TY - JOUR A1 - Lämke, Jörn A1 - Brzezinka, Krzysztof A1 - Altmann, Simone A1 - Bäurle, Isabel T1 - A hit-and-run heat shock factor governs sustained histone methylation and transcriptional stress memory JF - The EMBO journal N2 - In nature, plants often encounter chronic or recurring stressful conditions. Recent results indicate that plants can remember a past exposure to stress to be better prepared for a future stress incident. However, the molecular basis of this is poorly understood. Here, we report the involvement of chromatin modifications in the maintenance of acquired thermotolerance (heat stress [HS] memory). HS memory is associated with the accumulation of histone H3 lysine 4 di- and trimethylation at memory-related loci. This accumulation outlasts their transcriptional activity and marks them as recently transcriptionally active. High accumulation of H3K4 methylation is associated with hyper-induction of gene expression upon a recurring HS. This transcriptional memory and the sustained accumulation of H3K4 methylation depend on HSFA2, a transcription factor that is required for HS memory, but not initial heat responses. Interestingly, HSFA2 associates with memory-related loci transiently during the early stages following HS. In summary, we show that transcriptional memory after HS is associated with sustained H3K4 hyper-methylation and depends on a hit-and-run transcription factor, thus providing a molecular framework for HS memory. KW - chromatin KW - H3K4 methylation KW - heat shock transcription factor KW - priming KW - transcriptional memory Y1 - 2016 U6 - https://doi.org/10.15252/embj.201592593 SN - 0261-4189 SN - 1460-2075 VL - 35 SP - 162 EP - 175 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Kabelitz, Tina A1 - Brzezinka, Krzysztof A1 - Friedrich, Thomas A1 - Gorka, Michal A1 - Graf, Alexander A1 - Kappel, Christian A1 - Bäurle, Isabel T1 - A JUMONJI Protein with E3 Ligase and Histone H3 Binding Activities Affects Transposon Silencing in Arabidopsis JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - Transposable elements (TEs) make up a large proportion of eukaryotic genomes. As their mobilization creates genetic variation that threatens genome integrity, TEs are epigenetically silenced through several pathways, and this may spread to neighboring sequences. JUMONJI (JMJ) proteins can function as antisilencing factors and prevent silencing of genes next to TEs. Whether TE silencing is counterbalanced by the activity of antisilencing factors is still unclear. Here, we characterize JMJ24 as a regulator of TE silencing. We show that loss of JMJ24 results in increased silencing of the DNA transposon AtMu1c, while overexpression of JMJ24 reduces silencing. JMJ24 has a JumonjiC (JmjC) domain and two RING domains. JMJ24 autoubiquitinates in vitro, demonstrating E3 ligase activity of the RING domain(s). JMJ24-JmjC binds the N-terminal tail of histone H3, and full-length JMJ24 binds histone H3 in vivo. JMJ24 activity is anticorrelated with histone H3 Lys 9 dimethylation (H3K9me2) levels at AtMu1c. Double mutant analyses with epigenetic silencing mutants suggest that JMJ24 antagonizes histone H3K9me2 and requires H3K9 methyltransferases for its activity on AtMu1c. Genome-wide transcriptome analysis indicates that JMJ24 affects silencing at additional TEs. Our results suggest that the JmjC domain of JMJ24 has lost demethylase activity but has been retained as a binding domain for histone H3. This is in line with phylogenetic analyses indicating that JMJ24 (with the mutated JmjC domain) is widely conserved in angiosperms. Taken together, this study assigns a role in TE silencing to a conserved JmjC-domain protein with E3 ligase activity, but no demethylase activity. Y1 - 2016 U6 - https://doi.org/10.1104/pp.15.01688 SN - 0032-0889 SN - 1532-2548 VL - 171 SP - 344 EP - 358 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Brzezinka, Krzysztof A1 - Altmann, Simone A1 - Czesnick, Hjördis A1 - Nicolas, Philippe A1 - Gorka, Michal A1 - Benke, Eileen A1 - Kabelitz, Tina A1 - Jähne, Felix A1 - Graf, Alexander A1 - Kappel, Christian A1 - Bäurle, Isabel T1 - Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling JF - eLife N2 - Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/ SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory. Y1 - 2016 U6 - https://doi.org/10.7554/eLife.17061 SN - 2050-084X VL - 5 PB - eLife Sciences Publications CY - Cambridge ER - TY - THES A1 - Brzezinka, Krzysztof T1 - Chromatin dynamics during heat stress memory in plants Y1 - 2016 ER -