Metabolic Fate Research Articles

Lactate and Lactylation: Clinical Applications of Routine Carbon Source and Novel Modification in Human Diseases

Cell metabolism generates numerous intermediate metabolites that could serve as feedback and feed-forward regulation substances for posttranslational modification. Lactate, a metabolic product of glycolysis, has recently been conceptualized to play a pleiotropic role in shaping cell identities through metabolic rewiring and epigenetic modifications. Lactate-derived carbons, sourced from glucose, mediate the crosstalk among glycolysis, lactate, and lactylation. Furthermore, the multiple metabolic fates of lactate make it an ideal substrate for metabolic imaging in clinical application. Several studies have identified the crucial role of protein lactylation in human diseases associated with cell fate determination, embryonic development, inflammation, neoplasm, and neuropsychiatric disorders. Herein, this review will focus on the metabolic fate of lactate-derived carbon to provide useful information for further research and therapeutic approaches in human diseases. We comprehensively discuss its role in reprogramming and modification during the regulation of glycolysis, the clinical translation prospects of the hyperpolarized lactate signal, lactyl modification in human diseases, and its application with other techniques and omics.

Reconstructing hepatic metabolic profile and glutathione-mediated metabolic fate of acrylamide

The toxicity of acrylamide (AA) has continuously attracted wide concerns as its extensive presence from both environmental and dietary sources. However, its hepatic metabolic transformation and metabolic fate still remain unclear. This study aims to unravel the metabolic profile and glutathione (GSH) mediated metabolic fate of AA in liver of rats under the dose-dependent exposure. We found that exposure to AA dose-dependently alters the binding of AA and GSH and the generation of mercapturic acid adducts, while liver as a target tissue bears the metabolic transformation of AA via regulating GSH synthesis and consumption pathways, in which glutamine synthase (GSS), cytochrome P450 2E1 (CYP2E1), and glutathione S-transferase P1 (GSTP1) play a key role. In response to high- and low-dose exposures to AA, there were significant differences in liver of rats, including the changes in GSH and cysteine (CYS) activities and the conversion ratio of AA to glycidamide (GA), and liver can affect the transformation of AA by regulating the GSH-mediated metabolic pathway. Low-dose exposure to AA activates GSH synthesis pathway in liver and upregulates GSS activity and CYS content with no change in γ-glutamyl transpeptidase 1 (GGT1) activity. High-dose exposure to AA activates the detoxification pathway of GSH and increases GSH consumption by upregulating GSTP1 activity. In addition, molecular docking results showed that most of the metabolic molecules transformed by AA and GA other than themselves can closely bind to GSTP1, GSS, GGT1, N-acetyltransferase 8, and dimethyl sulfide dehydrogenase 1. The binding of AA-GSH and GA-GSH to GSTP1 and CYP2E1 enzymes determine the tendentiousness between toxicity and detoxification of AA, which exerts a prospective avenue for targeting protective role of hepatic enzymes against in vivo toxicity of AA.

S26-01: Evaluation of Microphysiological Systems combining skin models and systemic organs to elucidate the influence of application scenarios on the bioavailability, metabolic fate and biological effects of cosmetic chemicals

S26-01: Evaluation of Microphysiological Systems combining skin models and systemic organs to elucidate the influence of application scenarios on the bioavailability, metabolic fate and biological effects of cosmetic chemicals

The metabolic fate of izencitinib, a gut-selective pan-JAK inhibitor, in humans. Identification of unusual fecal metabolites and implications for MIST evaluation

The metabolic fate of izencitinib, a gut-selective pan-JAK inhibitor, in humans. Identification of unusual fecal metabolites and implications for MIST evaluation

An insight on chronopharmacology and its application in pharmacotherapy

Abstract Numerous pathophysiological conditions change over the course of a day. The biological rhythms that many physiological processes go through include the sleep-wake rhythm and metabolism. Chronopharmacology is a branch of science that studies the effects of various treatments on internal balance and biological timings. Chronopharmacology can aid with drug dose optimization problems, such as enhancing effectiveness or minimizing side effects. The metabolic fate of a pharmaceutical substance in a human is not stable throughout time. Thus, there is growing interest in chronotherapeutics in the fields of experimental biology, medicine, pharmacy, and medication delivery. Utilizing the timing of medicine consumption, this knowledge and the abundance of data should be used wisely to maximize the drug’s safety and efficacy. The goal of optimizing pharmacotherapy in accordance with the fundamental principles of clinical pharmacology is to maximize methodological individualism, assuring the highest level of efficacy and security for the patient’s treatment. This essay provides a succinct review of chronopharmacology, including its several subfields, the effects it has on the body’s various systems, and a general explanation of chronopharmacotherapeutics.

Metabolic Fate of Lignin in Birch Glucuronoxylan Extracts as Dietary Fiber Studied in a Rat Model.

While previously considered inert, recent studies suggest lignin metabolism with unknown metabolic fates is occurring in the gastrointestinal tract of several animal models. This study focuses on analyzing the potential metabolites of lignin. The diets of rats include relatively pure birch glucuronoxylan (pureGX) with residual lignin or lignin-rich GX (GXpoly) in their diet. Nuclear magnetic spectroscopy of the lignin isolated from the GXpoly-fed rats fecal sample shows high alteration in chemical structure, whereas lignin-carbohydrate complexes (LCCs) are enriched in fecal samples from the pureGX group. Moreover, the increased syringyl-to-guaiacyl (S/G) ratio suggests that lignin G-units are predominantly metabolized based on pyrolysis gas chromatography-mass spectrometry (pyr-GC/MS). The presence of small phenolic metabolites identified in urine samples of the GXpoly group, for example, ferulic and sinapic acids, their sulfate and glucuronide derivatives, and 4-sulfobenzylalcohol, suggests that the small fragmented lignin metabolites in the large intestine enter the plasma, and are further processed in the liver. Finally, the relative abundances of polyphenol-degrading Enterorhabdus and Akkermansia in the gut microbiota are associated with lignin metabolism. These findings give further evidence to lignin metabolism in the gut of nonruminants and provide insight to the potential microbes and metabolic routes.

Melatonin modulates L-arginine metabolism in tumor-associated macrophages by targeting arginase 1 in lymphoma.

L-Arginine metabolism plays a crucial role in determining the M1/M2 polarization of macrophages. The M1 macrophages express inducible nitric oxide synthase (iNOS), while the M2 macrophages express arginase 1 and metabolize arginine into nitric oxide and urea, respectively. The tumor microenvironment promotes M2 macrophage polarization and consequently switches the metabolic fate of arginine from nitric oxide towards urea production. Importantly, infiltration of M2 macrophages or tumor-associated macrophages (TAMs) has been correlated with poor prognosis of various cancer types. Melatonin is well reported to have antitumor and immunomodulatory properties. However, whether and how it impacts the polarization of TAMs has not been elucidated. Considering the crucial role of arginine metabolism in macrophage polarization, we were interested to know the fate of L-arginine in TAMs and whether it can be reinstated by melatonin or not. We used a murine model of Dalton's lymphoma and established an in vitro model of TAMs. For TAMs, we used the ascitic fluid of tumor-bearing hosts to activate the macrophages in the presence and absence of lipopolysaccharide (LPS). In these groups, L-arginine metabolism was evaluated, and then the effect of melatonin was assessed in these groups, wherein the metabolic fate of arginine as well as the expression of iNOS and arginase 1 were checked. Furthermore, in the in vivo system of the tumor-bearing host, the effect of melatonin was assessed. The in vitro model of TAMs showed a Th2 cytokine profile, reduced phagocytic activity, and increased wound healing ability. Upon investigating arginine metabolism, we observed high urea levels with increased activity and expression of arginase 1 in TAMs. Furthermore, we observed reduced levels of LPS-induced nitric oxide in TAMs; however, their iNOS expression was comparable. With melatonin treatment, urea level decreased significantly, while the reduction in nitric oxide level was not as significant as observed in its absence in TAMs. Also, melatonin significantly reduced arginase activity and expression at the transcriptional and translational levels, while iNOS expression was affected only at the translational level. This effect was further investigated in the in vivo system, wherein melatonin treatment reversed the metabolic fate of arginine, from urea towards nitric oxide, within the tumor microenvironment. This effect was further correlated with pro-apoptotic tumor cell death in the in vivo system. Our results reinforced the immunomodulatory role of melatonin and offered a strong prospect for activating the anti-tumor immune response in cancer conditions.

Lipid clearance and amyloid formation by serum amyloid A: exploring the links between beneficial and pathologic actions of an enigmatic protein

Serum amyloid A (SAA) is named after a life-threatening disease, yet this small evolutionarily conserved protein must have played a vital role in host defense. Most circulating SAA binds plasma lipoproteins and modulates their metabolism. However, this hardly justifies the rapid and dramatic SAA upregulation in inflammation, which is concomitant with upregulation of secretory phospholipase A2 (sPLA2). We proposed that these proteins synergistically clear cell membrane debris from the sites of injury. The present study uses biochemical and biophysical approaches to further explore the beneficial function of SAA and its potential links to amyloid formation. We show that murine and human SAA1 are powerful detergents that solubilize diverse lipids, including mammalian biomembranes, converting them into lipoprotein-size nanoparticles. These nanoparticles provide ligands for cell receptors, such as scavenger receptor CD36 or heparin/heparan sulfate, act as substrates of sPLA2, and sequester toxic products of sPLA2. Together, these functions enable SAA to rapidly clear unprotected lipids. SAA can also adsorb, without remodeling, to lipoprotein-size nanoparticles such as exosomal liposomes, which are proxies for lipoproteins. SAA in complexes with zwitterionic phospholipids stabilizes α-helices, while SAA in complexes containing anionic lipids or micelle-forming sPLA2 products forms metastable β-sheet–rich species that readily aggregate to form amyloid. Consequently, the synergy between SAA and sPLA2 extends from the beneficial lipid clearance to the pathologic amyloid formation. Furthermore, we show that lipid composition alters SAA conformation and thereby can influence the metabolic fate of SAA–lipid complexes, including their proamyloidogenic and proatherogenic binding to heparan sulfate.

Pyruvate anaplerosis is a targetable vulnerability in persistent leukaemic stem cells

Deregulated oxidative metabolism is a hallmark of leukaemia. While tyrosine kinase inhibitors (TKIs) such as imatinib have increased survival of chronic myeloid leukaemia (CML) patients, they fail to eradicate disease-initiating leukemic stem cells (LSCs). Whether TKI-treated CML LSCs remain metabolically deregulated is unknown. Using clinically and physiologically relevant assays, we generate multi-omics datasets that offer unique insight into metabolic adaptation and nutrient fate in patient-derived CML LSCs. We demonstrate that LSCs have increased pyruvate anaplerosis, mediated by increased mitochondrial pyruvate carrier 1/2 (MPC1/2) levels and pyruvate carboxylase (PC) activity, in comparison to normal counterparts. While imatinib reverses BCR::ABL1-mediated LSC metabolic reprogramming, stable isotope-assisted metabolomics reveals that deregulated pyruvate anaplerosis is not affected by imatinib. Encouragingly, genetic ablation of pyruvate anaplerosis sensitises CML cells to imatinib. Finally, we demonstrate that MSDC-0160, a clinical orally-available MPC1/2 inhibitor, inhibits pyruvate anaplerosis and targets imatinib-resistant CML LSCs in robust pre-clinical CML models. Collectively these results highlight pyruvate anaplerosis as a persistent and therapeutically targetable vulnerability in imatinib-treated CML patient-derived samples.

Metabolism Study of Anamorelin, a GHSR1a Receptor Agonist Potentially Misused in Sport, with Human Hepatocytes and LC-HRMS/MS.

Anamorelin, developed for the treatment of cancer cachexia, is an orally active medication that improves appetite and food intake, thereby increasing body mass and physical functioning. It is classified as a growth hormone secretagogue and strictly monitored by the World Anti-Doping Agency (WADA), owing to its anabolic enhancing potential. Identifying anamorelin and/or metabolite biomarkers of consumption is critical in doping controls. However, there are currently no data available on anamorelin human metabolic fate. The aim of this study was to investigate and identify biomarkers characteristic of anamorelin intake using in silico metabolite predictions with GLORYx, in vitro incubation with 10-donor-pooled human hepatocytes, liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) analysis, and data processing with Thermo Scientific's Compound Discoverer. In silico prediction resulted in N-acetylation at the methylalanyl group as the main transformation (score, 88%). Others including hydroxylation at the indole substructure, and oxidation and N-demethylation at the trimethylhydrazino group were predicted (score, ≤36%). Hepatocyte incubations resulted in 14 phase I metabolites formed through N-demethylation at the trimethylhydrazino group, N-dealkylation at the piperidine ring, and oxidation at the indole and methylalanyl groups; and two phase II glucuronide conjugates occurring at the indole. We propose four metabolites detected as specific biomarkers for toxicological screening.

Identification of intestinal metabolic activation of loganin generated dialdehyde reactive intermediates improves intestinal bile salt hydrolase activities

Loganin is an iridoid with potent pharmacological effects. Loganin contains a hemiacetal structure and can convert to dialdehyde intermediates after deglycosylation. We hypothesized that the metabolites of loganin with hemiacetal can generate reactive dialdehyde intermediates. This study aims to characterize the metabolic profiling of loganin and especially for the unstable dialdehyde intermediates by using ultra-performance liquid chromatograph-quadrupole orbitrap mass spectrometry. In this study, a total of 26 stable metabolites were identified in loganin-treated rats. Loganin underwent different metabolism in the intestine and liver, which was confirmed mainly by the metabolites in the hepatic portal vein. In the intestine, the major metabolic pathways were ester hydrolysis and deglycosylation, followed by methylation and dehydrogenation. The hepatic metabolism pathways were hydrogenation, hydroxylation, glucuronidation, and sulfonation. The circulating metabolites with high abundance were mainly derived from intestinal metabolism. Importantly, 11 unstable dialdehyde intermediates of loganin were identified and described for the first time. The dialdehyde intermediates were identified by their dihydropyridine conjugates with amino acids. The dialdehyde intermediates were mainly produced in the intestine. The dialdehyde intermediates enable covalent modification of intestinal proteins. Loganin can up-regulate the activity of intestinal bile salt hydrolase (BSH), catalyzing bile acid metabolism. The level of protein adducts was positively associated with BSH activity, indicating dialdehyde intermediates played a key role in the up-regulation of BSH activities. In conclusion, this study not only demonstrates the characteristic metabolic fate of loganin but also facilitates the understanding of the pharmacologic effects of dialdehyde intermediates.

Tracking the Metabolic Fate of Exogenous Arachidonic Acid in Ferroptosis Using Dual-Isotope Labeling Lipidomics.

Lipid metabolism is implicated in a variety of diseases, including cancer, cell death, and inflammation, but lipidomics has proven to be challenging due to the vast structural diversity over a narrow range of mass and polarity of lipids. Isotope labeling is often used in metabolomics studies to follow the metabolism of exogenously added labeled compounds because they can be differentiated from endogenous compounds by the mass shift associated with the label. The application of isotope labeling to lipidomics has also been explored as a method to track the metabolism of lipids in various disease states. However, it can be difficult to differentiate a single isotopically labeled lipid from the rest of the lipidome due to the variety of endogenous lipids present over the same mass range. Here we report the development of a dual-isotope deuterium labeling method to track the metabolic fate of exogenous polyunsaturated fatty acids, e.g., arachidonic acid, in the context of ferroptosis using hydrophilic interaction-ion mobility-mass spectrometry (HILIC-IM-MS). Ferroptosis is a type of cell death that is dependent on lipid peroxidation. The use of two isotope labels rather than one enables the identification of labeled species by a signature doublet peak in the resulting mass spectra. A Python-based software, D-Tracer, was developed to efficiently extract metabolites with dual-isotope labels. The labeled species were then identified with LiPydomics based on their retention times, collision cross section, and m/z values. Changes in exogenous AA incorporation in the absence and presence of a ferroptosis inducer were elucidated.

Electrochemistry/mass spectrometry (EC/MS) for fast generation and identification of novel reactive metabolites of two unsymmetrical bisacridines with anticancer activity

The development of a new drug requires knowledge about its metabolic fate in a living organism, regarding the comprehensive assessment of both drug therapeutic activity and toxicity profiles. Electrochemistry (EC) coupled with mass spectrometry (MS) is an efficient tool for predicting the phase I metabolism of redox-sensitive drugs. In particular, EC/MS represents a clear advantage for the generation of reactive drug transformation products and their direct identification compared to biological matrices. In this work, we focused on the characterization of novel electrochemical products of two representative unsymmetrical bisacridines (C-2028 and C-2045) with demonstrated high anticancer activity. The electrochemical thin-layer flow-through cell μ-PrepCell 2.0 (Antec Scientific) was used here for the effective metabolite electrosynthesis. The electrochemical simulation of C-2028 reductive and C-2045 oxidative metabolism resulted in the generation of new products that were not observed before. The formation of nitroso [M-O+H]+ and azoxy [2M-3O+H]+ species from C-2028, as well as a series of hydroxylated and/or dehydrogenated products, including possible quinones [M-2H+H]+ and [M+O-2H+H]+ from C-2045, was demonstrated. For the latter, a glutathione S-conjugate (m/z 935.3130) was also obtained in measurements supplemented with the excess of reduced glutathione. For the identification of the products of interest, structural confirmation based on MS/MS fragmentation experiments was performed. Novel products of electrochemical conversions of unsymmetrical bisacridines were discussed in the context of their possible biological effect on the human organism.

Isotope tracing reveals bacterial catabolism of host-derived glutathione during Helicobacter pylori infection.

Mammalian cells synthesize the antioxidant glutathione (GSH) to shield cellular biomolecules from oxidative damage. Certain bacteria, including the gastric pathogen Helicobacter pylori, can perturb host GSH homeostasis. H. pylori infection significantly decreases GSH levels in host tissues, which has been attributed to the accumulation of reactive oxygen species in infected cells. However, the precise mechanism of H. pylori-induced GSH depletion remains unknown, and tools for studying this process during infection are limited. We developed an isotope-tracing approach to quantitatively monitor host-derived GSH in H. pylori-infected cells by mass spectrometry. Using this method, we determined that H. pylori catabolizes reduced GSH from gastric cells using γ-glutamyl transpeptidase (gGT), an enzyme that hydrolyzes GSH to glutamate and cysteinylglycine (Cys-Gly). gGT is an established virulence factor with immunomodulatory properties that is required for H. pylori colonization in vivo. We found that H. pylori internalizes Cys-Gly in a gGT-dependent manner and that Cys-Gly production during H. pylori infection is coupled to the depletion of intracellular GSH from infected cells. Consistent with bacterial catabolism of host GSH, levels of oxidized GSH did not increase during H. pylori infection, and exogenous antioxidants were unable to restore the GSH content of infected cells. Altogether, our results indicate that H. pylori-induced GSH depletion proceeds via an oxidation-independent mechanism driven by the bacterial enzyme gGT, which fortifies bacterial acquisition of nutrients from the host. Additionally, our work establishes a method for tracking the metabolic fate of host-derived GSH during infection.

Validation of a metabolite-GWAS network for Populus trichocarpa family 1 UDP-glycosyltransferases.

Metabolite genome-wide association studies (mGWASs) are increasingly used to discover the genetic basis of target phenotypes in plants such as Populus trichocarpa, a biofuel feedstock and model woody plant species. Despite their growing importance in plant genetics and metabolomics, few mGWASs are experimentally validated. Here, we present a functional genomics workflow for validating mGWAS-predicted enzyme-substrate relationships. We focus on uridine diphosphate-glycosyltransferases (UGTs), a large family of enzymes that catalyze sugar transfer to a variety of plant secondary metabolites involved in defense, signaling, and lignification. Glycosylation influences physiological roles, localization within cells and tissues, and metabolic fates of these metabolites. UGTs have substantially expanded in P. trichocarpa, presenting a challenge for large-scale characterization. Using a high-throughput assay, we produced substrate acceptance profiles for 40 previously uncharacterized candidate enzymes. Assays confirmed 10 of 13 leaf mGWAS associations, and a focused metabolite screen demonstrated varying levels of substrate specificity among UGTs. A substrate binding model case study of UGT-23 rationalized observed enzyme activities and mGWAS associations, including glycosylation of trichocarpinene to produce trichocarpin, a major higher-order salicylate in P. trichocarpa. We identified UGTs putatively involved in lignan, flavonoid, salicylate, and phytohormone metabolism, with potential implications for cell wall biosynthesis, nitrogen uptake, and biotic and abiotic stress response that determine sustainable biomass crop production. Our results provide new support for in silico analyses and evidence-based guidance for in vivo functional characterization.

Investigations on the in vitro and in vivo metabolic fate of the new synthetic opioid desmethylmoramide using HPLC-HRMS/MS for toxicological screening purposes.

New synthetic opioids are an increasing challenge for clinical and forensic toxicologists that developed over the recent years. Desmethylmoramide (DMM), a structural analogue of methadone, is one of the most recent appearances on the drug market. This study investigated its metabolic fate in rat and pooled human liver S9 fraction (pHLS9) to allow the identification of suitable urinary screening targets beyond the parent compound. The analysis of rat urine after the administration of DMM revealed five metabolites, which were the result of pyrrolidine ring or morpholine ring hydroxylation and combinations of them. Additionally, an N',N-bisdesalkyl metabolite was formed. Incubations of DMM using pHLS9 revealed a pyrrolidine hydroxy metabolite, as well as an N-oxide. No Phase II metabolites were detected in either rat urine or incubations using pHLS9. The metabolism of DMM did in part comply with that of its archetype dextromoramide (DXM). Although morpholine ring hydroxylation and N-oxidation were described for DXM and detected for DMM, phenyl ring hydroxylation was not found for DMM but described for DXM. An analysis of 24 h pooled rat urine samples after DMM administration identified the hydroxy and dihydroxy metabolite as the most abundant excretion products, and they may, thus, serve as screening targets, as the parent compound was barely detectable.

Computational modeling of AMPK and mTOR crosstalk in glutamatergic synapse calcium signaling

Neuronal energy consumption is vital for information processing and memory formation in synapses. The brain consists of just 2% of the human body’s mass, but consumes almost 20% of the body’s energy budget. Most of this energy is attributed to active transport in ion signaling, with calcium being the canonical second messenger of synaptic transmission. Here, we develop a computational model of synaptic signaling resulting in the activation of two protein kinases critical in metabolic regulation and cell fate, AMP-Activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) and investigate the effect of glutamate stimulus frequency on their dynamics. Our model predicts that frequencies of glutamate stimulus over 10 Hz perturb AMPK and mTOR oscillations at higher magnitudes by up to 36% and change the area under curve (AUC) by 5%. This dynamic difference in AMPK and mTOR activation trajectories potentially differentiates high frequency stimulus bursts from basal neuronal signaling leading to a downstream change in synaptic plasticity. Further, we also investigate the crosstalk between insulin receptor and calcium signaling on AMPK and mTOR activation and predict that the pathways demonstrate multistability dependent on strength of insulin signaling and metabolic consumption rate. Our predictions have implications for improving our understanding of neuronal metabolism, synaptic pruning, and synaptic plasticity.

Extracellular enzyme mediated biotransformation of imidacloprid by white-rot fungus Phanerochaete chrysosporium: Mechanisms, pathways, and toxicity

As one of the widely used neonicotinoid insecticide, imidacloprid (IMI) poses serious threat on many kinds of non-target species. The acceleration of its removal from the contaminated environment is therefore an urgent task. Herein, the transformation of IMI by white-rot fungus Phanerochaete chrysosporium was examined, and the reaction mechanism underlying enzymes-mediated IMI biotransformation was elucidated. In addition, transformed products, pathways, and toxicity to Escherichia coli and Microcystis aeruginosa or the growth of rice seeds were investigated. P. chrysosporium could efficiently transform 93.5% of IMI for 6 days primarily through biotransformation, in which extracellular manganese peroxidase and lignin peroxidase substantially responded to transform IMI. IMI mainly underwent nitrate reduction, hydroxylation, and de-chlorination. A less neurologically toxic major metabolite of IMI, 6-chloronicotinic acid, was detected. Molecular dynamics simulation demonstrated that IMI stably bonded to active pocket of extracellular enzymes. This study reveals the key metabolic mechanism and fate of IMI in environment, and highlights the potential of fungi for IMI transformation.

End-binding protein 1 regulates the metabolic fate of CD4+ T lymphoblasts and Jurkat T cells and the organization of the mitochondrial network.

The organization of the mitochondrial network is relevant for the metabolic fate of T cells and their ability to respond to TCR stimulation. This arrangement depends on cytoskeleton dynamics in response to TCR and CD28 activation, which allows the polarization of the mitochondria through their change in shape, and their movement along the microtubules towards the immune synapse. This work focus on the role of End-binding protein 1 (EB1), a protein that regulates tubulin polymerization and has been previously identified as a regulator of intracellular transport of CD3-enriched vesicles. EB1-interferred cells showed defective intracellular organization and metabolic strength in activated T cells, pointing to a relevant connection of the cytoskeleton and metabolism in response to TCR stimulation, which leads to increased AICD. By unifying the organization of the tubulin cytoskeleton and mitochondria during CD4+ T cell activation, this work highlights the importance of this connection for critical cell asymmetry together with metabolic functions such as glycolysis, mitochondria respiration, and cell viability.

Short-chain fatty acids in cancer pathogenesis.

Cancer is a multi-step process that can be viewed as a cellular and immunological shift away from homeostasis in response to selected infectious agents, mutations, diet, and environmental carcinogens. Homeostasis, which contributes importantly to the definition of "health," is maintained, in part by the production of short-chain fatty acids (SCFAs), which are metabolites of specific gut bacteria. Alteration in the composition of gut bacteria, or dysbiosis, is often a major risk factor for some two dozen tumor types. Dysbiosis is often characterized by diminished levels of SCFAs in the stool, and the presence of a "leaky gut," permitting the penetration of microbes and microbial derived molecules (e.g., lipopolysaccharides) through the gut wall, thereby triggering chronic inflammation. SCFAs attenuate inflammation by inhibiting the activation of nuclear factor kappa B, by decreasing the expression of pro-inflammatory cytokines such as tumor necrosis factor alpha, by stimulating the expression of anti-inflammatory cytokines such as interleukin-10 and transforming growth factor beta, and by promoting the differentiation of naïve T cells into T regulatory cells, which down-regulate immune responses by immunomodulation. SCFA function epigenetically by inhibiting selected histone acetyltransferases that alter the expression of multiple genes and the activity of many signaling pathways (e.g., Wnt, Hedgehog, Hippo, and Notch) that contribute to the pathogenesis of cancer. SCFAs block cancer stem cell proliferation, thereby potentially delaying or inhibiting cancer development or relapse by targeting genes and pathways that are mutated in tumors (e.g., epidermal growth factor receptor, hepatocyte growth factor, and MET) and by promoting the expression of tumor suppressors (e.g., by up-regulating PTEN and p53). When administered properly, SCFAs have many advantages compared to probiotic bacteria and fecal transplants. In carcinogenesis, SCFAs are toxic against tumor cells but not to surrounding tissue due to differences in their metabolic fate. Multiple hallmarks of cancer are also targets of SCFAs. These data suggest that SCFAs may re-establish homeostasis without overt toxicity and either delay or prevent the development of various tumor types.