Project description:Histone H3 monoaminylations at glutamine(Q) 5 represent an important family of epigenetic markers in neurons that play critical roles in the mediation of permissive gene expression (1, 2). We previously demonstrated that H3Q5 serotonylation(ser) and dopaminylation(dop) are catalyzed by the Transglutaminase 2 (TGM2) enzyme and alter both local and global chromatin states (3, 4). Here, we found that TGM2 additionally functions as an “eraser” of H3 monoaminylations that is capable of “re-writing” these epigenetic marks in cells, including a new class of this modification, H3Q5 histaminylation(his), which displays dynamic diurnal expression in brain and contributes to neural rhythmicity. We found that H3Q5his inhibits binding of the MLL1 complex to the H3 N-terminus and attenuates its methyltransferase activity on H3 lysine(K) 4. We determined that H3Q5 monoaminylation dynamics are dictated by local monoamine concentrations, which are utilized by TGM2. Taken together, we present here a novel mechanism through which a single chromatin regulatory enzyme is capable of sensing chemical microenvironments to affect the epigenetic states of cells.
Project description:Histone H3 monoaminylations at glutamine(Q) 5 represent an important family of epigenetic markers in neurons that play critical roles in the mediation of permissive gene expression (1, 2). We previously demonstrated that H3Q5 serotonylation(ser) and dopaminylation(dop) are catalyzed by the Transglutaminase 2 (TGM2) enzyme and alter both local and global chromatin states (3, 4). Here, we found that TGM2 additionally functions as an “eraser” of H3 monoaminylations that is capable of “rewriting” these epigenetic marks in cells, including a new class of this modification, H3Q5 histaminylation(his), which displays dynamic diurnal expression in brain and contributes to neural rhythmicity. We found that H3Q5his inhibits binding of the MLL1 complex to the H3 N-terminus and attenuates its methyltransferase activity on H3 lysine(K) 4. We determined that H3Q5 monoaminylation dynamics are dictated by local monoamine concentrations, which are utilized by TGM2. Taken together, we present here a novel mechanism through which a single chromatin regulatory enzyme is capable of sensing chemical microenvironments to affect the epigenetic states of cells.
Project description:Histone H3 monoaminylations at glutamine(Q) 5 represent important epigenetic markers in neurons that play critical roles in the mediation of permissive gene expression. We previously demonstrated that H3Q5 serotonylation(ser) and dopaminylation(dop) are catalyzed by the Transglutaminase 2 (TGM2) enzyme. Here, we identified a new class of histone monoaminylation, H3Q5 histaminylation(his), which displayed dynamic diurnal expression in brain and contributed to neural rhythmicity. We found that H3Q5his, unlike H3Q5ser, electrostatically inhibited recruitment of the “reader” protein WDR5 and attenuated MLL1 methyltransferase activity on H3 lysine(K) 4. We determined that H3Q5 monoaminylation dynamics are dictated by local monoamine concentrations, which are sensed by TGM2. This noncanonical mechanism indicated that histone monoaminylations can be established and removed by a single enzyme based upon its sensing of cellular microenvironments.
Project description:MYB is a pivotal oncogenic driver in leukemia and is overexpressed through various mechanisms. Transcriptional regulation of MYB is complex with an alternative MYB promoter (TSS2) located in intron 1. Here, we identified two bidirectional enhancer RNAs transcribed from the -34 kb enhancer of MYB. These two eRNAs both upregulate MYB transcription, and promote proliferation and migration in leukemia cells. To further elucidate how eRNAs regulate MYB expression, we analyzed MYB differential exon usage in RNASeq data with the DEXSeq package after overexpression of eRNAs in K562 cells. We found that bidirectional enhancer RNAs regulate different MYB promoters. Transcription initiating from TSS2 produces N-terminally truncated MYB protein lacking the first 20 amino acids. To analyze the genes and pathways affected by both MYB isoforms, RNA-seq was performed after MYB or N-terminally truncated MYB was overexpressed in K562 cells. We found that N-terminally truncated MYB exhibits different activity in K562 cells, where it not only activates different primary targets, but also different downstream pathways altogether.