Liver peroxisomal alanine:glyoxylate aminotransferase and the effects of mutations associated with Primary Hyperoxaluria Type I: An overview

Oppici, Elisa; Montioli, Riccardo; Cellini, Barbara

doi:10.1016/j.bbapap.2014.12.029

Cited by 45 publications

(56 citation statements)

References 66 publications

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“…In PH1, it has been already documented that the coenzyme PLP enhances the thermodynamic and kinetic stability of pathogenic variants of AGT and, in some cases, improves their folding efficiency in the cytosolic milieu (7,39,40). These results prompted to the designation of PLP as a natural PC in PH1 and explained the responsiveness of some patients bearing folding mutations to pyridoxine, a PLP precursor (41).…”

Section: Discussionmentioning

confidence: 90%

The Chaperoning Activity of Amino-oxyacetic Acid on Folding-Defective Variants of Human Alanine:Glyoxylate Aminotransferase Causing Primary Hyperoxaluria Type I

et al. 2015

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The rare disease Primary Hyperoxaluria Type I (PH1) results from the deficit of liver peroxisomal alanine:glyoxylate aminotransferase (AGT), as a consequence of inherited mutations on the AGXT gene frequently leading to protein misfolding. Pharmacological chaperone (PC) therapy is a newly developed approach for misfolding diseases based on the use of small molecule ligands able to promote the correct folding of a mutant enzyme. In this report, we describe the interaction of amino-oxyacetic acid (AOA) with the recombinant purified form of two polymorphic species of AGT, AGT-Ma and AGT-Mi, and with three pathogenic variants bearing previously identified folding defects: G41R-Ma, G170R-Mi, and I244T-Mi. We found that for all these enzyme AOA (i) forms an oxime at the active site, (ii) behaves as a slow, tight-binding inhibitor with KI values in the nanomolar range, and (iii) increases the thermal stability. Furthermore, experiments performed in mammalian cells revealed that AOA acts as a PC by partly preventing the intracellular aggregation of G41R-Ma and by promoting the correct peroxisomal import of G170R-Mi and I244T-Mi. Based on these data, we carried out a small-scale screening campaign. We identified four AOA analogues acting as AGT inhibitors, even if only one was found to act as a PC. The possible relationship between the structure and the PC activity of these compounds is discussed. Altogether, these results provide the proof-of-principle for the feasibility of a therapy with PCs for PH1-causing variants bearing folding defects and provide the scaffold for the identification of more specific ligands.

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Section: Discussionmentioning

confidence: 90%

The Chaperoning Activity of Amino-oxyacetic Acid on Folding-Defective Variants of Human Alanine:Glyoxylate Aminotransferase Causing Primary Hyperoxaluria Type I

et al. 2015

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“…e l s e v i e r . c o m / l o c a t e / b b a p a p identified up to date in the human AGXT gene, 36 and 26 are on the background of the major and the minor allele, respectively, while only 5 are on the background of either the major or the minor allele [9]. For the remaining mutations the allele in which are present has not yet been identified.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 96%

Misfolding caused by the pathogenic mutation G47R on the minor allele of alanine:glyoxylate aminotransferase and chaperoning activity of pyridoxine

Montioli

Oppici

Dindo

et al. 2015

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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“…The indirect cell toxicity seen with glycolate was tempered by the metabolic efficiency of AGT variants and was consistent with both AGT activity patterns and metabolite production [4,23]. In the present model, the different transfected CHO cells lines may have different AGT to GO expression ratios despite having comparable GO and AGT expression [23,29], which has to be taken into account when direct comparisons between cell lines are made.…”

Section: Discussionmentioning

confidence: 72%

“…More than 170 mutations have been identified in the gene encoding AGT (i.e. AGXT ), which lead to a wide variety of molecular and cellular phenotypes, including accelerated AGT degradation, aggregation, loss of catalytic activity, and peroxisome-to-mitochondrion mistargeting [2–4]. …”

Section: Introductionmentioning

confidence: 99%

Effects of alanine:glyoxylate aminotransferase variants and pyridoxine sensitivity on oxalate metabolism in a cell-based cytotoxicity assay

Fargue

Knight

Holmes

et al. 2016

Biochimica et Biophysica Acta (BBA) - Molecular Basis of Diseas

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The hereditary kidney stone disease primary hyperoxaluria type 1 (PH1) is caused by a functional deficiency of the liver-specific, peroxisomal, pyridoxal-phosphate-dependent enzyme, alanine:glyoxylate aminotransferase (AGT). One third of PH1 patients, particularly those expressing the p.[(Pro11Leu; Gly170Arg; Ile340Met)] mutant allele, respond clinically to pharmacological doses of pyridoxine. To gain further insight into the metabolic effects of AGT dysfunction in PH1 and the effect of pyridoxine, we established an “indirect” glycolate cytotoxicity assay using CHO cells expressing glycolate oxidase (GO) and various normal and mutant forms of AGT. In cells expressing GO the great majority of glycolate was converted to oxalate and glyoxylate, with the latter causing the greater decrease in cell survival. Co-expression of normal AGTs and some, but not all, mutant AGT variants partially counteracted this cytotoxicity and led to decreased synthesis of oxalate and glyoxylate. Increasing the extracellular pyridoxine up to 0.3 μM led to an increased metabolic effectiveness of normal AGTs and the AGT-Gly170Arg variant. The increased survival seen with AGT-Gly170Arg was paralleled by a 40% decrease in oxalate and glyoxylate levels. These data support the suggestion that the effectiveness of pharmacological doses of pyridoxine results from an improved metabolic effectiveness of AGT; that is the increased rate of transamination of glyoxylate to glycine. The indirect glycolate toxicity assay used in the present study has potential to be used in cell-based drug screening protocols to identify chemotherapeutics that might enhance or decrease the activity and metabolic effectiveness of AGT and GO, respectively, and be useful in the treatment of PH1.

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Liver peroxisomal alanine:glyoxylate aminotransferase and the effects of mutations associated with Primary Hyperoxaluria Type I: An overview

Cited by 45 publications

References 66 publications

The Chaperoning Activity of Amino-oxyacetic Acid on Folding-Defective Variants of Human Alanine:Glyoxylate Aminotransferase Causing Primary Hyperoxaluria Type I

The Chaperoning Activity of Amino-oxyacetic Acid on Folding-Defective Variants of Human Alanine:Glyoxylate Aminotransferase Causing Primary Hyperoxaluria Type I

Misfolding caused by the pathogenic mutation G47R on the minor allele of alanine:glyoxylate aminotransferase and chaperoning activity of pyridoxine

Effects of alanine:glyoxylate aminotransferase variants and pyridoxine sensitivity on oxalate metabolism in a cell-based cytotoxicity assay

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