PDGF-RECEPTOR NEGATIVE CELLS

电泳法处理密度受阻的BALB/c-3T3细胞 均一或高纯度的血小板衍生生长制剂 因子(PDGF)刺激快速和选择性地积累几种 通过无细胞翻译鉴定了丰富的mRNA的种类。这些 可翻译的mRNAs在进入S阶段之前很久就出现了。较少的PDGF 与PDGF调节的DNA相比，选择性的mRNA积累是必需的 综合。可翻译的mRNA在加入 表皮生长因子，但在添加胰岛素或血小板不足后不能 血浆。它们的选择性积累被添加到 放线菌素D定义了三类PDGF调节的mRNAs。一个 早期(初级)RNA在加入PDGF后30至60分钟内出现；其 环己亚胺不能阻止蓄积。另一个早期的mRNA也是如此 在60分钟内出现，但PDGF和放线菌亚胺处理均为 最佳积累所必需的。第三类，次级核糖核酸，开始 在90到120分钟后积累；这个班级的出现是 被放线菌亚胺抑制。一、二维凝胶电泳法 的翻译产品证明了一个自发转变的 BALB/c-3T3(ST2-3T3)细胞株，不需要PDGF或EGF 生长，结构性积累的次生生长因子调节 MRNAs。这些可翻译的mRNAs的积累可能需要 PDGF调控的DNA合成。 我们最近利用了一种PDGF调节的溶酶体的cdna探针。 蛋白质(称为MEP)直接定量PDGF调节的mRNA。PDGF 在加入一次剂量后240分钟开始刺激MEP mRNA的积聚 依附时尚。其他生长因子，包括EGF、IGF-1、胰岛素、 而缺乏血小板的血浆则没有这种作用。调制后的PDGF 放线菌酮可抑制MEP基因的积累 这是PDGF调节蛋白质合成所必需的。一种自发的 不需要PDGF的BALB/c-3T3细胞的转化变体 生长以结构性方式积累MEP基因。因此，环保部 转录本是PDGF调控的二级RNA的一个例子。(J)

The treatment of density-arrested BALB/c-3T3 cells with electrophoretically homogenous or highly purified preparations of the platelet-derived growth factor (PDGF) stimulated the rapid and selective accumulation of several species of abundant mRNA identified by cell-free translation. These translatable mRNAs appeared long before entry into the S phase. Less PDGF was required for selective mRNA accumulation than for PDGF-modulated DNA synthesis. The translatable mRNAs also accumulated after addition of the epidermal growth factor but not after addition of insulin or platelet-poor plasma. Their selective accumulation was blocked by addition of actinoimycin D. Three classes of PDGF-modulated mRNAs were defined. An early (primary) RNA appeared within 30 to 60 min of PDGF addition; its accumulation was not blocked by cycloheximide. Another early mRNA also appeared within 60 min, but treatment with both PDGF and cycloheximide was required for optimal accumulation. A third class, secondary RNAs, began to accumulate later at 90 to 120 min; the appearance of this class was inhibited by cycloheximide. One-\and two-dimensional gel electrophoresis of translation products demonstrated that a spontaneously transformed BALB/c-3T3 (ST2-3T3) cell line, which does not require PDGF or EGF for growth, constitutively accumulated the secondary growth factor-regulated mRNAs. The accumulation of these translatable mRNAs may be required for PDGF-modulated DNA synthesis. We have recently utilized a cDNA probe of a PDGF-regulated lysosomal protein (termed MEP) to directly quantify a PDGF-modulated mRNA. PDGF began to stimulate MEP mRNA accumulation 240 min after addition in a dose dependent fashion. Other growth factors, including EGF, IGF-1, insulin, and platelet-poor plasma did not have this effect. The PDGF modulated accumulation of MEP mRNA was inhibitable by cycloheximide demonstrating that PDGF modulated protein synthesis is required. A spontaneously transformed variant of BALB/c-3T3 cells which does not require PDGF for growth accumulated MEP mRNA in a constitutive fashion. Thus the MEP transcript is an example of a PDGF-modulated secondary RNA. (J)