EGF促进RPE细胞β_2肾上腺能受体诱导的cAMP形成：受体间交互作用分析

EGF POTENTIATES THE β_2-ADRENERGIC RECEPTOR-INDUCED STIMULA-TION OF cAMP IN RPE CELLS:ANALYSIS OF RECEPTOR INTERACTION

研究证实表皮生长因子（ＥＧＦ）不影响培养人眼视网膜色素上皮（ＲＰＥ）细胞ｃＡＭＰ的基础水平，但促进异丙肾上腺素激活β＿２受体后诱导ｃＡＭＰ水平升高的效应，并呈量效依赖关系。ＥＧＦ对腺嘌呤核苷Ａ＿２受体激动剂ＮＥＣＡ诱导ｃＡＭＰ水平升高的效应没有明显影响。细胞增殖分析表明，ＥＧＦ刺激人眼ＲＰＥ细胞增殖，而ＤｉｂｕｔｙｒｙｌｃＡＭＰ和异丙肾上腺素抑制ＥＧＦ刺激增殖的效应。结果提示，在人眼ＲＰＥ细胞ＥＧＦ和β２受体之间存在受体间交互作用。

In this study,we show that epidermal growth factor(EGF)does not alter the basal levels of cAMP,but elevates in a dose-dependent manner the stimulation of cAMP produced by iso-proterenol via β2-type receptors in cultured human retinal pigment epithelium (RPE ) cells,In con-trast,EGF does not affect the elevation of cAMP caused by NECA(5-[N-ethyl]-carboxami-doadenosine),an adenosine A2-receptor agonist.Using 3H -thymidine incorporation into DNA of cul-tured RPE cells,as an index for proliferation,the further experiments demonstrated that EGF stimu-lates the RPE cell proliferation while isoproterenol and dibutyryl cAMP nullify the EGF effect.The data presented here,therefore,suggest the existence of an interaction between EGF and β2-type re-ceptors in the cultured human RPE cells。