Neutral-sugar transport by rat liver lysosomes

Jonas, Adam J.; Conrad, Paul B.; Jobe, H

doi:10.1042/bj2720323

Cited by 26 publications

(26 citation statements)

References 22 publications

(23 reference statements)

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“…The facilitated transport of hexoses in mammalian cells not only occurs across the PM but has been also described for membranes of the endoplasmatic reticulum and the lysosome (20)(21)(22). However, proteins accounting for this transport have not been identified to date.…”

Section: Discussionmentioning

confidence: 99%

GLUT8 Contains a [DE]XXXL[LI] Sorting Motif and Localizes to a Late Endosomal/Lysosomal Compartment

Augustin

Riley

Moley

2005

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Glucose transporter 8 (GLUT8) contains a cytoplasmic N-terminal dileucine motif and localizes to a thus far unidentified intracellular compartment. Translocation of GLUT8 to the plasma membrane (PM) was found in insulin-treated mouse blastocysts. Using overexpression of GLUT8 in adipocytes and neuronal cells however, insulin treatment or depolarization of the cells did not lead to GLUT8 PM translocation in other studies. In addition, other experiments showing dynamin-dependent endocytosis of GLUT8 suggested that GLUT8 recycles between an endosomal compartment and the PM. To reveal the functional/physiological role of GLUT8, we studied its subcellular localization in 3T3L1, HEK293 and CHO cells. We show that GLUT8 does not co-localize with GLUT4 and does not redistribute to the PM after treatment with insulin, ionophores or okadaic acid in these cell lines. Once endocytosed, GLUT8 does not recycle to the PM. GLUT8 localizes to late endosomes and lysosomes. An interspecies GLUT8 -sequence alignment revealed the presence of a highly conserved late endosomal/lysosomal-targeting motif ([DE]XXXL [LI]). Changing the glutamate to arginine as found in GLUT4 (RRXXXLL) alters GLUT8 endocytosis and retains the transporter at the PM. Furthermore, sorting GLUT8 to late endosomes/lysosomes does not require prior presence of GLUT8 at the PM followed by its endocytosis. In summary, GLUT8 does not reside in a recycling vesicle pool and is distinct from GLUT4. From our data, we postulate a role for GLUT8 in transport of hexoses across intracellular membranes, for example in specific compartments of GLUT8 expression such as the acrosome of mature spermatozoa or secretory granules in neurons. Furthermore, a role for GLUT8 in hexose transport across the lysosomal membrane, a transport mechanism that has long been suggested but unexplained, is discussed.

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Section: Discussionmentioning

confidence: 99%

GLUT8 Contains a [DE]XXXL[LI] Sorting Motif and Localizes to a Late Endosomal/Lysosomal Compartment

Augustin

Riley

Moley

2005

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“…These transport systems are affected by pH and the presence of other anions on the transside of a membrane preparation. Jonas and Jobe (Jonas and Jobe, 1990) described sulfate 2-transport across rat liver lysosomal membrane in exchange for Cl -and suggest the presence of an anion exchanger in this organelle that is regulated by pH or membrane potential. Phosphate 3-transport in human fibroblast lysosomes is strongly affected by pH, but appears highly specific as certain other anions (e.g.…”

Section: Discussionmentioning

confidence: 99%

Heavy metal detoxification in crustacean epithelial lysosomes: role of anions in the compartmentalization process

Sterling

Mandal

Roggenbeck

et al. 2007

Journal of Experimental Biology

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-. As a group, these experiments suggest the presence of an anion exchange mechanism exchanging monovalent for polyvalent anions. Polyvalent inorganic anions (SO 4 2-and PO 4 3-) are known to associate with metals inside vesicles and a detoxification model is presented that suggests how these anions may contribute to concretion formation through precipitation with metals at appropriate vesicular pH.

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“…Similar experiments have been successfully performed in mice where it has been shown that supplementation of fucose into the diet of FX-defective mice (FX is the enzyme directly downstream of GMD in the biosynthetic pathway for GDP-fucose) rescues defects resulting from lack of fucose (26). The fucose presumably enters the cells via a fucose-specific transporter that has been reported in several types of mammalian cells (27,28).…”

Section: Resultsmentioning

confidence: 54%

Resistance to Bacillus thuringiensis Toxin in Caenorhabditis elegans from Loss of Fucose

Barrows

Haslam

Bischof

et al. 2007

Journal of Biological Chemistry

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A mutation in the Caenorhabditis elegans bre-1 gene was isolated in a screen for Bacillus thuringiensis toxin-resistant (bre) mutants to the Cry5B crystal toxin made by B. thuringiensis. bre-1 mutant animals are different from the four other cloned bre mutants in that their level of resistance is noticeably lower. bre-1 animals also display a significantly reduced brood size at 25°C. Here we cloned the bre-1 gene and characterized the bre-1 mutant phenotype. bre-1 encodes a protein with significant homology to a GDP-mannose 4,6-dehydratase, which catalyzes the first step in the biosynthesis of GDP-fucose from GDP-mannose. Injection of GDP-fucose but not fucose into C. elegans intestinal cells rescues bre-1 mutant phenotypes. Thus, C. elegans lacks a functional fucose salvage pathway. Furthermore, we demonstrate that bre-1 mutant animals are defective in production of fucosylated glycolipids and that bre-1 mutant animals make quantitatively reduced levels of glycolipid receptors for Cry5B. We finally show that bre-1 mutant animals, although viable, show a lack of fucosylated N-and O-glycans, based on mass spectrometric evidence. Thus, C. elegans can survive with little fucose and can develop resistance to crystal toxin by loss of a monosaccharide biosynthetic pathway.The crystal (Cry) 3 proteins made by Bacillus thuringiensis are naturally occurring agents that are used for the control of insects that eat crops and carry disease (1). Cry proteins have been used for over 50 years as an environmentally safe and effective alternative to synthetic pesticides. One attractive feature of Cry proteins is their nontoxicity toward mammals and other vertebrates (2). Consistent with this lack of mammalian toxicity, several of the receptors for Cry proteins have been characterized and encode invertebrate-specific glycolipids and/or an insect family of cadherins (3). Because of their efficacy against invertebrates and safety toward vertebrates, Cry proteins are widely used worldwide as topical sprays on crops, as topical sprays to kill mosquitoes and black flies that carry disease, and as transgenes expressed in plants as an environmentally friendly alternative to chemical pesticides (4,5). In the year 2005, over 26 million hectares of B. thuringiensis transgenic corn and cotton were planted (6). In addition, B. thuringiensis crystal proteins are now also being explored for their possible use in the control of nematode parasites (7,8).In our efforts to gain insight into the important question of how invertebrates develop resistance to Cry proteins, we isolated mutations in five Caenorhabditis elegans genes that result in resistance to the crystal protein, Cry5B (9). Four of these bre genes have been cloned and characterized. These genes, bre-2, bre-3, bre-4, and bre-5, encode glycosyltransferase genes that catalyze the addition of monosaccharides onto invertebratespecific glycolipids (10 -12). The resulting oligosaccharide chain is a receptor for the Cry protein (11). Thus, loss of any one of these genes results in loss of t...

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Neutral-sugar transport by rat liver lysosomes

Cited by 26 publications

References 22 publications

GLUT8 Contains a [DE]XXXL[LI] Sorting Motif and Localizes to a Late Endosomal/Lysosomal Compartment

GLUT8 Contains a [DE]XXXL[LI] Sorting Motif and Localizes to a Late Endosomal/Lysosomal Compartment

Heavy metal detoxification in crustacean epithelial lysosomes: role of anions in the compartmentalization process

Resistance to Bacillus thuringiensis Toxin in Caenorhabditis elegans from Loss of Fucose

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