Dublin
How yeast can help us understand human
genetic disorders (and other biological
problems): the case of
Classic Galactosemia
Claudio Akio Masuda
Yeast Biochemistry and Molecular Biology Lab
Instituto de Bioquímica Médica Leopoldo de Meis
Universidade Federal do Rio de Janeiro
February 2015
Yeast Biochemistry and
Molecular Biology Lab
• Biomedicine:
– Lithium
– Classic Galactosemia (type I)
– Lipid metabolism
• Biotechnology:
– Alcoholic fermentation
– Lipid metabolism/SCO
Strategy
– Perform a genetic screening in yeast.
– Characterize the role of genes/pathways
identified on the screenings.
– Design ways to intervene with the biological
process.
Haploid KO library ~ 6.000 mutants
Growth in galactosemic conditions
UPR has a protective effect in
yeast models of galactosemia
De-Souza,
De-Souza,Pimentel,
Pimentel,Machado
Machadoetetal,al,2014
2014
UPR – unfolded protein response
New therapeutic strategy?
Can we target the UPR and/or ER stress to
treat Classic Galactosemia?
New drug target candidate?
Gene X has a human homologue with 59% similarity and
43% identity in protein sequence
Other hits
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Phosphate homeostasis
N-glycosylation
Calcium homeostasis
Calcium signalling
MAPK
Oxidative stress
Etc…
Acknoledgements
What do we do?
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Genetics
Biochemistry
Molecular Biology
Little bit of cell biology
Classic Galactosemia
• Human genetic disorder caused by deleterious mutations on
the GALT gene which encodes galactose-1-phosphate
uridyltransferase.
• Autossomic recessive (1:20.000 in Brazil)
• Symptoms include gastrointestinal problems, cataract
formation, hepatosplenomegaly and bacterial sepsis in
newborns that, if not treated properly, can lead to death.
• The only treatment is the implementation of a
galactose/lactose-free diet.
• Galactose-1-phosphate accumulation is a hallmark of this
disease.
Leloir pathway
gal7
Li+
Masuda et al., 2001
Summary of the results from the genetic screening
Galactokinase deletion abolishes
galactose-1-phosphate accumulation
gal7
Masuda et al., 2001
Deletion of galactokinase protects from galactose
toxicity
Galactokinase is a drug target candidate for
the treatment of type I galactosemia
De-Souza, Pimentel, Machado et al, 2014
Copy and Paste
• Can we use the same strategy to address
other biological problems?
• YES!
• We are already applying this same
strategy to study lipid metabolism.