Citrullination of Histone H3 drives IL-6 production by bone marrow mesenchymal stem cells in MGUS and multiple myeloma
Ontology highlight
ABSTRACT: Multiple myeloma (MM), an incurable plasma cell malignancy, requires localisation within the bone marrow in order to survive and proliferate. Interactions between the malignant plasma cell and bone marrow mesenchymal stem cell (BMMSC) are thought to be a critical determinant of this requirement, and include both physical and chemical components. There is increasing evidence that the phenotype of the BMMSC is stably altered in patients with MM. More recently, it has been suggested that this phenotypic transformation is also observed in patients with the benign condition known as monoclonal gammopathy of undetermined significance (MGUS), which almost always precedes MM. In this study, we describe a mechanism by which the peptidyl arginine deiminase 2 (PADI2) enzyme plays an key role in the control of malignant plasma cell phenotype by BMMSCs. PADI enzymes deiminate (citrullinate) peptidyl arginine residues, changing the function or interactions made by the target protein. We identified PADI2 as one of the most highly upregulated transcripts in BMMSCs from both MGUS and MM patients, and that through citrullination of arginine residue 26 of histone H3, it induces the upregulation of interleukin-6 (IL-6) expression. This directly leads to the acquisition of resistance to the chemotherapeutic agent, bortezomib, by malignant plasma cells. We therefore describe a novel mechanism by which BMMSC dysfunction in patients with MGUS and MM directly leads to pro-malignancy signalling through the citrullination of histone H3R26.
Project description:Multiple myeloma (MM), an incurable plasma cell malignancy, requires localisation within the bone marrow in order to survive and proliferate. Interactions between the malignant plasma cell and bone marrow mesenchymal stem cell (BMMSC) are thought to be a critical determinant of this requirement, and include both physical and chemical components. There is increasing evidence that the phenotype of the BMMSC is stably altered in patients with MM. More recently, it has been suggested that this phenotypic transformation is also observed in patients with the benign condition known as monoclonal gammopathy of undetermined significance (MGUS), which almost always precedes MM. In this study, we describe a mechanism by which the peptidyl arginine deiminase 2 (PADI2) enzyme plays an key role in the control of malignant plasma cell phenotype by BMMSCs. PADI enzymes deiminate (citrullinate) peptidyl arginine residues, changing the function or interactions made by the target protein. We identified PADI2 as one of the most highly upregulated transcripts in BMMSCs from both MGUS and MM patients, and that through citrullination of arginine residue 26 of histone H3, it induces the upregulation of interleukin-6 (IL-6) expression. This directly leads to the acquisition of resistance to the chemotherapeutic agent, bortezomib, by malignant plasma cells. We therefore describe a novel mechanism by which BMMSC dysfunction in patients with MGUS and MM directly leads to pro-malignancy signalling through the citrullination of histone H3R26. 30 samples, 10 from each of three categories (control, MGUS, MM)
Project description:Peptidylarginine deiminase (PADI) 2 catalyzes the posttranslational conversion of peptidyl-arginine to peptidyl-citrulline, a process called citrullination. However, the exact function of PADI2 in bone development and bone homeostasis remains unknown. In this study, we found that Padi2 deficiency lead to loss of bone mass and cleidocranial dysplasia (CCD)-like phenotype with delayed calvarial ossification and clavicular hypoplasia due to impaired osteoblast differentiation. Mechanistically, Padi2 depletion drastically reduced RUNX2 protein level and PADI2 stabilized RUNX2 from ubiquitin-proteasomal degradation. Furthermore, we identified a new modification at RUNX2, citrullination of arginine and its conversion to citrulline by PADI2. PADI2 citrullinates RUNX2 via a direct physical interaction and the citrullination sites at RUNX2 by PADI2 were identified by high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Interestingly, in mouse RUNX2 isoform 1 (528 a.a), loss of R381, a citrullination site by PADI2, drastically reduced RUNX2 protein levels, indicating that the citrullination of RUNX2 by PADI2 is required for the maintenance of RUNX2 protein stability. Collectively, our study demonstrates that PADI2-mediated citrullination play key roles in bone formation and bone homeostasis. Also, CCD may result from functional defects of RUNX2 by Padi2 deficiency. These insights into the role of PADI2 in postnatal bone formation and homeostasis and CCD pathogenesis may assist in the development of new therapies for bone diseases including CCD.
Project description:Citrullination, the deimination of arginine residues into citrulline, has been implicated in the aetiology of several diseases. In multiple sclerosis (MS), citrullination is thought to be a major driver of pathology, through hypercitrullination and destabilization of myelin. As such, inhibition of citrullination has been suggested as a therapeutical strategy for MS. Here we show that citrullination by peptidylarginine deiminase 2 (PADI2) is in contrast required for normal oligodendrocyte differentiation, myelination and motor function. We identify several targets for PADI2, including not only myelin-related proteins, but also several chromatin-associated proteins, implicating PADI2 in epigenetic regulation. Accordingly, we observe that PADI2 inhibition and its knockdown affect chromatin accessibility and prevent the upregulation of genes involved in oligodendrocyte differentiation. Moreover, mice lacking PADI2, display motoric dysfunction and a decreased number of myelinated axons in the corpus callosum. Our study demonstrates that citrullination is required for oligodendrocyte lineage progression and myelination and thus its targeted activation in the oligodendrocyte lineage might be beneficial in the context of remyelination in diseases as MS.
Project description:Evolutionary insights reveal a new role of peptidyl arginine deiminase 2 in transcription regulationA systematic evolutionary analysis identified positively selected residues in the non-catalytic domain of PADI2. We established a link between the positive evolution of key residues in the PADI2 and their role in transcription. Specifically, we identified the structurally exposed loop encompassing the positively selected L162 in the PADI2 middle domain and its role in transcription and cellular proliferation. This loop contributes to the PADI2 interaction with the P-TEFb complex and cellular proliferation. Our results showcase the use of combining evolutionary and experimental approaches to dissect the dynamic of evolutionary processes.
Project description:Estrogen receptor M-NM-1 (ER), a member of the nuclear hormone receptor superfamily, regulates transcriptional activity by ligand-dependent recruitment of cofactors which, in turn, locally alter chromatin structure. It is generally believed that co-factor activity at target promoters leads to a more open, transcriptionally permissive chromatin structure, however, these mechanisms remain to be fully established. Peptidylarginine deiminases (PADIs) catalyze the conversion of positively charged arginine and methylarginine residues to neutrally charged citrulline and this activity has been linked to the gene regulation. Here, we found that PADI2 citrullinate H3 Arginine 26 (H3R26) in vitro and, using a specific H3R26 citrulline (H3Cit26) antibody, we demonstrate that H3Cit26 occurs in vivo following 17M-NM-2-estradiol (E2) stimulation and this unique and pronounced global activation of H3Cit26 is ER-dependent. Using a mammalian-based promoter chromosomal array system, we observed that citrullination at H3R26 is robust and co-localizes with ER at decondensed chromatin loci. Additionally, this histone modification is specifically enriched at ER bound regions of target promoters, forming a permissive chromatin environment for gene transactivation. Interestingly, we have shown in a reciprocal way, that either depletion of PADI2 or inhibition of ER not only dramatically abolished E2-induced activation of H3Cit26 on gene promoters but also affect ER recruitment. Collectively, our results demonstrate that citrullination of H3R26 by PADI2 following estrogen stimulation plays a role in ER target gene activation, likely via decondensation of the local chromatin architecture. Two H3Cit26 ChIP-chip biological replicates under vehicle treatment and two H3Cit26 ChIP-chip biological replicates under E2 stimulation from MCF-7 human breast cancer cells are included.
Project description:Genetic events mediating transformation from the pre-malignant monoclonal gammopathies (MG) to multiple myeloma (MM) are unknown. To obtain a comprehensive genomic profile of MG from the early to the late stages we performed high resolution analysis on purified plasma cells from 20 MGUS, 20 smoldering MM (SMM) and 34 MM by high density 6.0 SNP-array.
Project description:Multiple myeloma (MM) and its premalignant precursor MGUS (monoclonal gammopathy of undetermined significance) are clonal plasma cell diseases that develop in the bone marrow (BM) and are dependent on microenvironmental interactions. Primary bone marrow stromal cells (BMSCs) are key players in the BM microenvironment, however, their role in MGUS/MM pathophysiology is not known. We therefore investigated potential disease-specific alterations in prospectively isolated BMSCs from MM, MGUS and healthy controls. Clear disease-related BMSC surface marker and gene expression differences were recorded, and deep sequencing identified shared MGUS/MM as well as MM-specific molecular signatures. Moreover, we identified genes that were deregulated in a disease-stage manner, thus reflecting the progression from normal to MGUS and MM. Analysis of primary BMSCs revealed disease-stage related protein and gene expression patterns, which provides novel insight into the stromal transitions and their functional implications for plasma cell disease development and progression.
Project description:Estrogen receptor α (ER), a member of the nuclear hormone receptor superfamily, regulates transcriptional activity by ligand-dependent recruitment of cofactors which, in turn, locally alter chromatin structure. It is generally believed that co-factor activity at target promoters leads to a more open, transcriptionally permissive chromatin structure, however, these mechanisms remain to be fully established. Peptidylarginine deiminases (PADIs) catalyze the conversion of positively charged arginine and methylarginine residues to neutrally charged citrulline and this activity has been linked to the gene regulation. Here, we found that PADI2 citrullinate H3 Arginine 26 (H3R26) in vitro and, using a specific H3R26 citrulline (H3Cit26) antibody, we demonstrate that H3Cit26 occurs in vivo following 17β-estradiol (E2) stimulation and this unique and pronounced global activation of H3Cit26 is ER-dependent. Using a mammalian-based promoter chromosomal array system, we observed that citrullination at H3R26 is robust and co-localizes with ER at decondensed chromatin loci. Additionally, this histone modification is specifically enriched at ER bound regions of target promoters, forming a permissive chromatin environment for gene transactivation. Interestingly, we have shown in a reciprocal way, that either depletion of PADI2 or inhibition of ER not only dramatically abolished E2-induced activation of H3Cit26 on gene promoters but also affect ER recruitment. Collectively, our results demonstrate that citrullination of H3R26 by PADI2 following estrogen stimulation plays a role in ER target gene activation, likely via decondensation of the local chromatin architecture.
Project description:To gain further insights into the role of the transcriptome deregulation in the transition from a normal plasma cell (NPC) to a clonal PC and from an indolent clonal PC to a malignant PC, we performed gene expression profiling in 20 patients with MGUS, 33 with high-risk SMM and 41 with MM. The analysis showed that 126 genes were differentially expressed in MGUS, SMM and MM as compared to NPC. Interestingly, 17 and 9 out of the 126 significant differentially expressed genes were small nucleolar RNA molecules (snoRNA) and zinc finger proteins. GADD45A was the most significant up-regulated gene in clonal PC compared to NPC. Several proapoptotic genes (AKT1 and AKT2) were downregulated and antiapoptotic genes (APAF1 and BCL2L1) were upregulated in MM, both symptomatic and asymptomatic, compared to MGUS. Myc mediated apoptosis signaling is one of the top canonical pathways differentiating the asymptomatic and symptomatic myeloma. When we looked for those genes progressively modulated through the evolving stages of monoclonal gammopathies, eight snoRNA showed a progressive increase while APAF1, VCAN and MEGF9 exhibited a progressive downregulation in the transition from MGUS to SMM and to MM. In conclusion, our data show that although MGUS, SMM and MM are not clearly distinguishable groups according to their GEP, several signaling pathways and genes were significant deregulated in the different steps of transformation process.
Project description:Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant precursor of multiple myeloma (MM) with a 1% risk of progression per year. Although targeted analyses have shown the presence of specific genetic abnormalities such as IGH translocations, RB1 deletion, 1q gain, hyperdiploidy or RAS genes mutations, little is known about the molecular mechanism of malignant transformation. We have performed whole-exome sequencing together with CGH+SNP array analysis in 33 flow-cytometry separated abnormal plasma cell samples from MGUS patients to describe somatic gene mutations and chromosome changes at the genome-wide level. Non-synonymous mutations and copy-number alterations were present in 97.0% and in 60.6% of cases, respectively. Importantly, the number of somatic mutations was significantly lower in MGUS compared to MM (p<10-4) and we have identified six genes that are significantly mutated in MM (KRAS, NRAS, DIS3, HIST1H1E, EGR1 and LTB) in the MGUS dataset. We also found a positive correlation with increasing chromosome changes and somatic mutations. IGH translocations were present in 27.3% of cases comprising t(4;14), t(11;14), t(14;16) or t(14;20) and were in a similar frequency to MM, which corresponded with the primary lesion hypothesis. Data from this study showed MGUS is a genetically comprehensive disease, however, overall genetic instability is significantly lower compared to MM.