Recovery of PEX1-Gly843Asp peroxisome dysfunction by small-molecule compounds

Abstract

Zellweger spectrum disorder (ZSD) is a heterogeneous group of diseases with high morbidity and mortality caused by failure to assemble normal peroxisomes. There is no therapy for ZSD, but management is supportive. Nevertheless, one-half of the patients have a phenotype milder than classic Zellweger syndrome and exhibit a progressive disease course. Thus, patients would benefit if therapies became available and were instituted early. Recent reports indicate several interventions that result in partial peroxisome recovery in ZSD fibroblasts. To identify drugs that recover peroxisome functions, we expressed a GFP-peroxisome targeting signal 1 reporter in fibroblasts containing the common disease allele, PEX1-p.Gly843Asp. The GFP reporter remained cytosolic at baseline, and improvement in peroxisome functions was detected by the redistribution of the GFP reporter from the cytosol to the peroxisome. We established a high-content screening assay based on this phenotype assay and evaluated 2,080 small molecules. The cells were cultured in chemical for 2 days and then, were fixed and imaged by epifluorescent microscopy on a high-content imaging platform. We identified four compounds that partially recover matrix protein import, and we confirmed three using independent assays. Our results suggest that PEX1-p.G843D is a misfolded protein amenable to chaperone therapy.Zellweger spectrum | AAA ATPase | misfolded protein | chemical screening | pharmacologic chaperone

Identification of Small Molecule Compounds for Pharmacological Chaperone Therapy of Aspartylglucosaminuria

“…The PEX1 protein is normally involved in peroxisomal import. It was shown that betaine improved peroxisomal import of various proteins in fibroblasts exhibiting mutant PEX1 protein with G843D substitution36. The G843D PEX1 substitution is associated with a mild form of the disease, and its function can be partially rescued by expression of its binding partner PEX6, indicating that a conformational rescue takes place, similarly to what we here observed upon coexpression of T122K and AGU-Fin with the wildtype AGA.…”

Hepatic dysfunction in peroxisomal disorders

“…Sofar, only in rats the in vivo effect of this drug on hepatic peroxisomal parameters have been investigated [152]. For PBD due to misfolded proteins, drugs belonging to the class of chaperones, are promising agents to restore peroxin function, as shown in fibroblasts [153]. To overrule premature stop mutations nonsense suppressor therapies have been tested in fibroblasts [154].…”

A new ocular phenotype associated with an unexpected but known systemic disorder and mutation: novel use of genomic diagnostics and exome sequencing

“…Patients with an infantile Refsum phenotype may survive through adolescence and manifest moderate-to-severe mental retardation, hypotonia, progressive retinopathy and sensorineural deafness and may not always have dysmorphic facies. The PEX1 p.Gly843Asp allele encodes a peroxin with residual protein function 8 9. The presence of at least one p.G843D allele predicts a phenotype milder than Zellweger syndrome 10.…”