Protein Thermal Stability Changes Induced by the Global Methylation Inhibitor 3-deazaneplanocin A (DZNep)
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ABSTRACT: DZNep (3-deazaneplanocin A) is commonly used to reduce lysine methylation. DZNep inhibits S-adenosyl-L-homocysteine hydrolase (AHCY), preventing the conversion of S-adenosyl-L-homocysteine (SAH) into L-homocysteine and reducing the level of S-adenosylmethionine (SAM). As a result, the SAM to SAH ratio decreases, an indicator of the methylation potential within a cell. Many studies have characterized the impact of DZNep on histone lysine methylation or in specific cell or disease contexts. Recently, protein thermal stability has provided a new dimension for studying the mechanism of action of small molecule inhibitors. In addition to ligand binding, post-translational modifications and protein-protein interactions impact thermal stability. Here, we sought to characterize protein thermal stability changes induced by DZNep treatment in HEK293T cells using the Protein Integral Solubility Alteration (PISA) assay. DZNep treatment altered the thermal stability of 135 proteins, with over half previously reported to be methylated at lysine residues. In addition to thermal stability, we identify changes in transcript and protein abundance after DZNep treatment to distinguish between direct and indirect impacts on thermal stability. Nearly one-third of the proteins with altered thermal stability had no changes at the transcript or protein level. Of these thermally altered proteins, CDK6 had a stabilized methylated peptide, while its unmethylated counterpart was unaltered. Multiple methyltransferases were among the proteins with thermal stability alteration, including DNMT1, potentially due to changes in SAM/SAH levels. This study systematically evaluates DZNep’s impact on the transcriptome, the proteome, and the thermal stability of proteins.
Project description:The aim of the project is to identify proteins the ustilize S-adenosyl methionine as cofactor for performing methylation of target molecules in D. melanogaster S2 cells. For this purpose, we applied a small-molecule capturing protocol using a SAH-capture compound with UV-activated crosslinker and biotin immobilization groups. We tested the protein affinity with and without crosslinking for two different photo-activatable crosslinkers benzophenone and nitrobenzene, respectively, as well as different concentrations of the capture compound. As control we incubated the cell lysate with the streptavidin beads without adding the capture compound. Two specific capture compounds containing a S-adenosyl homocysteine as capturing functionality and either benzophenone or azo-benzene as reactive crosslinkers as well as a biotin group for affinity purification were tested in this protocol. One sample representing a HeLa cell lysate (Waters) under equal conditions was added to the dataset.
Project description:Supplementation with S-adenosylhomocysteine (SAH) extends the lifespan of model organisms. To explore the impact of SAH on aging, we generated a Caenorhabditis elegans model with increased SAH levels through pathogenic mutation in the S-adenosylhomocysteine hydrolase (AHCY-1), which impairs SAH hydrolysis to adenosine and homocysteine. This submission contains results of the quantitative (TMT) measurements of the proteins in whole worm extracts originated from AHCY-1 Y143C mutant (equivalent to the human pathogenic variant) and control worms.
Project description:<p>This study has been designed to evaluate the possible therapeutic benefits of L-5-methyltetrahydrofolate (Metafolin), vitamin B12, creatine and betaine in children with Angelman Syndrome (AS).</p> <p>This study is based on the hypotheses 1) that dietary manipulation may increase global DNA methylation; 2) that increased methylation of the paternal chromosome in AS participants may increase expression of the Angelman gene causing clinical benefit; and 3) that dietary interventions with Metafolin in conjunction with creatine, betaine, and vitamin B12 would represent little risk, but some chance for benefit. The dietary regimen is felt to be quite benign and safe. The clinical response will be measured by recording: changes in seizure activity, changes in communication skills, changes in developmental skills and changes in behavioral patterns as indicated by formal developmental assessments and clinical evaluations. We will assess the progress of the participants by monitoring their changes from baseline throughout their participation in the study and measure their improvement in particular in the developmental parameters.</p> <p>As a secondary aim, we plan to measure the biochemical response to these compounds by obtaining levels of homocysteine, methionine, S-adenosyl-methionine (SAM), and S-adenosyl-homocysteine (SAH). The molecular response will be measured by global DNA methylation analysis.</p> <p>As an exploratory aim, we hope to use control data we have previously obtained from a double blind placebo-controlled trial done in the past using betaine and folic acid to compare the development of those children who have and those who have not received medications. More specifically, we wish to compare differences in the rate of development for those children who have never received study medications (from the first trial) with those who have received medications from the present trial. Developmental parameters used in the previous trial will be consistent with those used in the present trial in order to permit these comparisons. The previous trial was conducted at Baylor College of Medicine, Rady San Diego Children's Hospital and Boston Children's Hospital whereas a group of AS participants received folic acid and betaine or placebo in a randomized double-blind basis.</p> <p>All the participants for the study will include patients who have a documented molecular diagnosis of AS. The participants will be seen at Baylor College of Medicine, Rady Children's Hospital of San Diego, Boston Children's Hospital and the Greenwood Genetics Center at 0 months and at 12 months for follow-up. Clinical and relevant historical data will be collected during the clinical visit and examination and also by reviewing medical and laboratory records. This information will then be entered into a HIPAA compliant clinical research database.</p>
Project description:We report RNA-seq results from planarians of Dugesia japonica species which have developed resistance to a S-adenosyl homocysteine hydrolase inhibitor AdOx after prolonged exposure.
Project description:Ferroptosis, a novel form of regulated cell death triggered by the iron-dependent peroxidation of phospholipids, offers promising penitential for cancer therapy. Hydrogen sulfide (H2S), an endogenous metabolite of the transsulfuration pathway, has been implicated in ferroptosis. However, the precise regulatory mechanisms remain elusive. In this study, we systematically investigated the role of exogenous hydrogen sulfide in ferroptosis regulation in non-small-cell lung cancer (NSCLC). We demonstrated that H2S sensitizes NSCLC to ferroptosis both in vitro and in vivo. Mechanistically, hydrogen sulfide persulfurates the 195th cysteine residue of S-adenosyl homocysteine hydrolase (SAHH), thus impeding the binding of SAHH to its substrate S-adenosyl homocysteine (SAH). Consequently, this inhibition reduces SAHH activity, leading to a decreased homocysteine level. This reduction in homocysteine subsequently results in diminished levels of cysteine and glutathione, particularly under conditions of cystine depletion, which collectively potentiate the occurrence of ferroptosis. Together, our findings unveil H2S as pivotal regulator for homocysteine metabolism, increasing the sensitivity of NSCLC to ferroptosis. Importantly, these findings highlight its potential therapeutic value for enhancing ferroptosis-based cancer therapies for NCSCLC.
Project description:The SLC25A26 gene encodes a mitochondrial inner membrane carrier that transports S-adenosylmethionine (SAM) into the mitochondrial matrix in exchange for S-adenosylhomocysteine (SAH). SAM is the predominant methyl-group donor for most cellular methylation processes, of which SAH is produced as a by-product. Pathogenic, bi-allelic SLC25A26 variants are a recognized cause of mitochondrial disease in children, with a severe neonatal-onset caused by decreased SAM transport activity. We describe two, unrelated adult cases presenting with exercise intolerance and mitochondrial myopathy associated with bi-allelic variants in SLC25A26 which lead to marked respiratory chain deficiencies and mitochondrial histopathological abnormalities in skeletal muscle that are comparable to the early-onset cases. We demonstrate using both mouse and fruit fly models that impairment of SAH, rather than SAM, transport across the mitochondrial membrane is the cause of this milder, later onset clinical phenotype. In this submission, the total larval proteome was assessed at two, three and four days after egg laying in mutants expressing a SAMC.R166Q mutation versus wDah genetic background controls. Our finding of a novel pathomechanism associated with a known disease-causing protein highlights the potential of precision medicine in clinical decision making.
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification of mRNAs in most eukaryotes. Likewise, viral RNAs may acquire m6A methylation during replication within these cells. Here we show that RNAs of human respiratory syncytial virus (RSV), a medically important non-segmented negative-sense (NNS) RNA virus, are modified by m6A within discreet regions and that these modifications enhance viral replication and pathogenesis. Overexpression of m6A binding proteins significantly enhanced RSV replication and gene expression. Knockdown of m6A methyltransferases decreased viral replication and gene expression whereas knockdown of m6A demethylases had the opposite effect. The G gene contained the most abundant m6A modifications. Recombinant RSV expressing a G gene lacking different m6A sites, resulted in RSVs with various degrees of defects in replication in A549 cells, primary well differentiated human airway epithelial (HAE) cultures, upper and lower respiratory tract of cotton rats, and were also less pathogenic to the lungs of cotton rats. One of the m6A-deficient rgRSVs, rgRSV-G12, was completely attenuated yet retained high immunogenicity in cotton rats. Moreover, a small molecule that inhibits S-adenosyl-L-homocysteine (SAH) hydrolase, thereby reducing the cellular SAH pool and viral RNA m6A, also inhibited RSV replication in HAE cells. Collectively, our results demonstrate viral m6A methylation upregulates RSV replication and pathogenesis and identify viral m6A methylation as a target for rational design of live attenuated vaccine candidates and for novel antiviral therapeutic agents for RSV.
Project description:Epigenetics (DNA methylation) profiling of bovine in vitro cultured expanded blastocysts (EB) comparing control non-treated expanded blastocysts with SAM-treated expanded blastocysts. S-Adenosyl methionine (SAM) is the global methyl donor providing methyl
Project description:Genome-wide DNA methylation profiling of human PC3 invasive prostate cancer cell line treated with vehicle control (SAH, S-adenosylhomocysteine) and with SAM (S-adenosylmethionine) as well as of untreated human LNCaP non-invasive prostate cancer cell line. The Illumina Infinium 450k Human DNA Methylation BeadChip v1.2 was used to obtain DNA methylation profiles across approximately 450,000 CpGs in human cell lines exposed to described treatments. Samples included biological triplicate of PC3 control (SAH treated), biological triplicate of PC3 treated with SAM, and biological duplicate of LNCaP untreated.