Epigenetic changes are important mechanisms in the regulation of chromatin structure and gene expression. Cytosine methylation is one of the major epigenetic modifications, mediated by DNA ...methyltransferases, which transfer methyl groups from S‐adenosyl‐L‐methionine (SAM) to the fifth carbon of cytosine. Various external environmental conditions can change the global hypo/hypermethylation pattern of DNA. These alterations may affect the organism's response to stress conditions. In this study, for the first time, we investigated the effects of 5‐azacytidine, a DNA methyltransferase inhibitor, and cadmium, a toxic metal and environmental pollutant, on the growth, biosynthesis of secondary metabolites (phenols, flavonoids, carotenoids), SAM, S‐adenosylhomocysteine, 5′‐methylthioadenosine and global 5‐methylcytosine (5‐mC) in the green microalgae Chlamydomonas reinhardtii and Scenedesmus quadricauda. The studied species showed major differences in 5‐mC content, secondary metabolite content, and antioxidant activity. Cadmium increased GSH (glutathione) content in C. reinhardtii by 60% whereas 5‐azacytidine did not affect GSH. The biosynthesis of GSH in S. quadricauda in response to the stressors was the opposite. Global 5‐mC content of C. reinhardtii was 1%–1.5%, and the content in S. quadricauda was 3.5%. Amount of some investigated methionine cycle metabolites (SAM, S‐adenosyl homocysteine SAH, methionine) in S. quadricauda distinctly exceeded C. reinhardtii as well. However, chlorophylls a and b, carotenoids, total phenolic content, total flavonoid content and, antioxidant activity were significantly higher in C. reinhardtii than S. quadricauda. Therefore, in further studies it would be advisable to verify whether methylation of cytosine affects the expression of genes encoding certain secondary metabolites.
Mechanisms-of-resistance to decitabine and 5-azacytidine, mainstay treatments for myeloid malignancies, require investigation and countermeasures. Both are nucleoside analog pro-drugs processed by ...pyrimidine metabolism into a deoxynucleotide analog that depletes the key epigenetic regulator DNA methyltranseferase 1 (DNMT1). Here, upon serial analyses of DNMT1 levels in patients' bone marrows on-therapy, we found DNMT1 was not depleted at relapse. Showing why, bone marrows at relapse exhibited shifts in expression of key pyrimidine metabolism enzymes in directions adverse to pro-drug activation. Further investigation revealed the origin of these shifts. Pyrimidine metabolism is a network that senses and regulates deoxynucleotide amounts. Deoxynucleotide amounts were disturbed by single exposures to decitabine or 5-azacytidine, via off-target depletion of thymidylate synthase and ribonucleotide reductase respectively. Compensating pyrimidine metabolism shifts peaked 72-96 h later. Continuous pro-drug exposures stabilized these adaptive metabolic responses to thereby prevent DNMT1-depletion and permit exponential leukemia out-growth as soon as day 40. The consistency of the acute metabolic responses enabled exploitation: simple treatment modifications in xenotransplant models of chemorefractory leukemia extended noncytotoxic DNMT1-depletion and leukemia control by several months. In sum, resistance to decitabine and 5-azacytidine originates from adaptive responses of the pyrimidine metabolism network; these responses can be anticipated and thus exploited.
• A role for DNA hypomethylation has recently been suggested in the interaction between bacteria and plants; it is unclear whether this phenomenon reflects a conserved response.
• Treatment of plants ...of monocot rice and dicot tomato with nematode-associated molecular patterns from different nematode species or bacterial pathogen-associated molecular pattern flg22 revealed global DNA hypomethylation. A similar hypomethylation response was observed during early gall induction by Meloidogyne graminicola in rice. Evidence for the causal impact of hypomethylation on immunity was revealed by a significantly reduced plant susceptibility upon treatment with DNA methylation inhibitor 5-azacytidine.
• Whole-genome bisulphite sequencing of young galls revealed massive hypomethylation in the CHH context, while not for CG or CHG nucleotide contexts. Further, CHH hypomethylated regions were predominantly associated with gene promoter regions, which was not correlated with activated gene expression at the same time point but, rather, was correlated with a delayed transcriptional gene activation. Finally, the relevance of CHH hypomethylation in plant defence was confirmed in rice mutants of the RNA-directed DNA methylation pathway and DECREASED DNA METHYLATION 1.
• We demonstrated that DNA hypomethylation is associated with reduced susceptibility in rice towards root-parasitic nematodes and is likely to be part of the basal pattern-triggered immunity response in plants.
VEXAS: where do we stand 2 years later? Sujobert, Pierre; Heiblig, Maël; Jamilloux, Yvan
Current opinion in hematology,
03/2023, Letnik:
30, Številka:
2
Journal Article
Two years after the recognition of VEXAS (for Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, we propose an extensive review of the current understanding of VEXAS pathophysiology ...and therapeutic options.
Among the nearly 150 articles published about VEXAS, some have provided determinant insights into VEXAS pathophysiology and treatment. Clinical data from retrospective series support the JAK inhibitor ruxolitinib as the most efficient strategy to control inflammation, and interesting results were also described with azacytidine. Allogeneic stem cell transplantation remains the only curative option, but should be proposed to carefully selected patients.
Although waiting for more robust evidence from prospective clinical trials, therapeutic options emerge from retrospective studies. We propose a set of criteria that should be systematically reported to harmonize the evaluation of therapeutic outcomes. This will allow the collection of high-quality data and facilitate their subsequent meta-analysis with the overall aim of improving the management of VEXAS patients.
Synchronous diagnosis of acute myeloid leukemia (AML) and symptomatic multiple myeloma (MM) is a rare situation that poses serious therapeutic difficulties. We report the case of a 68-year-old male ...which evolved simultaneously to symptomatic MM and AML. Both diseases first responded to treatment for 40 months after 7+3 induction and maintenance therapy of azacytidine + lenalidomide. MM relapsed first and was treated with azacytidine + daratumumab, which led an additional 15 months of progression-free survival. Little myeloid clonal size reduction over time was seen. This case shows that AML and MM can be effectively treated simultaneously using appropriate combinations.
Experimental demethylation of plant DNA enables testing for epigenetic effects in a simple and straightforward way without the use of expensive and laborious DNA sequencing. Plants are commonly ...demethylated during their germination with the application of agents such as 5‐azacytidine (5‐azaC). However, this approach can cause unwanted effects such as underdeveloped root systems and high mortality of treated plants, hindering a full comparison with untreated plants, and can be applied only on plant reproducing by seeds. Here we test a simple alternative method of plant demethylation designed to overcome the shortcomings of the germinating method.
We compared a novel method of demethylating plants, based on periodical spraying of 5‐azaC aqueous solution on established seedlings, with the previous method in which seeds were germinated directly in 5‐azaC solution. We quantified the amount of methylated DNA and measured various aspects of plant performance. Also, we demonstrated its applicability in ecological epigenetic experiments by testing transgenerational effects of plant–plant competition.
We found that the spray application had similar DNA‐demethylating efficiency than the germination method, particularly in the earlier phases of plant development, but without unwanted effects. The spray application method did not reduce plant growth and performance compared to untreated plants, as opposed to the traditional method which showed reduced growth. Also, the spray application method equalized the epigenetically modified plant features of seedlings coming from plants grown under competition and plants growing without competition, demonstrating its application in ecological epigenetic experiments.
We conclude that regular spraying of 5‐azaC solution onto established seedlings surpassed the germination‐in‐solution method in terms of vigour and fitness of treated plants. This novel method could thus be better suited for experimental studies seeking valuable insights into ecological epigenetics. Furthermore, the spray method can be suitable for clonal species reproducing asexually, and most importantly, it opens the possibility of community‐level experimental demethylation of plants.
Stress can be remembered by plants in a form of stress legacy that can alter future phenotypes of previously stressed plants and even phenotypes of their offspring. DNA methylation belongs among the ...mechanisms mediating the stress legacy. It is however not known for how long the stress legacy is carried by plants. If the legacy is long‐lasting, it can become maladaptive in situations when parental–offspring environment do not match. We investigated for how long after the last exposure of a parental plant to drought can the phenotype of its clonal offspring be altered. We grew parental plants of three genotypes of Trifolium repens for five months either in control conditions or in control conditions that were interrupted with intense drought periods applied for two months in four different time slots. We also treated half of the parental plants with a demethylating agent (5‐azacytidine, 5‐azaC) to test for the potential role of DNA methylation in the stress memory. Then, we transplanted parental cuttings (ramets) individually to control environment and allowed them to produce offspring ramets for two months. The drought stress experienced by parents affected phenotypes of offspring ramets. The stress legacy resulted in enhanced number of offspring ramets originating from plants that experienced drought stress even 56 days before their transplantation to the control environment. 5‐azaC altered transgenerational effects on offspring ramets. We confirmed that drought stress can trigger transgenerational effects in T. repens that is very likely mediated by DNA methylation. Most importantly, the stress legacy in parental plants persisted for at least 8 weeks suggesting that the stress legacy can persist in a clonal plant Trifolium repens for relatively long period. We suggest that the stress legacy should be considered in future ecological studies on clonal plants.
Environmental stress can be remembered by plants in a form of “stress legacy.” We investigated for how long can a parental plant “remember” that it experienced a stress and pass the memory to its clonal offspring.
Based on our previous study of the combination of sorafenib with 5‐azacytidine (AZA) in relapsed/refractory patients with FLT3 mutated acute myeloid leukemia (AML), we hypothesized that the ...combination would be efficacious and well tolerated in untreated patients with FLT3 mutated AML who are unsuitable for standard chemotherapy due to advanced age or lack of fitness. Newly diagnosed patients with untreated FLT3 mutated AML who underwent frontline therapy on 2 separate protocols of AZA plus sorafenib were analyzed. The clinical trials were registered at clinicaltrials.gov (NCT02196857 and NCT01254890). Overall, 27 patients with untreated FLT3 mutated AML (median age of 74 years, range, 61‐86) were enrolled. The overall response rate was 78% (7 26% CR, 12 44% CRi/CRp, and 2 7% PR). Patients received a median of 3 treatment cycles (1–35). The median duration of CR/CRp/CRi is 14.5 months (1.1–28.7 months). Three (11%) responding patients (1 CR, 2 CRi) proceeded to allogeneic stem cell transplant. The median follow‐up for surviving patients was 4.1 months (3.0–17.3 months). The median overall survival for the entire group was 8.3 months, and 9.2 months in the 19 responders. The regimen was well tolerated in elderly patients with untreated FLT3 mutated AML with no early deaths.
PDF
