A <i>Drosophila melanogaster</i> model of classic galactosemia

Kushner, Rebekah F.; Ryan, Emily L.; Sefton, Jennifer M. I.; Sanders, Rebecca; Lucioni, Patricia Jumbo; Moberg, Kenneth H.; Fridovich‐Keil, Judith L.

doi:10.1242/dmm.005041

Cited by 31 publications

(62 citation statements)

References 33 publications

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“…Of particular relevance to galactosemia, the complexity of N-and O-linked glycans in Drosophila and the organismal effects of loss of specific enzymes in the glycosylation pathway have recently been reported (for a review, see Ten Hagen et al, 2009). Further, we recently confirmed GALE is essential for fly development RESEARCH ARTICLE that D. melanogaster encode (http://superfly.ucsd.edu/ homophila) and express functional orthologs of all three Leloir enzymes, designated dGALK (CG5288), dGALT (CG9232) and dGALE (CG12030) (Kushner et al, 2010).…”

Section: Introductionmentioning

confidence: 75%

UDP-galactose 4′ epimerase (GALE) is essential for development ofDrosophila melanogaster

Sanders¹,

Sefton

Moberg

et al. 2010

Disease Models &Amp; Mechanisms

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SUMMARYUDP-galactose 4' epimerase (GALE) catalyzes the interconversion of UDP-galactose and UDP-glucose in the final step of the Leloir pathway; human GALE (hGALE) also interconverts UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine. GALE therefore plays key roles in the metabolism of dietary galactose, in the production of endogenous galactose, and in maintaining the ratios of key substrates for glycoprotein and glycolipid biosynthesis. Partial impairment of hGALE results in the potentially lethal disorder epimerase-deficiency galactosemia. We report here the generation and initial characterization of a first whole-animal model of GALE deficiency using the fruit fly Drosophila melanogaster. Our results confirm that GALE function is essential in developing animals; Drosophila lacking GALE die as embryos but are rescued by the expression of a human GALE transgene. Larvae in which GALE has been conditionally knocked down die within days of GALE loss. Conditional knockdown and transgene expression studies further demonstrate that GALE expression in the gut primordium and Malpighian tubules is both necessary and sufficient for survival. Finally, like patients with generalized epimerase deficiency galactosemia, Drosophila with partial GALE loss survive in the absence of galactose but succumb in development if exposed to dietary galactose. These data establish the utility of the fly model of GALE deficiency and set the stage for future studies to define the mechanism(s) and modifiers of outcome in epimerase deficiency galactosemia.

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Section: Introductionmentioning

confidence: 75%

UDP-galactose 4′ epimerase (GALE) is essential for development ofDrosophila melanogaster

Sanders¹,

Sefton

Moberg

et al. 2010

Disease Models &Amp; Mechanisms

Self Cite

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“…The excess mortality among the intoxicated mouse pups is in-line with the galactose sensitivity phenotype seen in galactose-intoxicated gal7-deleted (GALT-deficient) yeast, 37,38 dGALT-null (GALT-deficient) fruitflies and human neonates. 25 Of course, it does not necessarily mean that the toxicity mechanisms involved are identical in all cases. At the moment, the cause of death for the intoxicated pups remains unclear, despite the fact that oxidative stress had a pathogenic role in the galactose-induced lethality in the GALT-less Drosophila model of Classic Galactosemia.…”

Section: Discussionmentioning

confidence: 99%

“…[22][23][24] The first dGALT-deficient Drosophila melanogaster model had arrested larval development with a high-galactose diet. 25 Impaired geotaxic response was also seen in these flies despite dietary restriction of galactose. 25 However, there were no reports on reduced fertility in these fruit flies and more importantly, the metamorphic changes in the life cycle of this insect are non-existent in humans, making it difficult to study any potential pre-natal effects of galactose toxicity in human patients.…”

Section: Introductionmentioning

confidence: 91%

Subfertility and growth restriction in a new galactose-1 phosphate uridylyltransferase (GALT) - deficient mouse model

et al. 2014

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The first GalT gene knockout (KO) mouse model for Classic Galactosemia (OMIM 230400) accumulated some galactose and its metabolites upon galactose challenge, but was seemingly fertile and symptom free. Here we constructed a new GalT genetrapped mouse model by injecting GalT gene-trapped mouse embryonic stem cells into blastocysts, which were later implanted into pseudo-pregnant females. High percentage GalT gene-trapped chimera obtained were used to generate heterozygous and subsequently, homozygous GalT gene-trapped mice. Biochemical assays confirmed total absence of galactose-1 phosphate uridylyltransferase (GALT) activity in the homozygotes. Although the homozygous GalT gene-trapped females could conceive and give birth when fed with normal chow, they had smaller litter size (P ¼ 0.02) and longer time-to-pregnancy (P ¼ 0.013) than their wild-type littermates. Follicle-stimulating hormone levels of the mutant female mice were not significantly different from the age-matched, wild-type females, but histological examination of the ovaries revealed fewer follicles in the homozygous mutants (P ¼ 0.007). Administration of a high-galactose (40% w/w) diet to lactating homozygous GalT gene-trapped females led to lethality in over 70% of the homozygous GalT gene-trapped pups before weaning. Cerebral edema, abnormal changes in the Purkinje and the outer granular cell layers of the cerebellum, as well as lower blood GSH/GSSG ratio were identified in the galactose-intoxicated pups. Finally, reduced growth was observed in GalT gene-trapped pups fed with normal chow and all pups fed with high-galactose (20% w/w) diet. This new mouse model presents several of the complications of Classic Galactosemia and will be useful to investigate pathogenesis and new therapies.

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“…For this reason, mouse models have also been developed, although these do not display as severe pathology as humans with the same alleles (9). The recent development of a fly (Drosophila melanogaster) model for type I galactosemia is an exciting advance, which will provide a genetically tractable multicellular model system (10).…”

Section: Structural and Enzymological Consequences Of Disease-associamentioning

confidence: 99%

Structural and molecular biology of type I galactosemia: Disease‐associated mutations

McCorvie

Timson

2011

IUBMB Life

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SummaryType I galactosemia results from reduced galactose 1-phosphate uridylyltransferase (GALT) activity. Signs of disease include damage to the eyes, brain, liver, and ovaries. However, the exact nature and severity of the pathology depends on the mutation(s) in the patient's genes and his/her environment. Considerable enzymological and structural knowledge has been accumulated and this provides a basis to explain, at a biochemical level, impairment in the enzyme in the more than 230 disease-associated variants, which have been described. The most common variant, Q188R, occurs close to the active site and the dimer interface. The substitution probably disrupts both UDPsugar binding and homodimer stability. Other alterations, for example K285N, occur close to the surface of the enzyme and most likely affect the folding and stability of the enzyme. There are a number of unanswered questions in the field, which require resolution. These include the possibility that the main enzymes of galactose metabolism form a supramolecular complex and the need for a high resolution crystal structure of human GALT.2011 IUBMB IUBMB Life, 63(11): 949-954, 2011 Keywords galactose metabolism; disease-associated mutation;GALT; galactose 1-phosphate uridylyltransferase; histidine triad transferase; UMP-histidine.Abbreviations GALT, galactose 1-phosphate uridylyltransferase; GALE, activities of GALT and UDP-galactose 40-epimerase.

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A Drosophila melanogaster model of classic galactosemia

Cited by 31 publications

References 33 publications

UDP-galactose 4′ epimerase (GALE) is essential for development ofDrosophila melanogaster

UDP-galactose 4′ epimerase (GALE) is essential for development ofDrosophila melanogaster

Subfertility and growth restriction in a new galactose-1 phosphate uridylyltransferase (GALT) - deficient mouse model

Structural and molecular biology of type I galactosemia: Disease‐associated mutations

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