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Chromatin remodeling during temperature sensing in plants
Šlesingerová, Terezie
The evolutionary conserved transcriptional co-activator Spt–Ada–Gcn5 Acetyltransferase (SAGA) complex in Arabidopsis thaliana is tightly involved in numerous cellular processes by histone posttranslational modifications. The GENERAL CONTROL NON-REPRESSED PROTEIN 5 (GCN5), a SAGA subunit, is a histone acetyltransferase that impacts chromatin remodeling. Arabidopsis mutants lacking GCN5 are sensitive to heat stress, but the molecular mechanisms implicating GCN5 in heat stress are currently unknown. To get an insight into the molecular pathways underlying the heat sensitivity of gcn5, we assessed global proteome changes triggered by heat stress in the gcn5 background. Even though most of the identified proteins responded similarly both in gcn5 and wild type plants, some of them like CONSTITUTIVE PHOTOMORPHOGENIC 11 (COP11) were unaffected by heat in the gcn5 mutant background but decreased drastically in the wild type. We further screened mutants affected in putative GCN5 interactors under heat stress and identified that lack of SAGA COMPLEX SUBUNIT 2A (SCS2A) and INHIBITOR OF GROWTH 1 (ING1) results in heat sensitivity. Taken together, our results pave the way for a more detailed understanding of the role of GCN5 in stress responses.
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Regulation of alternative splicing
Dušková, Eva ; Staněk, David (advisor) ; Trejbalová, Kateřina (referee)
Alternative splicing is an important cellular mechanism. It allows to produce multiple protein isoforms from a limited number of genes. Regulation of alternative splicing involves cis-acting elements on pre-mRNA and trans-acting splicing factors (SR and hnRNP proteins). Because splicing occurs co-transcriptionaly, chromatin structure appears to have a role in the regulation of alternative splicing. We have studied the effect of histone acetylation on alternative splicing. We have prepared splicing reporter for alternative EDB exon, which is part of the fibronectin gene. We have shown, that the inhibition of histone deacetylases affects splicing pattern of EDB exon from the reporter in the same way as the splicing of the endogenous EDB exon. Furthermore, we have shown, that the structure of the promoter affects splicing of alternative EDB exon from splicing reporter. Currently we have found out, that the structure of the promoter influences the degree of histone H4 acetylation. Inclusion of alternative EDB exon in mRNA was inversely proportional to histon acetylation on the reporter. This work might explain why various promoters have different splicing patterns of alternative exons.
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Connections between intermediary metabolism and acetylation of histones
Zach, Róbert ; Převorovský, Martin (advisor) ; Bieberstein, Nicole (referee)
Acetylation of histone proteins affects chromatin structure and functions as a coactivating signal for transcription. Acetylation of histone lysine residues is mediated by histone acetyltransferases, which utilize molecule of Ac-CoA as a donor of acetyl group. Ac-CoA is located in the centre of intermediary carbon metabolism, where it fuels citric acid cycle and fatty acid synthesis. Level of intracellular Ac-CoA fluctuates in response to changes in availability of utilizable carbon sources and metabolic activity of the cell. Since changes in intracellular concentration of Ac-CoA positively correlate with histone acetylation level, Ac-CoA might contribute to transcriptional modulation in response to nutritional stress. Moreover, Ac-CoA takes part in process of differentiation and seems to be important for cell cycle regulation. Key words: Ac-CoA, histone acetylation, nutrition, intermediary metabolism, regulation of transcription, cell cycle, glucose
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Connections between intermediary metabolism and acetylation of histones
Zach, Róbert ; Převorovský, Martin (advisor) ; Bieberstein, Nicole (referee)
Acetylation of histone proteins affects chromatin structure and functions as a coactivating signal for transcription. Acetylation of histone lysine residues is mediated by histone acetyltransferases, which utilize molecule of Ac-CoA as a donor of acetyl group. Ac-CoA is located in the centre of intermediary carbon metabolism, where it fuels citric acid cycle and fatty acid synthesis. Level of intracellular Ac-CoA fluctuates in response to changes in availability of utilizable carbon sources and metabolic activity of the cell. Since changes in intracellular concentration of Ac-CoA positively correlate with histone acetylation level, Ac-CoA might contribute to transcriptional modulation in response to nutritional stress. Moreover, Ac-CoA takes part in process of differentiation and seems to be important for cell cycle regulation. Key words: Ac-CoA, histone acetylation, nutrition, intermediary metabolism, regulation of transcription, cell cycle, glucose
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Regulation of alternative splicing
Dušková, Eva ; Staněk, David (advisor) ; Trejbalová, Kateřina (referee)
Alternative splicing is an important cellular mechanism. It allows to produce multiple protein isoforms from a limited number of genes. Regulation of alternative splicing involves cis-acting elements on pre-mRNA and trans-acting splicing factors (SR and hnRNP proteins). Because splicing occurs co-transcriptionaly, chromatin structure appears to have a role in the regulation of alternative splicing. We have studied the effect of histone acetylation on alternative splicing. We have prepared splicing reporter for alternative EDB exon, which is part of the fibronectin gene. We have shown, that the inhibition of histone deacetylases affects splicing pattern of EDB exon from the reporter in the same way as the splicing of the endogenous EDB exon. Furthermore, we have shown, that the structure of the promoter affects splicing of alternative EDB exon from splicing reporter. Currently we have found out, that the structure of the promoter influences the degree of histone H4 acetylation. Inclusion of alternative EDB exon in mRNA was inversely proportional to histon acetylation on the reporter. This work might explain why various promoters have different splicing patterns of alternative exons.
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