GENETIC CONTROL OF NUTRITIONAL STARVATION IN YEAST

设计实验以确定在酿酒酵母中基因表达受倍性控制的机制。 这项工作对人类异常细胞生长有影响，因为异常细胞控制的肿瘤细胞通常含有异常数量的染色体。 虽然超倍性通常被视为异常细胞周期控制的结果，但该提议表明，超倍性本身可能导致细胞增殖所需的关键分子的异常表达。 基因阵列将用于确定倍性从单倍体到四倍体不等的同基因酵母菌株中基因转录倍性控制的分子基础。 一组实验旨在确定G1细胞周期蛋白转录在细胞大小和细胞增殖的倍性控制中的作用。 这些研究将确定倍性控制本身是否受细胞周期调控。 由于多倍体细胞比其整倍体对应物对营养饥饿更敏感，因此将鉴定导致整倍体和多倍体生长控制差异的基因。 交配型位点的杂合性和染色体配对在多倍体对营养饥饿的反应中的作用将被确定。 将分析已知由倍性转录控制的基因之一的启动子，以鉴定响应倍性控制的顺式作用序列。 另一个筛选被设计来鉴定介导倍性控制的反式作用基因。 盐抗性，倍性敏感表型，将用于筛选倍性依赖表型的抑制因子。 此外，盐敏感性的细胞基础将得到阐明。 第三组实验确定了Rim 1转录因子在稳定期代谢中的作用。这种已知的青霉素生产真菌调节剂的酵母同系物被提议用于控制酵母属中的稳定期代谢。 第四组实验的重点是双苯酰氨，一个保守的翻译后修饰的延伸因子2在细胞调控的作用。 DPH突变体具有稳定期缺陷，其在二倍体中比在单倍体中更严重。 提出的实验将导致更深入地了解倍性在异常细胞增殖中的作用。

Experiments are designed to determine the mechanism by which gene expression is controlled by ploidy in the yeast Saccharomyces cerevisiae. This work has implications for abnormal cell growth in humans because tumor cells with aberrant cell control often contain an abnormal number of chromosomes. Although hyperploidy is usually viewed as a consequence of aberrant cell cycle control, this proposal suggests that hyperploidy itself may cause the abnormal expression of key molecules required for cell proliferation. Gene arrays will be used to determine the molecular basis for the ploidy control of gene transcription in isogenic yeast strains whose ploidy varies from haploid to tetraploid. One set of experiments is designed to identify the role of G1 cyclin transcription in the ploidy control of cell size and cell proliferation. These studies will determine whether ploidy control is itself cell cycle regulated. As polyploid cells are much more sensitive to nutritional starvation that their euploid counterparts, the genes responsible for the differences in euploid and polyploid growth control will be identified. The role of heterozygosity at the mating type locus and chromosome pairing in the response of polyploids to nutritional starvation will be ascertained. The promoter of one of the genes known to be transcriptionally controlled by ploidy will be analyzed to identify cis-acting sequences that respond to ploidy control. Another screen is designed to identify the trans-acting genes that mediate ploidy control. Salt resistance, a ploidy sensitive phenotype, will be used to screen for suppressors of the ploidy dependent phenotype. In addition the cellular basis for salt sensitivity will be elucidated. A third set of experiments identifies the role of the Rim1 transcription factor in stationary phase metabolism. This yeast homolog of a known fungal regulator of penicillin production is proposed to control stationary phase metabolism in Saccharomyces. A fourth set of experiments focuses on the role of dipthamide, a conserved posttranslational modification of elongation factor2 in cellular regulation. dph mutants have a stationary phase defect that is again more severe in diploids that in haploids. The experiments proposed will lead to a deeper understanding of the role of ploidy in aberrant cell proliferation.