表皮生长因子对细胞核转录活性的直接作用

表皮生长因子（ＥＧＦ）对纯化的鼠胚成纤维细胞（Ｃ３Ｈ１０Ｔ１／２Ｃ１８）胞核＾３Ｈ－ＵＴＰ掺入有明显的促进作用。这一作用在ＥＧＦ与细胞核共同培养９０ｍｉｎ时达到高峰。该作用是ＥＧＦ浓度依赖性的。ＥＧＦ对β射线转化的上述细胞的纯化细胞核,亦同样有促进转录作用。本实验所用的细胞核经光镜,电子显微镜观察,细胞膜、细胞浆标志酶检测及放射性同位素示踪法鉴定,未检出有核外成份的污染。本实验结果为膜受体信号传递     

表皮生长因子对游离细胞核特异基因体外转录的影响

ＥＧＦ作用于ＮＣ３Ｈ１０和ＴＣ３Ｈ１０细胞核,对ＲＮＡ聚合酶Ⅱ有促进作用,但对ＲＮＡ聚合酶Ｉ和酶Ⅲ没有影响,此外还发现转化细胞核内的ＲＮＡ聚合酶Ｉ和酶Ⅲ的活性比正常细胞高１倍多,但两种细胞的ＲＮＡ聚合酶Ⅱ差别不大,同时,以非放射性标记的ｃ－ｆｏｓ,ＣＬＮ１,ＣＬＮ３探针进行点杂交,结果发现,ＥＧＦ直接作用于细胞核可使ｃ－ｆｏｓ,ＣＬＮ１基因的转录水平提高,但是,对ＣＬＮ３无影响。     

表皮生长因子对游离细胞核特异基因体外转录的影响

ＥＧＦ作用于ＮＣ３Ｈ１０和ＴＣ３Ｈ１０细胞核,对ＲＮＡ聚合酶Ⅱ有促进作用,但对ＲＮＡ聚合酶Ⅰ和酶Ⅲ没有影响,此外还发现转化细胞核内的ＲＮＡ聚合酶Ⅰ和酶Ⅱ的活性比正常细胞高１倍多。但两种细胞的ＲＮＡ聚合酶Ⅱ差别不大。同时,以非放射性标记的ｃ－ｆｏｓ、ＣＬＮ１、ＣＬＮ３探针进行点杂交,结果发现,ＥＧＦ直接作用于细胞核可使ｃ－ｆｏｓ、ＣＬＮ１基因的转录水平提高;但是,对ＣＬＮ３无影响。     

表皮生长因子对生殖内分泌作用的研究进展

表皮生长因子是一种具有广泛生物学效应的单链多肽。人类多种组织中都含有ＥＧＦ及其受体,在生殖系统亦同样存在,因此ＥＧＦ在生殖系统所起的作用愈来愈被人们所重视,它可通过自分泌、分泌及内分泌途径对生殖器官及生殖激素产生调控作用,从而在性腺功能,胎儿发育及胎盘功能等方面起重要作用。     

表皮生长因子对正常细胞与转化细胞染色质蛋白激酶活性的影响

本文研究了正常C3H/10T1/2CI8细胞(一种源于小鼠胚胎的成纤维细胞,简称NC3H/10)与用~3H-TdR转化的C3H/10T1/2CI8细胞(简称TC3H/10)染色质蛋白激酶(CAPK)的作用物特异性,发现这两种细胞的CAPK均能以外源性酸性酪蛋白为作用物,而不以外源性碱性组蛋白为作用物,由此推测CAPK的天然作用物主要为非组蛋白。观察了表皮生长因子(EGF)对培养细胞的CAPK活性的影响,EGF能使NC_3H/10和TC3H/10的CAPK活性分别增加105.6％(P<0.01)和50.7％(P<0.01),后者增加的幅度仅为前者的1/2,说明转化细胞CAPK活性对EGF刺激的敏感性较正常细胞低。EGF和1-油酰-2-乙酰-消旋-甘油(OAG)对无细胞体系的CAPK活性无直接影响,提示EGF可能通过核内受体或OAG以外的其它第二信使来影响CAPK的活性。     

成纤维细胞表皮生长因子的胞吞和向细胞核转移研究

本文以C3H小鼠胚胎正常成纤维细胞株C3H10T1/2C18(简称NC3H10)及其由氚标记脱氧胸苷(~3H-TdR)恶性转化的细胞株(简称TC 3H 10)为对象,研究了表皮生长因子(EGF)在受体介导下的胞吞和向细胞核转移现象。~(125)I-EGF 与细胞膜上的EGF 受体结合后,胞吞和向细胞核转移呈时间依赖性。两种细胞的EGF 的胞吞和向细胞核转移率接近。但是NC 3 H 10细胞~(125)I-EGF 胞知和向细胞核转移的绝对量明显高于TC 3 H 1 0细胞(p<0.05)。SDS-PAGE 电泳表明向细胞核转移的~(125)I-EGF 是未被降解的完整分子,溶酶体抑制剂NH_4Cl 对~(125)I-EGF 向细胞核转移有明显促进作用(p<0.05)。这些结果表明受体介导下的EGF 胞吞和向细胞核转移可能与EGF 的细胞核内凋节作用密切相关。     

表皮生长因子对精原干细胞的作用研究

应用不连续Percoll梯度液和选择性贴壁法分离纯化精原干细胞:c-kit细胞免疫组化鉴定细胞类型;MTT法研究EGF对精原干细胞增殖的效应;加入MAPK-ERK信号通路特异性抑制剂PD98059,探讨EGF对精原干细胞增殖作用的可能机制.证明:1)c-kit细胞免疫组化结果显示分离得到细胞为精原千细胞;2)MTT结果显示各实验组比对照组细胞数量均有显著增多(p＜0.01),且20 ng/mL剂量组的增殖作用最明显;3)与对照组相比,加入PD98095组的活细胞数有显著下降(p＜0.01).结论:EGF能够促进精原干细胞的增殖,并且可以通过MAPK-ERK信号通路起作用.     

表皮生长因子对P34^cdc2激酶活性的影响

表皮生长因子对Ｐ３４~（ｃｄｃ２）激酶活性的影响蔡家新,童坦君（北京医科大学生物化学教研室,１０００８３）关键词表皮生长因子：Ｐ３４~（ｃｄｃ２）激酶;细胞周期表皮生长因于（ＥＧＦ）在细胞增殖和分裂过程中起重要作用。近期研究表明其作用过程与核内多种成分...     

Acute Regulation of the Epidermal Growth Factor Receptor in Response to Nerve Growth Factor

PC12 cells possess specific receptors for both nerve growth factor and epidermal growth factor, and by an unknown mechanism, nerve growth factor is able to attenuate the propagation of a mitogenic response to epidermal growth factor. The differentiation response of PC12 cells to nerve growth factor, therefore, predominates over the proliferative response to epidermal growth factor. We have observed that the addition of nerve growth factor to PC12 cells rapidly produces a decrease in surface 125I-epidermal growth factor binding capacity. Unlike previously described nerve growth factor effects on 125I-epidermal growth factor binding capacity, which required several days of nerve growth factor exposure, the decreases we report occur within minutes of nerve growth factor addition: A 50% decrease in 125I-epidermal growth factor binding capacity is evident at 10 min. This rapid nerve growth factor response is concentration dependent; inhibition of 125I-epidermal growth factor binding is detectable at nerve growth factor levels as low as 0.2 ng/ml and is maximal at approximately 50 ng/ml, consistent with known ranges of biological activity. No demonstrable differences in the rate of epidermal growth factor receptor synthesis or degradation were observed in cells acutely exposed to nerve growth factor. Scatchard analysis revealed that acute nerve growth factor treatment decreased the number of both high- and low-affinity 125I-epidermal growth factor binding sites, while the receptor affinity remained unchanged. We have also investigated the involvement of various potential intracellular mediators of nerve growth factor action and of known intracellular modulatory systems of the epidermal growth factor receptor for their capacity to participate in this nerve growth factor activity.     

Schwannoma-Derived Growth Factor Interacts with the Epidermal Growth Factor Receptor

Abstract: Schwannoma-derived growth factor (SDGF) is a potent mitogen and neuronal differentiation factor. Because of its relationship to epidermal growth factor (EGF) and the heregulins, it was asked if SDGF interacts with the EGF receptor or HER2/neu. SDGF binds to and causes the phosphorylation on tyrosine of the EGF receptor but not HER2/neu.     

肽类生长因子对游离细胞核中拓扑异构酶活性的影响

将表皮生长因子及神经生长因子分别作用于分离所得的鼠胚成纤维细胞及其转化细胞的细胞核。结果表明表皮生长因子可以提高游离细胞核中ＤＮＡ拓扑异构酶的活性,但神经生长因子无此作用。     

阿霉素肾病大鼠表皮生长因子及其受体的表达

目的研究阿霉素肾病大鼠肾组织中表皮生长因子(EGF)及其受体EGFR的表达分布以及表达量与尿蛋白之间关系。方法选择第5天、14天、28天作为动态观察的时点,同期设立正常对照。采用荧光定量RT-PCR、免疫组织化学及计算机图像定量分析EGF mRNA以及EGF、EGFR蛋白在肾组织的表达,同时测定24 h尿蛋白定量。WT1和EGFR双重免疫组化确定EGFR在肾小球内确切细胞定位。结果阿霉素注射后第5天,EGFmRNA即较正常增高,28 d明显增高并高于5 d和14 d。正常对照组EGF阳性细胞主要分布于远曲小管和髓袢,阿霉素组EGF还在集合管和近曲小管上表达;EGF阳性表达范围和强度随尿蛋白增加而增加;EGFmRNA表达量以及EGF在肾小管中的表达强度与24 h尿蛋白量呈正相关。肾小管上皮细胞广泛表达EGFR,阿霉素组EGFR在小管表达均高于正常,但组间各时点差异无显著性;随尿蛋白增加EGFR在肾小球内表达逐渐增多。EGFR在肾小球和肾小管中的表达强度均与24 h尿蛋白量呈正相关。WT1和EGFR双重免疫组化显示阿霉素肾病组EGFR可在足突细胞上表达,正常组则无。结论阿霉素肾病大鼠的肾小球脏层上皮有EGFR的表达。EGF/EGFR可能参与了阿霉素肾病的发病过程以及蛋白尿的形成。     

EGF对EGFR基因和c-fos、c-myc原癌基因DNA结合蛋白质的影响

基因转录调控作用是EGF的细胞核内作用之一,而序列特异的DNA结合蛋白质与基因转录的调控密切相关。本文以C_3H小鼠胚胎正常成纤维细胞C_3H_(10)T_(1/2)C18(简称NC_3H_(10))株及其氚标记脱氧胸苷(~3H-TdR)恶性转化的细胞株(简称TC_3H_(10))为对象,我们研究了EGF作用下,核内蛋白质与EGFR基因和c-fos、c-myc二种原癌基因的结合状态。研究发现,EGF的持续作用可使EGFR基因的特异结合蛋白质P120、c-fos基因的特异结合蛋白质P80、以及c-myc基因的特异结合蛋白质P125等明显增加。这些结果提示基因的特异结合蛋白质可能与EGF对基因转录的调控密切相关。上述结果尚未见到国内外同类报道。     

Epidermal Growth Factor and Basic Fibroblast Growth Factor Have Independent Actions on Mesencephalic Dopamine Neurons in Culture

Abstract: Epidermal growth factor (EGF) and basic fibro-blast growth factor (bFGF) are both trophic for dopamine neurons s in cultures of dissociated embryonic rat mesen-cephaion, but the significance of this apparent overlap in neurotrophic activity is not yet known. In this study, we investigated the mechanisms of action of these two growth factors and the potential relationship between them, Using a nuclease protection assay, we determined that bFGF mRNA was expressed in the cultures. Double-label immunocytochemistry revealed that bFGF immunore-active material could be detected in tyrosine hydroxylase immunoreactive neurons and glial fibrillary acidic protein immunoreactive astrocytes. EGF treatment increased bFGF mRNA content per culture dish. As we have previously demonstrated that EGF exerts its dopaminergic neurotrophic activity via an intermediate cell type, studies were designed to address whether the pathway by which EGF acts on dopaminergic neurons is mediated by the release of bFGF. However, the trophic action of EGF on dopamine neurons, represented by high-affinity neuronal dopamine uptake, could not be blocked by immunoneutralization of bFGF, suggesting that the actions of EGF were not mediated by bFGF release. The time course of the effects of EGF and bFGF on dopamine uptake were similar, with significant increases detectable only after 5 days in culture. Both growth factors were active in the picomolar-to-nannomolar range with maximal trophic activity between 0.4 and 2.5 n M. EGF, however, was the more potent mitogen under these conditions. When cultures were simultaneously incubated with maximal concentrations of EGF and bFGF, the effect on dopamine uptake was significantly greater than with either growth factor alone and, in fact, approximated the sum of the individual effects. On the basis of these results we conclude that these growth factors have independent effects on dopamine neurons of the mesencephalon.     

上皮生长因子受体和癌胚抗原分子内血型Y配基表达的免疫生化分析

以抗CEA、EGF-γ和血型前体Y配基抗原的单抗进行分析,结果表明:结肠癌组织中表达CEA和血型前体Y配基较强,而EGF-γ表达水平极低;进一步鉴定分析,识别血型前体Y配基抗原决定簇的单抗C_(14)与肿瘤具有较好的反应性。并发现这种决定簇存在于各种生物大分子中,包括以糖蛋白和糖脂形式存在,并表达于EGF-γ与CEA分子中。这一结果提示血型前体抗原过量表达于肿瘤细胞中,不但是血型组织相容抗原,可能也参与到一些特殊生物分子中,应深入研究和鉴定其功能。     

Epidermal Growth Factor in Synaptosomal Fractions of Mouse Cerebral Cortex

Using a specific and sensitive epidermal growth factor radioimmunoassay (EGF-RIA) we measured EGF concentrations in whole brain, cerebral cortex, and cerebral cortical synaptosomal (pinched-off presynaptic nerve terminals) fractions of 26-day-old mouse brain. The relative EGF concentration in synaptosomal fractions was significantly greater than the growth factor concentrations in whole brain or cerebral cortex. Intracerebral injection, in an amount of EGF, several-fold greater than whole brain EGF content, did not appreciably increase synaptosomal EGF concentration, suggesting that no artifact was involved. The high synaptosomal EGF content suggests a neurotransmitter or a neuromodulator role for EGF in the CNS.     

Epidermal Growth Factor and Basic Fibroblast Growth Factor Protect Dopaminergic Neurons from Glutamate Toxicity in Culture

Abstract: In this report we characterize the toxicity of the excitatory amino acid l -glutamate with respect to dopaminergic neurons cultured from embryonic rat mesencephalon. We also demonstrate that two growth factors, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), can protect these neurons from damage. Micromolar concentrations of l -glutamate, as well as agonists that specifically activate N -methyl- d -aspartate (NMDA) and non-NMDA receptors, are all toxic to dopamine neurons in a concentration-dependent manner, as reflected by decreases in high-affinity dopamine uptake and confirmed by decreases in numbers of tyrosine hydroxylase-immunoreactive neurons. Although the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione could attenuate the effects of quisqualate, treatment with this antagonist could not eliminate the effects of glutamate itself. Similarly, (±)-2-amino-5-phosphonopentanoic acid was effective against NMDA toxicity but could not protect cells from quisqualate toxicity. Thus, each type of receptor could mediate neurotoxicity independently of the other. The presence of EGF or bFGF in the culture medium conferred a relative resistance of dopaminergic neurons to glutamate and quisqualate neurotoxicity by increased glutamate transport. However, treatment of the cultures with l - trans -pyrrolidine-2,4-dicarboxylic acid, an inhibitor of glutamate transport, attenuated but did not eliminate the protective effects of both growth factors against glutamate toxicity. When cultures were incubated with conditioned medium from growth factor-treated cultures, neuroprotection was also achieved. These results suggest that both EGF and bFGF can protect neurons from neurotoxicity in culture by increasing the capacity of the culture for glutamate uptake as well as by the secretion of soluble factors into the medium.