scholarly journals Regulation of Fructose 1,6-Bisphosphatase in Procyclic Form Trypanosoma brucei

Pathogens ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 617
Author(s):  
Christina Wilkinson ◽  
Meredith T. Morris
Keyword(s):  
Trypanosoma Brucei ◽  
Post Translational Modifications ◽  
Procyclic Form ◽  
Protein Levels ◽  
Glucose Levels ◽  
Fructose 1,6 Bisphosphatase ◽  
Extracellular Glucose ◽  
Low Glucose ◽  
The Relationship

Glycolysis is well described in Trypanosoma brucei, while the importance of gluconeogenesis and one of the key enzymes in that pathway, fructose 1,6-bisphosphatase, is less understood. Using a sensitive and specific assay for FBPase, we demonstrate that FBPase activity in insect stage, procyclic form (PF), parasite changes with parasite cell line, extracellular glucose levels, and cell density. FBPase activity in log phase PF 2913 cells was highest in high glucose conditions, where gluconeogenesis is expected to be inactive, and was undetectable in low glucose, where gluconeogenesis is predicted to be active. This unexpected relationship between FBPase activity and extracellular glucose levels suggests that FBPase may not be exclusively involved in gluconeogenesis and may play an additional role in parasite metabolism. In stationary phase cells, the relationship between FBPase activity and extracellular glucose levels was reversed. Furthermore, we found that monomorphic PF 2913 cells had significantly higher FBPase levels than pleomorphic PF AnTat1.1 cells where the activity was undetectable except when cells were grown in standard SDM79 media, which is glucose-rich and commonly used to grow PF trypanosomes in vitro. Finally, we observed several conditions where FBPase activity changed while protein levels did not, suggesting that the enzyme may be regulated via post-translational modifications.

scholarly journals In Vitro Increase in Intracellular Calcium Concentrations Induced by Low or High Extracellular Glucose Levels in Ependymocytes and Serotonergic Neurons of the Rat Lower Brainstem

Endocrinology ◽  
2004 ◽  
Vol 145 (5) ◽  
pp. 2507-2515 ◽  
Author(s):  
Ryutaro Moriyama ◽  
Hiroko Tsukamura ◽  
Mika Kinoshita ◽  
Hirokatsu Okazaki ◽  
Yukio Kato ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
High Glucose ◽  
Male Rats ◽  
Dependent Manner ◽  
Isolated Cells ◽  
Serotonergic Neurons ◽  
Glucose Levels ◽  
Extracellular Glucose ◽  
Low Glucose

Abstract Pancreatic glucokinase (GK)-like immunoreactivities are located in ependymocytes and serotonergic neurons of the rat brain. The present study investigated in vitro changes in intracellular calcium concentrations ([Ca2+]i) in response to low (2 mm) or high (20 mm) extracellular glucose concentrations in isolated cells from the wall of the central canal (CC), raphe obscurus nucleus (ROb), ventromedial hypothalamus (VMH), and lateral hypothalamic area (LHA) in male rats. An increase in [Ca2+]i was found in cells from the CC (21.1% or 9.8% of ependymocytes), ROb (10.9% or 14.5% of serotonergic neurons), VMH (7.8% and 25.2% of neurons), and LHA (20% or 15.7% of neurons), when extracellular glucose levels were changed from 10 to either 2 or 20 mm, respectively. Most of the ependymocytes and serotonergic neurons responding to the glucose changes were immunoreactive to the anti-GK in the CC (96.8% for low glucose and 100% for high glucose) and ROb (100% for low and high glucose). The [Ca2+]i increase was blocked with calcium-free medium or L-type calcium channel blocker. Cells with an increase in [Ca2+]i in response to low glucose did not respond to high glucose and vice versa. Inhibition of GK activity with acute alloxan treatment blocked low or high glucose-induced [Ca2+]i increases in most GK-immunoreactive cells from the CC or ROb. The glucose-sensitive [Ca2+]i increase in neurons of the VMH and LHA was also alloxan-sensitive, but no cells taken from the VMH and LHA were immunoreactive to the antibody used. The present study further indicates that ependymocytes of the CC and serotonergic neurons in the ROb are also sensitive to the changes in extracellular glucose in a GK-dependent manner, but that the subtype of GK in these cells could be different from that in the VMH and LHA.

scholarly journals IL-33/ST2 axis promotes the inflammatory response of nasal mucosal epithelial cells through inducing the ERK1/2 pathway

2020 ◽  
Vol 26 (6) ◽  
pp. 505-513
Author(s):  
Yun-Qiu Li ◽  
Yu Zhong ◽  
Xu-Ping Xiao ◽  
Dan-Dan Li ◽  
Zheng Zhou ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Ar Model ◽  
Inflammatory Factors ◽  
Mrna Levels ◽  
Model Group ◽  
Protein Levels ◽  
Tnf Α ◽  
Der P1 ◽  
The Relationship

Allergic rhinitis (AR) is a nasal mucosal inflammatory disease mediated by environmental allergens. At present, the relationship between the IL-33/ST2 axis, ERK1/2 pathway and AR progression needs further exploration. In our study, an AR model was constructed in vitro by treating HNEpC cells with Der p1. qRT-PCR was applied to assess the mRNA levels of IL-33, ST2, TNF-α, IL-6, and IL-8. Western blotting was used to measure the protein levels of IL-33, ST2, and the downstream proteins p-ERK1/2, ERK1/2, p-RSK, and RSK. IL-6, IL-8, IL-33, and TNF-α protein levels in cell supernatants were evaluated by ELISA. Flow cytometry was performed to check cell apoptosis of HNEpC in the presence or absence of Der p1. Our results indicate that the relative levels of IL-33, ST2, TNF-α, IL-6, and IL-8 were increased significantly in the AR model group. The above effects were notably reversed after transfection with shIL-33 or shST2. IL-33 stimulation further resulted in the increase in both ST2 and inflammation-associated cytokines, and these effects were restored after shST2 treatment. Also, the levels of inflammatory factors induced by IL-33 stimulation or ST2 overexpression were reversed after applying an ERK1/2 pathway blocker. In conclusion, IL-33/ST2 mediated inflammation of nasal mucosal epithelial cells by inducing the ERK1/2 pathway.

scholarly journals Flux Analysis of the Trypanosoma brucei Glycolysis Based on a Multiobjective-Criteria Bioinformatic Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Amine Ghozlane ◽  
Frédéric Bringaud ◽  
Hayssam Soueidan ◽  
Isabelle Dutour ◽  
Fabien Jourdan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Glucose Metabolism ◽  
Metabolic Network ◽  
Trypanosoma Brucei ◽  
Drug Targets ◽  
Flux Analysis ◽  
Insect Vector ◽  
Procyclic Form ◽  
New Genes

Trypanosoma brucei is a protozoan parasite of major of interest in discovering new genes for drug targets. This parasite alternates its life cycle between the mammal host(s) (bloodstream form) and the insect vector (procyclic form), with two divergent glucose metabolism amenable to in vitro culture. While the metabolic network of the bloodstream forms has been well characterized, the flux distribution between the different branches of the glucose metabolic network in the procyclic form has not been addressed so far. We present a computational analysis (called Metaboflux) that exploits the metabolic topology of the procyclic form, and allows the incorporation of multipurpose experimental data to increase the biological relevance of the model. The alternatives resulting from the structural complexity of networks are formulated as an optimization problem solved by a metaheuristic where experimental data are modeled in a multiobjective function. Our results show that the current metabolic model is in agreement with experimental data and confirms the observed high metabolic flexibility of glucose metabolism. In addition, Metaboflux offers a rational explanation for the high flexibility in the ratio between final products from glucose metabolism, thsat is, flux redistribution through the malic enzyme steps.

scholarly journals GPI-anchored Proteins and Free GPI Glycolipids of Procyclic Form Trypanosoma brucei Are Nonessential for Growth, Are Required for Colonization of the Tsetse Fly, and Are Not the Only Components of the Surface Coat

2006 ◽  
Vol 17 (12) ◽  
pp. 5265-5274 ◽  
Author(s):  
Maria Lucia Sampaio Güther ◽  
Sylvia Lee ◽  
Laurence Tetley ◽  
Alvaro Acosta-Serrano ◽  
Michael A.J. Ferguson
Keyword(s):  
Cell Surface ◽  
Trypanosoma Brucei ◽  
Current Model ◽  
Apparent Molecular Weight ◽  
Tsetse Fly ◽  
Surface Coat ◽  
Procyclic Form ◽  
Cell Surface Biotinylation ◽  
A Cell

The procyclic form of Trypanosoma brucei exists in the midgut of the tsetse fly. The current model of its surface glycocalyx is an array of rod-like procyclin glycoproteins with glycosylphosphatidylinositol (GPI) anchors carrying sialylated poly-N-acetyllactosamine side chains interspersed with smaller sialylated poly-N-acetyllactosamine–containing free GPI glycolipids. Mutants for TbGPI12, deficient in the second step of GPI biosynthesis, were devoid of cell surface procyclins and poly-N-acetyllactosamine–containing free GPI glycolipids. This major disruption to their surface architecture severely impaired their ability to colonize tsetse fly midguts but, surprisingly, had no effect on their morphology and growth characteristics in vitro. Transmission electron microscopy showed that the mutants retained a cell surface glycocalyx. This structure, and the viability of the mutants in vitro, prompted us to look for non-GPI–anchored parasite molecules and/or the adsorption of serum components. Neither were apparent from cell surface biotinylation experiments but [3H]glucosamine biosynthetic labeling revealed a group of previously unidentified high apparent molecular weight glycoconjugates that might contribute to the surface coat. While characterizing GlcNAc-PI that accumulates in the TbGPI12 mutant, we observed inositolphosphoceramides for the first time in this organism.

scholarly journals Persistently Low Extracellular Glucose Correlates with Poor Outcome 6 Months after Human Traumatic Brain Injury despite a Lack of Increased Lactate: A Microdialysis Study

2003 ◽  
Vol 23 (7) ◽  
pp. 865-877 ◽  
Author(s):  
Paul M. Vespa ◽  
David McArthur ◽  
Kristine O'Phelan ◽  
Thomas Glenn ◽  
Maria Etchepare ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Oxygen Saturation ◽  
Glucose Levels ◽  
Poor Outcome ◽  
Glucose Ratio ◽  
Venous Oxygen Saturation ◽  
Extracellular Glucose ◽  
Low Glucose ◽  
Pyruvate Ratio

Disturbed glucose brain metabolism after brain trauma is reflected by changes in extracellular glucose levels. The authors hypothesized that posttraumatic reductions in extracellular glucose levels are not due to ischemia and are associated with poor outcome. Intracerebral microdialysis, electroencephalography, and measurements of brain tissue oxygen levels and jugular venous oxygen saturation were performed in 30 patients with traumatic brain injury. Levels of glucose, lactate, pyruvate, glutamate, and urea were analyzed hourly. The 6-month Glasgow Outcome Scale extended (GOSe6) score was assessed for each patient. In regions of increased glucose utilization defined by positron emission tomography, the extracellular glucose concentration was less than 0.2 mmol/l. Extracellular glucose values were less than 0.2 mmol during postinjury days 0 to 7 in 19% to 30% of hourly samples on each day. Transient decreases in glucose levels occurred with electrographic seizures and nonischemic reductions in cerebral perfusion pressure and jugular venous oxygen saturation. Glutamate levels were elevated in the majority of low-glucose samples, but the lactate/pyruvate ratio did not indicate focal ischemia. Terminal herniation resulted in reductions in glucose with increases in the lactate/pyruvate ratio but not in lactate concentration alone. GOSe6 scores correlated with persistently low glucose levels, combined early low glucose levels and low lactate/glucose ratio, and with the overall lactate/glucose ratio. These results suggest that the level of extracellular glucose is typically reduced after traumatic brain injury and associated with poor outcome, but is not associated with ischemia.

Carnosine decreases IGFBP1 production in db/db mice through suppression of HIF-1

2015 ◽  
Vol 225 (3) ◽  
pp. 159-167 ◽  
Author(s):  
Elisabete A Forsberg ◽  
Ileana R Botusan ◽  
Jing Wang ◽  
Verena Peters ◽  
Ishrath Ansurudeen ◽  
...  
Keyword(s):  
Metabolic Control ◽  
Hypoxia Inducible Factor ◽  
Insulin Level ◽  
Protein Levels ◽  
Glucose Levels ◽  
Gene Assay ◽  
Igf Binding ◽  
Insulin Dependent ◽  
Animal Models Of Diabetes

IGF binding protein 1 (IGFBP1) is a member of the binding proteins for the IGF with an important role in glucose homeostasis. Circulating IGFBP1 is derived essentially from the liver where it is mainly regulated negatively by insulin. Carnosine, a natural antioxidant, has been shown to improve metabolic control in different animal models of diabetes but its mechanisms of action are still not completely unraveled. We therefore investigate the effect of carnosine treatment on the IGFBP1 regulation in db/db mice. Db/db mice and heterozygous non-diabetic mice received for 4 weeks regular water or water supplemented with carnosine.Igfbp1mRNA expression in the liver was evaluated using qPCR and the protein levels in plasma by western blot. Plasma IGF1 and insulin were analyzed using immunoassays. HepG2 cells were used to study thein vitroeffect of carnosine on IGFBP1. The modulation of hypoxia inducible factor-1 alpha (HIF-1α) which is the central mediator of hypoxia-induction of IGFBP1 was analyzed using: WB, reporter gene assay and qPCR. Carnosine decreased the circulating IGFBP1 levels and the liver expressionIgfbp1, through a complex mechanism acting both directly by suppressing the HIF-1α-mediated IGFBP1 induction and indirectly through increasing circulating insulin level followed by a decrease in the blood glucose levels and increased the plasma levels or IGF1. Reduction of IGFBP1 in diabetes through insulin-dependent and insulin-independent pathways is a novel mechanism by which carnosine contributes to the improvement of the metabolic control in diabetes.

scholarly journals A UDP-GlcNAc : βGal β1-6 GlcNAc transferase involved in bloodstream form N-glycan and procyclic form GPI anchor elaboration in Trypanosoma brucei.

2021 ◽  
Author(s):  
Samuel Martin Duncan ◽  
Rupa Nagar ◽  
Manuela Damerow ◽  
Dmitry V. Yashunsky ◽  
Benedetta Buzzi ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Bloodstream Form ◽  
Wild Type ◽  
Dual Roles ◽  
Gpi Anchor ◽  
Procyclic Form ◽  
Life Cycle Stages ◽  
Glcnac Transferase

Trypanosoma brucei has large carbohydrate extensions on its N-linked glycans and glycosylphosphatidylinositol (GPI) anchors in its bloodstream form (BSF) and procyclic form (PCF), respectively. The parasites glycoconjugate repertoire suggests at least 38 glycosyltransferase (GT) activities, 16 of which are unknown. Here, we probe the function(s) of a putative β3GT gene, TbGT10. The BSF null mutant is viable in vitro and in vivo and can differentiate into PCF, demonstrating non-essentiality. However, the absence of TbGT10 led to impaired elaboration of N-glycans and GPI anchor sidechains in BSF and PCF parasites, respectively. Glycosylation defects include reduced BSF glycoprotein binding to ricin and to monoclonal antibodies mAb139 and mAbCB1. The latter bind a carbohydrate epitope of lysosomal glycoprotein p67 that we show here, using synthetic glycans, consists of (-6Gal1-4GlcNAc1-)≥4 poly-N-acetyllactosamine repeats. Methylation linkage analysis of Pronase glycopeptides isolated from BSF wild-type and TbGT10 null parasites show a reduction in 6-O-substituted- and 3,6-di-O-substituted-Gal residues. Together, these data suggest that TbGT10 encodes a UDP-GlcNAc : βGal β1-6 GlcNAc-transferase active in both BSF and PCF life-cycle stages elaborating complex N-glycans and GPI sidechains, respectively. The β1-6 specificity of this β3GT gene product and its dual roles in N-glycan and GPI glycan elaboration are notable.

scholarly journals A voltage-dependent depolarization induced by low external glucose in neurons of the nucleus of the tractus solitarius of rats: interaction with KATP channels regulated by external glucose.

2018 ◽  
Author(s):  
Cahue de Bernardis Murat ◽  
Ricardo Leao
Keyword(s):  
Membrane Potential ◽  
Glucose Solution ◽  
Reversal Potential ◽  
Membrane Hyperpolarization ◽  
Cationic Current ◽  
Voltage Dependent ◽  
Extracellular Glucose ◽  
Low Glucose ◽  
External Glucose

The brainstem nucleus of the tractus solitarius (NTS) is an integrative center for autonomic counterregulatory responses to hypoglycemia, NTS neurons can also sense fluctuations in extracellular glucose levels altering their membrane potential. KATP channels links the metabolic status of the neuron to its excitability, but the role of KATP channels in controlling NTS neurons excitability and in sensing extracellular glucose changes is not clear. Here we investigated using in vitro electrophysiological recordings in brainstem slices the influence of KATP channels on the membrane potential of NTS neurons in normoglicemic and hyperglycemic external glucose concentrations, and after switching the external glucose to a hypoglycemic level. We found that in normoglicemic (5 mM) external glucose application of tolbutamide, a KATP blocker, induced a substantial depolarization of most NTS neurons, while application of diazoxide, a KATP opener, hyperpolarized the membrane of all NTS neurons. Interestingly, neurons not responsive to tolbutamide were more depolarized than responsive neurons. In a hyperglycemic solution (10 mM glucose) few neurons depolarized in response to tolbutamide. We found that these neurons were more depolarized than neurons in 5 mM glucose and only the more hyperpolarized responded to tolbutamide. The non-responsive neurons did not respond to tolbutamide even when hyperpolarized. Interestingly application of a low-gucose solution (0.5 mM) did not hyperpolarized the RMP but produced a depolarization in most neurons. This effect was voltage-dependent not seen in neurons more depolarized, but could be observed when the neurons were hyperpolarized. Depolarization by tolbutamide avoided further depolarization by low glucose, unless the membrane was hyperpolarized. Application of 0.5 mM glucose solution in neurons incubated in 10 mM glucose depolarized the membrane only in more hyperpolarized neurons, which responded to tolbutamide, or after membrane hyperpolarization. The effect of glucose was caused by activation of a cationic current with a reversal potential around the potential were the neurons were non-responsive to low glucose. We conclude that NTS neurons present KATP channels open at rest in normoglicemic conditions, and that their state is affected by extracellular glucose. Moreover, NTS neurons depolarize the membrane in response to the application of a low-glucose solution, but this effect is occluded by membrane depolarization triggered by KATP blockage. This suggests a homeostatic regulation of the membrane potential by glucose and a possible mechanism related to hypoglycemia-associated autonomic failure.

Hyperglycemia exacerbates cadmium-induced glomerular nephrosis

2021 ◽  
pp. 074823372110378
Author(s):  
Mengyang Li ◽  
Xiuxiu Liu ◽  
Zengli Zhang
Keyword(s):  
High Glucose ◽  
Saline Control ◽  
In Vivo Models ◽  
Nitrogen Levels ◽  
Glucose Levels ◽  
Elevated Glucose ◽  
Low Glucose ◽  
Cd Exposure

Current research suggests that cadmium (Cd) exposure may be associated with the progression of diabetic nephropathy; however, the details of this relationship are insufficiently understood. The present study investigated the effects of elevated glucose on Cd-induced toxicity to glomerular cells using in vitro and in vivo models, and it demonstrated that Cd exposure and the hyperglycemia of diabetes acting together increased the risk of developing glomerular nephrosis . In vitro, human podocytes were exposed to a DMEM low-glucose media without (control), or with Cd (as CdCl2), or a high-glucose media plus Cd. The CCK-8, ROS, apoptosis, and mitochondrial transmembrane potential (ΔΨm) assays showed that human podocytes exposed to Cd in a high-glucose media had greater degrees of injury compared with cells treated with Cd at low (euglycemic)-glucose levels. In vivo, diabetic hyperglycemia was induced by streptozotocin in 8-week-old male C57BL/6 mice to which either CdCl2 or saline (control) was intraperitoneally injected twice weekly for 24 weeks. Compared with euglycemic saline-treated controls, the diabetic mice exposed to Cd demonstrated decreased body weight and increased blood urea nitrogen levels along with histopathological renal architecture changes including collagen fiber accumulation. The results of this study supported the hypothesis that hyperglycemia plus Cd exposure increases the risk of damage to glomerular podocytes compared with Cd exposure in euglycemia.

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