Disease relevance of EGF

• Chicken heart mesenchymal cells do not proliferate in culture medium containing heat-defibrinogenated plasma but proliferate briskly when incubated with epidermal growth factor (EGF) or brain fibroblast growth factor (bFGF) plus insulin-like growth factors (IGFs) or when infected with sarcoma or erythroblastosis viruses [1].
• In epidermis which was induced to differentiation toward keratinization by hydrocortisone or mucous metaplasia by retinol, EGF inhibited DNA synthesis [2].
• All hatched chicks were found to express vector-encoded EGFP gene, which was under the control of the Rous sarcoma virus promoter and boosted post-transcriptionally by woodchuck hepatitis virus post-transcriptional regulatory element sequence [3].
• Here, we successfully demonstrate expression of the EGFP (enhanced green fluorescence protein) gene in chickens using replication-defective MLV (murine leukemia virus)-based retrovirus vectors encapsidated with VSV-G (vesicular stomatitis virus G glycoprotein) [4].
• Distribution studies were done using plasmids encoding enhanced green fluorescent protein (EGFP) reporter gene and a bivalent DNA vaccine coding for infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) immunogenic protein genes [5].

High impact information on EGF

• Heparin-treated MC29-infected cells are, however, 100 times more sensitive to EGF than are their normal, uninfected counterparts [1].
• Both the 80-kilodalton (kDa) (A) and the 105-kDa (B) progesterone receptor subunits were phosphorylated in a reaction that required EGF and EGF receptor [6].
• The increase in tyrosine phosphorylation after serum or EGF stimulation was transient, reaching a maximum at about 5 min and then declining [7].
• By fine-resolution analysis of proteins separated on sodium dodecyl sulfate-polyacrylamide gels, we found that after EGF stimulation, the major increase in phosphotyrosine content was in a 42K Mr protein, with a smaller increase in a 40K Mr protein [7].
• Both the insulin and EGF receptors phosphorylated progesterone receptor at high affinity, exclusively at tyrosine residues and with maximal stoichiometries that were near unity [8].

Biological context of EGF

• Purified preparations of epidermal growth factor (EGF) receptor were used to test hen oviduct progesterone receptor subunits as substrates for phosphorylation catalyzed by EGF receptor [6].
• Heparin-treated, v-myc-transformed chicken heart mesenchymal cells assume a normal morphology but are hypersensitive to epidermal growth factor (EGF) and brain fibroblast growth factor (bFGF); cells transformed by the v-Ha-ras oncogene are refractory to EGF and bFGF but are hypersensitive to insulin-like growth factors [1].
• We have found that exogenous TGF-alpha and EGF inhibit chondrogenesis and myogenesis of limb mesenchyme in vitro [9].
• The transforming proteins of these src-related oncogenes as well as receptors for EGF, platelet-derived growth factor (PDGF), and insulin are associated with tyrosine-specific protein kinases [10].
• The transforming protein erbB of avian erythroblastosis virus (AEV) has considerable sequence homology with the epidermal growth factor (EGF) and appears to represent a truncated form of this receptor [10].

Anatomical context of EGF

• Increased tyrosine phosphorylation of proteins of similar Mr was found in 3T3 cells treated with EGF, but not in NR-6 cells, which lack detectable EGF receptors [7].
• We found that exogenous TGF-alpha and EGF can promote the outgrowth of limb mesoderm in the absence of the AER in vitro and can also promote the outgrowth of limbless and wingless wing bud explants [9].
• EGF is present in ventral but not dorsal limb ectoderm, suggesting a role for EGF in specification of ventral ectoderm [9].
• These studies suggest for the first time that intracellular alkalinization resulting from activation of the Na+/H+ antiporter may be a part of the transmembrane signaling pathway in the action of EGF on chicken granulosa cells [11].
• This work indicates that the related tyrosyl kinase receptors of insulin and EGF may provoke identical responses within hepatocytes, but through the utilization of different transduction systems which merge to common control points [12].

Associations of EGF with chemical compounds

• Purified preparations of insulin, epidermal growth factor (EGF), and platelet-derived growth factor (PDGF) receptors were compared for their abilities to phosphorylate purified hen oviduct progesterone receptors [8].
• For comparison with the growth-promotive effect of the posterior fragment, fibroblast growth factor (FGF), epidermal growth factor (EGF), insulin, and retinoic acid were tested in cell culture [13].
• Estradiol or epidermal growth factor (EGF) induce a 40% increase in cells in 4 days when cultures are grown in serum levels that do not support growth [14].
• When a 13-day-old chick embryonic tarsometatarsal skin was cultured for 4 days in medium containing hydrocortisone (20 nM) and 5% delipidized fetal calf serum (FCS), epidermal growth factor (EGF, 100 ng/ml) decreased epidermal DNA content 42% and inhibited epidermal DNA synthesis 87% [15].
• In the absence of FCS, however, EGF did not inhibit steroid-induced alpha-type keratinization and did not affect either steroid-induced epidermal transglutaminase activity or amount of epidermal glucocorticoid receptor [15].

Regulatory relationships of EGF

• Furthermore, EGF caused a twofold increase in glucocorticoid-induced epidermal transglutaminase activity and in the amount of epidermal glucocorticoid receptor [15].
• Transforming growth factor-alpha (TGF-alpha) is a 50 amino acid polypeptide which has been shown to stimulate proliferation in both neoplastic and normal cell types acting through the epidermal growth factor (EGF) receptor [16].

Other interactions of EGF

• By contrast, theca cell PA activity was not significantly altered by EGF (16.4 nM), IGF-I (131 nM), FGF (7.5 nM), or PDGF (1 nM) [17].
• Of the other factors known to be present in bone, platelet-derived growth factor (PDGFA/B) and epidermal growth factor (EGF) had a small effect on calcium mobilization but had no effect on ALP activity. bFGF reduced ALP activity slightly without an effect on calcium metabolism [18].
• Fibronectin secreted into the medium by unstimulated cells also increased with the stage of follicular maturation and was enhanced by EGF and TGF-alpha [19].
• The present studies were conducted to establish interactions between transforming growth factor (TGF)-beta and the epidermal growth factor (EGF) family members, TGFalpha and betacellulin (BTC), relative to proliferation and differentiation of granulosa cells in hen ovarian follicles [20].

Analytical, diagnostic and therapeutic context of EGF

• Northern analysis, reverse transcription-polymerase chain reaction, and radioimmunoassay indicated that the GD and granulosa cells but not theca cells are the sources of EGF in chicken preovulatory follicles [21].
• Immunocytochemistry revealed that EGF, but not TGFalpha, was present in the germinal disc of the four largest preovulatory follicles of the hen [22].
• The effect of epidermal growth factor (EGF) on the basement membrane structure of chick embryonic skin cultured in a chemically defined medium (BGJb) containing 20 mM hydrocortisone, and EGF at 10, 50, or 100 ng/ml supplemented with 5% delipidized fetal calf serum, was examined by electron microscopy [23].
• After 20 h culture in the presence of 10 ng/ml EGF, the incorporation of tritiated thymidine into DNA is stimulated two- to three-fold following a 2 h labelling period, as revealed by scintillation counting [24].
• To determine if Epidermal Growth Factor (EGF) affects cardiac muscle cells, immunostaining and autoradiography were performed to find the Muscle Cell Labeling Index (MLI) [25].

References