原肌球蛋白1在大鼠肝纤维化模型及肝星状细胞中的动态表达及其意义

目的 观察原肌球蛋白1 (TPMl)在大鼠肝纤维化模型及肝星状细胞(HSC)中的动态表达.方法 将SD大鼠随机分为正常对照组(6只)和模型组(24只).二甲基亚硝胺腹腔注射建立大鼠肝纤维化模型,于第2、4、6、8周(每组各6只)门静脉采血及取肝组织标本; HSC-T6细胞设对照组及刺激组,刺激组以5 ng/ml转化生长因子β 1(TGF β 1)作用48h.苏木素-伊红和Masson染色观察肝组织病理变化,RT-PCR、免疫组织化学和Western blot检测组织与细胞中TPMl,TGF β1及α平滑肌肌动蛋白(α-SMA)的mRNA和蛋白的表达,以及TPMl在肝组织中的定位.两样本均数比较采用独立样本t检验;相关性采用Pearson直线相关分析.结果 成功建立肝纤维化模型,TPMl在正常肝组织中低表达于汇管区血管内皮上,在模型组TPMl强表达于增生的肝纤维间隔,TPMl及α-SMA的mRNA及蛋白的表达在肝纤维化过程中均逐渐升高,6周时高于其他各组,8周时下降,与对照组相比,差异均有统计学意义(P＜ 0.05);TGF β 1先升高,4周时高于其他各组,6周时下降(P＜0.05);相关性分析表明TPMl与o-SMA和TGF β 1的表达均呈正相关(rs=0.688和rs=0.692,P＜0.01); HSC-T6细胞中,TGF β 1刺激组TPM1及α- SMA的mRNA表达均升高,差异有统计学意义(P＜0.05).结论 TPMl参与了肝纤维化的发生和发展过程,有望成为肝纤维化诊断与治疗的新靶点.     

灵芪蠲肝胶囊对大鼠肝星状细胞JAK/STAT信号通路的影响

目的 分析不同浓度的灵芪蠲肝胶囊含药血清对血小板源性生长因子(PDGF)诱导的大鼠肝星状细胞-T6 (HSC-T6)增殖和酪氨酸激酶2(JAK2)、磷酸化的信号传导与转录活化因子3(p-STAT3)蛋白量表达的影响及可能的调控机制. 方法 SD大鼠25只,随机分为5组:正常血清对照组(A组)、复方鳖甲软肝片(B组)、灵芪蠲肝胶囊小剂量组(C1组)、灵芪蠲肝胶囊中剂量组(C2组)、灵芪蠲肝胶囊大剂量组(C3组),药物灌胃7d,经腹主动脉采血,制备含药血清.将各组含药血清分别作用于10 ng/ml PDGF刺激的HSC-T6,24、48、72 h后用CCK-8法测定各组HSC-T6的吸光度值,免疫印迹法检测24 h时各组细胞中JAK2、p-STAT3蛋白量的表达.各组重复测量的数据采用重复测量的方差分析,各组间比较用单因素方差分析,多样本均数两两比较用SNK-q检验.结果 与A组比较,C2、C3组SD大鼠药物血清在24、48、72h均可明显抑制HSC-T6的增殖,根据重复测量的方差分析,F=36.292,P值均＜0.05,差异均有统计学意义.C1组24 h吸光度值为1.522±0.128,与A组24h的吸光度值1.550±0.065比较,P＞0.05,差异无统计学意义;C1组48、72 h可抑制HSC-T6增殖,吸光度值分别为1.153±0.183、0.753±0.210,与A组48、72 h的吸光度值1.311±0.650和1.039±0.103比较,F=36.292,p值均＜0.05,差异均有统计学意义.与A组比较,24 h时C1、C2、C3各组HSC-T6中JAK2、p-STAT3蛋白表达量均明显减少.结论 灵芪蠲肝胶囊能抑制PDGF诱导的HSC-T6增殖,且作用呈剂量依赖性;同时能降低JAK2、p-STAT3在活化的HSC-T6中的表达,阻碍JAK/STAT信号通路的传导,发挥抗肝纤维化作用.     

外源性转化生长因子β3对HSC-T6细胞内源性转化生长因子β3表达的影响

目的 通过对大鼠肝星状细胞株(HSC-T6)中内源性转化生长因子β3 (TGF- β 3)mRNA和蛋白水平的检测,探讨外源性TGF- β 3对HSC-T6分泌内源性TGF-β3的影响.方法 体外培养HSC-T6,未加入外源性TGF-β 3培养的细胞为对照组,加入外源性TGF-β 3(10 ng/ml)培养的细胞为TGF-β 3组.(1)分别在l、2、4、12h和24h收集细胞,用实时荧光定量PCR法检测内源性TGF-β 3 mRNA表达;(2)分别在0、l、6h和12h收集细胞,用Western blot法检测细胞内TGF-β 3蛋白的表达;(3)分别在0、1、2、4、8、14h和24h收集细胞上清液,用酶联免疫吸附法(ELISA)检测细胞外总TGF-β 3蛋白的表达;加入外源性TGF-β 3培养HSC-T6 2 h,然后换用无血清的DMEM培养液继续培养细胞至2.25、2.5、3、4、6、10h和14h收集细胞上清液,用ELISA法检测细胞外内源性TGF-β 3蛋白的表达.对数据进行单因素方差分析.结果 (1)TGF-β 3组细胞内TGF-β 3 mRNA表达水平明显增高,于2h达峰值(2.796±0.518),为对照组(1.022±0.038)的2.74倍(P＜0.05);随后缓慢降低,维持在1.45倍水平达10h,24h时表达水平仍为对照组的1.18倍(P＜0.05).(2)不同时间点细胞内TGF-β3表达水平均无明显变化(P＞0.05).(3) TGF-β 3组细胞外总TGF-β 3含量明显增加,于4h时达高峰[(18.931±2.904)ng/ml],约为诱导量[(10.026±0.022) ng/ml]的1.89倍,随后开始下降;内源性TGF-β 3于诱导后3h达高峰[(0.835±0.027) ng/ml],为对照组[(0.026±0.022) ng/ml]的32.12倍,之后开始逐渐降低,直至维持一个弱增长的状态(P＜ 0.05).结论 外源性TGF-β 3可促进HSC-T6细胞分泌大量内源性TGF-β3.     

转化生长因子β1及基质金属蛋白酶抑制剂1、2siRNA真核表达载体的构建与鉴定

目的 用RNA干扰技术,分别以转化生长因子(TGF)β 1、基质金属蛋白酶抑制剂(TIMP)-1和TIMP-2为靶基因,设计并构建针对TGF β 1、TIMP-1和TIMP-2基因的小干扰RNA(siRNA)真核表达载体,并在体外检测其对大鼠肝星状细胞株(HSC-T6)的TGF β 1、TIMP-1和TIMP-2基因表达的抑制情况.方法 设计合成TGF β 1、TIMP-1和TIMP-2的siRNA并与含绿色荧光蛋白的pGenesil-1载体连接,构建siRNA真核表达载体,并测序鉴定.体外转染HSC-T6细胞,观察转染效率,并用荧光定量PCR以及Western blot分析对目的 基因的抑制效率.组间比较用方差分析,两两比较用q检验.结果 成功构建了针对TGF β 1、TIMP-1和TIMP-2基因的siRNA真核表达载体.体外成功转染HSC-T6细胞,转染后的细胞TGF β 1、TIMP-1及TIMP-2 mRNA表达分别下调63.4%±8.0%,64.5%±9.0%,55.0%±17.0%(F值分别为17.55、128.42、210.36,P值均＜0.01),TGF β 1、TIMP-1及TIMP-2蛋白表达分别下降57.8%±3.0%,55.1%±5.0%,49.3%±1.0%(F值分别为130.75、159.09、35.72,P值均＜0.01).结论 成功构建了针对TGF β 1、TIMP-1和TIMP-2基因的siRNA真核表达载体;将重组载体成功转染入体外培养的HSC-T6细胞,并显著抑制了目的 基因的表达;为进一步研究其在体抑制表达提供了实验工具.

Abstract：

Objective To construct the siRNA eukaryotic expression vectors targeting on TGF β1,TIMP-1 and TIMP-2 and to investigate the inhibitory efficiency of target genes expression on rat hepatic stellate cell in vitro. Methods The siRNA cDNA sequences ofTGF β 1, TIMP-1 and TIMP-2 were designed,synthesized and inserted into plasmid pGenesil-1 respectively to generate eukaryotic expression plasmids.The plasmids were transfected into HSC T6 cells in vitro and the inhibitory efficiency of target genes expression was observed with real-time PCR and Western blot. Results The eukaryotic expression vectors were constructed successfully. The expressions of TGF β1 mRNA, TIMP-1 mRNA and TIMP-2mRNA in siRNAtransfected groups were decreased by 63.4% ± 8.0%, 64.5% ± 9.0% and 55.0% ± 17.0% respectively and the expressions of TGF β1 protein, TIMP-1 protein and TIMP-2 protein were decreased by 57.8% ± 3.0%,55.1% ± 5.0%, 49.3% ± 1.0% respectively as compared to the control groups. Conclusions The siRNA eukaryotic expression vectors constructed targeting on TGF β1, TIMP-1 and TIMP-2 could reduce the expressions of target genes and they might be able to used for the exploration of new anti-fibrosis drugs genetically.     

干扰素α对Ⅰ型胶原及转化生长因子β1基因表达的影响

目的 观察干扰素α(IFN α)对血小板衍生生长因子-BB(PDGF-BB)刺激的大鼠肝星状细胞(HSC)分泌Ⅰ型胶原及转化生长因子β1(TGF β1)基因表达的影响,探讨IFN α抗肝纤维化的可能机制.方法 体外培养大鼠HSC系rHSC-99,分别用0、0.0125、0.0250、0.0500,0.1000、0.2000,0.4000 ng/ml IFN α,PDGF-BB干预和两者共同干预,用四甲基偶氮唑盐实验观察各组对HSC细胞活力的影响,采用逆转录聚合酶链反应方法测定各组对HSC细胞Ⅰ型胶原mRNA和TGF β1 mRNA表达的影响.结果 (1)HSC细胞活力(A值)PDGF-BB干预组为1.35±0.22,空白对照组为0.89±0.12,两组比较,F=16.311,P＜0.05,差异有统计学意义,说明PDGF-BB可提高HSC细胞活力.0.025,0.050、0.100、0.2000,0.400ng/ml IFN α加PDGF-BB共干预组,A值分别为0.84±0.18.0.45±0.15、0.26±0.01、0.33±0.07,0.30±0.06,较空白对照组明显降低,F=7.430,P＜0.05,差异有统计学意义,说明IFN α与PDGF-BB共同作用可抑制HSC细胞活力,且在0.025-0.100 ng/ml范围内随着IFN α浓度的增加其抑制作用越明显.(2)0.050、0.100、0.200ng/ml IFN α加PDGF-BB共干预各组Ⅰ型胶原mRNA相对表达值分别为0.94±0.19、0.61±0.12,0.52±0.02,空白对照组为1.41±0.01,共干预各组比空白对照组均明显降低,F=127.921,P＜0.05,差异有统计学意义.0.050、0.100,0.200ng/mlIFN α加PDGF-BB共干预组各组TGFβ1 mRNA相对表达值分别为1.18±0.06、1.15±0.10、1.39±0.04,空白对照组为1.62±0.12,共干预各组比空白对照组均明显降低,F=82.115,P＜0.05,差异有统计学意义,说明IFN α与PDGF-BB共同作用对HSC细胞Ⅰ型胶原、TGFβ1基因的表达有抑制作用,且随着浓度的增加其抑制作用越明显.结论 IFN α对PDGF-BB诱导的HSC细胞活力及Ⅰ型胶原、TGF β1基因的表达有抑制作用,且随着浓度的增加其抑制作用越明显.这可能是IFN α发挥抗肝纤维化作用的途径之一.     

β-连环蛋白对转化生长因子β 1活化HSC-T6细胞的影响

目的 观察β-连环蛋白对转化生长因子β 1(TGF β1)活化肝星状细胞(HSC)的影响. 方法通过脂质体介导,将β-连环蛋白真核表达质粒[pcDNA3.1(+)-β-catenin]和绿色荧光质粒pEGFP-N1共转染体外培养的HSC-T6细胞株,用逆转录PCR和Western blot法检测经TGF β1刺激后两组细胞smad3、β-连环蛋白mRNA及蛋白质的表达.组间比较采用方差分析.结果 β-连环蛋白转染阳性的HSC-T6细胞株经TGF β 1刺激后表达smad3、β-连环蛋白及其mRNA明显强于未转染β-连环蛋白基因的HSC-T6细胞,更强于正常培养的HSC-T6细胞,smad3mRNA相对表达量分别为;0.642±0.011、0.501±0.021、0.511±0.019、0.356±0.017,F=135.304,P<0.05;β-连环蛋白mRNA相对表达量分别为:0.783±0.021、0.543±0.033、0.538±0.024、0.212±0.019,F=267.340,P值均<0.05.smad3蛋白质相对表达量分别为:0.892±0.012、0.124±0.011、0.130±0.021、0.003±0.001,F=2823.813,P<0.05;β-连环蛋白相对表达量分别为:0.921±0.020、0.210±0.010、0.208±0.008、0.002±0.001,F=3440.982,P<0.05.β-连环蛋白和smad3蛋白质的表达均与α-平滑肌肌动蛋白的表达显著相关(r=0.901,P<0.01;r=0.939,P<0.01).结论 β-连环蛋白基因转染体外培养的HSC-T6细胞株,促使HSC表达smad3、α-平滑肌肌动蛋白增强,提示β-连环蛋白能增强TGF β1的致纤维化作用.     

罗格列酮对肝星状细胞增殖与胶原合成的影响

目的 观察罗格列酮对肝星状细胞增殖与Ⅰ型胶原合成的影响.方法 采用HSC-T6肝星状细胞系,将培养的肝星状细胞(HSC)分为对照组、不同浓度的罗格列酮组(5、10、20 μmol/L).采用MTT法观察罗格列酮对HSC增殖的影响,采用ELISA法检测细胞培养液上清中Ⅰ型胶原的含量.结果 与对照组相比,在10、20μmol/L罗格列酮组,罗格列酮可以抑制HSC的增殖(P<0.05),同时细胞堵养液上清中Ⅰ型胶原含量分别为135.72±6.00 ng/ml、128.65±5.34 ng/ml,均低于对照组(149.35±6.65 ng/ml),差异有统计学意义(P<0.05).结论 罗格列酮可以抑制HSC的增殖,抑制肝星状细胞Ⅰ型胶原的合成.     

沉默结缔组织生长因子对鼠转化生长因子β/Smads信号的影响

目的 研究小干扰RNA(siRNA)沉默结缔组织生长因子(CTGF)对大鼠转化生长因子(TGF)β/Smads信号通路的影响.方法 将化学合成CTGF siRNA转染肝星状细胞(HSC)T6和经门静脉注入CCl4诱导6周的肝纤维化大鼠,设空白及随机siRNA对照,抽提HSC T6及大鼠肝组织总RNA和蛋白质,应用Western blot和RT-PCR检测HSC T6及肝组织CTGF及TGF β1,Smad2、3、7蛋白质和基因表达. 结果与空白对照组相比,siRNA能显著下调HSC T6 CTGF蛋白表达,以48 h最明显,CTGF蛋白表达下调94%±4%(t=46.196,P<0.01),而TGF β1、Smad2,3,7 mRNA表达差异无统计学意义;模型组及对照siRNA组,CCl4诱导的大鼠肝组织CTGF和TGF β1蛋白表达明显上调,与模型组相比,CTGF siRNA组大鼠肝组织CTGF及TGF β1蛋白表达分别下调95%±2%(F=21.234,P<0.01)和74%±8%(F=13.464,P<0.05),但Smad2和Smad7蛋白表达无明显改变. 结论沉默CTGF基因表达对大鼠肝TGF β/Smads信号具有阻抑作用.     

白细胞介素10对肝星状细胞激活的调节

目的 探讨白细胞介素10(IL-10)通过血小板衍生生长因子(PDGF)和丝裂原活化激酶(MAPK)信号通路蛋白对肝星状细胞(HSC)激活的影响。 方法 将培养的HSC随机分为4组:1组:对照组;2组:加入1 ng/ml IL-10;3组:加入5 ng/ml IL-10;4组:加入25 ng/ml IL-10。培养2d后,逆转录-聚合酶链反应法检测各组细胞中PDGF mRNA的表达;western blot法检测各组细胞PDGF、MAPK信号通路蛋白细胞外信号调节激酶(ERK)和p38以及α-平滑肌肌动蛋白(α-SMA)的表达。 结果 1、5、25 ng/ml的IL-10作用后,与对照组相比HSC的ERK、p38以及α-SMA的表达显著降低(F值分别为240.47、21.39、28.86,P值均<0.01),并呈量效依赖关系;5、25 ng/ml的IL-10可以使PDGF表达显著降低(P值均<0.01),并呈量效依赖关系。 结论 IL-10可通过PDGF/MAPK信号通路抑制肝星状细胞激活。     

丹参酸乙对转化生长因子β1刺激的大鼠肝星状细胞的观察

目的 探讨丹参酸乙（SAB）对转化生长因子β1（TGFβ1）刺激的大鼠肝星状细胞活化、Ⅰ型胶原及c-fos基因表达的影响。方法 原位灌注、消化大鼠肝脏,分离肝星状细胞。以不同浓度SAB温TGFβ1刺激的大鼠肝星状细胞。异硫氰酸胍一步法提取细胞总RNA,RT－PCR法检测目的基因的表达。结果 1μmol/L SAB和10μmol/L SAB可分别抑制Ⅰ型胶原及c-fos基因表达,但1μmol/L SAB和10μmol/L SAB对SM α-actin mRNA均无显著影响。结论 TGFβ1对体外活化的大鼠肝星状细胞表达SM α-actin mRNA无明显影响,可促进Ⅰ型胶原和c-fos mRNA的表达。SAB可抑制TGFβ1促进细胞Ⅰ型胶原mRNA表达的作用。     

Inhibitory effect of human interferon-beta-1a on activated rat and human hepatic stellate cells

Background and Aims: Hepatic stellate cells (HSC) are the primary cell type mediating hepatic fibrosis. Although known for its antiviral effects, the inhibitory effects of interferon‐beta (IFN‐β) on HSC treatment have not yet been established. Methods: Both human and rat activated HSC cell lines were incubated with increasing concentrations of recombinant human IFN‐β1a (rhIFN‐β1a) for 24, 48 or 72 h. The effects of rhIFN‐β1a on α‐smooth muscle actin (α‐SMA), collagen types I and III, transforming growth factor‐β1 (TGF‐β1), platelet‐derived growth factor‐BB (PDGF‐BB), and mothers against decapentaplegic homolog (Smad4, Smad7) expression in HSC were examined using Western blotting and immunocytochemistry. Proliferation of HSC was evaluated via bromodeoxyuridine assay. Results: rhIFN‐β1a treatment had a dose‐dependent, inhibitory effect on α‐SMA and collagen type I protein expression. In addition, rhIFN‐β1a decreased the expression of collagen type III, TGF‐β1, PDGF‐BB and Smad4 protein expression in HSC compared with untreated cells. We also observed increased Smad7 protein expression and decreased proliferation in rhIFN‐β1a‐treated HSC. Conclusions: Our data suggest that rhIFN‐β1a treatment decreased α‐SMA and collagen expression and inhibited the activation of HSC through the inhibition of the TGF‐β and PDGF pathways.     

Effects of the tyrosine protein kinase inhibitor genistein on the proliferation,activation of cultured rat hepatic stellate cells

AIM：Hepatic stellate cell(HSC)plays a pivotal role in liver fibrosis and is considered as the therapeutic target for the treatment of hepatic fibrosis,Tyrosine protein kinase plays an important role in the proliferation,activation of HSC.The purpose of the study is to investigate the effects of the tyosine protein kinase inhibitor genistein on the proliferation and activation of cultured rat HSC.METHODS:Rat HSC were isolated from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient,Culture-activated HSC were serum-starved and incubated with10^-9to10^-5mol/L concentration of genistein for 24,48or 72h,In PDGF-induced HSC proliferation,HSC were stimulated with10μg&#183;L^-1PDGF-BBfo15min,and thentreated with genistein for the same time.Cell proliferation was measured by MПassay and based on flow cytometric analysis of cell cycle.The a-smooth muscle actin(α-SMA）expression in HSC was studied with confocallaser microscopy and flow cytometry.c-fos,c-jun and cyclinD1expression in HSCwas also detected by flow cytometry.RESULTS:Genistein inhibited basal and PDGF-induced proliferation of HSCat the concentration of 10^-8to10^-5mol/L,and treatment with10^-7mol/L concentration of genistein for 48h inhibited the HSCproliferation significantly(the inhibition rate was 70.3%,P&lt;0.05).Immunofluorescence detected by confocal laser microscopy and flow cytometry showed that treatment with10^-7mol/L genistein for48h suppressed the expression of α-SMA significantly in HSC(the specific fluorescence intensity were60.2&#177;21.5vs35.3&#177;11.6and12.8&#177;10.4vs9.54&#177;6.39,respectively,bothP&lt;0.05).The intensity of c-fos,c-jun and cyclinD1 expression of HSCs treated with 10^-7mol/L genistein for 48h was also significantly decreased compared with the controls.CONCLUSION;Genistein influences proliferation of HSC,suppresses the expression of α-SMA in HSC and tinhibits the intensity of c-fos,c-jun and cyclinD1 expression of HCSs,Genistein has therapeutic potential against liver fibrosis.     

去甲肾上腺素对大鼠肝星状细胞作用的实验研究

目的 探讨交感神经系统在肝纤维化发生和发展中的作用. 方法采用免疫荧光和RT-PCR检测体外培养的肝星状细胞(HSC)中α1、β2-肾上腺素能受体的表达;用四甲基偶氮唑盐法检测不同浓度的去甲肾上腺素(NE)对HSC增殖活性的影响.同时用RT-PCR检测受NE作用后HSC的活化指标胶原蛋白-1、转化生长因子β(TGF β)及α-平滑肌动蛋白(α-SMA)的表达.用高效液相色谱-电化学法测定活化的HSC中交感神经递质NE的水平. 结果α1和β2-肾上腺素能受体表达于HSC的胞膜和胞质内;NE可呈剂量依赖性地促进HSC增殖,在浓度为100μmol/L时达到最大效应,F=140.464,P<0.05,差异有统计学意义.以NE 100 μmol/L作用细胞24h后,可显著促进反应HSC活化的指标上升,胶原蛋白-1表达为0.3022±0.0610,TGF β表达为2.2080±0.2151,α-SMA mRNA表达为0.5469±0.0108,与对照组胶原蛋白-1(0.1040±0.0556)、TGF β(1.1190±0.0070)、α-SMA mRNA表达(0.0759±0.0449)比较,t值分别为-4.160、-8.763和-17.651,P值均<0.05,差异均有统计学意义.HSC可以合成并释放NE,且受血小板衍生生长因子(10ng/ml)刺激后HSC中NE含量为(14.24±0.21)ng/ml,对照组为(11.34±0.15)ng/ml,两组比较,t=-32.907,P<0.05,差异有统计意义.结论 抑制交感神经系统使HSC活性降低对临床上治疗肝纤维化有一定的指导意义.     

Pancreatic stellate cells are activated by proinflammatory cytokines: implications for pancreatic fibrogenesis

BACKGROUND: The pathogenesis of pancreatic fibrosis is unknown. In the liver, stellate cells play a major role in fibrogenesis by synthesising increased amounts of collagen and other extracellular matrix (ECM) proteins when activated by profibrogenic mediators such as cytokines and oxidant stress. AIMS: To determine whether cultured rat pancreatic stellate cells produce collagen and other ECM proteins, and exhibit signs of activation when exposed to the cytokines platelet derived growth factor (PDGF) or transforming growth factor beta (TGF-beta). METHODS: Cultured pancreatic stellate cells were immunostained for the ECM proteins procollagen III, collagen I, laminin, and fibronectin using specific polyclonal antibodies. For cytokine studies, triplicate wells of cells were incubated with increasing concentrations of PDGF or TGF-beta. RESULTS: Cultured pancreatic stellate cells stained strongly positive for all ECM proteins tested. Incubation of cells with 1, 5, and 10 ng/ml PDGF led to a significant dose related increase in cell counts as well as in the incorporation of 3H-thymidine into DNA. Stellate cells exposed to 0.25, 0.5, and 1 ng/ml TGF-beta showed a dose dependent increase in alpha smooth muscle actin expression and increased collagen synthesis. In addition, TGF-beta increased the expression of PDGF receptors on stellate cells. CONCLUSIONS: Pancreatic stellate cells produce collagen and other extracellular matrix proteins, and respond to the cytokines PDGF and TGF-beta by increased proliferation and increased collagen synthesis. These results suggest an important role for stellate cells in pancreatic fibrogenesis.     

Sites of interaction between epidermal growth factor and transforming growth factor-beta 1 in the control of steroidogenesis in cultured porcine Leydig cells.

The present study examines how the hormonal action of gonadotropin is modulated by transforming growth factor-beta 1 (TGF beta 1) and epidermal growth factor (EGF) in primary cultures of purified porcine Leydig cells. Although TGF beta 1 (1 ng/ml; 48 h) and EGF (10 ng/ml; 72 h) individually enhanced hCG-stimulated testosterone formation, the effects of EGF were more pronounced than those of TGF beta 1. When studied in combination, the effects of maximal concentrations of TGF beta 1 and EGF were additive on gonadotropin hormonal action. In the present study we demonstrate that their additive effects resulted from a complex interaction occurring at the levels of cholesterol substrate availability in the mitochondria and of 3 beta-hydroxysteroid dehydrogenase/isomerase activity (3 beta HSDI). First, TGF beta 1 (1 ng/ml; 48 h) and EGF (10 ng/ml; 72 h) were, respectively, shown to reduce and enhance dehydroepiandrosterone (DHEA) formation (evaluated in the presence of 10(-5) M WIN 24540, an inhibitor of 3 beta HSDI) in Leydig cells when acutely (3 h) stimulated with hCG (0.01-1 ng/ml), but not when incubated with 22R-hydroxycholesterol (3 micrograms/ml). Such findings indicate that TGF beta 1 and EGF did not affect cholesterol side-chain cleavage cytochrome P450 activity, but, respectively, decreased and increased cholesterol substrate availability for this enzyme in the mitochondria. Furthermore, when Leydig cells were treated with the combined factors, the formation of delta 5-steroid intermediates (such as DHEA) in untreated (control) and EGF-plus TGF beta 1-treated cells was not significantly different whether the cells were acutely stimulated with the gonadotropin or incubated with 22R-hydroxycholesterol. Such findings indicate that the effects of EGF and TGF beta 1 on cholesterol substrate availability in the mitochondria are antagonistic. Second, EGF, TGF beta 1, and EGF plus TGF beta 1 significantly (P less than 0.001) increased delta 5-steroid intermediate (i.e. pregnenolone and DHEA), but not delta 4-steroid intermediate (i.e. progesterone and androstenedione), conversion into testosterone, indicating that the growth factors increased, individually or in combination in an additive manner, 3 beta HSDI activity (respectively, 90.7 +/- 0.6%, 80.6 +/- 2.6%, and 164 +/- 4.5% increase in the presence of EGF, TGF beta 1, and EGF plus TGF beta 1). Together, the reciprocal suppression of the effects of TGF beta 1 and EGF on the mitochondrial cholesterol substrate availability coupled to their stimulatory additive actions on 3 beta HSDI activity provide an explanation of the additive actions of the two growth factors on gonadotropin-induced testicular androgen formation.