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Major depressive disorder (MDD) is a common and severe disease characterized by mood changes, somatic alterations, and often suicide. MDD is treated with antidepressants, but the molecular mechanism of their action is unknown. We found that widely used antidepressants such as amitriptyline and fluoxetine induce autophagy in hippocampal neurons via the slow accumulation of sphingomyelin in lysosomes and Golgi membranes and of ceramide in the endoplasmic reticulum (ER). ER ceramide stimulates phosphatase 2A and thereby the autophagy proteins Ulk, Beclin, Vps34/Phosphatidylinositol 3-kinase, p62, and Lc3B. Although treatment with amitriptyline or fluoxetine requires at least 12 days to achieve sphingomyelin accumulation and the subsequent biochemical and cellular changes, direct inhibition of sphingomyelin synthases with tricyclodecan-9-yl-xanthogenate (D609) results in rapid (within 3 days) accumulation of ceramide in the ER, activation of autophagy, and reversal of biochemical and behavioral signs of stress-induced MDD. Inhibition of Beclin blocks the antidepressive effects of amitriptyline and D609 and induces cellular and behavioral changes typical of MDD. These findings identify sphingolipid-controlled autophagy as an important target for antidepressive treatment methods and provide a rationale for the development of novel antidepressants that act within a few days.

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Methyleugenol is a genotoxic carcinogen in mice and rats, the liver being the primary target tissue. Methyleugenol occurs in fennel and many herbs and spices. Furthermore, methyleugenol-containing plant extracts and chemically prepared methyleugenol are used as flavoring agents. We analyzed surgical human liver samples from 30 subjects for the presence of DNA adducts originating from methyleugenol using isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Twenty-nine samples unambiguously contained the N (2)-(trans-methylisoeugenol-3'-yl)-2'-deoxyguanosine adduct. A second adduct, N (6)-(trans-methylisoeugenol-3'-yl)-2'-deoxyadenosine, was also found in most samples, but at much lower levels, in agreement with the results from experimental models. The maximal and median levels of both adducts combined were 37 and 13 per 10(8) nucleosides (corresponding to 4700 and 1700, respectively, adducts per diploid genome). This is the first demonstration of DNA adducts formed by a xenobiotic in human liver using UPLC-MS/MS, the most reliable method available. It has been estimated for diverse rat and mouse hepatocarcinogens that 50-5500 adducts per 10(8) nucleosides are present after repeated treatment at the TD50 (daily dose that halves the probability to stay tumor-free in long-term studies). We conclude that the exposure to methyleugenol leads to substantial levels of hepatic DNA adducts and, therefore, may pose a significant carcinogenic risk.

Dietary methionine restriction (MR) is well known to reduce body weight by increasing energy expenditure (EE) and insulin sensitivity. An elevated concentration of circulating fibroblast growth factor 21 (FGF21) has been implicated as a potential underlying mechanism. The aims of our study were to test whether dietary MR in the context of a high-fat regimen protects against type 2 diabetes in mice and to investigate whether vegan and vegetarian diets, which have naturally low methionine levels, modulate circulating FGF21 in humans. New Zealand obese (NZO) mice, a model for polygenic obesity and type 2 diabetes, were placed on isocaloric high-fat diets (protein, 16 kcal%; carbohydrate, 52 kcal%; fat, 32 kcal%) that provided methionine at control (Con; 0.86% methionine) or low levels (0.17%) for 9 wk. Markers of glucose homeostasis and insulin sensitivity were analyzed. Among humans, low methionine intake and circulating FGF21 levels were investigated by comparing a vegan and a vegetarian diet to an omnivore diet and evaluating the effect of a short-term vegetarian diet on FGF21 induction. In comparison with the Con group, MR led to elevated plasma FGF21 levels and prevented the onset of hyperglycemia in NZO mice. MR-fed mice exhibited increased insulin sensitivity, higher plasma adiponectin levels, increased EE, and up-regulated expression of thermogenic genes in subcutaneous white adipose tissue. Food intake and fat mass did not change. Plasma FGF21 levels were markedly higher in vegan humans compared with omnivores, and circulating FGF21 levels increased significantly in omnivores after 4 d on a vegetarian diet. These data suggest that MR induces FGF21 and protects NZO mice from high-fat diet–induced glucose intolerance and type 2 diabetes. The normoglycemic phenotype in vegans and vegetarians may be caused by induced FGF21. MR akin to vegan and vegetarian diets in humans may offer metabolic benefits via increased circulating levels of FGF21 and merits further investigation.—Castaño-Martinez, T., Schumacher, F., Schumacher, S., Kochlik, B., Weber, D., Grune, T., Biemann, R., McCann, A., Abraham, K., Weikert, C., Kleuser, B., Schürmann, A., Laeger, T. Methionine restriction prevents onset of type 2 diabetes in NZO mice.

Recent studies have demonstrated that various DNA adducts can be detected in human tissues and fluids using LC-MS/MS. However, the utility of a single DNA adduct as a biomarker in risk assessment is debatable because humans are exposed to many genotoxicants. We established a method to measure DNA adducts derived from sixteen ubiquitous genotoxicants and developed an analytical technique for their simultaneous quantification by UPLC-MS/MS. Methods for the enrichment of the analytes from DNA hydrolysates and chromatographic separation preceding mass spectrometric analysis were optimized and the resultant technique was used for the simultaneous analysis of the 16 DNA adducts in human lung biopsy specimens. Eleven adducts (formed by benzo[a]pyrene, 1-methylpyrene, 4-aminobiphenyl, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 1-methoxy-3-indolylme-thylglucosinolate, 5-hydroxymethylfurfural and malondialdehyde) were not detected in any tissue sample (limits of detection: 0.02 – 7.1 adducts/108 nucleosides). 3,N4-etheno-2′-deoxycytidine and 1,N6-etheno-2′-deoxyadenosine, formed from 2,3-epoxyaldehydes of endogenous lipid peroxidation products, were present in all subjects (16.9 – 115.3 and 27.2 – 179/108 nucleosides, respectively). The same was true for N2-(trans-methylisoeugenol-3′-yl)-2′-deoxyguanosine, the major adduct of methyleugenol (1.7 – 23.7/108 nucleosides). A minor adduct of methyleugenol and two adducts of furfuryl alcohol were detected in several pulmonary specimens. Taken together, we developed a targeted approach for the simultaneous mass spectrometric analyses of 16 DNA adducts, which can be easily extended by adducts formed from other mutagens. The method allowed detecting adducts of furfuryl alcohol and methyleugenol in samples of human lung.

Automated glycan assembly (AGA) enables rapid access to oligosaccharides. The overall length of polymers created via automated solid phase synthesis depends on very high yields at every step to obtain full length products. The synthesis of long polymers serves as the ultimate test of the efficiency and reliability of synthetic processes. A series of Man-(1 -6)-a-Man linked oligosaccharides up to a 50mer, the longest synthetic sequence yet assembled from monosaccharides, has been realized via a 102 step synthesis. We identified a suitable mannose building block and applied a capping step in the final five AGA cycles to minimize (n À 1) deletion sequences that are otherwise difficult to remove by HPLC.Carbohydrates play important structural roles and are key to many biological events.1 Unlike peptides 2 and nucleotides 3 for which sequences of greater than 50 monomer units can now be rapidly assembled by commercial synthesizers, the chemical synthesis of polysaccharides is still challenging due to inherent structural complexities requiring stereo-and regio-control during glycosylation. Though immense progress has been made in the development of chemical glycosylation methods, reports of synthetic polysaccharides longer than 18mers are few in number. 4,5 The syntheses of a mycobacterial arabinogalactan 92mer, a heparin-related 40mer, and a mycobacterial mannose capped arabinomannan 21mer were accomplished using block couplings. 5 From a biomaterials perspective, it is necessary to overcome these synthetic limitations to enable the exploration of the properties of chemically well-defined and pure carbohydrates. As naturally derived saccharide-based materials have served as scaffolds for stem cell based tissue engineering, 6 the relatively facile automated synthesis of peptides and oligonucleotides has enabled the identification of hybrid hydrogels for bioprinting. Solid-phase automated glycan assembly (AGA) 8,9 of polysaccharides is an evolving technique that has enabled rapid access to complex yet well-defined oligosaccharides such as glycosaminoglycans (GAGs), bacterial cell wall antigens, and plant polysaccharides. The longest synthetic polysaccharide prepared by AGA to date is a 30mer oligomannoside. 10 Though AGA has proven to be versatile, all aspects of the process require improvement and the methodology is still developing. We present a systematic study of Man-(1 -6)-a-Man oligomers that addresses building block reactivity and product purification and culminates in the 102 step synthesis of a 50mer polysaccharide. The key to successful AGA is the identification of building blocks that enable high yielding coupling reactions and facilitate downstream purification. To select the best building block, we designed three differentially protected thiomannoside monomers (1-3, Scheme 1) for the synthesis of long linear polysaccharides containing Man-(1 -6)-a-Man linkages. Although the AGA (ii) (a) NaOMe/MeOH, rt; (b) Pd/C, H 2 , MeOH/THF/AcOH.

The lipid hydrolase enzyme acid sphingomyelinase (ASM) is required for the conversion of the lipid cell membrane component sphingomyelin into ceramide. In cancer cells, ASM-mediated ceramide production is important for apoptosis, cell proliferation, and immune modulation, highlighting ASM as a potential multimodal therapeutic target. In this study, we demonstrate elevated ASM activity in the lung tumor environment and blood serum of patients with non-small cell lung cancer (NSCLC). RNAi-mediated attenuation of in human NSCLC cells rendered them resistant to serum starvation-induced apoptosis. In a murine model of lung adenocarcinoma, ASM deficiency reduced tumor development in a manner associated with significant enhancement of Th1-mediated and cytotoxic T-cell-mediated antitumor immunity. Our findings indicate that targeting ASM in NSCLC can act by tumor cell-intrinsic and -extrinsic mechanisms to suppress tumor cell growth, most notably by enabling an effective antitumor immune response by the host..