Dublin

How yeast can help us understand human genetic disorders (and other biological

problems): the case of

Classic Galactosemia

Claudio Akio MasudaYeast 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 mutantsGrowth in galactosemic conditions

UPR has a protective effect in yeast models of galactosemia

De-Souza, Pimentel, Machado et al, 2014De-Souza, Pimentel, Machado et al, 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

• Phosphate homeostasis

• N-glycosylation

• Calcium homeostasis

• Calcium signalling

• MAPK

• Oxidative stress

• Etc…

Acknoledgements

• Genetics

• Biochemistry

• Molecular Biology

• Little bit of cell biology

What do we do?

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.

Li+

Leloir pathway

gal7

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

De-Souza, Pimentel, Machado et al, 2014

Galactokinase is a drug target candidate for the treatment of type I galactosemia

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.