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Biochem J
2013 Dec 01;4562:219-29. doi: 10.1042/BJ20131101.
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FGT-1 is the major glucose transporter in C. elegans and is central to aging pathways.
Feng Y
,
Williams BG
,
Koumanov F
,
Wolstenholme AJ
,
Holman GD
.
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Caenorhabditis elegans is widely used as a model for investigation of the relationships between aging, nutrient restriction and signalling via the DAF-2 (abnormal dauer formation 2) receptor for insulin-like peptides and AGE-1 [ageing alteration 1; orthologue of PI3K (phosphoinositide 3-kinase)], but the identity of the glucose transporters that may link these processes is unknown. We unexpectedly find that of the eight putative GLUT (glucose transporter)-like genes only the two splice variants of one gene have a glucose transport function in an oocyte expression system. We have named this gene fgt-1 (facilitated glucose transporter, isoform 1). We show that knockdown of fgt-1 RNA leads to loss of glucose transport and reduced glucose metabolism in wild-type worms. The FGT-1 glucose transporters of C. elegans thus play a key role in glucose energy supply to C. elegans. Importantly, knockdown of fgt-1 leads to an extension of lifespan equivalent, but not additive, to that observed in daf-2 and age-1 mutant worms. The results of the present study are consistent with DAF-2 and AGE-1 signalling stimulating glucose transport in C. elegans and this process being associated with the longevity phenotype in daf-2 and age-1 mutant worms. We propose that fgt-1 constitutes a common axis for the lifespan extending effects of nutrient restriction and reduced insulin-like peptide signalling.
Figure 1. Comparison of FGT-1A and -1B with GLUT1 and GLUT4Alignment allows comparison of invariant and non-charged residues, particularly in the C-terminal half of the protein. Boxes with a dotted-fill highlight charged residues in the TM regions. Highly conserved signature residues (boxed residues), particularly in the TM7 region, are thought to be important in substrate recognition (see the Supplementary Online Data at http://www.biochemj.org/bj/456/bj4560219add.htm for more information).
Figure 2. Glucose transport activity of C. elegans GLUT-like transporters expressed in Xenopus oocytes(A) The levels of GLUT-like transporters at the cell surface as determined using exofacial HA epitopes. cRNAs for transporters HA-tagged in the first exofacial loop were injected into oocytes. The HA tag at the cell surface was detected with an anti-HA antibody and a β-galactosidase-conjugated secondary antibody. Results are means±S.E.M. for three separate experiments. *P<0.05 compared with the water-injected control oocytes. (B) Glucose-transport activity associated with the indicated putative GLUT-like transporters (without HA tags). Results are means±S.E.M. for three separate experiments. ns, not significantly different compared with the water-injected control oocytes. (C) Comparison of glucose-transport activities, in the presence and absence of the HA tags, that are associated with the expression of hGLUT1 and C. elegans FGT-1A and FGT-1B. Results are means±S.E.M. for three separate experiments. *P<0.05 compared with the water-injected control oocytes. (D) Uptake of 50 μM D-glucose via FGT-1A expressed in oocytes. Time courses were found to be linear. Results are means±S.E.M. for three separate experiments. (E) Rates of maximal transport for glucose in Xenopus oocytes expressing 50 ng of cRNA for FGT-1A and FGT-1B. Oocytes were incubated with the indicated concentrations of D-glucose (S). The rates of [14C]glucose uptake (v, pmol glucose/oocyte per min) were used in least-square fits to the Michaelis–Menten equation. Results are means±S.E.M. for three separate experiments.
Figure 3. Knockdown of fgt-1a and fgt-1b in wild-type and signalling mutant C. elegans strains(A) C. elegans wild-type strain (N2) L1 larvae were seeded on to NGM plates seeded with fgt-1a or fgt-1b RNAi bacteria (with or without 1 mM IPTG to induce knockdown). The young adult worms were transferred on to NGM plates (50 μM FUDR, with or without 1 mM IPTG) seeded with fgt-1a or fgt-1b RNAi bacteria. The worms were maintained on the plates without exhaustion of bacteria food source for 10 days. Total RNAs of each sample were extracted and the extent of knockdown of the total fgt-1 mRNA was determined by qPCR using primers to a region present in both transcripts. Results are means±S.E.M. for three separate experiments. (B) C. elegans L1 larvae of wild-type strain (N2) or strains mutated in the DAF-2 receptor [daf-2 (e1370)], or the PI3K [age-1 (hx546)] were seeded on to NGM plates seeded with fgt-1a and fgt-1b RNAi bacteria mixture (1:1 ratio) (with or without 1 mM IPTG to induce knockdown). The young adult worms were transferred to NGM plates (50 μM FUDR, with or without 1 mM IPTG) seeded with fgt-1a and fgt-1b RNAi bacteria mixture (1:1 ratio). The worms were maintained on the plates without exhaustion of bacteria food source for 10 days. Total RNA of each sample were extracted and the extent of knockdown of the total fgt-1 mRNA was determined by qPCR using primers to a region present in both transcripts. Results are means±S.E.M. for three separate experiments. *P<0.05 compared with the uninduced control. mRNA levels in mutant strains daf-2 and age-1 were not significantly different (n.s.) compared with the wild-type strain (P=0.072 and 0.075 respectively).
Figure 4. Knockdown of fgt-1 influences whole-body glucose uptake and metabolism in C. elegans(A) Whole-body 2DG uptake in the indicated C. elegans strains was determined. *P<0.05 compared with the control uninduced RNAi. ΨP<0.05 compared with the wild-type C. elegans strain fed with control uninduced RNAi bacteria. (B) Whole-body glucose oxidation in the indicated C. elegans strains was determined from the conversion of medium 500 μM [14C]glucose into 14CO2 which was trapped in KOH. *P<0.05 compared with the control RNAi. ΨP<0.05 compared with the wild-type C. elegans strain fed with control uninduced RNAi bacteria. (C) Whole-body glucose into fat conversion in the indicated C. elegans strains was determined from the 14C fat content extracted from worm lysates with heptane. *P<0.05 compared with the control RNAi. ΨP<0.05 compared with the wild-type C. elegans strain fed with control RNAi bacteria. Results are means±S.E.M. for three separate experiments.
Figure 5. fgt-1 knockdown extends lifespan in C. elegans(A) Determination of lifespan for wild-type (N2) worms exposed to fgt-1a RNAi (▲) and fgt-1b RNAi (●) with high (20 mM) glucose concentration medium. ∆ and ○, control uninduced RNAi. (B) Determination of lifespan for wild-type (N2) worms exposed to fgt-1a RNAi (▲) and fgt-1b RNAi (●) together with NGM. ∆ and ○, control uninduced RNAi. (C) Determination of lifespan for wild-type (N2) worms exposed to a fgt-1a and fgt-1b RNAi mixture (1:1 ratio) together with NGM. ▲, fgt-1 RNAi; ∆, control uninduced RNAi.
Figure 6. The lifespan-extending effects of fgt-1 knockdown are reduced on the daf-2 background, whereas there is no significant lifespan extension on the age-1 background(A) Determination of lifespan for daf-2 (e1370) mutant worms exposed to fgt-1a RNAi (▲) and fgt-1b RNAi (●) with NGM. ∆ and ○, control uninduced RNAi. (B) Determination of lifespan for daf-2 (e1370) mutant worms exposed to a fgt-1a and fgt-1b RNAi mixture (1:1 ratio) together with NGM. ▲, fgt-1 RNAi; ∆, control RNAi. (C) Determination of lifespan for age-1 (hx546) mutant worms exposed to fgt-1a RNAi (▲) and fgt-1b RNAi (●) together with NGM. ∆ and ○, control uninduced RNAi. (D) Determination of lifespan for age-1 (hx546) mutant worms exposed to a fgt-1a and fgt-1b RNAi mixture (1:1 ratio) together with NGM. ▲, fgt-1 RNAi; ∆, control uninduced RNAi.
Al-Hasani,
Roles of the N- and C-termini of GLUT4 in endocytosis.
2002, Pubmed
Al-Hasani,
Roles of the N- and C-termini of GLUT4 in endocytosis.
2002,
Pubmed
Baldwin,
Mammalian passive glucose transporters: members of an ubiquitous family of active and passive transport proteins.
1993,
Pubmed
Biddinger,
From mice to men: insights into the insulin resistance syndromes.
2006,
Pubmed
Bogan,
Regulation of glucose transporter translocation in health and diabetes.
2012,
Pubmed
Burnett,
Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila.
2011,
Pubmed
Cope,
Domain assembly of the GLUT1 glucose transporter.
1994,
Pubmed
Doege,
Serine-294 and threonine-295 in the exofacial loop domain between helices 7 and 8 of glucose transporters (GLUT) are involved in the conformational alterations during the transport process.
1998,
Pubmed
Foley,
Endocytosis, recycling, and regulated exocytosis of glucose transporter 4.
2011,
Pubmed
Friedman,
A mutation in the age-1 gene in Caenorhabditis elegans lengthens life and reduces hermaphrodite fertility.
1988,
Pubmed
Gould,
The glucose transporter family: structure, function and tissue-specific expression.
1993,
Pubmed
Hashiramoto,
Site-directed mutagenesis of GLUT1 in helix 7 residue 282 results in perturbation of exofacial ligand binding.
1992,
Pubmed
Heilbronn,
Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial.
2006,
Pubmed
Hirokawa,
SOSUI: classification and secondary structure prediction system for membrane proteins.
1998,
Pubmed
Hursting,
Calorie restriction, aging, and cancer prevention: mechanisms of action and applicability to humans.
2003,
Pubmed
Inzucchi,
Oral antihyperglycemic therapy for type 2 diabetes: scientific review.
2002,
Pubmed
Kaeberlein,
Lifespan extension in Caenorhabditis elegans by complete removal of food.
2006,
Pubmed
Katic,
Mitochondrial gene expression and increased oxidative metabolism: role in increased lifespan of fat-specific insulin receptor knock-out mice.
2007,
Pubmed
Kenyon,
A C. elegans mutant that lives twice as long as wild type.
1993,
Pubmed
Kenyon,
The plasticity of aging: insights from long-lived mutants.
2005,
Pubmed
Kimura,
daf-2, an insulin receptor-like gene that regulates longevity and diapause in Caenorhabditis elegans.
1997,
Pubmed
Kitaoka,
FGT-1 is a mammalian GLUT2-like facilitative glucose transporter in Caenorhabditis elegans whose malfunction induces fat accumulation in intestinal cells.
2013,
Pubmed
,
Xenbase
Koumanov,
Thrifty Tbc1d1 and Tbc1d4 proteins link signalling and membrane trafficking pathways.
2007,
Pubmed
Lee,
Glucose shortens the life span of C. elegans by downregulating DAF-16/FOXO activity and aquaporin gene expression.
2009,
Pubmed
Masoro,
Overview of caloric restriction and ageing.
2005,
Pubmed
Mattson,
Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems.
2005,
Pubmed
Min,
Drosophila lifespan control by dietary restriction independent of insulin-like signaling.
2008,
Pubmed
Mori,
Substitution of tyrosine 293 of GLUT1 locks the transporter into an outward facing conformation.
1994,
Pubmed
Morris,
A phosphatidylinositol-3-OH kinase family member regulating longevity and diapause in Caenorhabditis elegans.
1996,
Pubmed
Mudaliar,
New oral therapies for type 2 diabetes mellitus: The glitazones or insulin sensitizers.
2001,
Pubmed
Naftalin,
Interactions of androgens, green tea catechins and the antiandrogen flutamide with the external glucose-binding site of the human erythrocyte glucose transporter GLUT1.
2003,
Pubmed
Narasimhan,
Converging pathways in lifespan regulation.
2009,
Pubmed
Notredame,
T-Coffee: A novel method for fast and accurate multiple sequence alignment.
2000,
Pubmed
Piper,
Diet and aging.
2008,
Pubmed
Quon,
Tyrosine kinase-deficient mutant human insulin receptors (Met1153-->Ile) overexpressed in transfected rat adipose cells fail to mediate translocation of epitope-tagged GLUT4.
1994,
Pubmed
Ristow,
Antioxidants prevent health-promoting effects of physical exercise in humans.
2009,
Pubmed
Rowland,
Mapping insulin/GLUT4 circuitry.
2011,
Pubmed
Russell,
Endocrine regulation of ageing.
2007,
Pubmed
Saul,
Diversity of polyphenol action in Caenorhabditis elegans: between toxicity and longevity.
2011,
Pubmed
Schulz,
Glucose restriction extends Caenorhabditis elegans life span by inducing mitochondrial respiration and increasing oxidative stress.
2007,
Pubmed
Selman,
Ribosomal protein S6 kinase 1 signaling regulates mammalian life span.
2009,
Pubmed
Sharma,
Heterogeneous effects of calorie restriction on in vivo glucose uptake and insulin signaling of individual rat skeletal muscles.
2014,
Pubmed
So,
Uric acid transport and disease.
2010,
Pubmed
Stiernagle,
Maintenance of C. elegans.
2006,
Pubmed
Stöckli,
GLUT4 exocytosis.
2011,
Pubmed
Sun,
Crystal structure of a bacterial homologue of glucose transporters GLUT1-4.
2012,
Pubmed
Taguchi,
Brain IRS2 signaling coordinates life span and nutrient homeostasis.
2007,
Pubmed
Taniguchi,
Critical nodes in signalling pathways: insights into insulin action.
2006,
Pubmed
Uldry,
Identification of a mammalian H(+)-myo-inositol symporter expressed predominantly in the brain.
2001,
Pubmed
,
Xenbase
Wetter,
Effect of calorie restriction on in vivo glucose metabolism by individual tissues in rats.
1999,
Pubmed
Wood,
Sirtuin activators mimic caloric restriction and delay ageing in metazoans.
2004,
Pubmed
Zarse,
Impaired insulin/IGF1 signaling extends life span by promoting mitochondrial L-proline catabolism to induce a transient ROS signal.
2012,
Pubmed