scholarly journals Glucose Uptake in Trichoderma harzianum: Role of gtt1

2003 ◽  
Vol 2 (4) ◽  
pp. 708-717 ◽  
Author(s):  
Jesús Delgado-Jarana ◽  
Miguel Ángel Moreno-Mateos ◽  
Tahía Benítez
Keyword(s):  
Gene Expression ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Trichoderma Harzianum ◽  
Glucose Transporter ◽  
Biochemical Characterization ◽  
Carbon Sources ◽  
Low Carbon ◽  
Filamentous Ascomycete

ABSTRACT Using a differential display technique, the gene gtt1, which codes for a high-affinity glucose transporter, has been cloned from the mycoparasite fungus Trichoderma harzianum CECT 2413. The deduced protein sequence of the gtt1 gene shows the 12 transmembrane domains typical of sugar transporters, together with certain residues involved in glucose uptake, such as a conserved arginine between domains IV and V and an aromatic residue (Phe) in the sequence of domain X. The gtt1 gene is transcriptionally regulated, being repressed at high levels of glucose. When carbon sources other than glucose are utilized, gtt1 repression is partially alleviated. Full derepression of gtt1 is obtained when the fungus is grown in the presence of low carbon source concentrations. This regulation pattern correlates with the role of this gene in glucose uptake during carbon starvation. Gene expression is also controlled by pH, so that the gtt1 gene is repressed at pH 6 but not at pH 3, a fact which represents a novel aspect of the influence of pH on the gene expression of transporters. pH also affects glucose transport, since a strongly acidic pH provokes a 40% decrease in glucose transport velocity. Biochemical characterization of the transport shows a very low Km value for glucose (12 μM). A transformant strain that overexpresses the gtt1 gene shows a threefold increase in glucose but not galactose or xylose uptake, a finding which confirms the role of the gtt1 gene in glucose transport. The cloning of the first filamentous ascomycete glucose transporter is the first step in elucidating the mechanisms of glucose uptake and carbon repression in aerobic fungi.

Effects of epinephrine on insulin-stimulated glucose uptake and GLUT-4 phosphorylation in muscle

1997 ◽  
Vol 273 (3) ◽  
pp. C1082-C1087 ◽  
Author(s):  
A. D. Lee ◽  
P. A. Hansen ◽  
J. Schluter ◽  
E. A. Gulve ◽  
J. Gao ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Inhibitory Effect ◽  
Phosphate Concentration ◽  
Intrinsic Activity ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Glut 4

beta-Adrenergic stimulation has been reported to inhibit insulin-stimulated glucose transport in adipocytes. This effect has been attributed to a decrease in the intrinsic activity of the GLUT-4 isoform of the glucose transporter that is mediated by phosphorylation of GLUT-4. Early studies showed no inhibition of insulin-stimulated glucose transport by epinephrine in skeletal muscle. The purpose of this study was to determine the effect of epinephrine on GLUT-4 phosphorylation, and reevaluate the effect of beta-adrenergic stimulation on insulin-activated glucose transport, in skeletal muscle. We found that 1 microM epinephrine, which raised adenosine 3',5'-cyclic monophosphate approximately ninefold, resulted in GLUT-4 phosphorylation in rat skeletal muscle but had no inhibitory effect on insulin-stimulated 3-O-methyl-D-glucose (3-MG) transport. In contrast to 3-MG transport, the uptakes of 2-deoxyglucose and glucose were markedly inhibited by epinephrine treatment. This inhibitory effect was presumably mediated by stimulation of glycogenolysis, which resulted in an increase in glucose 6-phosphate concentration to levels known to severely inhibit hexokinase. We conclude that 1) beta-adrenergic stimulation decreases glucose uptake by raising glucose 6-phosphate concentration, thus inhibiting hexokinase, but does not inhibit insulin-stimulated glucose transport and 2) phosphorylation of GLUT-4 has no effect on glucose transport in skeletal muscle.

Role of Non-PTS dependent glucose permease (GlcU) in maintaining the fitness cost during acquisition of nisin-resistance by Enterococcus faecalis

2019 ◽  
Author(s):  
Sandeep Kumar ◽  
Kapil Singh Narayan ◽  
Shruti Shandilya ◽  
Shiv Kumar Sood ◽  
Suman Kapila
Keyword(s):  
Gene Expression ◽  
Glucose Uptake ◽  
Buffalo Milk ◽  
Food Preservation ◽  
Sensitive Strain ◽  
Fitness Cost ◽  
Expression Studies ◽  
Significant Difference ◽  
Gene Expression Studies

ABSTRACT Nisin is used for food preservation due to its antibacterial activity. However, some bacteria survive under the prevailing conditions owing to the acquisition of resistance. This study aimed to characterize nisin-resistant E. faecalis isolated from raw buffalo milk and investigate their fitness cost. FE-SEM, biofilm and cytochrome-c assay were used for characterization. Growth kinetics, HPLC, qPCR, and western-blotting were performed to confer their fitness cost. Results revealed that nisin-resistant E. faecalis were morphologically different from sensitive strain and internalize more glucose. However, no significant difference was observed in the growth pattern of the resistant strain compared to that of the sensitive strain. A non-phosphotransferase glucose permease (GlcU) was found to be associated with enhanced glucose uptake. Conversely, Mpt, a major phospho-transferase system responsible for glucose uptake, did not play any role, as confirmed by gene expression studies and western blot analysis of HPr protein. The phosphorylation of His-15 residue of HPr phosphoprotein was reduced, while that of the Ser-46 residue increased with progression in nisin-resistance, indicating that it may be involved in the regulation of pathogenicity. In conclusion, resistance imposes a significant fitness cost and GlcU plays a key role in maintaining the fitness cost in nisin-resistant variants.

Na+-independent D-glucose transport in rabbit renal basolateral membranes

1988 ◽  
Vol 254 (5) ◽  
pp. F711-F718 ◽  
Author(s):  
P. T. Cheung ◽  
M. R. Hammerman
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Basolateral Membrane Vesicles ◽  
Proximal Tubular

To define the mechanism by which glucose is transported across the basolateral membrane of the renal proximal tubular cell, we measured D-[14C]glucose uptake in basolateral membrane vesicles from rabbit kidney. Na+-dependent D-glucose transport, demonstrable in brush-border vesicles, could not be demonstrated in basolateral membrane vesicles. In the absence of Na+, the uptake of D-[14C]glucose in basolateral vesicles was more rapid than that of L-[3H]glucose over a concentration range of 1-50 mM. Subtraction of the latter from the former uptakes revealed a saturable process with apparent Km of 9.9 mM and Vmax of 0.80 nmol.mg protein-1.s-1. To characterize the transport component of D-glucose uptake in basolateral vesicles, we measured trans stimulation of 2 mM D-[14C]glucose entry in the absence of Na+. Trans stimulation could be effected by preloading basolateral vesicles with D-glucose, 2-deoxy-D-glucose, or 3-O-methyl-D-glucose, but not with L-glucose or alpha-methyl-D-glucoside. Trans-stimulated D-[14C]glucose uptake was inhibited by 0.1 mM phloretin or cytochalasin B but not phlorizin. In contrast, Na+-dependent D-[14C]glucose transport in brush-border vesicles was inhibited by phlorizin but not phloretin or cytochalasin B. Our findings are consistent with the presence of a Na+-independent D-glucose transporter in the proximal tubular basolateral membrane with characteristics similar to those of transporters present in nonepithelial cells.

Functional Expression of Sodium-Dependent Glucose Transporter in Amelogenesis

2020 ◽  
Vol 99 (8) ◽  
pp. 977-986
Author(s):  
H. Ida-Yonemochi ◽  
K. Otsu ◽  
H. Harada ◽  
H. Ohshima
Keyword(s):  
Organ Culture ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Glucose Transporters ◽  
Maturation Stage ◽  
Sodium Dependent ◽  
Tooth Morphogenesis

Glucose is an essential source of energy for mammalian cells and is transported into the cells by glucose transporters. There are 2 types of glucose transporters: one is a passive glucose transporter, GLUT ( SLC2A), and the other is a sodium-dependent active glucose transporter, SGLT ( SLC5A). We previously reported that the expression of GLUTs during tooth development is precisely and spatiotemporally controlled and that the glucose uptake mediated by GLUT1 plays a crucial role in early tooth morphogenesis and tooth size determination. This study aimed to clarify the localization and roles of SGLT1 and SGLT2 in murine ameloblast differentiation by using immunohistochemistry, immunoelectron microscopy, an in vitro tooth organ culture experiment, and in vivo administration of an inhibitor of SGLT1/2, phloridzin. SGLT1, which has high affinity with glucose, was immunolocalized in the early secretory ameloblasts and the ruffle-ended ameloblasts in the maturation stage. However, SGLT2, which has high glucose transport capacity, was observed in the stratum intermedium, papillary layer, and ameloblasts at the maturation stage and colocalized with Na+-K+-ATPase. The inhibition of SGLT1/2 by phloridzin in the tooth germs induced the disturbance of ameloblast differentiation and enamel matrix formation both in vitro (organ culture) and in vivo (mouse model). The expression of SGLT1 and SGLT2 was significantly upregulated in hypoxic conditions in the ameloblast-lineage cells. These findings suggest that the active glucose uptake mediated by SGLT1 and SGLT2 is strictly regulated and dependent on the intra- and extracellular microenvironments during tooth morphogenesis and that the appropriate passive and active glucose transport is an essential event in amelogenesis.

Effect of diet on insulin- and contraction-mediated glucose transport and uptake in rat muscle

1995 ◽  
Vol 269 (3) ◽  
pp. R544-R551 ◽  
Author(s):  
X. Han ◽  
T. Ploug ◽  
H. Galbo
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Fiber Types ◽  
Transport Capacity ◽  
Glut 1 ◽  
Glut 4 ◽  
Red Muscle ◽  
Muscle Glucose Transport ◽  
Stimulation Of

A diet rich in fat diminishes insulin-mediated glucose uptake in muscle. This study explored whether contraction-mediated glucose uptake is also affected. Rats were fed a diet rich in fat (FAT, 73% of energy) or carbohydrate (CHO, 66%) for 5 wk. Hindquarters were perfused, and either glucose uptake or glucose transport capacity (uptake of 3-O-[14C]-methyl-D-glucose (40 mM)) was measured. Amounts of glucose transporter isoform GLUT-1 and GLUT-4 glucose-transporting proteins were determined by Western blot. Glucose uptake was lower (P < 0.05) in hindlegs from FAT than from CHO rats at submaximum and maximum insulin [4 +/- 0.4 vs. 5 +/- 0.3 (SE) mumol.min-1.leg-1 at 150 microU/ml insulin] as well as during prolonged stimulation of the sciatic nerve (4.4 +/- 0.4 vs. 5.6 +/- 0.6 mumol.min-1.leg-1). Maximum glucose transport elicited by insulin (soleus: 1.7 +/- 0.2 vs. 2.6 +/- 0.2 mumol.g-1.5 min-1, P < 0.05) or contractions (soleus: 1.8 +/- 0.2 vs. 2.6 +/- 0.3, P < 0.05) in red muscle was decreased in parallel in FAT compared with CHO rats. GLUT-4 content was decreased by 13-29% (P < 0.05) in the various fiber types, whereas GLUT-1 content was identical in FAT compared with CHO rats. It is concluded that a FAT diet reduces both insulin and contraction stimulation of glucose uptake in muscle and that these effects are associated with diminished skeletal muscle glucose transport capacities and GLUT-4 contents.

Stimulation of GLUT-1 glucose transporter expression in response to exposure to calcium ionophore A-23187

1995 ◽  
Vol 269 (5) ◽  
pp. C1228-C1234 ◽  
Author(s):  
Y. Mitani ◽  
A. Behrooz ◽  
G. R. Dubyak ◽  
F. Ismail-Beigi
Keyword(s):  
Gene Expression ◽  
Glucose Transport ◽  
Gene Transcription ◽  
Glucose Transporter ◽  
Calcium Ionophore ◽  
Tetraacetic Acid ◽  
Glut 1 ◽  
Mrna Induction ◽  
A 23187 ◽  
Mrna Content

We tested the hypothesis that an increase in cytosolic calcium concentration stimulates glucose transporter isoform (GLUT-1) gene expression. Exposure of a rat liver cell line (Clone 9) to 3 microM A-23187 for 12 h resulted in 3-, 5-, and 10-fold increases in cytochalasin B-inhibitable 3-O-methyl-D-glucose transport, GLUT-1 protein, and GLUT-1 mRNA content, respectively. The induction of GLUT-1 mRNA in response to A-23187 is not preceded by a significant decrease in cell ATP content. This induction is prevented by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid in conjunction with ethylene glycol-bis(beta-aminoethyl ether)-N,N, N',N'-tetraacetic acid. To investigate the mechanism of GLUT-1 mRNA induction, we found that exposure to A-23187 stabilized GLUT-1 mRNA: with the employment of actinomycin D, GLUT-1 mRNA had a half-life of 1.5 and 5.5 h in control and A-23187-treated cells, respectively. In nuclear run-on assays, the rate of GLUT-1 gene transcription was stimulated 1.5- to 1.7-fold in nuclei isolated from cells exposed to A-23187 for either 30 min or 2 h. These results demonstrate that exposure to A-23187 stimulates GLUT-1 gene expression and that the increase in GLUT-1 mRNA content is mediated in part by enhanced GLUT-1 gene transcription as well as decreased GLUT-1 mRNA degradation. The increase in GLUT-1 mRNA content, in turn, is associated with increased cell GLUT-1 content and enhanced glucose transport.

scholarly journals Sorting of GLUT4 into its insulin-sensitive store requires the Sec1/Munc18 protein mVps45

2013 ◽  
Vol 24 (15) ◽  
pp. 2389-2397 ◽  
Author(s):  
Jennifer Roccisana ◽  
Jessica B. A. Sadler ◽  
Nia J. Bryant ◽  
Gwyn W. Gould
Keyword(s):  
Glucose Transport ◽  
Glucose Transporter ◽  
Vitro Assay ◽  
Protein Receptor ◽  
Storage Vesicles ◽  
Storage Vesicle ◽  
Impaired Insulin ◽  
Endosomal Pathway

Insulin stimulates glucose transport in fat and muscle cells by regulating delivery of the facilitative glucose transporter, glucose transporter isoform 4 (GLUT4), to the plasma membrane. In the absence of insulin, GLUT4 is sequestered away from the general recycling endosomal pathway into specialized vesicles, referred to as GLUT4-storage vesicles. Understanding the sorting of GLUT4 into this store is a major challenge. Here we examine the role of the Sec1/Munc18 protein mVps45 in GLUT4 trafficking. We show that mVps45 is up-regulated upon differentiation of 3T3-L1 fibroblasts into adipocytes and is expressed at stoichiometric levels with its cognate target–soluble N-ethylmaleimide–sensitive factor attachment protein receptor, syntaxin 16. Depletion of mVps45 in 3T3-L1 adipocytes results in decreased GLUT4 levels and impaired insulin-stimulated glucose transport. Using sub­cellular fractionation and an in vitro assay for GLUT4-storage vesicle formation, we show that mVps45 is required to correctly traffic GLUT4 into this compartment. Collectively our data reveal a crucial role for mVps45 in the delivery of GLUT4 into its specialized, insulin-regulated compartment.

scholarly journals Proteolytic cleavage of cellubrevin and vesicle-associated membrane protein (VAMP) by tetanus toxin does not impair insulin-stimulated glucose transport or GLUT4 translocation in rat adipocytes

1997 ◽  
Vol 321 (1) ◽  
pp. 233-238 ◽  
Author(s):  
Eric HAJDUCH ◽  
J. Carlos ALEDO ◽  
Colin WATTS ◽  
Harinder S. HUNDAL
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Tetanus Toxin ◽  
Glucose Transporter ◽  
Detectable Effect ◽  
Glut4 Translocation ◽  
Rat Adipocytes ◽  
Isolated Rat

Acute insulin stimulation of glucose transport in fat and skeletal muscle occurs principally as a result of the hormonal induced translocation of the GLUT4 glucose transporter from intracellular vesicular stores to the plasma membrane. The precise mechanisms governing the fusion of GLUT4 vesicles with the plasma membrane are very poorly understood at present but may share some similarities with synaptic vesicle fusion, as vesicle-associated membrane protein (VAMP) and cellubrevin, two proteins implicated in the process of membrane fusion, are resident in GLUT4-containing vesicles isolated from rat and murine 3T3-L1 adipocytes respectively. In this study we show that proteolysis of both cellubrevin and VAMP, induced by electroporation of isolated rat adipocytes with tetanus toxin, does not impair insulin-stimulated glucose transport or GLUT4 translocation. The hormone was found to stimulate glucose uptake by approx. 16-fold in freshly isolated rat adipocytes. After a single electroporating pulse, the ability of insulin to activate glucose uptake was lowered, but the observed stimulation was nevertheless nearly 5-fold higher than the basal rate of glucose uptake. Electroporation of adipocytes with 600 nM tetanus toxin resulted in a complete loss of both cellubrevin and VAMP expression within 60 min. However, toxin-mediated proteolysis of both these proteins had no effect on the ability of insulin to stimulate glucose transport which was elevated approx. 5-fold, an activation of comparable magnitude to that observed in cells electroporated without tetanus toxin. The lack of any significant change in insulin-stimulated glucose transport was consistent with the finding that toxin-mediated proteolysis of both cellubrevin and VAMP had no detectable effect on insulin-induced translocation of GLUT4 in adipocytes. Our findings indicate that, although cellubrevin and VAMP are resident proteins in adipocyte GLUT4-containing vesicles, they are not required for the acute insulin-induced delivery of GLUT4 to the plasma membrane.

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