Effects of H19/SAHH/DNMT1 on the Oxidative DNA Damage Related to Benzo[a]Pyrene Exposure

The mechanisms that long noncoding RNA (lncRNA) H19 binding to S-adenosylhomocysteine hydrolase (SAHH) interacted with DNA methyltransferase 1 (DNMT1) and then regulated DNA damage caused by PAHs remain unclear. A total of 146 occupational workers in a Chinese coke-oven plant in 2014 were included in the final analyses. We used high performance liquid chromatography mass spectrometry (HPLC-MS) equipped to detect urine biomarkers of PAHs exposure, including 2-hydroxynaphthalene (2-NAP), 2-hydroxyfluorene (2-FLU), 9-hydroxyphenanthrene (9-PHE), 1-hydroxypyrene (1-OHP). The levels of SAM and SAH in plasma were detected by HPLC-ultraviolet. By constructing various BEAS-2B cell models exposed to 16 µM Benzo[a]pyrene (BaP) for 24 h, toxicological parameters reflecting distinct mechanisms were evaluated. We documented that urinary 1-hydroxypyrene (1-OHP) levels were positively associated with blood H19 RNA expression (OR: 1.51, 95% CI: 1.03 - 2.19), but opposite to plasma SAHH activity (OR: 0.63, 95% CI: 0.41 - 0.98) in coke oven workers. Moreover, by constructing various BEAS-2B cell models exposed to Benzo[a]pyrene (BaP), we investigated that H19 binding to SAHH exaggerated DNMT1 expressions and activity. Suppression of H19 enhanced the interaction of SAHH and DNMT1 in BaP-treated cells, decreased OGG1 methylation, reduced oxidative DNA damage and lessened S phase arrest. However, SAHH or DNMT1 single knockdown and SAHH/DNMT1 double knockdown showed the opposite trend. A H19/SAHH/DNMT1 axis was involved in OGG1 methylation, oxidative DNA damage and cell cycle arrest by carcinogen BaP.

Effects of H19/SAHH/DNMT1 on the oxidative DNA damage related to Benzo[a]pyrene exposure

Background: The mechanisms that long noncoding RNA (lncRNA) H19 binding to S-adenosylhomocysteine hydrolase (SAHH) interacted with DNA methyltransferase 1 (DNMT1) and then regulated DNA damage caused by PAHs remain unclear. Results: We documented that urinary 1-hydroxypyrene (1-OHP) levels were positively associated with blood H19 RNA expression (OR: 1.51, 95% CI: 1.03 - 2.19), but opposite to plasma SAHH activity (OR: 0.63, 95% CI: 0.41 - 0.98) in coke oven workers. Moreover, by constructing various BEAS-2B cell models exposed to Benzo[a]pyrene (BaP), we investigated that H19 binding to SAHH exaggerated DNMT1 expressions and activity. Suppression of H19 enhanced the interaction of SAHH and DNMT1 in BaP-treated cells, decreased OGG1 methylation, reduced oxidative DNA damage and lessened S phase arrest. However, SAHH or DNMT1 single knockdown and SAHH/DNMT1 double knockdown showed the opposite trend. Conclusions: A H19/SAHH/DNMT1 axis was involved in OGG1 methylation, oxidative DNA damage and cell cycle arrest by carcinogen BaP.

Adenosine turnover in GtoPdb v.2021.3

A multifunctional, ubiquitous molecule, adenosine acts at cell-surface G protein-coupled receptors, as well as numerous enzymes, including protein kinases and adenylyl cyclase. Extracellular adenosine is thought to be produced either by export or by metabolism, predominantly through ecto-5’-nucleotidase activity (also producing inorganic phosphate). It is inactivated either by extracellular metabolism via adenosine deaminase (also producing ammonia) or, following uptake by nucleoside transporters, via adenosine deaminase or adenosine kinase (requiring ATP as co-substrate). Intracellular adenosine may be produced by cytosolic 5’-nucleotidases or through S-adenosylhomocysteine hydrolase (also producing L-homocysteine).

Advanced skeletal muscle imaging in S-Adenosylhomocysteine Hydrolase Deficiency: A case series

BackgroundS-Adenosylhomocysteine ​​hydrolase (SAHH) deficiency is a rare inherited multisystemic disease with muscle involvement associated with increased activity of creatine kinase being one of the most prominent and poorly understood feature. Therefore, skeletal muscles were analyzed by magnetic resonance imaging (MRI) and MR spectroscopy (MRS) in three brothers with SAHH deficiency in a different age group.Case presentationAt the time of this study, the brothers were at age of 13, 11, and 8 years, respectively. They presented with similar symptoms in early infancy. Motor developmental delay began in the first months of life. Myopathy was more pronounced in the lower extremities and proximal skeletal muscle groups. MRI revealed lipid infiltration, and MRS curve showed an elevated muscle lipid fraction (higher peak of lipid) increased with age and in proximal skeletal muscle in lower extremities. The data was consistent with muscle biopsy findings in two of them, and third patient had no specific pathological changes in examined muscle tissue.ConclusionsThese findings open the possibility of insight into the extent of muscle involvement, monitoring the course of SAHH deficiency and response to therapy with an accessible and non-invasive method of MRI and MRS.

S-adenosylhomocysteine hydrolase regulates anterior patterning in Dugesia japonica

BackgroundBiological methylation requires S-adenosylmethionine (SAM) and participates in a range of processes from modulation of gene expression via histone modifications to neurotransmitter synthesis. An important factor in all methylation reactions is the concentration ratio of SAM to methylation byproduct S-adenosylhomocysteine (SAH). SAH hydrolase, also known as adenosylhomocysteinase, depletes SAH and thereby facilitates metabolite recycling and maintains the methylation permissive SAM/SAH ratio. While the importance of SAH hydrolase in sustaining methylation is obvious on the cellular level, the function of this metabolic process on the organismal scale is not clear.ResultsWe used planarian Dugesia japonica to investigate the role SAH hydrolase in physiological homeostasis on the body-wide scale. Remarkably, pharmacological inhibition of the SAH hydrolase results in regression of anterior tissues and is accompanied by extensive apoptosis throughout the planarian body. Moreover, exposure to the SAHH inhibitor AdOx leads to changes in brain morphology and spatial shift in the expression of Wnt-modulator Notum. Strikingly, planarians are able to overcome these destructive patterning defects through regeneration of the anterior tissues and adaptation to the used inhibitor. Transcriptome analysis indicates that resistance to the SAHH inhibitor is at least partly mediated by changes in folate cycle and lipid metabolism.ConclusionsSAH hydrolase plays a critical role in planarian homeostasis and anterior patterning potentially through modulation of Wnt signaling. Moreover, planarian adaptation to the SAHH inhibitor via metabolic reprogramming suggests potential targets for addressing methylation-related human conditions.

PSXIV-3 Expression of genes within the methionine-folate cycle are altered by glucose and one-carbon metabolite supplementation in bovine embryonic fibroblasts

We hypothesized that supplementation with one-carbon metabolites (OCM; methionine, folate, choline, and vitamin B12) in divergent glucose media would alter expression of genes in the methionine-folate cycle of DNA methylation in bovine embryonic tracheal fibroblasts. Cells were cultured in EMEM medium containing 1 g/L (Low) or 4.5 g/L (High) of glucose with no added OCM (CON), or 2.5, 5, or 10 times folate, choline, and B12 (2.5X, 5X, or 10X, respectively) in the CON media. Methionine was limited to 2X CON. The data were analyzed as a completely randomized design with a 2 × 4 factorial arrangement of treatments. Cells were passaged three times in treated media before RNA extraction. Gene expression analysis was conducted on Methionine Adenosyltransferase 2A and 2B (MAT2A and MAT2B) DNA Methyltransferase 1, 3A, and 3B (DNMT1, DNMT3A, and DNMT3B), S-Adenosylhomocysteine Hydrolase (AHCY), and Methionine Synthase (MTR). There was no glucose × OCM interaction for DNMT1, DNMT3A, DNMT3B, AHCY, or MTR (P > 0.17). Expression of MAT2B was greater (P < 0.01) in 2.5X, 5X, and 10X OCM in High media compared with all other treatments. Expression of DNMT1 was greater in CON, 5X, and 10X OCM in Low media compared with all other treatments. Expression of MTR was greater (P = 0.03) in CON and 10X OCM treatments compared with 2.5X and 5X levels. Finally, MAT2A and AHCY expression was affected by glucose level, with MAT2A being greater (P = 0.02) in Low compared with High, and AHCY being greater (P < 0.01) in High compared with Low media. These data suggest that glucose and OCM supplementation differentially affect the expression of genes in the methionine-folate cycle of DNA methylation. Additionally, these data demonstrate that additional work elucidating the changes in protein abundance of these enzymes, concentrations of methionine-folate cycle intermediates (specifically S-adenosylmethionine:S-adenosylhomocysteine), as well as changes in DNA methylation are needed.