Related Genes And Regularity Effectof Stress Granules Formation In Saccharomyces Cerevisiae Hansen

When faced with stressful conditions, eukaryotic cells respond by forming large cytoplasmic granules consisting of complexes of m RNAs, ribosomal components, and RNA-binding proteins including translation factors. In these granules, m RNA is kept translational silent, allowing the cell to focus its energy on translation of the transcripts required for survival under stress. These transcripts can be degraded, or returned to translation when conditions improve. A distinction is made between two types of RNA granules with different protein compositions: Processing bodies(PBs), smaller and with a distinct shape, exist in low numbers throughout. Stress granules(SGs), which are the main subject of this research, larger with an irr egular shape, are consisted of messenger ribonucleo protein particle(m RNP) and formed under severe stress, including heat shock, deprivation of carbon source, peroxidation, hyperosmosis, virus infection and ultraviolet radiation, but not X radiation or DN A damaging.It is believed that the capacity to form cytoplasmic RNA granules is important for organismal survival under stress conditions, as well as to strike the balance between the apoptotic response and survival in eukaryotic cells. Formation of stres s granules provides a molecular explanation of stress ability of Saccharomyces cerevisiae Hansen, at the same time, the references of survival selection, even the formation of cancer cell for other eukaryotic cells. So far, the overall composition of SGs, as well as their assembly requirements and regulation through stress-activated signaling pathways remain largely unknown, the purpose of this research is to explain the mechanism of them.The genome DNA sequence of S. cerevisiae is acquired already. Also, the technology of automated yeast synthetic genetic array(SGA) and high throughput or high content microscopy(HCM) are successfully developed. Base on the technical platform above, this research transforms a red fluorescent protein with stress granule marker PAB1-RFP into S. cerevisiae genome, 4600 single gene knockout mutants and 800 temperature sensitive mutants were treated with stress, mainly deoxy glucose, as stress granule induction. Difference in tress granules abundance of mutant and wild type is the way to pick out the candidates, with analyzing the interaction between stress granule and bio-function of the mutant missing gene, to make clear the metabolic pathways and mechanisms of cell process in related in the formation of stress granules.The screen revealed numerous genes not previously implicated in stress granule formation. The GO analysis shows that stress granule formation required genes group in endosomal components, ribosomal components, GAPR complex, EGO-GSE complex and protein folding. Missing gene lead to increase of stress granule, which working on resolution, is related to biological membrane structure, vesicle transport and autophagy. Most mutants with strong phenotypes are equally stress granule defective when challenged with heatshock or hyperosmosis stress, but a considerable fraction is stress-specific. Proteins associated with stress granule defects are enriched in low-complexity regions, indicating that multiple weak macromolecule interactions are responsible for the structural integrity of stress granules. Heat shock, an induction of stress granules and mutation frequency variation of budding yeast. Certain stress granule defective mutants, display an enhanced heat-induced mutation rate. We found several mutations affecting the Ran GTPase, regulating nucleocytoplasmic transport of RNA and proteins, to confer stress granule defects.Stress-regulated transcripts reach more extreme levels in mutants unable to form SGs: stress-induced m RNAs accumulate to higher levels than in the wi ld-type, whereas stress-repressed m RNAs are reduced further in such mutants. It indicates not only are SGs being regulated by stress signaling pathways, but SGs also modulate the extent of stress responses. We speculate that nucleocytoplasmic shuttling of RNA-binding proteins is required for gene expression regulation during stress, and that SGs modulate this traffic. The absence of SGs thus leads the cell to excessive, and potentially deleterious, reactions to stress. Stress granule formation might be the reason of reduced cell response on superimposed stress.In addition, this thesis has also compared damage protein aggregates and stress granules in S. cerevisiae during aging. First of all, the two kinds of aggregates are not co-located. Then we found that stress granules could be induced by cellular senescence, but their granular synthesis would be inhibited in aging cells under other stress. The abundance of protein aggregates, which is similar to stress granules, in senescent cells is higher than that of new born cells in non-stress conditions, but the young cells is higher than old cells under stress. That means aging is inhibiting protein aggregates from assemble in old cells.