Inhibition of DNA methyltransferase by microbial inhibitors and fatty acids

Oleic acid availability impacts thymocyte preprogramming and subsequent peripheral Treg cell differentiation

The nature of activation signals is essential in determining T cell subset differentiation; however, the features that determine T cell subset preference acquired during intrathymic development remain elusive. Here we show that naive CD4+ T cells generated in the mouse thymic microenvironment lacking Scd1, encoding the enzyme catalyzing oleic acid (OA) production, exhibit enhanced regulatory T (Treg) cell differentiation and attenuated development of experimental autoimmune encephalomyelitis. Scd1 deletion in K14+ thymic epithelia recapitulated the enhanced Treg cell differentiation phenotype of Scd1-deficient mice. The dearth of OA permitted DOT1L to increase H3K79me2 levels at the Atp2a2 locus of thymocytes at the DN2-DN3 transition stage. Such epigenetic modification persisted in naive CD4+ T cells and facilitated Atp2a2 expression. Upon T cell receptor activation, ATP2A2 enhanced the activity of the calcium-NFAT1-Foxp3 axis to promote naive CD4+ T cells to differentiate into Treg cells. Therefore, OA availability is critical for preprogramming thymocytes with Treg cell differentiation propensities in the periphery.

Fatty acids, esters, and biogenic oil disinfectants: novel agents against bacteria

For hundreds of years, disinfectants have comprised a variety of active chemical agents that destroy microorganisms through a wide spectrum of mechanisms. In recent years, there has been growing interest in novel disinfectants. One novel method for disinfectant is aerosols. Since the beginning of the 20th century, aerosols produced by the volatilization and subsequent recondensation of oil vapors have been utilized as obscurants (smoke) screens during military operations. Specifically, a petroleum middle distillate, known as the FOG oil, has been used in the US military battlefield to create obscurant smoke screens. Biogenic oils are non-petroleum-based oils that resemble FOG oil in terms of their physical characteristics. Furthermore, FOG and biogenic oils have characteristics that make them preferable to other disinfectants that are frequently employed. In this review, we examine the antimicrobial activities of mineral oils and biogenic oil esters aerosols/vapors as novel disinfectants against bacteria and other microorganisms.

Examining the non-spatial pretraining effect on a water maze spatial learning task in rats treated with multiple intracerebroventricular (ICV) infusions of propionic acid: Contributions to a rodent model of ASD

Propionic acid (PPA) is produced by enteric gut bacteria and is a dietary short chain fatty acid. Intracerebroventricular (ICV) infusions of PPA in rodents have been shown to produce behavioural changes, including adverse effects on cognition, similar to those seen in autism spectrum disorders (ASD). Previous research has shown that repeated ICV infusions of PPA result in impaired spatial learning in a Morris water maze (MWM) as evidenced by increased search latencies, fewer direct and circle swims, and more time spent in the periphery of the maze than control rats. In the current study rats were first given non-spatial pretraining (NSP) in the water maze in order to familiarize the animals with the general requirements of the non-spatial aspects of the task before spatial training was begun. Then the effects of ICV infusions of PPA on acquisition of spatial learning were examined. PPA treated rats failed to show the positive effects of the non-spatial pretraining procedure, relative to controls, as evidenced by increased search latencies, longer distances travelled, fewer direct and circle swims, and more time spent in the periphery of the maze than PBS controls. Thus, PPA treatment blocked the effects of the pretraining procedure, likely by impairing sensorimotor components or memory of the pretraining.

Altered brain phospholipid and acylcarnitine profiles in propionic acid infused rodents: further development of a potential model of autism spectrum disorders

Recent studies have demonstrated intraventricular infusions of propionic acid (PPA) a dietary and enteric short-chain fatty acid can produce brain and behavioral changes similar to those observed in autism spectrum disorder (ASD). The effects of PPA were further evaluated to determine if there are any alterations in brain lipids associated with the ASD-like behavioral changes observed following intermittent intraventricular infusions of PPA, the related enteric metabolite butyric acid (BUT) or phosphate-buffered saline vehicle. Both PPA and BUT produced significant increases (p < 0.001) in locomotor activity (total distance travelled and stereotypy). PPA and to a lesser extent BUT infusions decreased the levels of total monounsaturates, total omega6 fatty acids, total phosphatidylethanolamine plasmalogens, the ratio of omega6 : omega3 and elevated the levels of total saturates in separated phospholipid species. In addition, total acylcarnitines, total longchain (C12-C24) acylcarnitines, total short-chain (C2 to C9) acylcarnitines, and the ratio of bound to free carnitine were increased following infusions with PPA and BUT. These results provide evidence of a relationship between changes in brain lipid profiles and the occurrence of ASD-like behaviors using the autism rodent model. We propose that altered brain fatty acid metabolism may contribute to ASD.

[Metabolites produced by actinomycetes--antiviral antibiotics and enzyme inhibitors]

In 1995, we discovered new antiherpetic antibiotics, called fattiviracins. The producing organism was classified as a strain belonging to Streptomyces microflavus. The strain produced at least 13 fattiviracin derivatives (FV-1 to FV-13). Fattiviracins were obtained as a white amorphous powder, and their molecular weights are in the range of 1400 to 1500. They are readily soluble in water, methanol, pyridine, and DMSO, but insoluble in other organic solvents. Fattiviracins have macrocyclic diesters formed by the binding of two trihydroxy fatty acids and two D-glucose residues in the molecule, and they can be divided into five families according to the length of the fatty acid moiety. Fattiviracins have potent activity against enveloped DNA viruses such as the herpes family, HSV-1, and VZV and enveloped RNA viruses such as influenza A and B viruses, and three strains of HIV-1, with EC(50) values on the order of a few micrograms per milliliter. The biosynthetic pathway of fattiviracins is also becoming clearer. Using bacitracin-resistant strains, enhanced and astringent production of fattiviracin was achieved. Fattiviracin FV-13, which has the longest fatty acid chains in the molecule, was dramatically enhanced by a C(55)-isoprenyl phosphate metabolism. In addition, we have screened various inhibitors of enzymes such as alkaline protease, glucosyltransferase, glucuronidase, phospholipase, deoxyribonuclease, DNA methyltransferase, and DNA topoisomerase. All the inhibitors we discovered are briefly summarized in this paper.

Inhibition of topoisomerases by fatty acids

The inhibitory effects of various fatty acids on topoisomerases were examined, and their structure activity relationships and mechanism of action were studied. Saturated fatty acids (C6:0 to C22:0) did not inhibit topoisomerase I, but cis-unsaturated fatty acids (C16:1 to C22:1) with one double bond showed strong inhibition of the enzyme. The inhibitory potency depended on the carbon chain length and the position of the double bond in the fatty acid molecule. The trans-isomer, methyl ester and hydroxyl derivative of oleic acid had no or little inhibitory effect on topoisomerases I and II. Among the compounds studied petroselinic acid and vaccenic acid (C18:1) with a cis-double bond were the potent inhibitors. Petroselinic acid was a topoisomerase inhibitor of the cleavable complex-nonforming type and acted directly on the enzyme molecule in a noncompetitive manner without DNA intercalation.

1513-DMIa and 1513-DMIb, DNA methyltransferase inhibitors produced by Streptomyces sp. strain No. 1513

Two new methyltransferase inhibitors were isolated from the culture filtrate of Streptomyces sp. strain No. 1513 and named 1513-DMIa and 1513-DMIb. 1513-DMIa and 1513-DMIb were distinguished in certain properties from DMI-1, DMI-2, DMI-3 and DMI-4 previously reported. The molecular weight of 1513-DMIa and 1513-DMIb were estimated to be 576 and 8400 from the results of FAB-MS and gel filtration, respectively. The inhibitory activities of 1513-DMIa and 1513-DMIb were shown to be pH- and temperature-dependent and both inhibited M. EcoRI in an uncompetitive manner with respect to DNA or S-adenosylmethionine (SAM).