Identification of Human Alanine–Glyoxylate Aminotransferase Ligands as Pharmacological Chaperones for Variants Associated with Primary Hyperoxaluria Type 1

Abstract

Primary hyperoxaluria type I (PH1) is a rare kidney disease due to the deficit of alanine:glyoxylate aminotransferase (AGT), a pyridoxal-5′-phosphate-dependent enzyme responsible for liver glyoxylate detoxification, which in turn prevents oxalate formation and precipitation as kidney stones. Many PH1-associated missense mutations cause AGT misfolding. Therefore, the use of pharmacological chaperones (PCs), small molecules that promote correct folding, represents a useful therapeutic option. To identify ligands acting as PCs for AGT, we first performed a small screening of commercially available compounds. We tested each molecule by a dual approach aimed at defining the inhibition potency on purified proteins and the chaperone activity in cells expressing a misfolded variant associated with PH1. We then performed a chemical optimization campaign and tested the resulting synthetic molecules using the same approach. Overall, the results allowed us to identify a promising hit compound for AGT and draw conclusions about the requirements for optimal PC activity.

Insights into the pathogenesis of primary hyperoxaluria type I from the structural dynamics of alanine:glyoxylate aminotransferase variants

“…5), indicating that structural destabilization of the native state plays a role (but maybe not the main role) in PH1 pathogenesis. Consistent with this view, development of very high affinity ligands (with apparent dissociation constants even in the low n m range) only leads to a modest correction in an aggregating PH1 variant in model cells of PH1 [47] and an AGT variant with extremely high kinetic stability do not show higher expression levels in transfected eukaryotic cells [46]. A plausible alternative for a main mechanism leading to protein misfolding in PH1 is a reduced folding efficiency in vivo (e.g., as observed as steady‐state enhanced interaction with molecular chaperones in PH1 variants; [28,29]).…”

Searching glycolate oxidase inhibitors based on QSAR, molecular docking, and molecular dynamic simulation approaches

“…With these methods, the ligand-receptor interaction can be explored, and the formation of stable complexes predicted. For example, molecular docking is a powerful technique used to predict the interaction between small drugs and glyoxylate aminotransferase (AGT), identifying promising compounds for PHT1 26 .…”

Molecular Mechanisms, Genotype–Phenotype Correlations and Patient-Specific Treatments in Inherited Metabolic Diseases

“…Dindo and coworkers describe in this Special Issue the importance of the dimerization of human alanine:glyoxylate amino transferase (AGT) for the proper folding of the enzyme in cells and its import to peroxisomes, where the enzyme is metabolically useful, as well as the chaperone role of the protein cofactor pyridoxal 5′-phosphate (PLP) for dimerization and function [ 24 ]. More recently, the same group have described the successful development of pharmacological chaperones that partially restore the normal AGT activity of PH1-causing mutations [ 25 ]. Moya-Garzón and coworkers present in this Special Issue an alternative for the treatment of PH1 based on inhibitors of oxalate formation that is currently under further development by using tools from medicinal chemistry [ 22 , 26 ].…”