STRUCTURE AND FUNCTION OF ONCOGENES AND ANTI-ONCOGENES

我们的研究目标是了解分子结构和功能 在正常生长中起关键作用的基因， 分化、肿瘤转化和凋亡， 人体组织和肿瘤。我们研究癌基因，特别是c-myc，v-raf， v-abl和v-cbl;抑癌基因，特别是细胞周期调节基因 蛋白质（细胞周期蛋白）及其抑制剂，p21（waf）和p16; bcl-2 家族;以及在细胞内传递信号的分子， 尤其是，蛋白激酶C（PKC）。我们和其他人已经表明， 继发于染色体易位的c-myc表达失调 在c-myc区域是一个重要的因素，在一系列的遗传 在BALB/c小鼠中涉及浆细胞发生的改变， Burkitt和艾滋病相关淋巴瘤。 目前尚不清楚为什么BALB/c小鼠对这些特别敏感。 遗传变异但我们有一个候选机制我们发现 BALB/c小鼠在一种特殊形式的 DNA损伤的切除修复。这种形式的切除修复是不寻常的 与大多数形式的DNA切除修复不同， RNA转录。此外，缺陷仅在修复中显现 c-myc、Pvt 1、开关IG a和IG k基因中的DNA损伤，即 B淋巴细胞中复发性染色体易位的位点 肿瘤。这是一种合理的基因产生机制- 特异性、菌株特异性基因组不稳定性，易使BALB/c 小鼠的染色体易位，导致组成性 c-myc的表达。这种c-myc表达失调，反过来， 导致基因特异性遗传不稳定性扩展到新的 基因的子集，包括细胞周期蛋白D2、RNR 2（核糖核苷酸的亚基2 还原酶）和二氢叶酸还原酶（DHFR）。这些基因 作为对c-myc的应答， 过度表达，可能导致细胞失控 增殖 我们克隆了八种蛋白激酶C（PKC）同工酶， 表达载体和产生的细胞系，过表达每一种 这些异构体。我们还生产了嵌合PKC分子，即，一半 PKC-d和半PKC-e，以及过表达它们的细胞系，以确定 无论是调节性的一半还是催化性的一半， PKC的功能。PKC-d能够介导TPA诱导的巨噬细胞 早幼粒细胞分化，而PKC-e的过度表达， 啮齿类成纤维细胞在体外转化，在体内致瘤。 PKC嵌合体的过表达表明，C末端的一半， 含有催化结构域，似乎携带大部分同种型- 髓样分化和成纤维细胞的特异性决定因素 转型

Our research goal is to understand the molecular structure and function of the genes that play critical roles in normal growth and differentiation, neoplastic transformation, and apoptosis in mouse and human tissues and tumors. We study oncogenes, particularly c-myc, v-raf, v-abl and v- and c-cbl; anti-oncogenes, esp. the cell cycle-regulating proteins (cyclins) and their inhibitors, p21 (waf) and p16; the bcl-2 family; as well as molecules that transduce signals within the cell, esp., protein kinase C (PKC). We and others have shown that the deregulated expression of c-myc secondary to chromosomal translocations in the c-myc region is an essential element in the series of genetic alterations that are involved in plasmacytomagenesis in BALB/c mice and in Burkitt and AIDS-associated lymphomas in man. It is not known why BALB/c mice are particularly susceptible to these genetic aberratons, but we have a candidate mechanism. We have found that the BALB/c mouse has an unusual defect in a special form of excision repair of DNA damage. This form of excision repair is unusual in that, unlike most forms of DNA excision repair it is not coupled to RNA transcription. Furthermore, the defect is only manifest in repair of DNA damage in the c-myc, Pvt1, switch Ig a and Ig k genes, namely the sites of recurrent chromosomal translocations in B-lymphocytic neoplasms. This is a plausible mechanism for the production of the gene- specific, strain-specific genomic instability that predisposes BALB/c mice to the chromosome translocations that lead to constitutive expression of c-myc. This dysregulated expression of c-myc, in turn, leads to an extension of gene-specific genetic instability to a new subset of genes, including cyclin D2, RNR2 (subunit 2 of ribonucleotide reductase) and dihydro- folate reductase (dhfr). This subset of genes uniquely becomes amplified and overexpressed as a response to c-myc overexpression, possibly contributing to uncontrolled cell proliferation. We have cloned eight Protein Kinase C (PKC) isozymes into a variety of expression vectors and produced cell lines that overexpress each of these isoforms. We have also produced chimeric PKC molecules, i.e., half PKC-d and half PKC-e, and cell lines that overexpress them, to determine whether the regulatory half or the catalytic half controls various functions of PKC. PKC-d is able to mediate TPA-induced macrophage differentiation of promyelocytes, while overexpression of PKC-e in rodent fibroblasts is transforming in vitro and tumorigenic in vivo. Overexpression of the PKC chimeras showed that the C-terminal half, containing the catalytic domain, appears to bear most of the isoform- specific determinants of myeloid differentiation and fibroblast transformation.