Macrocycle-stabilization of its interaction with 14-3-3 increases plasma membrane localization and activity of CFTR

Impaired activity of the chloride channel CFTR is the cause of cystic fibrosis. 14-3-3 proteins have been shown to stabilize CFTR and increase its biogenesis and activity. Here, we report the identification and mechanism of action of a macrocycle stabilizing the 14-3-3/CFTR complex, a first-in-class molecular glue. This molecule rescues plasma membrane localization and chloride transport of F508del-CFTR and works additively with the CFTR pharmacological chaperone corrector lumacaftor (VX-809).

The New Pharmacological Chaperones PBXs Increase α-Galactosidase A Activity in Fabry Disease Cellular Models

Fabry disease is an X-linked multisystemic disorder caused by the impairment of lysosomal α-Galactosidase A, which leads to the progressive accumulation of glycosphingolipids and to defective lysosomal metabolism. Currently, Fabry disease is treated by enzyme replacement therapy or the orally administrated pharmacological chaperone Migalastat. Both therapeutic strategies present limitations, since enzyme replacement therapy has shown low half-life and bioavailability, while Migalastat is only approved for patients with specific mutations. The aim of this work was to assess the efficacy of PBX galactose analogues to stabilize α-Galactosidase A and therefore evaluate their potential use in Fabry patients with mutations that are not amenable to the treatment with Migalastat. We demonstrated that PBX compounds are safe and effective concerning stabilization of α-Galactosidase A in relevant cellular models of the disease, as assessed by enzymatic activity measurements, molecular modelling, and cell viability assays. This experimental evidence suggests that PBX compounds are promising candidates for the treatment of Fabry disease caused by mutations which affect the folding of α-Galactosidase A, even for GLA variants that are not amenable to the treatment with Migalastat.

Fabry Nephropathy in a Young Female Patient Presenting with Only Urinary Mulberry Bodies Treated with Chaperone Therapy

Fabry disease (FD) is an X-linked disorder of the sphingolipid metabolism, caused by deficiency or decreased activity of α-galactosidase A. We report a rare case of Fabry nephropathy (FN) in a 21-year-old Japanese female patient presenting with only urinary mulberry bodies; she was treated with pharmacological chaperone therapy (PCT) after renal biopsy. The patient underwent a detailed examination because her mother was diagnosed with FD in the Division of Community Medicine of our hospital. She did not have renal dysfunction or proteinuria, and only mulberry bodies were detected in the urine. The activity of α-galactosidase A was low, and genetic analysis revealed the R301Q mutation. A percutaneous renal biopsy was performed, and the findings revealed enlargement and vacuolation of glomerular podocytes by light microscopy, and myelin and zebra bodies were detected in podocytes by electron microscopy. She was diagnosed with FN by renal biopsy and gene analysis. PCT was selected as the treatment to prevent cardiac events and renal dysfunction. The present case suggests that renal biopsy may be necessary even for young women with only mulberry bodies for the diagnosis of FN. It could be useful to evaluate the effect of treatment using the counts of mulberry bodies in the urine. In addition, due to its oral administration, PCT may be suitable for patients who are unable to visit the hospital frequently.

Pharmacological Chaperone Therapy for Pompe Disease

Pompe disease (PD), a lysosomal storage disease, is caused by mutations of the GAA gene, inducing deficiency in the acid alpha-glucosidase (GAA). This enzymatic impairment causes glycogen burden in lysosomes and triggers cell malfunctions, especially in cardiac, smooth and skeletal muscle cells and motor neurons. To date, the only approved treatment available for PD is enzyme replacement therapy (ERT) consisting of intravenous administration of rhGAA. The limitations of ERT have motivated the investigation of new therapies. Pharmacological chaperone (PC) therapy aims at restoring enzymatic activity through protein stabilization by ligand binding. PCs are divided into two classes: active site-specific chaperones (ASSCs) and the non-inhibitory PCs. In this review, we summarize the different pharmacological chaperones reported against PD by specifying their PC class and activity. An emphasis is placed on the recent use of these chaperones in combination with ERT.

In vitro pharmacological profiling of selected small molecules compound using recombinant human iduronate-2-sulphatase

Background: Mucopolysaccharidoses type II (MPS II) is an X-linked lysosomal storage disease (LSD). It is due to mutation in IDS gene encoding iduronate-2-sulphatase (IDS) involved in the catabolism of dermatan sulphate and heparan sulphate. Currently, the treatments for MPS II patients are enzyme replacement therapy (ERT) and bone marrow transplantation (BMT). However, ERT is not effectively reducing the central nervous system manifestation and finding the suitable donor maybe quite challenging in BMT. Over the past decades, pharmacological chaperone has been an alternative approach for management of MPS II patient. Here, we described the in vitro profiling of small molecules in group of chondroitin/dermatan (CD) sulphate disaccharide, heparin oligosaccharides, unsaturated heparin disaccharides and 6-O-desulphated heparin oligosaccharide, using recombinant human iduronate-2-sulphatase (rhIDS). Twenty-one small molecule compounds with several concentrations were each screened by inhibition and thermal stability assays. Results: Our study revealed that condroitin dermatan trisulphate (CD3S), heparin tetrasaccharide (H4Sac), heparin octasaccharide (H8Sac) and heparin octadecasaccharide (H18Sac) showed high inhibition constant, Ki and low inhibition concentration, IC50 in comparison to others. In the thermal stability study, only rhIDS incubated with CD3S was found to preserve enzyme activity (20%) after incubated at 67oC. Conclusion: Overall, our experiments discovered that CD3S was able to bind, inhibit and chaperone rhIDS. These features suggest a potential pharmacological chaperone for MPS II.

Protein structural features predict responsiveness to pharmacological chaperone treatment for three lysosomal storage disorders

Three-dimensional structures of proteins can provide important clues into the efficacy of personalized treatment. We perform a structural analysis of variants within three inherited lysosomal storage disorders, comparing variants responsive to pharmacological chaperone treatment to those unresponsive to such treatment. We find that predicted ΔΔG of mutation is higher on average for variants unresponsive to treatment, in the case of datasets for both Fabry disease and Pompe disease, in line with previous findings. Using both a single decision tree and an advanced machine learning approach based on the larger Fabry dataset, we correctly predict responsiveness of three Gaucher disease variants, and we provide predictions for untested variants. Many variants are predicted to be responsive to treatment, suggesting that drug-based treatments may be effective for a number of variants in Gaucher disease. In our analysis, we observe dependence on a topological feature reporting on contact arrangements which is likely connected to the order of folding of protein residues, and we provide a potential justification for this observation based on steady-state cellular kinetics.

Distinct proteostasis states drive pharmacologic chaperone susceptibility for Cystic Fibrosis Transmembrane Conductance Regulator misfolding mutants

ABSTRACTPharmacological chaperones represent a class of therapeutic compounds for treating protein misfolding diseases. One of the most prominent examples is the FDA-approved pharmacological chaperone lumacaftor (VX-809), which has transformed cystic fibrosis (CF) therapy. CF is a fatal disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). VX-809 corrects folding of F508del CFTR, the most common patient mutation, yet F508del exhibits only mild VX-809 response. In contrast, rarer mutations P67L and L206W are hyper-responsive to VX-809, while G85E is non-responsive. Despite the clinical success of VX-809, the mechanistic origin for the distinct susceptibility of mutants remains unclear. Here, we use interactomics to characterize the impact of VX-809 on proteostasis interactions of P67L and L206W and compare these to F508del and G85E. We determine hyper-responsive mutations P67L and L206W exhibit decreased interactions with proteasomal, and autophagy degradation machinery compared to F508del and G85E. We then show inhibiting the proteasome attenuates P67L and L206W VX-809 response, and inhibiting the lysosome attenuates F508del VX-809 response. Our data suggests a previously unidentified but required role for protein degradation in VX-809 correction. Furthermore, we present an approach for identifying proteostasis characteristics of mutant-specific therapeutic response to pharmacological chaperones.

Considerations for Home-Based Treatment of Fabry Disease in Poland during the COVID-19 Pandemic and Beyond

Current therapy for Anderson–Fabry disease in Poland includes hospital or clinic-based intravenous enzyme replacement therapy with recombinant agalsidase alpha or beta, or oral pharmacological chaperone therapy with migalastat. Some countries around the world offer such treatment to patients in the comfort of their own homes. The 2020–2021 COVID-19 pandemic has pushed global healthcare providers to evolve their services so as to minimize the risk of COVID-19 exposure to both patients and providers; this has led to advances in telemedicine services and the increasing availability of at-home treatment for various procedures including parenteral drug administration. A total of 80% of surveyed Anderson–Fabry disease patients in Poland would prefer home-based treatment, which would be a safe and convenient alternative to clinic-based treatment if patient selection is based on our proposed algorithm. Our recommendations for home-based treatments appear feasible for the long term care of Anderson–Fabry disease patients during the COVID-19 pandemic and beyond. This may also serve as a basis for home-based treatment programs in other rare and ultra-rare genetic diseases.

Fabry Disease

Fabry disease (FD) is a lysosomal storage disorder where deficient or completely absent activity of the enzyme α-galactosidas A leads to accumulation of globotriaosylceramide (Gb3) and other glycosphingolipids in lysosomes. The condition is rare, approximately 1:50,000, although underdiagnosis seems frequent. The condition can affect multiple organ systems, including the skin, nervous system, kidneys, and heart. Early manifestations include skin lesions (angiokeratoma), neuropathic pain, and gastrointestinal symptoms. Later on, FD can result in cardiomyopathy, kidney failure, and stroke. Both lifespan and health-related quality of life are affected negatively by FD. Patients are divided into a classical or a non-classical phenotype based on presentation, where the diagnosis of classical FD requires that a set of specific criteria are met. Patients with non-classical FD often have a less severe disease course, sometimes limited to one organ. The hereditary pattern is X-linked. Thus, men are in general more severely affected than women, although there is an overlap in symptomatic burden. Two types of specific treatment options are available: enzyme replacement therapy and pharmacological chaperone therapy. In addition to this, management of each organ manifestation with usual treatment is indicated.

Synthetic corticosteroids as tryptophan hydroxylase stabilizers

Background: Clinically, corticosteroids are used mainly for their immune-modulatory properties but are also known to influence mood. Despite evidence of a role in regulating tryptophan hydroxylases (TPHs), key enzymes in serotonin biosynthesis, a direct action of corticosteroids on these enzymes has not been systematically investigated. Methodology & Results: Corticosteroid effects on TPHs were tested using an in vitro assay. The compound with the strongest modulatory effect, beclomethasone dipropionate, activated TPH1 and TPH2 with low micromolar potency. Thermostability assays suggested a stabilizing mechanism, and computational docking indicated that Beclomethasone dipropionate interacts with the TPH active site. Conclusion: Beclomethasone dipropionate is a stabilizer of TPHs, acting as a pharmacological chaperone. Our findings may inspire further development of steroid scaffolds as putative antidepressant drugs.