Metabolic Enzyme Triosephosphate Isomerase 1 and Nicotinamide Phosphoribosyltransferase, Two Independent Inflammatory Indicators in Rheumatoid Arthritis: Evidences From Collagen-Induced Arthritis and Clinical Samples

Metabolic intervention is a novel anti-rheumatic approach. The glycolytic regulator NAMPT has been identified as a therapeutic target of rheumatoid arthritis (RA), while other metabolic regulators coordinating NAMPT to perpetuate inflammation are yet to be investigated. We continuously monitored and validated expression changes of Nampt and inflammatory indicators in peripheral while blood cells from rats with collagen-induced arthritis (CIA). Gene transcriptional profiles of Nampt+ and Nampt++ samples from identical CIA rats were compared by RNA-sequencing. Observed gene expression changes were validated in another batch of CIA rats, and typical metabolic regulators with persistent changes during inflammatory courses were further investigated in human subjects. According to expression differences of identified genes, RA patients were assigned into different subsets. Clinical manifestation and cytokine profiles among them were compared afterwards. Nampt overexpression typically occurred in CIA rats during early stages, when iNos and Il-1β started to be up-regulated. Among differentially expressed genes between Nampt+ and Nampt++ CIA rat samples, changes of Tpi1, the only glycolytic enzyme identified were sustained in the aftermath of acute inflammation. Similar to NAMPT, TPI1 expression in RA patients was higher than general population, which was synchronized with increase in RFn as well as inflammatory monocytes-related cytokines like Eotaxin. Meanwhile, RANTES levels were relatively low when NAMPT and TPI1 were overexpressed. Reciprocal interactions between TPI1 and HIF-1α were observed. HIF-1α promoted TPI1 expression, while TPI1 co-localized with HIF-1α in nucleus of inflammatory monocytes. In short, although NAMPT and TPI1 dominate different stages of CIA, they similarly provoke monocyte-mediated inflammation.

Activating silent glycolysis bypasses in Escherichia coli

All living organisms share similar reactions within their central metabolism to provide precursors for all essential building blocks and reducing power. To identify whether alternative metabolic routes of glycolysis can operate in E. coli, we complementarily employed in silico design, rational engineering, and adaptive laboratory evolution. First, we used a genome-scale model and identified two potential pathways within the metabolic network of this organism replacing canonical Embden-Meyerhof-Parnas (EMP) glycolysis to convert phosphosugars into organic acids. One of these glycolytic routes proceeds via methylglyoxal, the other via serine biosynthesis and degradation. Then, we implemented both pathways in E. coli strains harboring defective EMP glycolysis. Surprisingly, the pathway via methylglyoxal immediately operated in a triosephosphate isomerase deletion strain cultivated on glycerol. By contrast, in a phosphoglycerate kinase deletion strain, the overexpression of methylglyoxal synthase was necessary for implementing a functional methylglyoxal pathway. Furthermore, we engineered the serine shunt which converts 3-phosphoglycerate via serine biosynthesis and degradation to pyruvate, bypassing an enolase deletion. Finally, to explore which of these alternatives would emerge by natural selection we performed an adaptive laboratory evolution study using an enolase deletion strain. The evolved mutants were shown to use the serine shunt. Our study reveals the flexible redesignation of metabolic pathways to create new metabolite links and rewire central metabolism.

Proteomic analysis of Saccharomyces cerevisiae grown on glucose or glycerol

<p>The goal of this research was to use two-dimensional electrophoresis to examine changes in abundance of enzymes of the glycolytic pathway in the yeast Saccharomyces cerevisiae grown on carbon sources that support either fermentation to ethanol or oxidative metabolism. Large-scale profiling of protein abundances (expression proteomics) often detects changes in protein abundance between physiological states. Such changes in enzyme abundance are often interpreted as evidence of metabolic change although most textbooks emphasise control of enzyme activities not enzyme amount. Two-dimensional difference gel electrophoresis (2DDIGE) was therefore used to examine differences in protein abundance between S. cerevisiae strain BY4741 grown on either glucose (fermentation) or glycerol. Growth on 2% glucose, but not on glycerol, was accompanied by extensive production of ethanol. Doubling times for growth were 2 h 5 min in glucose and 9 h 41 min in glycerol. Conditions for extraction and two-dimensional electrophoresis of proteins were established. One hundred and seventy nine proteins were identified by MALDI mass spectrometry of tryptic digests of protein spots excised from Coomassie stained gels. All of the enzymes for conversion of glucose to ethanol, except for the second enzyme of glycolysis phosphoglucose isomerase, were identified using twodimensional electrophoresis of 100 μg of protein from cells grown on 2% glucose. Identification of proteins excised from the DIGE gels was more challenging, partly because of the lower amount of protein. Eight of the proteins that showed statistically significant differences in abundance (≥ 2-fold, p ≤ 0.01) between glucose and glycerol were identified by mass spectrometry of proteins excised from the 2DDIGE gels, and a further 18 varying proteins were matched to proteins identified from the Coomassie stained gels. Of these total 26 identified or matched proteins, subunits of five of the enzymes for conversion of glucose to ethanol were more abundant from the fermentative cells grown on glucose. The more abundant glycolytic enzymes were phosphofructokinase 2, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase and enolase, plus pyruvate decarboxylase that was required for conversion of the glycolytic product pyruvate to acetaldehyde. The alcohol dehydrogenases Adh1 and Adh4 that convert acetaldehyde to ethanol were detected but did not vary significantly between growth on glucose or glycerol. The results confirmed that in this case changes in abundance of some enzymes were consistent with the altered metabolic output. Future studies should examine whether changes in the abundance and activity of these enzymes are responsible for the differences in metabolism.</p>

Proteomic analysis of Saccharomyces cerevisiae grown on glucose or glycerol

<p>The goal of this research was to use two-dimensional electrophoresis to examine changes in abundance of enzymes of the glycolytic pathway in the yeast Saccharomyces cerevisiae grown on carbon sources that support either fermentation to ethanol or oxidative metabolism. Large-scale profiling of protein abundances (expression proteomics) often detects changes in protein abundance between physiological states. Such changes in enzyme abundance are often interpreted as evidence of metabolic change although most textbooks emphasise control of enzyme activities not enzyme amount. Two-dimensional difference gel electrophoresis (2DDIGE) was therefore used to examine differences in protein abundance between S. cerevisiae strain BY4741 grown on either glucose (fermentation) or glycerol. Growth on 2% glucose, but not on glycerol, was accompanied by extensive production of ethanol. Doubling times for growth were 2 h 5 min in glucose and 9 h 41 min in glycerol. Conditions for extraction and two-dimensional electrophoresis of proteins were established. One hundred and seventy nine proteins were identified by MALDI mass spectrometry of tryptic digests of protein spots excised from Coomassie stained gels. All of the enzymes for conversion of glucose to ethanol, except for the second enzyme of glycolysis phosphoglucose isomerase, were identified using twodimensional electrophoresis of 100 μg of protein from cells grown on 2% glucose. Identification of proteins excised from the DIGE gels was more challenging, partly because of the lower amount of protein. Eight of the proteins that showed statistically significant differences in abundance (≥ 2-fold, p ≤ 0.01) between glucose and glycerol were identified by mass spectrometry of proteins excised from the 2DDIGE gels, and a further 18 varying proteins were matched to proteins identified from the Coomassie stained gels. Of these total 26 identified or matched proteins, subunits of five of the enzymes for conversion of glucose to ethanol were more abundant from the fermentative cells grown on glucose. The more abundant glycolytic enzymes were phosphofructokinase 2, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase and enolase, plus pyruvate decarboxylase that was required for conversion of the glycolytic product pyruvate to acetaldehyde. The alcohol dehydrogenases Adh1 and Adh4 that convert acetaldehyde to ethanol were detected but did not vary significantly between growth on glucose or glycerol. The results confirmed that in this case changes in abundance of some enzymes were consistent with the altered metabolic output. Future studies should examine whether changes in the abundance and activity of these enzymes are responsible for the differences in metabolism.</p>

Microsatellites reveal that genetic mixing commonly occurs between invasive fall armyworm populations in Africa

Understanding the population structure and movements of the invasive fall armyworm (FAW, Spodoptera frugiperda) is important as it can help mitigate crop damage, and highlight areas at risk of outbreaks or evolving insecticide resistance. Determining population structure in invasive FAW has been a challenge due to genetic mutations affecting the markers traditionally used for strain and haplotype identification; mitochondrial cytochrome oxidase I (COIB) and the Z-chromosome-linked Triosephosphate isomerase (Tpi). Here, we compare the results from COIB and Tpi markers with highly variable repeat regions (microsatellites) to improve our understanding of FAW population structure in Africa. There was very limited genetic diversity using the COIB marker, whereas using the TpiI4 marker there was greater diversity that showed very little evidence of genetic structuring between FAW populations across Africa. There was greater genetic diversity identified using microsatellites, and this revealed a largely panmictic population of FAW alongside some evidence of genetic structuring between countries. It is hypothesised here that FAW are using long-distance flight and prevailing winds to frequently move throughout Africa leading to population mixing. These approaches combined provide important evidence that genetic mixing between invasive FAW populations may be more common than previously reported.

Triosephosphate Isomerase from Mycobacterium tuberculosis as Potential Target to Develop a New Anti-TB Drug

Tuberculosis (TB) is possibly the most prevalent infectious disease in the world, reports from the World Health Organization (WHO) indicate that TB is one of the top 10 causes of death and an estimated 10 million people worldwide, in addition, there are increasing the TB resistant to conventional antibiotics, multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). Lastly, TB has become more important and requires more attention since it has been proposed as a risk factor for the severity of COVID-19. Therefore, the need to develop new anti-TB drugs. In this study, we propose to use the glycolytic enzyme triosephosphate isomerase from Mycobacterium tuberculosis (MtTIM) as a therapeutic target against TB. The triosephosphate isomerase (TIM) is a target used in different proposals to develop new drugs against different organisms. The MtTIM is an extremely attractive drug target due to the characteristics of its amino acids sequence. In addition, it has been determined that this enzyme (MtTIM) is necessary for the viability of in vitro and in vivo cultures of Mycobacterium tuberculosis. In this way, using the MtTIM as a therapeutic target, we propose potential compounds against MtTIM by molecular docking.

Proteinous Components of Neutrophil Extracellular Traps Are Arrested by the Cell Wall Proteins of Candida albicans during Fungal Infection, and Can Be Used in the Host Invasion

One of defense mechanisms of the human immune system to counteract infection by the opportunistic fungal pathogen Candida albicans is the recruitment of neutrophils to the site of invasion, and the subsequent production of neutrophil extracellular traps (NETs) that efficiently capture and kill the invader cells. In the current study, we demonstrate that within these structures composed of chromatin and proteins, the latter play a pivotal role in the entrapment of the fungal pathogen. The proteinous components of NETs, such as the granular enzymes elastase, myeloperoxidase and lactotransferrin, as well as histones and cathelicidin-derived peptide LL-37, are involved in contact with the surface of C. albicans cells. The fungal partners in these interactions are a typical adhesin of the agglutinin-like sequence protein family Als3, and several atypical surface-exposed proteins of cytoplasmic origin, including enolase, triosephosphate isomerase and phosphoglycerate mutase. Importantly, the adhesion of both the elastase itself and the mixture of proteins originating from NETs on the C. albicans cell surface considerably increased the pathogen potency of human epithelial cell destruction compared with fungal cells without human proteins attached. Such an implementation of adsorbed NET-derived proteins by invading C. albicans cells might alter the effectiveness of the fungal pathogen entrapment and affect the further host colonization.

Confounding factors in the diagnosis and clinical course of rare congenital hemolytic anemias

Congenital hemolytic anemias (CHAs) comprise defects of the erythrocyte membrane proteins and of red blood cell enzymes metabolism, along with alterations of erythropoiesis. These rare and heterogeneous conditions may generate several difficulties from the diagnostic point of view. Membrane defects include hereditary spherocytosis and elliptocytosis, and the group of hereditary stomatocytosis; glucose-6-phosphate dehydrogenase and pyruvate kinase, are the most common enzyme deficiencies. Among ultra-rare forms, it is worth reminding other enzyme defects (glucosephosphate isomerase, phosphofructokinase, adenylate kinase, triosephosphate isomerase, phosphoglycerate kinase, hexokinase, and pyrimidine 5′-nucleotidase), and congenital dyserythropoietic anemias. Family history, clinical findings (anemia, hemolysis, splenomegaly, gallstones, and iron overload), red cells morphology, and biochemical tests are well recognized diagnostic tools. Molecular findings are increasingly used, particularly in recessive and de novo cases, and may be fundamental in unraveling the diagnosis. Notably, several confounders may further challenge the diagnostic workup, including concomitant blood loss, nutrients deficiency, alterations of hemolytic markers due to other causes (alloimmunization, infectious agents, rare metabolic disorders), coexistence of other hemolytic disorders (autoimmune hemolytic anemia, paroxysmal nocturnal hemoglobinuria, etc.). Additional factors to be considered are the possible association with bone marrow, renal or hepatic diseases, other causes of iron overload (hereditary hemochromatosis, hemoglobinopathies, metabolic diseases), and the presence of extra-hematological signs/symptoms. In this review we provide some instructive clinical vignettes that highlight the difficulties and confounders encountered in the diagnosis and clinical management of CHAs.

Non-conserved metabolic regulation by LKB1 distinguishes human and mouse lung adenocarcinoma

KRAS is the most frequently mutated oncogene in human lung adenocarcinomas (hLUAD) and activating mutations in KRAS frequently co-occur with loss-of-function mutations in the tumor suppressor genes, TP53 or STK11/LKB1. However, mutation of all three genes is rarely observed in hLUAD, even though engineered mutations of all three genes produces a highly aggressive lung adenocarcinoma in mice (mLUAD). Here we provide an explanation of this difference between hLUAD and mLUAD by uncovering an evolutionary divergence in regulation of the glycolytic enzyme triosephosphate isomerase (TPI1). Using KRAS/TP53 mutant hLUAD cell lines, we show that TPI1 enzymatic activity can be altered via phosphorylation at Ser21 by the Salt Inducible Kinases (SIKs) in an LKB1-dependent manner; this allows modulation of glycolytic flux between completion of glycolysis and production of glycerol lipids. This metabolic flexibility appears to be critical in rapidly growing cells with KRAS and TP53 mutations, explaining why loss of LKB1 creates a metabolic liability in these tumors. In mice, the amino acid at position 21 of TPI1 is a Cys residue which can be oxidized to alter TPI1 activity, allowing regulation of glycolytic flux balance without a need for SIK kinases or LKB1. Our findings reveal an unexpected role for TPI1 in metabolic reprogramming and suggest that LKB1 and SIK family kinases are potential targets for treating KRAS/TP53 mutant hLUAD. Our data also provide a cautionary example of the limits of genetically engineered murine models as tools to study human diseases such as cancers.