scholarly journals PRMT5-mediated histone arginine methylation antagonizes transcriptional repression by polycomb complex PRC2

2020 ◽  
Vol 48 (6) ◽  
pp. 2956-2968 ◽  
Author(s):  
Fan Liu ◽  
Ye Xu ◽  
Xiaoqing Lu ◽  
Pierre-Jacques Hamard ◽  
Daniel L Karl ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Leukemia Cell ◽  
Arginine Methylation ◽  
Sequencing Analysis ◽  
Chip Sequencing ◽  
Proliferative Effect ◽  
Leukemia Cell Lines ◽  
H3k27me3 Level ◽  
Arginine Residues ◽  
Histone Arginine Methylation

Abstract Protein arginine methyltransferase 5 (PRMT5) catalyzes the symmetric di-methylation of arginine residues in histones H3 and H4, marks that are generally associated with transcriptional repression. However, we found that PRMT5 inhibition or depletion led to more genes being downregulated than upregulated, indicating that PRMT5 can also act as a transcriptional activator. Indeed, the global level of histone H3K27me3 increases in PRMT5 deficient cells. Although PRMT5 does not directly affect PRC2 enzymatic activity, methylation of histone H3 by PRMT5 abrogates its subsequent methylation by PRC2. Treating AML cells with an EZH2 inhibitor partially restored the expression of approximately 50% of the genes that are initially downregulated by PRMT5 inhibition, suggesting that the increased H3K27me3 could directly or indirectly contribute to the transcription repression of these genes. Indeed, ChIP-sequencing analysis confirmed an increase in the H3K27me3 level at the promoter region of a quarter of these genes in PRMT5-inhibited cells. Interestingly, the anti-proliferative effect of PRMT5 inhibition was also partially rescued by treatment with an EZH2 inhibitor in several leukemia cell lines. Thus, PRMT5-mediated crosstalk between histone marks contributes to its functional effects.

scholarly journals Histone arginine methylations: their roles in chromatin dynamics and transcriptional regulation

2009 ◽  
Vol 29 (2) ◽  
pp. 131-141 ◽  
Author(s):  
Michael Litt ◽  
Yi Qiu ◽  
Suming Huang
Keyword(s):  
Transcriptional Repression ◽  
Regulation Of Gene Expression ◽  
Arginine Methylation ◽  
Nuclear Proteins ◽  
Lysine Methylation ◽  
Histone Tails ◽  
Dynamic Regulation ◽  
Chromatin Dynamics ◽  
Arginine Residues ◽  
Histone Arginine Methylation

PRMTs (protein arginine N-methyltransferases) specifically modify the arginine residues of key cellular and nuclear proteins as well as histone substrates. Like lysine methylation, transcriptional repression or activation is dependent upon the site and type of arginine methylation on histone tails. Recent discoveries imply that histone arginine methylation is an important modulator of dynamic chromatin regulation and transcriptional controls. However, under the shadow of lysine methylation, the roles of histone arginine methylation have been under-explored. The present review focuses on the roles of histone arginine methylation in the regulation of gene expression, and the interplays between histone arginine methylation, histone acetylation, lysine methylation and chromatin remodelling factors. In addition, we discuss the dynamic regulation of arginine methylation by arginine demethylases, and how dysregulation of PRMTs and their activities are linked to human diseases such as cancer.

Arginine Methylation of Runx1 Regulates Its Biological and Transcriptional Activities.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2041-2041
Author(s):  
Xinyang Zhao ◽  
Animesh Parkanani ◽  
Jin Zhang ◽  
Richard Dunne ◽  
Andrew Xiao ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Arginine Methylation ◽  
Serine Phosphorylation ◽  
Context Dependency ◽  
Mass Spectrometry Analysis ◽  
Runt Domain ◽  
Spectrometry Analysis ◽  
Gene Reporter Assay ◽  
Arginine Residues

Abstract The AML1/Runx1 protein is required for definitive hematopoiesis and for the maturation of adult megakaryocytic cells. Alterations of the Runx1 gene by mutations, deletions and chromosome translocations are associated with several types of acute leukemia. Runx1 functions as both an activator and repressor of gene transcription with promoter and cell type context dependency. Likely, this relates to the ability of Runx1 to interact with a variety of transcription factors such as MEF, C/EBPa, Ets-1 and GATA-1 and also with repressor proteins such as Groucho, mSin3 and HDACs. Runx1 is post-translationally modified through acetylation and phosphorylation, and the acetylable and phosphorylable forms of Runx1 can activate transcription to higher level in Runx1 dependent reporter assays when HATs or Erk2 are coexpressed. Runx1 has also been shown to be methylated on lysine residues by SUV39H1 methyltransferase in fibroblasts. Based on the presence of a SGRGK motif in the runt domain of Runx1, we have been examining whether Runx1 is methylated on arginine residues by the protein arginine methyltransferases (PRMT). We have found that PRMT1 and PRMT5 are associated with Runx1 in AML cells by co-immunoprecipitation assays and using in vitro by GST-pulldown assays with in vitro translated PRMT(s) have shown that the interactions are direct. Using a luciferase gene reporter assay, we show that PRMT1 acts synergistically with p300 to activate Runx1 mediated transcription in response to cell proliferation signals. We have mapped the arginine methylation sites in Runx1 using GST-Runx1 fusion proteins, site-specific mutagenesis and mass spectrometry analysis. We have found three potential arginine methylation sites, one in the Runt domain, and two in the Runx1 carboxy-terminal region. Interestingly, one of these sites is in the region shown to interact with both the mSIN3A transcriptional repression complex and with p300. This suggests that arginine methylation of Runx1 may affects its transcriptional activating and repressing functions. Chromatin immunoprecipitation assays are underway to show how arginine methylation of Runx1 affects its activities in hematopoietic cells. Additional studies examining the effects of cross-talk between arginine methylation, lysine acetylation and serine phosphorylation has on Runx1 functions (biological and biochemical) will be presented.

JAK2V617F-Mediated Phosphorylation of PRMT5 Down-Regulates Its Methyltransferase Activity and Promotes Myeloproliferation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 794-794
Author(s):  
Fan Liu ◽  
Xinyang Zhao ◽  
Fabiana Perna ◽  
Lan Wang ◽  
Priya Koppikar ◽  
...  
Keyword(s):  
Cord Blood ◽  
Colony Formation ◽  
Erythroid Differentiation ◽  
Arginine Methylation ◽  
Wild Type ◽  
Methyltransferase Activity ◽  
Cd34 Cells ◽  
Cord Blood Cd34 ◽  
Arginine Residues ◽  
Histone Arginine Methylation

Abstract Abstract 794 Background: The cytoplasmic, non-receptor JAK2 tyrosine kinase is mutated at amino acid residue 617 (from valine to phenylalanine) in most patients with myeloproliferative neoplasms (MPNs), resulting in a constitutively activated kinase that phosphorylates STAT proteins in the absence of upstream signals. Overexpression of JAK2V617F leads to cytokine-independent growth of Ba/F3 cells and the JAK2V617F transgenic and knockin mice develop a disease phenotype resembling human polycythemia vera. Results: We hypothesized that the JAK2V617F occurs so consistently in MPNs because it gains some functional property. The type II arginine methyltransferase PRMT5 was initially identified because of its interaction with JAK2 in a yeast two hybrid screen. We examined the interaction between JAK2 and PRMT5 and found that JAK2V617F and JAK2K539L (another active JAK2 kinase) bound PRMT5 more strongly than did wild-type JAK2. PRMT5 mediates the symmetrical dimethylation of arginine residues within histones H2A and H4 and methylates other cellular proteins as well, such as p53. The oncogenic forms of JAK2 acquire the ability to phosphorylate PRMT5, which greatly impaired its methyltransferase activity. We have shown the in vivo importance of this post-translation modification as treating JAK2V617F-positive cells (but not the wild-type JAK2-harboring cells) with different JAK2 inhibitors significantly increased histone arginine methylation levels. To define the effect of inhibiting PRMT5 activity on hematopoiesis, we knocked down PRMT5 in human cord blood derived CD34+ cells using shRNA and observed increased colony formation and erythroid differentiation; In contrast, PRMT5 overexpression in these cells led to reduced colony formation and inhibition of erythroid differentiation. Furthermore, overexpression of PRMT5, especially a phosphorylation site mutant form of PRMT5 (PRMT5M6), diminishes the proliferative and erythroid generating capacity of JAK2V617F+ CD34+ cells isolated from MPN patients to a greater degree than normal cord blood CD34+ cells. Importantly, we found marked increase in PRMT5 phosphorylation in JAK2V617F-positive MPN patents relative to normal cord blood CD34+ cells, suggesting that this phosphorylation is important for the myeloproliferation phenotype. Conclusion: we show that the oncogenic mutant forms of JAK2 kinase, such as JAK2V617F and JAK2K539L, are not simply constitutively active forms of wild-type JAK2, rather they have specific gains-of-function that allow them to phosphorylate PRMT5 and down-regulate its enzymatic activity. Inhibition of PRMT5 contributes to the myeloproliferation and erythroid differentiation promoting effects of JAK2V617F. This gain-of –function mutation results in cross-talk between oncogenic kinases and histone arginine methylation. Taken together, we demonstrate a novel link between the mutant JAK2 kinases and PRMT5 methyltransferase activity, which contributes to MPN pathogenesis. Further insights about the shared gene expression profile of JAK2 inhibition vs. PRMT5 knockdown will be presented to understand the basics for the behavior change in hematopoietic stem/progenitor cells brought about by these two interventions. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Ampelopsin Inhibits Cell Proliferation and Induces Apoptosis in HL60 and K562 Leukemia Cells by Downregulating AKT and NF-κB Signaling Pathways

2021 ◽  
Vol 22 (8) ◽  
pp. 4265
Author(s):  
Jang Mi Han ◽  
Hong Lae Kim ◽  
Hye Jin Jung
Keyword(s):  
Signaling Pathways ◽  
Cell Lines ◽  
White Blood Cells ◽  
Leukemia Cell ◽  
Leukemia Cells ◽  
Ros Generation ◽  
Anticancer Activities ◽  
Nuclear Condensation ◽  
Leukemia Cell Lines ◽  
Antileukemic Effect

Leukemia is a type of blood cancer caused by the rapid proliferation of abnormal white blood cells. Currently, several treatment options, including chemotherapy, radiation therapy, and bone marrow transplantation, are used to treat leukemia, but the morbidity and mortality rates of patients with leukemia are still high. Therefore, there is still a need to develop more selective and less toxic drugs for the effective treatment of leukemia. Ampelopsin, also known as dihydromyricetin, is a plant-derived flavonoid that possesses multiple pharmacological functions, including antibacterial, anti-inflammatory, antioxidative, antiangiogenic, and anticancer activities. However, the anticancer effect and mechanism of action of ampelopsin in leukemia remain unclear. In this study, we evaluated the antileukemic effect of ampelopsin against acute promyelocytic HL60 and chronic myelogenous K562 leukemia cells. Ampelopsin significantly inhibited the proliferation of both leukemia cell lines at concentrations that did not affect normal cell viability. Ampelopsin induced cell cycle arrest at the sub-G1 phase in HL60 cells but the S phase in K562 cells. In addition, ampelopsin regulated the expression of cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors differently in each leukemia cell. Ampelopsin also induced apoptosis in both leukemia cell lines through nuclear condensation, loss of mitochondrial membrane potential, increase in reactive oxygen species (ROS) generation, activation of caspase-9, caspase-3, and poly ADP-ribose polymerase (PARP), and regulation of Bcl-2 family members. Furthermore, the antileukemic effect of ampelopsin was associated with the downregulation of AKT and NF-κB signaling pathways. Moreover, ampelopsin suppressed the expression levels of leukemia stemness markers, such as Oct4, Sox2, CD44, and CD133. Taken together, our findings suggest that ampelopsin may be an attractive chemotherapeutic agent against leukemia.

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