dldhcri3 zebrafish exhibit altered mitochondrial ultrastructure, morphology, and dysfunction partially rescued by probucol or thiamine
Manuela Lavorato, … , Vernon E. Anderson, Marni J. Falk
Manuela Lavorato, … , Vernon E. Anderson, Marni J. Falk
Published August 20, 2024
Citation Information: JCI Insight. 2024;9(18):e178973. https://doi.org/10.1172/jci.insight.178973.
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Research Article Genetics Metabolism

dldhcri3 zebrafish exhibit altered mitochondrial ultrastructure, morphology, and dysfunction partially rescued by probucol or thiamine

Abstract

Dihydrolipoamide dehydrogenase (DLD) deficiency is a recessive mitochondrial disease caused by variants in DLD, the E3 subunit of mitochondrial α-keto (or 2-oxo) acid dehydrogenase complexes. DLD disease symptoms are multisystemic, variably manifesting as Leigh syndrome, neurodevelopmental disability, seizures, cardiomyopathy, liver disease, fatigue, and lactic acidemia. While most DLD disease symptoms are attributed to dysfunction of the pyruvate dehydrogenase complex, the effects of other α-keto acid dehydrogenase deficiencies remain unclear. Current therapies for DLD deficiency are ineffective, with no vertebrate animal model available for preclinical study. We created a viable Danio rerio (zebrafish) KO model of DLD deficiency, dldhcri3. Detailed phenotypic characterization revealed shortened larval survival, uninflated swim bladder, hepatomegaly and fatty liver, and reduced swim activity. These animals displayed increased pyruvate and lactate levels, with severe disruption of branched-chain amino acid catabolism manifest as increased valine, leucine, isoleucine, α-ketoisovalerate, and α-ketoglutarate levels. Evaluation of mitochondrial ultrastructure revealed gross enlargement, severe cristae disruption, and reduction in matrix electron density in liver, intestines, and muscle. Therapeutic modeling of candidate therapies demonstrated that probucol or thiamine improved larval swim activity. Overall, this vertebrate model demonstrated characteristic phenotypic and metabolic alterations of DLD disease, offering a robust platform to screen and characterize candidate therapies.

Authors

Manuela Lavorato, Donna Iadarola, Cristina Remes, Prabhjot Kaur, Chynna Broxton, Neal D. Mathew, Rui Xiao, Christoph Seiler, Eiko Nakamaru-Ogiso, Vernon E. Anderson, Marni J. Falk

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Figure 9

Preclinical candidate drug screening in dldh–/– zebrafish larvae.

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Preclinical candidate drug screening in dldh–/– zebrafish larvae. (A) Re...
(A) Representative ZebraBox activity time course as in Figure 4C for WT (olive), dldh–/– (green), and dldh–/– treated with 0.5, 1.0, or 5.0 mM thiamine (black, orange, gray), respectively. Notably, at 5.0 mM thiamine, there was minimal observable swim activity (n = 3 biological replicates). (B) Four replicates of the effect of 0.1, 0.5, or 1 mM thiamine treatment from 4 dpf to 6 dpf on the swimming activity of dldh–/– zebrafish larvae. Quantitation across the dark cycles was by AUC. Four biological replicates are represented by coloring the data points red, green, blue, or purple. One-way ANOVA with multiple comparisons to dldh–/– identified treatment with either 0.1 or 0.5 mM as enhancing the swimming activity of the dldh–/– by ~100%; **P < 0.01. (C) Similarly, probucol treatment (5 μM, 4–dpf) also increased swim activity of 7 dpf dldh–/– zebrafish larvae (*P ≤ 0.05 by unpaired Student’s t test with a Bonferroni correction) but not of WT; n = 5 biological replicates per condition, n = 12 zebrafish larvae for each condition per biological replicate experiment.