MECHANISM OF BLEOMYCIN INDUCED COLLAGEN SYNTHESIS

博莱霉素会导致肺纤维化。 分离自 博来霉素处理的成纤维细胞合成增加的前胶原， 以控制多核糖体，而非胶原蛋白的合成不受影响。 I型和II型细胞和多聚体合成的时间响应 博来霉素处理的雏鸡肺中的III型前胶原将被 与博来霉素处理的鸡中这些前胶原的合成相比 肺成纤维细胞 细胞总Ⅰ型前胶原mRNA含量 不会被博莱霉素治疗改变。 然而，I型前胶原mRNA 在多聚核糖体中升高，在核和多聚核糖体后 细胞质 这些数据表明I型前胶原蛋白的分配效应 mRNA。 博来霉素增加多聚体的分子机制 测定前胶原的合成。 I型和I型的合成 III总细胞、细胞核中的前胶原mRNA及其在细胞中的积累 将测定多聚核糖体后的细胞质和多聚核糖体。 效果 博来霉素对前胶原hnRNA的核数量的影响也将是 测定 将从对照组和博来霉素处理组中分离细胞核 成纤维细胞并在体外转录。 I型和III型的运输 将评估来自细胞核和多核糖体的前胶原mRNA。 的影响 博来霉素对细胞、细胞质和细胞核总降解的影响 将测定I型和III型前胶原mRNA序列。 到 确定多聚体前胶原合成增加的机制， 将分离多聚体mRNP，并测定I型前胶原和 将测定III型mRNA。 I型和III型前胶原 将确定这些mRNP体外合成的量。 盐洗 将从对照和博来霉素处理的成纤维细胞分离的多聚体 加入到含有对照的体外蛋白质合成系统中 多聚核糖体以确定博来霉素诱导的刺激性 因数。 前胶原合成抑制因子的存在， 评价对照多核糖体。 如果存在这样的因素，我们 分离这些。 我们还将确定博来霉素治疗是否改变了 前胶原的分泌、积累和/或降解。 这个成纤维细胞 博来霉素诱导的肺毒性模型可用于筛选 博莱霉素及其类似物对成纤维细胞胶原的直接作用 新陈代谢. 此外，这些研究可能阐明了 博莱霉素引起的肺纤维化

Bleomycin causes pulmonary fibrosis. Polysomes isolated from bleomycin-treated fibroblasts synthesize increased procollagen as compared to control polysomes, while noncollagen protein synthesis is not effected. The temporal response of cellular and polysomal synthesis of type I and type III procollagens in the lungs of bleomycin-treated chicks will be compared to the synthesis of these procollagens in bleomycin-treated chick lung fibroblasts. The contents of total cellular procollagen type I mRNAs are not altered by bleomycin treatment. However, type I procollagen mRNAs are elevated in polysomes and decreased in nuclei and in the post-polysomal cytoplasm. These data indicate a partitioning effect on type I procollagen mRNAs. The molecular mechanism(s) by which bleomycin increases polysomal procollagen synthesis will be determined. The synthesis of type I and type III procollagen mRNAs in the total cell, nuclei and their accumulation into the post-polysomal cytoplasm and polysomes will be determined. The effect of bleomycin on the nuclear quantities of procollagen hnRNAs will also be determined. Nuclei will be isolated from control and bleomycin-treated fibroblasts and transcribed in vitro. The transport of type I and type III procollagen mRNAs from nuclei and polysomes will be assessed. The effects of bleomycin on the degradation of total cellular, cytoplasmic and nuclear type I and type III procollagen mRNA sequences will be determined. To identify the mechanism(s) of increased polysomal procollagen synthesis, polysomal mRNPs will be isolated and the contents of procollagen type I and type III mRNAs will be determined. Procollagen type I and type III synthesized by these mRNPs in vitro will be determined. The salt wash of polysomes isolated from control and bleomycin-treated fibroblasts will be added to an in vitro protein synthesizing system containing control polysomes to determine the presence of a bleomycin-induced stimulating factor(s). The presence of a procollagen synthesis inhibiting factor in the control polysomes will be assessed. If such a factor(s) exists we isolate these. We will also determine if bleomycin treatment alters the secretion, accumulation and/or degradation of procollagen. This fibroblast model of bleomycin-induced lung toxicity may be then used to screen the direct effect of bleomycin and its analogues on fibroblast collagen metabolism. In addition, these studies may elucidate the molecular basis of bleomycin-induced pulmonary fibrosis.