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Physiological concentration changes of intracellular spermine activates DNA methyltransferase 3A and 3B and affects gene methylation

ABSTRACT: Polyamines are essential for various cell functions and are produced in most cells, as well as being taken up from extracellular sources. Polyamines, especially spermine, in blood cells increase when polyamines are supplied from the digestive tract. Altered polyamine metabolism has an impact on substrate concentrations and enzyme activities involved in gene methylation, and may affect gene expression. Therefore, we investigated the effect of decreased polyamine synthesis and extracellular spermine supply on substrate concentrations and enzyme activities involved in gene methylation and on changes of methylation in promoter regions using methylation arrays. In Jurkat cells and human mammary epithelial cells, changes in polyamine concentrations differed after polyamine synthesis inhibition. However, S-adenosylmethionine decarboxylase activity and the decarboxylated S-adenosylmethionine to S-adenosyl-L-methionine ratio were decreased by spermine addition in both cells. After inhibiting polyamine synthesis in Jurkat cells by D,L-alpha-difluoromethylornithine, the protein levels of DNA methyltransferase (DNMT) 1, 3A and 3B were not changed, but the activity of the three enzymes markedly decreased. The protein levels of these enzymes were not changed by addition of spermine; however, DNMT 3B was markedly activated and DNMT 3A was also activated. DNMT 1 was not activated. Effects on methylation of promoter regions included significant changes for tumor suppressor genes in response to altered polyamine metabolism. However, no significant changes in methylation status were found on genes of which methylation status and their related protein levels were affected by spermine. When considering these results, there are many genes for which polyamines have an impact on expression via methylation of promoter regions.

ORGANISM(S): Homo sapiens

PROVIDER: GSE111807 | GEO | 2018/03/15

REPOSITORIES: GEO

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Project description:Polyamines (putrescine, spermidine, and spermine) are major organic polycations essential for a wide spectrum of cellular processes. The cells require mechanisms to maintain homeostasis of intracellular polyamines to prevent otherwise severe adverse effects. We performed a detailed transcriptome profile analysis of P. aeruginosa in response to agmatine and putrescine with an emphasis in polyamine catabolism. Agmatine serves as precursor compound for putrescine (and hence spermidine and spermine), which was proposed to convert into GABA and succinate before entering the TCA cycle in support of cell growth as the sole source of carbon and nitrogen. Two acetylpolyamine amidohydrolases, AphA and AphB, were identified to be involved in the conversion of agmatine into putrescine. Enzymatic products of AphA were confirmed by mass spectrometry analysis. Interestingly, the alanine-pyruvate cycle was shown indispensable for polyamine utilization. The newly identified dadRAX locus, encoding the regulator, alanine transaminase and racemase respectively, coupled with SpuC, the major putrescine-pyruvate transaminase, were key components to maintain alanine homeostasis. Corresponding mutant strains were severely hampered in polyamine utilization. On the other hand, the alternative gamma-glutamylation pathway for the conversion of putrescine into GABA was also discussed. Subsequently, GabD, GabT and PA5313 were identified for GABA utilization. Growth defect of PA5313 gabT double mutant in GABA suggested the importance of these two transaminases. The succinic-semialdehyde dehydrogenase activity of GabD and its induction by GABA was also demonstrated in vitro. Polyamine utilization in general was proven independent of the PhoPQ two-component system even the expression of which was induced by polyamines. Multiple potent catabolic pathways as depicted in this study could serve pivotal roles in control of intracellular polyamine levels. Keywords: Metabolism, polyamines, agmatine, putrescine, glutamate, phoPQ.

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Physiological concentration changes of intracellular spermine activates DNA methyltransferase 3A and 3B and affects gene methylation

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