Leukotriene D4-induced, epithelial cell-derived transforming growth factor β1 in human bronchial smooth muscle cell proliferation

Background Cysteinyl‐leukotrienes (cys‐LTs) orchestrate many pathognomonic features of asthma in animal models of allergic airway inflammation, including bronchial smooth muscle cell (BSMC) hyperplasia. However, because cys‐LTs alone do not induce mitogenesis in monocultures of human BSMC, the effect observed in vivo seemingly involves indirect mechanisms, which are still undefined. Objective This study aims to investigate the regulatory role of leukotriene (LT)D₄ on TGF‐β1 expression in airway epithelial cells and the consequence of this interplay on BSMC proliferation. Methods HEK293 cells stably transfected with cys‐LT receptor 1 (CysLT1) (293LT1) were stimulated with LTD₄ and TGF‐β1 mRNA and protein expression was measured using Northern blot and ELISA, respectively. Conditioned medium (CM) harvested from LTD₄‐treated cells was then assayed for its proliferative effect on primary human BSMC. TGF‐β1 mRNA expression was also determined in tumoural type II pneumocytes A549 and in normal human bronchial epithelial cells (NHBE) following LTD₄ stimulation. Results The results demonstrated that LTD₄‐induced TGF‐β1 mRNA production in a time‐ and concentration‐dependent manner in 293LT1. TGF‐β1 secretion was also up‐regulated and CM from LTD₄‐treated 293LT1 was shown to increase BSMC proliferation in a TGF‐β1‐dependent manner. The increased expression of TGF‐β1 mRNA by LTD₄ also occured in A549 and NHBE cells via a CysLT1‐dependent mechanism. Conclusion In conclusion, elevated expression of cys‐LTs in asthmatic airways might contribute to BSMC hyperplasia and concomitant clinical features of asthma such as airway hyperresponsiveness via a paracrine loop involving TGF‐β1 production by airway epithelial cells.     

转化生长因子β1对乳鼠心肌细胞转化生长因子结合蛋白2表达的影响

 目的：探讨转化生长因子β1（TGF-β1）在诱导心肌细胞表达转化生长因子结合蛋白2（LTBP2）中的作用及信号传导通路。 方法：培养乳鼠心肌细胞;实时定量聚合酶链式反应（Real-time PCR）、蛋白质印迹和免疫细胞化学方法检测不同时间和不同浓度的TGF-β1对大鼠乳鼠心肌细胞LTBP2基因及蛋白表达的影响;用TGF-β1相关信号通路阻断剂探讨TGF-β1调节LTBP2表达改变的信号传导机制。 结果：LTBP2基因表达随着TGF-β1浓度增加（0、2、5、10 ng/mL）而明显升高,在5 ng/mL时刺激最强（P < 0.05）;5 ng/mL的TGF-β1刺激下心肌细胞内LTBP2基因和蛋白表达的升高呈时间依赖性,均在12 h最高,24 h开始呈下降趋势（P < 0.05或P<0.01）;免疫细胞化学结果显示TGF-β1明显升高LTBP2的表达。信号传导通路研究显示TGF-β1在心肌细胞内主要通过ERK信号通路和PI3K信号通路诱导LTBP2的表达。 结论：TGF-β1在乳鼠心肌细胞内通过ERK信号通路和PI3K信号通路上调LTBP2的表达。     

Effect of transforming growth factor beta 1 on neonatal rat latent transforming growth factor beta binding protein 2 in cardiomyocytes

目的 探讨转化生长因子β1 (TGF-β1)在诱导心肌细胞表达转化生长因子结合蛋白2(LTBP2)中的作用及信号传导通路.方法 培养乳鼠心肌细胞;实时定量聚合酶链式反应、蛋白质印迹和免疫细胞化学方法检测不同时间和不同浓度的TGF-β1对大鼠乳鼠心肌细胞LTBP2基因及蛋白表达的影响;用TGF-β1相关信号通路阻断剂探讨TGF-β1调节LTBP2表达改变的信号传导机制.结果 LTBP2基因表达随着TGF-β1浓度增加(0、2、5及10 μg/L)而明显升高,在5μg/L时刺激最强(P＜0.05);5μg/L的TGF-β1刺激下心肌细胞内LTBP2基因和蛋白表达的升高呈时间依赖性,均在12 h最高,24 h开始呈下降趋势(P＜0.05或P＜0.01);免疫细胞化学结果显示TGF-β1明显升高LTBP2的表达.信号传导通路研究显示TGF-β1在心肌细胞内主要通过ERK信号通路和PI3K信号通路诱导LTBP2的表达.结论TGF-β1在乳鼠心肌细胞内通过ERK信号通路和PI3K信号通路上调LTBP2的表达.     

Fibroblast growth factor 2 modulates transforming growth factor beta signaling in mouse embryonic fibroblasts and human ESCs (hESCs) to support hESC self-renewal.

Fibroblast growth factor 2 (FGF2) is known to promote self-renewal of human embryonic stem cells (hESCs). In addition, it has been shown that transforming growth factor beta (TGFbeta) signaling is crucial in that the TGFbeta/Activin/Nodal branch of the pathway needs to be activated and the bone morphogenic protein (BMP)/GDF branch repressed to prevent differentiation. This holds particularly true for Serum Replacement-based medium containing BMP-like activity. We have reinvestigated a widely used protocol for conditioning hESC medium with mouse embryonic fibroblasts (MEFs). We show that FGF2 acts on MEFs to release supportive factors and reduce differentiation-inducing activity. FGF2 stimulation experiments with supportive and nonsupportive MEFs followed by genome-wide expression profiling revealed that FGF2 regulates the expression of key members of the TGFbeta pathway, with Inhba, Tgfb1, Grem1, and Bmp4 being the most likely candidates orchestrating the above activities. In addition, restimulation experiments in hESCs combined with global expression analysis revealed downstream targets of FGF2 signaling in these cells. Among these were the same factors previously identified in MEFs, thus suggesting that FGF2, at least in part, promotes self-renewal of hESCs by modulating the expression of TGFbeta ligands, which, in turn, act on hESCs in a concerted and autocrine manner.     

Fibroblast growth factor-1-induced ERK1/2 signaling reciprocally regulates proliferation and smooth muscle cell differentiation of ligament-derived endothelial progenitor cell-like cells

The periodontal ligament (PDL) is a fibrous connective tissue located between the tooth root and the alveolar bone. We previously demonstrated that a single cell-derived culture of primarily cultured PDL fibroblasts has the potential to construct an endothelial cell (EC) marker-positive blood vessel-like structure, suggesting that the fibroblastic lineage cells in ligament tissue could act as the endothelial progenitor cells (EPCs), which regenerate to construct a vascular system around the damaged ligament tissue. Moreover, we showed that EPC-like fibroblasts expressed not only EC markers but also smooth muscle cell (SMC) markers. Generally, an interaction between ECs and SMCs regulates blood vessel development and remodeling, and is required for the formation of a mature and functional vascular network. However, the mechanism underlying the SMC differentiation of the ligament-derived EPC-like fibroblasts remains to be clarified. In this study, we showed that suppression of fibroblast growth factor 1 (FGF-1)-induced extracellular signal-regulated kinase 1/2 (ERK1/2) signaling with the MAPK/ERK kinase (MEK) inhibitor U0126 completely abolished the FGF-1-induced proliferation of the ligament-derived EPC-like fibroblasts. In addition, U0126 treatment of FGF-1-stimulated ligament-derived EPC-like fibroblasts significantly induced the SMC differentiation of the cells. Thus, FGF-1-induced ERK1/2 signaling not only promoted the proliferation of the ligament-derived EPC-like fibroblasts, but also suppressed the SMC differentiation of the cells, suggesting that FGF-1 controls the construction of a vascular network around the ligament tissue by regulating the proliferation and SMC differentiation of the EPC-like cells through ERK-mediated signaling.     

Expression of transforming growth factor beta1 and its receptors in normal human urothelium and human transitional cell carcinomas

Previous studies indicated that transforming growth factor beta1 (TGFbeta1) is expressed by normal urothelial cells and exerts regulatory autocrine functions in urothelial maintenance and wound healing. However, little is known about the expression patterns of TGFbeta1 and its receptors in bladder tumors. Therefore, we studied the protein and mRNA localization of TGFbeta1 and TGFbeta receptor types I and II (TGFbetaRI and TGFbetaRII) in normal human urothelium and transitional cell carcinomas (TCCs) of different grades and stages. Expression of TGFbeta1 and its receptors was examined by immunocytochemistry and mRNA in situ hybridization in normal urothelium and TCCs using a semiquantitative method. By immunocytochemistry, the expression of TGFbeta1 and TGFbetaRII was higher in superficial and basal cell layers of normal urothelium than in the intermediate layer. A similar localization was seen in superficial TCCs. TGFbetaRI was mainly present in basal and intermediate cell layers of normal urothelium and superficial TCCs. In contrast, in muscle invasive TCCs, all tumor cells stained intensely for all three proteins. No correlation was found between immunostaining and TCC grade. In situ hybridization pointed out that all cell layers in normal urothelium exhibit similar TGFbeta1 mRNA levels. Elevated TGFbeta1 mRNA levels were noted in TCCs irrespective of grade or stage. In conclusion, these data indicate that in normal urothelium TGFbeta1, TGFbetaRI, and TGFbetaRII expression depend on maturation and differentiation. This pattern is particularly lost in muscle invasive TCCs, in which the expression of the three proteins is enhanced. These data suggest autocrine TGFbeta1 mechanisms in human TCC cells that may be more pronounced in muscle invasive TCC cells.     

Two novel polymorphisms in the human transforming growth factor beta 2 gene

We have identified two novel polymorphisms in the transforming growth factor beta 2 (TGFbeta2) gene; an insertion in the 5'-untranslated region (5'UTR) and a single nucleotide polymorphism (SNP) in exon 1. A 895-bp fragment was analysed covering part of the 5'UTR and exon 1. Single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR) products was performed to detect sequence variations. This was followed by the sequencing of samples demonstrating distinct banding patterns. A 4-bp insertion (ACAA) in the 5'UTR and a SNP (G > A) within exon 1 was identified. The 5'UTR polymorphism was found to be common in three Caucasian populations from Spain, Turkey and the UK. Exon 1 polymorphism is rare and results in an R to H amino acid substitution in codon 91. Both polymorphisms may prove useful for investigating possible associations of TGFbeta2 with disease.     

转化生长因子β1对横纹肌肉瘤RD细胞系的生长调节及机制探讨

目的 研究转化生长因子(TGF)-β1对横纹肌肉瘤RD细胞系的生长调节及作用机制。方法^3H-thymidine掺入实验、四甲基偶氮唑盐(MTT)实验和生长曲线检测经TGF-β1处理不同时间的RD细胞生长活力的变化;应用流式细胞术榆测RD细胞周期的改变;激光扫描共聚焦显微镜观察细胞周期抑制蛋白p15、p21和p27在RD中分布的变化;逆转录一聚合酶链反应(RT-PCR)和Western bolt检测RD细胞中细胞周期抑制蛋白P15、p21、p27mRNA和蛋白水平的变化：结果TGF-β1处理RD细胞后,其牛长活力明显降低,并出现G1期停滞。p21,p27在mRNA和蛋白水平表达上升,且p21南胞核表达改变为胞核胞质内均有表达。p15在mRNA和蛋白水平上均无明显改变。结论 TGF-β1对RD细胞具有生长抑制作用,促使细胞G1期停滞。TGF-β1可在mRNA和蛋白水平上调RD细胞中p21、p27的表达。TGF-β1可能通过上调p2和p27而非p15抑制RD细胞生长。     

Fibroblast growth factor 2-stimulated proliferation is lower in muscle precursor cells from old rats

In aged skeletal muscle, impairments in regrowth and regeneration may be explained by a decreased responsiveness of muscle precursor cells (MPCs) to environmental cues such as growth factors. We hypothesized that impaired responsiveness to fibroblast growth factor 2 (FGF2) in MPCs from old animals would be explained by impaired FGF2 signalling. We determined that 5-bromo-2'-deoxyuridine (BrdU) incorporation and cell number increase less in MPCs from 32- compared with 3-month-old rats. In the presence of FGF2, we demonstrated that there were age-associated differential expression patterns for FGF receptor 1 and 2 mRNAs. Measurement of downstream signalling revealed that that mitogen-activated protein kinase/ERK kinase 1/2 (MEK1/2)–extracellular signal-regulated kinase 1/2, protein kinase C and p38 were FGF2-driven pathways in MPCs. Uniquely, protein kinase C signalling was shown to play the largest role in FGF2-stimulated proliferation in MPCs. c-Jun N-terminal kinase (JNK) signalling was ruled out as an FGF2-stimulated proliferation pathway in MPCs. Inhibition of JNK had no effect on FGF2 signalling to BrdU incorporation, and FGF2 treatment was associated with increased phosphorylation of p38, which inhibits, rather than stimulates, BrdU incorporation in MPCs. Surprisingly, the commonly used vehicle, dimethyl sulphoxide, rescued proliferation in MPCs from old animals. These findings provide insight for the development of effective treatment strategies that target the age-related impairments of MPC proliferation in old skeletal muscle.     

Collagen synthesis of human arterial smooth muscle cells: Effects of platelet-derived growth factor,transforming growth factor-β1 and interleukin-1

The effects of platelet-derived growth factor (PDGF), transforming growth factor-β1 (TGF-β1) and interleukin-1 (IL-1) on collagen synthesis of cultured human arterial smooth muscle cells in a confluent state were investigated. Synthetic activity of collagenous protein was determined with [³H]-proline uptake, and subsequent analysis of collagen types by sodium dodecylsulfte-polyacrylmide gel electrophoresis (SDS-PAGE) followed by fluorography. Although PDGF (0.5 U/mL and 5.0 U/mL) enhanced total collagen synthesis per dish, it suppressed total collagen synthesis per DNA (DNA content in a dish). TGF-β1 (10 pmol/L and 100 pmol/L) enhanced total collagen synthesis both per dish and per DNA. IL-1 (0.1 U/mL and 1.0 U/mL) suppressed total collagen synthesis both per dish and per DNA. A fluorogram revealed that human arterial smooth muscle cells synthesize types I, III, IV and V collagen. Densitometric analysis showed PDGF suppressed the proportion of type V collagen. TGF-β1 increased the proportions of types IV and V collagen. IL-1 elicited un-remarkable change in the proportion of collagen types. These results suggest that, in the event of human atherosclerosis, TGS-β1 is most effective in enhancing collagen synthesis, and PDGF modulates collagen metabolism by stimulating a cell division of smooth muscle cells with a resultant increase of collagenous protein, especially of type V collagen.     

Fibroblast growth factor 9 signaling inhibits airway smooth muscle differentiation in mouse lung

In mammalian lungs, airway smooth muscle cells (airway SMCs) are present in the proximal lung adjacent to bronchi and bronchioles, but are absent in the distal lung adjacent to terminal sacs that expand during gas exchange. Evidence suggests that this distribution is essential for the formation of a functional respiratory tree, but the underlying genetic mechanism has not been elucidated. In this study, we test the hypothesis that fibroblast growth factor 9 (Fgf9) signaling is essential to restrict SMC differentiation to the proximal lung. We show that loss of Fgf9 or conditional inactivation of Fgf receptors (Fgfr) 1 and 2 in mouse lung mesenchyme results in ectopic SMCs. Our data support a model where FGF9 maintains a SMC progenitor population by suppressing differentiation and promoting growth. This model also represents our findings on the genetic relationship between FGF9 and sonic hedgehog (SHH) in the establishment of airway SMC pattern. Developmental Dynamics 238:123–137, 2009. © 2008 Wiley‐Liss, Inc.     

Differential regulation of mouse B cell development by transforming growth factor beta1

Transforming growth factor beta (TGFbeta) can inhibit the in vitro proliferation, survival and differentiation of B cell progenitors, mature B lymphocytes and plasma cells. Here we demonstrate unexpected, age-dependent reductions in the bone marrow (BM) B cell progenitors and immature B cells in TGFbeta1-/- mice. To evaluate TGFbeta responsiveness during normal B lineage development, cells were cultured in interleukin 7 (IL7) +/- TGFbeta. Picomolar doses of TGFbeta1 reduced pro-B cell recoveries at every timepoint. By contrast, the pre-B cells were initially reduced in number, but subsequently increased compared to IL7 alone, resulting in a 4-fold increase in the growth rate for the pre-B cell population. Analysis of purified BM sub-populations indicated that pro-B cells and the earliest BP1- pre-B cells were sensitive to the inhibitory effects of TGFbeta1. However, the large BP1+ pre-B cells, although initially reduced, were increased in number at days 5 and 7 of culture. These results indicate that TGFbeta1 is important for normal B cell development in vivo, and that B cell progenitors are differentially affected by the cytokine according to their stage of differentiation.     

ET-1和bFGF促进大鼠血管平滑肌细胞增殖的协同作用及其机制研究

目的:观察碱性成纤维细胞生长因子(bFGF)和内皮素-1(ET-1)促进血管平滑肌细胞(VSMC)增殖的协同作用,并进一步研究可能的机制。方法:5-溴-2’-脱氧尿嘧啶(BrdU)掺入法和细胞计数法观察对VSMC增殖的影响,Western免疫印迹法观察ET-1对VSMCbFGF和成纤维细胞生长因子受体-1(FGFR-1)蛋白表达的影响。结果:bFGF和ET-1能协同促进VSMCBrdU掺入和细胞增多,并且在一定剂量和时间范围内呈量效、时效关系。同时ET-1剂量依赖性上调bFGF和FGFR-1蛋白,表达高峰分别为24和48h,二丁酸佛波脂(PDBU)预耗竭细胞内蛋白激酶C(PKC)后该上调作用显著下降。结论:bFGF和ET-1对VSMC增殖具有协同作用,与ET-1上调bFGF和FGFR-1蛋白有关,上调作用呈PKC依赖性。     

蛇床子素干预人增生性瘢痕成纤维细胞增殖及转化生长因子β1的表达

背景：蛇床子素对体外培养人增生性瘢痕成纤维细胞增殖和细胞分泌的转化生长因子β1有抑制作用,但其具体作用机制尚待进一步研究。 目的：体外观察蛇床子素对人增生性瘢痕成纤维细胞增殖以及对细胞转化生长因子β1的影响。 方法：体外原代培养人增生性瘢痕成纤维细胞,以不同浓度的蛇床子素作用于成纤维细胞,观察细胞形态的变化,应用MTT法和生长曲线法检测蛇床子素对细胞增殖活性的影响。免疫组织化学检测细胞转化生长因子β1的表达。 结果与结论：蛇床子素能明显抑制人增生性瘢痕成纤维细胞的生长。MTT法检测的IC50为(15.2±2.0) μmol/L,可以明显下调细胞转化生长因子β1的表达(P < 0.05)。说明蛇床子素对人增生性瘢痕成纤维细胞有很强的生长抑制作用并可以下调转化生长因子β1的表达。