required for ventral furrow formation

The formation of the ventral furrow during Drosophila gastrulation is driven by coordinated apical constriction. Cell–cell adhesion is thought to regulate apical constriction, but the mechanisms are poorly understood. DE‐cadherin, an epithelial classic cadherin, has in its membrane‐proximal extracellular region a suite of domains absent from vertebrate/urochordate classic cadherins. We constructed DEΔP, a DE‐cadherin derivative that lacks the membrane‐proximal half of the extracellular region but retains the entire cytoplasmic domain and still exhibits strong cell–cell binding ability. The extracellular region of DEΔP consists of only cadherin repeats, mimicking vertebrate/urochordate classic cadherins. In animals lacking DE‐cadherin, DEΔP organized adherens junction assembly and functioned fully in many cadherin‐dependent processes, including oogenesis. Embryos in which DE‐cadherin was entirely replaced by DEΔP established the blastoderm epithelium but failed to form a ventral furrow. Apical constrictions were initiated relatively normally but subsequently decelerated. These were then followed by catastrophic disruption of the junctional network. Our results suggest that although the membrane‐proximal half of the DE‐cadherin extracellular region is dispensable for many developmental events, it is essential for efficient and robust apical constriction during ventral furrow formation.     

Dynamic smad‐mediated BMP signaling revealed through transgenic zebrafish

Bone morphogenic protein (BMP) signaling is fundamental to development, injury response, and homeostasis. We have developed transgenic zebrafish that report Smad‐mediated BMP signaling in embryos and adults. These lines express either enhanced green fluorescent protein (eGFP), destabilized eGFP, or destabilized Kusabira Orange 2 (KO2) under the well‐characterized B MP R esponse E lement (BRE). These fluorescent proteins were found to be expressed dynamically in regions of known BMP signaling including the developing tail bud, hematopoietic lineage, dorsal eye, brain structures, heart, jaw, fins, and somites, as well as other tissues. Responsiveness to changes in BMP signaling was confirmed by observing fluorescence after activation in an hsp70:bmp2b transgenic background or by inhibition in an hsp70:nog3 background. We further demonstrated faithful reportage by the BRE transgenic lines following chemical repression of BMP signaling using an inhibitor of BMP receptor activity, dorsomorphin. Overall, these lines will serve as valuable tools to explore the mechanisms and regulation of BMP signal during embryogenesis, in tissue maintenance, and during disease. Developmental Dynamics 240:712–722, 2011. © 2011 Wiley‐Liss, Inc.     

Dynamic analysis of BMP‐responsive smad activity in live zebrafish embryos

Bone morphogenetic proteins (BMPs) are critical players in development and disease, regulating such diverse processes as dorsoventral patterning, palate formation, and ossification. These ligands are classically considered to signal via BMP receptor‐specific Smad proteins 1, 5, and 8. To determine the spatiotemporal pattern of Smad1/5/8 activity and thus canonical BMP signaling in the developing zebrafish embryo, we generated a transgenic line expressing EGFP under the control of a BMP‐responsive element. EGFP is expressed in many established BMP signaling domains and is responsive to alterations in BMP type I receptor activity and smad1 and smad5 expression. This transgenic Smad1/5/8 reporter line will be useful for determining ligand and receptor requirements for specific domains of BMP activity, as well as for genetic and pharmacological screens aimed at identifying enhancers or suppressors of canonical BMP signaling. Developmental Dynamics 240:682–694, 2011. © 2011 Wiley‐Liss, Inc.     

β‐Catenin activation contributes to the pathogenesis of adenomyosis through epithelial–mesenchymal transition

Adenomyosis is defined by the presence of endometrial glands and stroma within the myometrium. Despite its frequent occurrence, the precise aetiology and physiopathology of adenomyosis is still unknown. WNT/β‐catenin signalling molecules are important and should be tightly regulated for uterine function. To investigate the role of β‐catenin signalling in adenomyosis, the expression of β‐catenin was examined. Nuclear and cytoplasmic β‐catenin expression was significantly higher in epithelial cells of human adenomyosis compared to control endometrium. To determine whether constitutive activation of β‐catenin in the murine uterus leads to development of adenomyosis, mice that expressed a dominant stabilized β‐catenin in the uterus were used by crossing PR‐Cre mice with Ctnnb1^f(ex3)/+ mice. Uteri of PR^cre/+ Ctnnb1^f(ex3)/+ mice displayed an abnormal irregular structure and highly active proliferation in the myometrium, and subsequently developed adenomyosis. Interestingly, the expression of E‐cadherin was repressed in epithelial cells of PR^cre/+ Ctnnb1^f(ex3)/+ mice compared to control mice. Repression of E‐cadherin is one of the hallmarks of epithelial–mesenchymal transition (EMT). The expression of SNAIL and ZEB1 was observed in some epithelial cells of the uterus in PR^cre/+ Ctnnb1^f(ex3)/+ mice but not in control mice. Vimentin and COUP‐TFII, mesenchymal cell markers, were expressed in some epithelial cells of PR^cre/+ Ctnnb1^f(ex3)/+ mice. In human adenomyosis, the expression of E‐cadherin was decreased in epithelial cells compared to control endometrium, while CD10, an endometrial stromal marker, was expressed in some epithelial cells of human adenomyosis. These results suggest that abnormal activation of β‐catenin contributes to adenomyosis development through the induction of EMT. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

E‐cadherin: From epithelial glue to immunological regulator

E‐cadherin is best known as a central molecule in adherens junctions, joining adjacent epithelial cells together, thereby safeguarding epithelial barrier function. However, recent findings have uncovered an immunological role for this adhesion molecule, linked to its expression in dendritic cells (DCs) and alternatively activated macrophages (MPHs) and its impact on intracellular signaling pathways. In this respect, E‐cadherin has been shown to influence the immunogenicity/tolerogenicity of DCs through the regulation of β‐catenin functionality. For Langerhans cells (LCs), the DC type found in the skin epidermis, E‐cadherin is known to mediate interactions with keratinocytes (KCs), thereby immobilizing immature LCs in the epidermis and preventing their maturation. In this issue of the European Journal of Immunology, a study by Mayumi et al. [Eur. J. Immunol. 2013. 43: 270–280] now describes a role for E‐cadherin in the final steps of LC differentiation from human peripheral blood monocytes. Although TGF‐β induces LC‐like cells, these intermediates still express the dermal DC marker DC‐SIGN along with Langerin; E‐cadherin ligation is sufficient to induce the full LC phenotype in these cells. Here, we place these findings in the context of current knowledge and propose new avenues for future research.     

Diverse roles of TGF-β receptor II in renal fibrosis and inflammation in vivo and in vitro

TGF-β1 binds receptor II (TβRII) to exert its biological activities but its functional importance in kidney diseases remains largely unclear. In the present study, we hypothesized that TβRII may function to initiate the downstream TGF-β signalling and determine the diverse role of TGF-β1 in kidney injury. The hypothesis was examined in a model of unilateral ureteral obstructive (UUO) nephropathy and in kidney fibroblasts and tubular epithelial cells in which the TβRII was deleted conditionally. We found that disruption of TβRII inhibited severe tubulointerstitial fibrosis in the UUO kidney, which was associated with the impairment of TGF-β/Smad3 signalling, but not with the ERK/p38 MAP kinase pathway. In contrast, deletion of TβRII enhanced NF-κB signalling and renal inflammation including up-regulation of Il-1β and Tnfα in the UUO kidney. Similarly, in vitro disruption of TβRII from kidney fibroblasts or tubular epithelial cells inhibited TGF-β1-induced Smad signalling and fibrosis but impaired the anti-inflammatory effect of TGF-β1 on IL-1β-stimulated NF-κB activation and pro-inflammatory cytokine expression. In conclusion, TβRII plays an important but diverse role in regulating renal fibrosis and inflammation. Impaired TGF-β/Smad3, but not the non-canonical TGF-β signalling pathway, may be a key mechanism by which disruption of TβRII protects against renal fibrosis. In addition, deletion of TβRII also enhances NF-κB signalling along with up-regulation of renal pro-inflammatory cytokines, which may be associated with the impairment of anti-inflammatory properties of TGF-β1.     

The small heat‐shock protein αB‐crystallin is essential for the nuclear localization of Smad4: impact on pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by the proliferation of myofibroblasts and the accumulation of extracellular matrix (ECM) in the lungs. TGF‐β1 is the major profibrotic cytokine involved in IPF and is responsible for myofibroblast proliferation and differentiation and ECM synthesis. αB‐crystallin is constitutively expressed in the lungs and is inducible by stress, acts as a chaperone and is known to play a role in cell cytoskeleton architecture homeostasis. The role of αB‐crystallin in fibrogenesis remains unknown. The principal signalling pathway involved in this process is the Smad‐dependent pathway. We demonstrate here that αB‐crystallin is strongly expressed in fibrotic lung tissue from IPF patients and in vivo rodent models of pulmonary fibrosis. We also show that αB‐crystallin‐deficient mice are protected from bleomycin‐induced fibrosis. Similar protection from fibrosis was observed in αB‐crystallin KO mice after transient adenoviral‐mediated over‐expression of IL‐1β or TGF‐β1. We show in vitro in primary epithelial cells and fibroblasts that αB‐crystallin increases the nuclear localization of Smad4, thereby enhancing the TGF‐β1–Smad pathway and the consequent activation of TGF‐β1 downstream genes. αB‐crystallin over‐expression disrupts Smad4 mono‐ubiquitination by interacting with its E3–ubiquitin ligase, TIF1γ, thus limiting its nuclear export. Conversely, in the absence of αB‐crystallin, TIF1γ can freely interact with Smad4. Consequently, Smad4 mono‐ubiquitination and nuclear export are favoured and thus TGF‐β1–Smad4 pro‐fibrotic activity is inhibited. This study demonstrates that αB‐crystallin may be a key target for the development of specific drugs in the treatment of IPF or other fibrotic diseases. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

龟板促进Parkinson病大鼠黑质骨形态发生蛋白信号分子的表达

为了进一步探讨骨形态发生蛋白(BMP)/分化抑制因子(Id)通路在龟板抗PD大鼠多巴胺能神经元凋亡中的作用,本实验用6-羟基多巴胺(6-OHDA,0.2%)于大鼠左侧黑质致密带注射2μl造成PD模型,设立正常对照组、模型组和龟板组,用免疫组织化学染色方法观察PD大鼠中脑黑质骨形态发生蛋白IB受体(BMPR-IB),Smad8和Id1阳性细胞数目;用Western-blotting检测BMPR-IA、BMPR-IB、BMPR-Ⅱ、Smad1、Smad5、Smad8和Id1蛋白表达水平的变化。免疫组化染色显示龟板组PD大鼠中脑黑质BMPR-IB,Smad8和Id1的阳性细胞数明显多于模型组(P<0.05)。Western-blotting结果显示龟板组PD大鼠中脑黑质BM-PR-IB,Smad8和Id1的蛋白表达水平高于模型组,而BMPR-IA,BMPR-Ⅱ,Smad1和Smad5没有被检测出。以上结果表明龟板能上调6-OHDA诱导的PD大鼠中脑黑质BMPR-IB,Smad8和Id1的表达,这可能是其抗PD大鼠多巴胺能神经元凋亡的分子机制。