Chua C C, Geiman D E, Ladda R L
Mech Ageing Dev. 1986 Mar;34(1):35-55. doi: 10.1016/0047-6374(86)90103-x.
Cellular responsiveness to epidermal growth factor (EGF) and the structure of the receptor for epidermal growth factor (EGF-R) were compared in young and senescent human fibroblast (HF) cells. Biosynthetic labeling of HF cells with [35S] methionine followed by immunoprecipitation with EGF-R antibody revealed the presence of Mr 170 000 EGF-R in cells from both stages. Autophosphorylation of EGF-R in response to EGF was identical in young and senescent cells. Phosphoamino acid analysis of the autophosphorylated EGF-R indicated that tyrosine residues were phosphorylated in each preparation. Two-dimensional peptide mapping of [125I]EGF-R from young and senescent cells showed essentially the same pattern, indicating that EGF-R does not apparently undergo detectable changes in senescent human fibroblasts. The responsiveness of aging HF cells to EGF for the induction of ornithine decarboxylase activity and for the production of secretory proteins was measured. Young and senescent HF cells showed about a three-fold induction of collagenase activity upon addition of EGF. Ornithine decarboxylase activity was also stimulated by EGF to a comparable level in young and senescent cells. Our results indicate that the responsiveness of HF cells to EGF for these two biochemical parameters does not decline with the loss of proliferative activity.
对年轻和衰老的人成纤维细胞（HF）中细胞对表皮生长因子（EGF）的反应性以及表皮生长因子受体（EGF-R）的结构进行了比较。用[35S]甲硫氨酸对HF细胞进行生物合成标记，然后用EGF-R抗体进行免疫沉淀，结果显示两个阶段的细胞中均存在分子量为170000的EGF-R。年轻和衰老细胞中EGF刺激下的EGF-R自身磷酸化情况相同。对自身磷酸化的EGF-R进行磷酸氨基酸分析表明，每种样品中酪氨酸残基均被磷酸化。对来自年轻和衰老细胞的[125I]EGF-R进行二维肽图谱分析，结果显示基本相同的模式，表明在衰老的人成纤维细胞中EGF-R显然未发生可检测到的变化。测定了衰老HF细胞对EGF诱导鸟氨酸脱羧酶活性和分泌蛋白产生的反应性。添加EGF后，年轻和衰老的HF细胞中胶原酶活性均有大约三倍的诱导。EGF对年轻和衰老细胞中鸟氨酸脱羧酶活性的刺激程度相当。我们的结果表明，HF细胞对EGF在这两个生化参数方面的反应性不会随着增殖活性的丧失而下降。
