Pharmacological Chaperon Therapy for Type I Mucopolysaccharidosis

Type I mucopolysaccharidosis (MPS I) is caused by mutations of the lysosomal glycosidase α-L-iduronidase (IDUA) gene and
functional deficiency of the IDUA (E.C. 3.2.1.76) (Hampe et al. 2020). The enzymatic deficiency results in extensive accumulation of
glycosaminoglycans (GAGs) in viscera, bones and central nervous system (CNS), which cause high morbidity, physical and
neurological deficit and reduced lifespan (Kingma et al. 2021). Different clinical features involving connective tissue, central nervous
system, skeletal system and heart (Neufeld and Muenzer, 2001) are somehow correlated to the different subtypes of MPS I: Hurler
syndrome (severe form MPS I H) leading to death in early childhood; Hurler-Scheie syndrome (moderate form MPS I H/S); Scheie
syndrome (mild MPS I S) (Mckusik et al. 1972, Neufeld and Muenzer, 1995). MPS I is characterized by noticeable mutational diversity
and ethnic/geographic heterogeneity, with mutations including missense, nonsense, and splice site and deletions/insertions
mutations.
To date, more than two hundreds variants in the IDUA gene have been described in the literature (Borges et al. 2021) and most of
these produce misfolding of the encoded IDUA protein, with retrotraslocation from ER to cytosol, ubiquitilation, proteosomal
degradation and loss of enzyme activity. As already demonstrated in other genetic diseases, refolding of IDUA mutants by molecular
chaperones is potentially able to preserve the molecule from degradation, recovering the enzymatic activity in the lysosomes.
The project will focus on IDUA mutations that produce misfolding of the protein. To this purpose, wild type protein, as well as
mutations that produce protein misfolding, will be analyzed in silico with the aim to identify small molecules able to recover the
catalytic site of the enzyme and preserve the protein from degradation. The small molecules will be synthetized, crystallographically
characterized and tested in vitro on COS-7 cell lines expressing IDUA genes mutations that produce protein misfolding.