Roles of transforming growth factor-α in mammary development and disease

Transforming growth factor-alpha (TGFα) is a member of the epidermal growth factor (EGF) family. Expression of TGFα is highly regulated in response to exogenous cellular signals including cytokines and other growth factors. The growth factor has been found to be indispensable for proper development of many tissues and organs. TGFα has also been implicated in numerous disease states including forms of breast cancer. This minireview summarizes the basic biology of TGFα and its actions during normal and pathogenic development of the mammary epithelium.     

Amniotic membrane stimulates cell migration by modulating transforming growth factor‐β signalling

Keratinocyte migration is a mandatory aspect of wound healing. We have previously shown that amniotic membrane (AM) applied to chronic wounds assists healing through a process resulting in the overexpression of c‐Jun at the wound's leading edge. We have also demonstrated that AM modifies the genetic programme induced by transforming growth factor‐ß (TGF‐ß) in chronic wounds. Here we used a scratch assay of mink lung epithelial cells (Mv1Lu) and a spontaneously immortalized human keratinocyte cell line (HaCaT) cells to examine the influence of AM application on the underlying signalling during scratch closure. AM application induced c‐Jun phosphorylation at the leading edge of scratch wounds in a process dependent on MAPK and JNK signalling. Strikingly, when the TGF‐ß‐dependent Smad‐activation inhibitor SB431542 was used together with AM, migration improvement was partially restrained, whereas the addition of TGF‐ß had a synergistic effect on the AM‐induced cell migration. Moreover, antagonizing TGF‐ß with specific antibodies in both cell lines or knocking out TGF‐ß receptors in Mv1Lu cells had similar effects on cell migration as using SB431542. Furthermore, we found that AM was able to attenuate TGF‐ß‐Smad signalling specifically at the migrating edge; AM treatment abated Smad2 and Smad3 nuclear localization in response to TGF‐ß in a process dependent on mitogen‐activated protein kinase kinase 1 (MEK1) activation but independent of EGF receptor or JNK activation. The involvement of Smad signalling on AM effects on HaCaT keratinocytes was further corroborated by overexpression of either Smad2 or Smad3 and the use of Smad phosphorylation‐specific inhibitors, revealing a differential influence on AM‐induced migration for each Smad. Thus, AM TGF‐ß‐Smad signalling abating is essential for optimal cell migration and wound closure.     

参芎注射液对腹膜透析患者转化生长因子β1的影响

目的观察参芎注射液对腹膜透析患者转化生长因子β1(TGFβ1)及腹膜功能的影响。方法选择2012年12月至2014年5月我院肾内科进行腹膜透析的60例患者,随机分为2组:常规腹膜透析组(对照组)和参芎注射液腹膜透析组(观察组),每组30例。比较两组相关临床和生化指标,应用ELISA法检测TGFβ1表达。结果治疗前,两组肌酐透析液与血浓度之比(D/Pcr)、尿素清除指数(KT/V)、肌酐清除率(Ccr)、尿量和超滤量比较差异无统计学意义(P>0.05)。治疗后,对照组上述指标无显著变化(P>0.05);观察组D/Pcr、KT/V、Ccr、尿量与治疗前比较差异无统计学意义(P>0.05),但超滤量升高(P<0.01)。两组血浆白蛋白(ALB)、钙(Ca)、磷(P)、甲状旁腺素(iP TH)在治疗前、后比较差异均无统计学意义(P>0.05)。治疗前,两组TGFβ1表达水平比较差异无统计学意义(P>0.05);治疗后,对照组TGFβ1表达无显著变化(P>0.05),但观察组显著减低(P<0.01)。结论参芎注射液可显著提高腹透患者的超滤量,抑制腹膜细胞的TGFβ1分泌,具有抗腹膜纤维化的功效。     

Human Antibody Fragments Specific for the Epidermal Growth Factor Receptor Selected from Large Non-immunised Phage Display Libraries

Antibodies to EGFR have been shown to display anti-tumour effects mediated in part by inhibition of cellular proliferation and angiogenesis, and by enhancement of apoptosis. Humanised antibodies are preferred for clinical use to reduce complications with HAMA and HAHA responses frequently seen with murine and chimaeric antibodies. We have used depletion and subtractive selection strategies on cells expressing the EGFR to sample two large antibody fragment phage display libraries for the presence of human antibodies which are specific for the EGFR. Four Fab fragments and six scFv fragments were identified, with affinities of up to 2.2 nM as determined by BIAcore analysis using global fitting of the binding curves to obtain the individual rate constants (k_a and k_d). This overall approach offers a generic screening method for the identification of growth factor specific antibodies and antibody fragments from large expression libraries and has potential for the rapid development of new therapeutic and diagnostic reagents.     

Smad蛋白研究进展

Smad蛋白家族是转化生长因子β（TGFβs）超家族重要的细胞因子，共同担负着调节细胞生长、分化、凋亡等过程，主要由8种不同的蛋白构成整个Smad家族，通过可逆磷酸化对多种信号传导通路的功能起着荚键的调节作用，分别行使兴奋和抑制等不同作用。本文对Smad蛋白调节作用机制进行综述。     

调控TGFβ1/SMAD通路的microRNAs在失神经支配骨骼肌中的表达

目的:本研究拟探讨骨骼肌失神经支配后差异性表达的microRNAs,并明确其是否参与调控TGFβ1/SMAD信号通路。方法:C57/BL6J小鼠,随机分为正常对照组和实验组,实验组小鼠切断右下肢坐骨神经为手术组,左下肢游离坐骨神经作为假手术组。4周后处死小鼠取腓肠肌Masson染色观察肌纤维形态变化,比较各组肌纤维横截面积。以TGFβ1/SMAD为靶基因,通过生物信息学分析寻找到18个可能的miRNAs指标。定量PCR检测其表达,并针对表达升高的microRNAs采用荧光素酶报告基因实验确认其靶基因。结果:手术组肌纤维横截面积比对照组明显缩小,对照组与假手术组肌肉之间的差异无统计学意义。在失神经骨骼肌中特异性高表达的有miR-424、miR-744、miR-15a。在C2C12细胞系中行报告基因实验显示,与对照组比较,转染miR-744后,SMAD3的荧光素酶强度下降;转染miR-15a后,TGFβ1的荧光素酶强度下降;转染miR-424后,SMAD3的荧光素酶强度变化无统计学意义。PCR验证microRNAs的靶基因显示,转染miR-744、miR-15a的模拟物后,分别对应的SMAD3、TGFβ1表达下调,差异有统计学意义。结论:miR-424、miR-744、miR-15a可能参与调控失神经支配导致的骨骼肌萎缩纤维化,其中miR-744的靶基因是SMAD3,miR-15a的靶基因是TGFβ1。     

Retinoic acid improves recovery after nephrectomy and decreases renal TGF‐β1 expression. Gender‐related effects

End‐stage renal disease is a cause for death worldwide. Renal transplant is a therapeutic alternative, restricted by the scant number of donors. Function of the donor kidney is under risk of adverse circumstances such as fibrosis, where profibrotic effect of transforming growth factor beta 1 (TGF‐β1) plays a key role. Efforts to diminish risks of damage in the remnant kidney of the donor are required. Vitamin A represents one alternative. It has beneficial effects on some nephropathies, mainly those related to oxidative stress. It also participates in normal intrauterine renal development. We studied the effect of all‐trans retinoic acid (ATRA), active form of vitamin A, on postnephrectomy compensatory growth, in male or female rats. Compensatory growth and renal function were evaluated on four experimental groups: Control without treatment (CTL), ATRA‐treated intact rats (CTL + RA), nephrectomized rats (NFX), and ATRA‐treated nephrectomized rats (NFX + RA). We evaluated glomerular function (inulin clearance), tubular function (fractional excretions of sodium and potassium), and urinary flow. Renal mass was also estimated. In ATRA‐treated animals, compensatory growth was higher than in nephrectomized rats without treatment. Hyperfiltration after nephrectomy was less intense in ATRA‐treated female than in male rats. In tubular functions, effect of ATRA was more evident in female than in male rats. Glomerular expression of TGF‐β1 was lower in ATRA‐treated animals than in controls. ATRA reduced intensity and duration of compensatory changes after nephrectomy, improving recovery.