肝再生的分子生物学研究进展

肝细胞具有很强的增殖能力。肝损伤后机体能精确地调控肝细胞增殖、生长 ,迅速恢复其原有体积和重量。当肝细胞复制被阻断或延误时 ,肝内就会启动干细胞增生。最近研究发现再生肝基因表达可分几个阶段 :肝再生的启动始于大量即刻基因表达 ,G1期的肝细胞对生长因子肝细胞生长因子 (HGF) ,转化生长因子α、β(TGFα、β)、表皮生长因子 (EGF)和肿瘤坏死因子 (TNF)及IL 6等细胞因子有反应 ;至少有四种转录因子即NFkB、STAT3、AP 1和C/EBPβ在起动肝再生中发挥重要作用。本文对近年这方面研究进展作一综述     

肿瘤坏死因子-α（TNF-α）在肝再生中的作用

肝脏具有强大的再生能力,多种细胞因子和生长因子参与了肝再生过程的调控。其中肿瘤坏死因子-α（TNF-α）在肝细胞再生中都发挥着不可或缺的作用。本文就TNF-α在启动肝再生、促进或抑制肝细胞凋亡调控机制的研究进展作一综述。     

肝细胞生长因子与肝刺激物质

肝脏有很强的再生能力，在肝损伤尤其是肝大部切除后，肝细胞能迅速分裂增殖。在残余肝细胞代偿性增生过程中，肝细胞增殖刺激因子、增殖抑制因子和激素类辅助因子在肝再生中起重要调节作用。增殖刺激因子如表皮生长因子（EGF），转化生长因子a（TGFa），肝刺激物质（HSS），促     

大鼠肝再生启动阶段肝细胞CCAAT增强子结合蛋白βmRNA、微小RNA-369-3p和rno-Rmdn2_0006的表达和作用

目的 了解大鼠肝再生启动阶段CCAAT增强子结合蛋白3(CEBPβ)mRNA、miR-369-3p和mo-Rmdn2_0006调节肝细胞处于G0期还是G1期的途径和方法.方法 按Higgins等方法制备大鼠2/3肝切除(PH)模型,按Smedsrod等方法分离肝细胞,用大规模定量分析技术检测大鼠肝再生中肝细胞竞争性内源RNA(ceRNA)表达的变化,用Cytoscape 3.2软件构建ceRNA的相互作用网络,用ceRNA综合分析等方法解析它们表达的相关性和作用相关性.结果 PH后0h和6h时,CEBP3 mRNA的比值为1.11±0.11和2.57±0.10,miR-136-3p为0.70±0.22和0.28±0.03,rno-Rmdn2_0006为1.26±0.34和2.62±0.70.CEBPp促进的G0期相关基因生长停滞和DNA损伤诱导型β(GADD45β)为0.12±0.09和2.50±0.44,细胞周期蛋白依赖性激酶抑制剂1A(CDKN1A)为0.39±0.07和0.93±0.15,抑制的G0期相关基因细胞周期蛋白依赖性激酶2相关蛋白2(CDK2AP2)为2.55±0.42和0.74±0.11,信号转导子和转录激活因子1(STAT1)为2.57±0.13和1.32±0.13.CEBPβ促进的G1期相关基因ETS变异转录因子6(ETV6)为0.77±0.05和2.22±0.68,血红蛋白加氧酶1(HMOX1)为1.05±0.21和4.57±0.88,丝裂原活化蛋白激酶14(MAPK14)为1.01±0.15和2.01±0.32,硫氧还蛋白相互作用蛋白(TXNIP)为1.03±0.07和2.50±0.19,抑制的G1期相关基因红细胞衍生核因子2样蛋白2(NFE2L2)为0.66±0.09和0.35±0.05.结论 PH后0h时,CEBPβ mRNA未上调,有利于CEBPβ抑制的G0期相关基因表达和肝细胞处于G0期.相反,PH后6h时,rno-Rmdn2_0006和miR-369-3p通过相互作用解除了后者对CEBPp mRNA的抑制,有利于CEBPp形成,有利于CEBPβ促进的G1期相关基因表达和肝细胞处于G1期.     

转移生长因子-β在早期胚胎组织的表达

目的：研究转移生长因子－β(Transform Growth Factor,TGF-β)在胚胎的肝、脑室、和脊髓等组织器官中增殖和分化中的作用。方法：用51天的人胚胎行免疫细胞化学ABC法染色。结果：在胚胎第51天，肝、脑室、和脊髓等组织器官中均有TGF－β阳性细胞存在，不同器官其阳性细胞的数量、反应强弱和表达情况有差异。结论：TGF－B在人胚胎发育过程,肝、脑室和脊髓等组织器官的增殖分化起着自分泌和旁分泌的作用。     

大鼠肝再生启动阶段肝细胞CCAAT增强子结合蛋白δmRNA、微小RNA-3553和rno-Acad8_0002的表达和作用

目的 了解大鼠肝再生启动阶段CCAAT增强子结合蛋白δ(CEBPδ) mRNA、miR-3553和rno-Acad8_0002调节肝细胞处于G0期还是G1期的途径和方法.方法 按Higgins等方法制备大鼠2/3肝切除(PH)模型,按Smedsrod等方法分离肝细胞,用大规模定量分析技术检测大鼠肝再生中肝细胞竞争性内源RNA (ceRNA)表达的变化,用Cytoscape 3.2软件构建ceRNA的相互作用网络,用ceRNA综合分析等方法解析它们表达和作用的相关性.结果 PH后0h和6h时,CEBPδ mRNA的比值为0.40±0.08和2.15±0.24,miR-3553为2.53±0.47和1.17±0.31,rno-Acad8_0002为1.24±0.04和2.66±0.54.CEBPδ抑制的G0期相关基因转化生长因子β受体2(TGFBR2)为2.77±0.20和0.79±0.13,磷脂酶A2-IVA(PLA2G4A)为2.56±0.76和0.42±0.13.CEBPδ促进的G1期相关基因纤溶酶原激活剂尿激酶受体(PLAUR)为0.27±0.08和2.62±0.31,丝裂原活化蛋白激酶14(MAPK14)为1.01±0.15和2.01±0.32,ETS变异转录因子6(ETV6)为0.77±0.05和2.22±0.68,血红蛋白加氧酶1(HMOXl)为1.05±0.21和4.57±0.88.结论 PH后0h时,CEBPδmRNA下调,有利于CEBPδ抑制的G0期相关基因表达和肝细胞处于G0期.相反,PH后6h时,rno-Acad8_0002和miR-3553的相互作用解除了后者对CEBPδ mRNA的抑制,有利于CEBPδ形成,有利于CEBPδ促进的G,期相关基因表达和肝细胞处于G1期.     

转化生长因子β的研究进展

转化生长因子（Transforming growth factor，TGF）最初的研究始于1978年，Delarco和Todaro发现小鼠肉瘤病毒转化3T3细胞系所产生的多肽因子可诱导非肿瘤细胞转化为失去接触抑制，获得具有在软琼脂层中生长能力的肿瘤细胞，当时称为肉瘤生长因子。后续研究发现某些人体肿瘤细胞也产生类似多肽因子，随后这些能刺激静止性生长的细胞呈非静止性生长的因子称为转化生长因子（TGF）。TGF包括TGF-α和TOF-β。两名字类似，但结构和功能却截然不同。越来越多的证据表明，TGF除了能使正常细胞转化外，在细胞增殖、生长和分化等基本活动中行使多种重要的调节作用和其他生物学效应。     

石蜡包埋人胰腺癌组织中Smad4蛋白和转化生长因子β_1及其Ⅱ型受体的表达

目的　探讨转化生长因子 (TGF) β通路中Smad4蛋白、TGFβ1和转化生长因子 βⅡ型受体 (TβRⅡ )的关系及它们在胰腺癌中的可能作用机制。 方法　用EnVision免疫组织化学技术检测5 6份石蜡包埋人胰腺癌标本Smad4蛋白、TGFβ1和TβRⅡ蛋白表达的情况。 结果　 5 6份胰腺癌组织Smad4、TGFβ1和TβRⅡ阳性率分别为 5 8 93%(33)、6 6 0 7%(37)和 6 0 71%(34 ) ,对应正常胰腺组织阳性率分别为 89 2 9%(5 0 )、2 5 0 0 %(14)和 2 5 0 0 %(14)。TGFβ1的表达与临床分期、肿瘤的有无转移相关 (P <0 0 5 )。TGFβ1与TβRⅡ之间也有相关关系 (P <0 0 5 )。 结论　胰腺癌组织中Smad4表达降低 ,TGFβ1与TβRⅡ则呈过表达。TGFβ1与TβRⅡ对胰腺癌的发生可能有协同作用。Smad4在TGF β诱导基因表达调控和随后的生长抑制中是关键的转录因子 ,但TGFβ有时也可能以与Smad4无关的形式起作用。     

口腔癌患者血清中细胞因子水平的变化

癌症患者的细胞因子变化除反映出患者的细胞免疫功能外, 还对分析肿瘤的发展, 判断预后治疗效果, 以及制定治疗措施有参考价值.为此,本文检测了95例口腔癌患者血清中肿瘤坏死因子α(ΤNFα)、白介素1β(IL-1β)、白介素2(IL-2)、粒细胞-巨噬细胞集落刺激因子(GM-CSF)与转化生长因子α(TGFα)水平的变化并探讨其临床意义.     

肝细胞生长因子在肿瘤坏死因子相关凋亡诱导配体作用下对原代肝星状细胞增殖及凋亡的影响**☆

背景：活化的肝星状细胞是肝纤维化的关键因素,研究表明肝细胞生长因子能促进星状细胞凋亡,其具体机制可能与增强肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导星状细胞凋亡有关。 目的：观察肿瘤坏死因子相关凋亡诱导配体作用下,肝细胞生长因子对原代肝星状细胞增殖、凋亡的影响并初步探讨其可能机制。 方法：将SD大鼠原代肝星状细胞复苏、传代,细胞增殖明显时用于实验。实验分为4组：空白对照组为单纯肝星状细胞培养;肝细胞生长因子组：将100 μg/L肝细胞生长因子作用于肝星状细胞;TRAIL组：将2 mg/L的TRAIL作用于肝星状细胞;肝细胞生长因子+TRAIL组：将肝细胞生长因子预先刺激肝星状细胞24 h,再加入2 mg/L TRAIL。 结果与结论：MTT检测显示肝细胞生长因子及TRAIL分别在50~200 μg/L、0.5~1.5 mg/L各浓度下对肝星状细胞增殖抑制率无影响,TRAIL在2 mg/L作用下对肝星状细胞有抑制作用。流式细胞仪检测肝细胞生长因子+TRAIL组的中晚期凋亡率明显高于空白对照组及肝细胞生长因子组(P < 0.05);肝细胞生长因子+TRAIL组DR5荧光强度明显高于其他3组(P < 0.01)。提示在TRAIL作用下,肝细胞生长因子能促进肝星状细胞的凋亡、抑制其增殖。可能与肝细胞生长因子上调活化肝星状细胞表面DR5表达有关。      

Mechanism of Growth Promoting Activity of Epiregulin in Primary Cultures of Rat Hepatocytes

In spite of lower receptor affinity, epiregulin exhibits a stronger stimulation of DNA synthesis than epidermal growth factor (EGF) in rat hepatocytes. To determine the mechanism of stimulation, we examined the activities of epiregulin on growth stimulation, signal transduction, and mRNA induction of hepatotrophic factors in primary cultures of rat hepatocytes. Epiregulin stimulated hepatocyte proliferation as efficiently as hepatotrophic factors, including heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor- &#102 (TGF- &#102 ). Epiregulin induced a more prolonged activation of EGF receptor (EGFR) and p42/44 mitogen-activated protein kinase (MAPK) than EGF. Furthermore, epiregulin up-regulated the mRNAs of TGF- &#102 and HB-EGF, and in turn, these growth factors enhanced the expression of epiregulin mRNA. In vivo, increased production of epiregulin was noted in extracts of the remnant liver obtained 24 h after partial hepatectomy, and EGFR phosphorylation by these extracts was partially inhibited by anti-epiregulin antibody. Our results showed a more potent hepatocyte proliferative activity for epiregulin compared with EGF in vitro, which depends on prolonged activation of EGFR and p42/44 MAPK. Our findings suggest that epiregulin may play significant roles in liver regeneration following partial hepatectomy in cooperation with other growth factors.     

Growth factor interactions in bone regeneration

Bone regeneration is a complex process regulated by a large number of bioactive molecules. Many growth factors and cytokines involved in the natural process of bone healing have been identified and tested as potential therapeutic candidates to enhance the regeneration process. Although many of these studies show an enhancement of the bone regeneration process by a single drug therapy, in vivo bone regeneration is the result of a complex interplay between the applied growth factor and various endogenous produced growth factors. To investigate these growth factor interactions, various studies have investigated the effect of growth factor combinations on bone regeneration. This review provides an overview of the growth factor and cytokine combinations tested in translational bone regeneration studies and shows that their interaction may result in an enhancement or inhibition of bone formation.     

转化生长因子β1在吸烟所致病理变化中的作用

转化生长因子β1(TGF-β1)是一类重要的细胞因子,作用的细胞谱型较广。吸烟及香烟烟雾提取物(CSE)均能使细支气管上皮细胞TGF-β1表达增加,从而促进上皮的修复与再生,同时又引起炎性细胞聚集,与小气道中气道重塑和导致阻塞改变有关;在吸烟所引起的肺气肿中,TGF-β1可能在抑制成纤维细胞增殖的过程中起关键作用。另外,TGF-β1与碱性成纤维细胞生长因子(bFGF)在尼古丁诱导的动脉粥样硬化的发生发展中起关键作用,TGF-β1在CSE导致的骨质疏松症、烟草烟雾提取物(TSE)诱导的皮肤年龄相关性变化的过程中也起一定的作用。     

The role of Kupffer cells in liver regeneration

The liver has a remarkable proliferative capacity after a partial hepatectomy. Previous studies have indicated that Kupffer cells have the potential to exert both stimulatory and inhibitory influences on hepatocyte proliferation. To elucidate the role of Kupffer cells in liver regeneration, mice were selectively depleted of Kupffer cells by injection of liposome-encapsulated dichloromethylene diphosphonate (lipo-MDP) at day 3 after a two-thirds hepatectomy. Results showed that liver regeneration was delayed after Kupffer cell-depletion. In control mice, hepatocyte growth factor (HGF) mRNA expressions were enhanced during liver regeneration and expressions of HGF were localized in fat-storing cells (Ito cells). In Kupffer cell-depleted mice, the number of HGF-expressing cells decreased in the regenerating liver, and expressions of HGF and its receptor (c-met) as well as other growth factors/cytokines were less prominent than in control mice. In contrast, expressions of TNF-alpha, another potent cytokine involved in liver regeneration, did not differ between Kupffer cell-depleted and control mice during the regeneration. Administration of TNF-alpha antibody did not reduce the expression of HGF or liver regeneration. These findings imply that Kupffer cells play a stimulatory role in liver regeneration by enhancing HGF expression via TNF-alpha-non-mediated mechanisms.     

转化生长因子β与骨骼肌损伤修复的研究进展

肌肉的损伤修复是一个动态协调而又极其复杂的过程,TGF-β是一种内源性的生长因子,在肌肉损伤后通过重新编码肌肉细胞基因,抑制生肌细胞基因的表达,骨骼肌内TGF-β产生于损伤反应中,在损伤愈合的各个阶段均起作用并受TGF-β浓度的影响,TGF-β的生物学效应也受到其它生长因子的拮抗或协同作用,使用TGF-β阻断剂可以拮抗TGF-β进而减少肌肉纤维化,改善肌肉愈合质量。本文回顾了骨骼肌损伤修复与转化生长因子β的作用,并对转化生长因子β在肌肉损伤修复方面的应用前景进行了分析和探讨。     

Hypoxia augments cytokine (transforming growth factor-beta (TGF-β) and IL-1)-induced vascular endothelial growth factor secretion by human synovial fibroblasts

Vascular endothelial growth factor (VEGF) is abundant in synovium and synovial fluids, where it probably contributes to vascular permeability and angiogenesis in arthritic joints. To investigate the probable sources of VEGF in synovium, we compared the ability of several cytokines (TGF-β, platelet-derived growth factor (PDGF), IL-1, tumour necrosis factor (TNF), basic fibroblast growth factor (bFGF) that are associated with arthritis and angiogenesis, to stimulate secretion of VEGF protein by human synovial fibroblasts. TGF-β was the strongest inducer of VEGF secretion; six times more VEGF was secreted when cells were stimulated by TGF-β than when stimulated by PDGF or IL-1 for 24 h. TNF-α and bFGF did not stimulate any secretion of VEGF. The stimulatory effects of TGF-β and IL-1 on VEGF secretion were additive. Hypoxic culture alone also stimulated VEGF secretion, but more importantly, hypoxic culture conditions doubled the rate of VEGF secretion stimulated by the cytokines TGF-β and IL-1. When dermal and synovial fibroblasts were stimulated identically by hypoxia and cytokines (TGF-β and IL-1), synovial fibroblasts secreted four times more VEGF than did dermal fibroblasts. Thus in rheumatoid arthritis, the capacity of synovial fibroblasts in the hypoxic environment to secrete large amounts of VEGF in response to cytokines such as TGF-β probably contributes significantly to angiogenesis in the synovium.     

A platform technique for growth factor delivery with novel mode of action

Though growth factors allow tissue regeneration, the trade-off between their effectiveness and adverse effects limits clinical application. The key issues in current growth factor therapy largely derive from initial burst pharmacokinetics, rapid clearance, and proteolytic cleavage resulting in clinical ineffectiveness and diverse complications. While a number of studies have focused on the development of carriers, issues arising from soluble growth factor remain. In this study, we report a prodrug of growth factors constituting a novel mode of action (MoA). To mimic endogenous protein processing in cells, we developed a recombinant BMP-2 polypeptide based on a protein transduction domain (PTD) to transduce the protein into cells followed by furin-mediated protein cleavage and secretion of active growth factor. As proof of concept, a few micrograms scale of PTD-BMP-2 polypeptide sufficed to induce bone regeneration in vivo. As a simple platform, our technique can easily be extended to delivery of BMP-7 and DKK-1 as therapeutics for TGF-β and canonical Wnt signaling, respectively, to suppress the epithelial–mesenchymal transition (EMT), which constitutes a fundamental biological mechanism of many diseases. This technique largely overcomes the limitations of current soluble growth factors and opens the door to next generation growth factor therapeutics.     

Angiogenic cell therapy for hepatic fibrosis

Progression of liver fibrosis has been linked with injuries associated with hypoxia and neovascularization. Neovascularization consists of angiogenesis and vasculogenesis, representing formation of blood vessels by differentiation of endothelial progenitor cells (EPCs). We investigated antifibrogenic and regenerative effects of EPC transplantation in chronic liver injury. Rat EPCs were isolated from bone marrow cells and examined in vitro for lineage markers. Recipient rats were injected intraperitoneally with dimethylnitrosamine (DMN) three times weekly for 4 weeks, plus EPC transplantation once weekly for 4 weeks. Transplanted rats showed suppression of liver fibrogenesis. Expression of growth factors promoting liver regeneration such as hepatocyte growth factor (HGF), transforming growth factor (TGF)-α, epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) was increased in transplanted rats, together with hepatocyte proliferation. Normal liver function parameters such as transaminase, total bilirubin, total protein, and albumin were maintained in transplanted rats. EPC transplantation is effective not only for preventing liver fibrosis but also for promoting regeneration in chronically damaged livers. Also, recently it has been reported that green fluorescent protein-positive bone marrow cells contribute to the liver tissue repair of fibrosis model rats. EPC transplantation might become an alternative if further preclinical investigation finds it to be effective in severely cirrhotic livers.     

中药单体调控TGF-β1/Smads信号通路抗纤维化的研究

肝纤维化是多种慢性肝病的共同结局,是肝硬化的必经阶段。因此,抗纤维化治疗十分迫切,当前缺乏有效的抗纤维化治疗。中药单体可通过多种途径、多个靶点干预肝纤维化的进展。转化生长因子β1（TGF-β1）/Smads 信号通路在肝纤维化的发生发展中扮演着至关重要的角色。本文就中药单体调控TGF-β1/Smads信号通路抗纤维化的研究作一综述。