Ambroxol as a pharmacological chaperone for mutant glucocerebrosidase

Abstract

Gaucher disease (GD) is characterized by accumulation of glucosylceramide in lysosomes due to mutations in the GBA1 gene encoding the lysosomal hydrolase β-glucocerebrosidase (GCase). The disease has a broad spectrum of phenotypes, which were divided into three different Types; Type 1 GD is not associated with primary neurological disease while Types 2 and 3 are associated with central nervous system disease. GCase molecules are synthesized on endoplasmic reticulum (ER)-bound polyribosomes, translocated into the ER and following modifications and correct folding, shuttle to the lysosomes. Mutant GCase molecules, which fail to fold correctly, undergo ER associated degradation (ERAD) in the proteasomes, the degree of which is one of the factors that determine GD severity.Several pharmacological chaperones have already been shown to assist correct folding of mutant GCase molecules in the ER, thus facilitating their trafficking to the lysosomes. Ambroxol, a known expectorant, is one such chaperone. Here we show that ambroxol increases both the lysosomal fraction and the enzymatic activity of several mutant GCase variants in skin fibroblasts derived from Type 1 and Type 2 GD patients.

Glucocerebrosidase mutations and the pathogenesis of Parkinson disease

“…My data supports those of others (Sun et al, 2012;; Bendikov-Bar et al, 2013; by confirming that the GBA mutation is associated with a reduction in GCase activity. However, the level of GCase activity varied between mutations and is to some degree, patient dependent.…”

“…In summary my studies show that heterozygous GBA mutation positive NCSC- Recent data has placed the spotlight on pharmacological chaperones (PC) as an emerging therapeutic strategy for GD (Bendikov-Bar et al, 2013), but also their potential use in PD . PC are small molecules that are able to bind mutant misfolded GCase stalled in the ER and enhance its folding, stability and trafficking to the lysosome, where the residual activity of the enzyme can hydrolyse its substrate.…”

“…ambroxol and isofagomine, have been shown to bind mutant misfolded GCase stalled in the ER, assisting in the refolding and passage to the lysosome, where the chaperone-enzyme complex dissociates in the low pH and the residual activity of the enzyme can hydrolyse substrate (Sun et al, 2012;; Bendikov-Bar et al, 2013). …”

Ambroxol effects in glucocerebrosidase and α‐synuclein transgenic mice

“…To this end, small molecular chaperones designed to cross the blood–brain barrier that are capable of increasing GCase activity are being investigated as a novel therapy for PD to decrease α‐synuclein levels 17, 18, 19, 20, 21, 22, 23, 24, 25…”

Substrate and Substrate-Mimetic Chaperone Binding Sites in Human α-Galactosidase A Revealed by Affinity-Mass Spectrometry

“…The effect on galactose recognition was also evaluated for Ambroxol (ABX), a compound well-known medically and used as an expectorant 12]. Recent work demonstrated therapeutic effects of ABX on β-glucocerebrosidase (GCase), the deficient enzyme in Gaucher's disease; moreover, the application of ABX in vivo in patient-derived fibroblasts was shown to increase mutant GCase activity [12,18]. Proteolytic-affinity mass spectrometry approaches have been previously developed and successfully applied to the molecular identification of ligand binding sites in several biopolymers such as proteinpeptide and antibody-antigen interactions, and to specific carbohydrate-binding peptides from galectins [19][20][21][22][23][24].…”