Dichloroacetate improves mitochondrial function, physiology, and morphology in FBXL4 disease models
Manuela Lavorato, … , Christoph Seiler, Marni J. Falk
Manuela Lavorato, … , Christoph Seiler, Marni J. Falk
Published July 26, 2022
Citation Information: JCI Insight. 2022;7(16):e156346. https://doi.org/10.1172/jci.insight.156346.
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Research Article Genetics Metabolism

Dichloroacetate improves mitochondrial function, physiology, and morphology in FBXL4 disease models

Abstract

Pathogenic variants in the human F-box and leucine-rich repeat protein 4 (FBXL4) gene result in an autosomal recessive, multisystemic, mitochondrial disorder involving variable mitochondrial depletion and respiratory chain complex deficiencies with lactic acidemia. As no FDA-approved effective therapies for this disease exist, we sought to characterize translational C. elegans and zebrafish animal models, as well as human fibroblasts, to study FBXL4–/– disease mechanisms and identify preclinical therapeutic leads. Developmental delay, impaired fecundity and neurologic and/or muscular activity, mitochondrial dysfunction, and altered lactate metabolism were identified in fbxl-1(ok3741) C. elegans. Detailed studies of a PDHc activator, dichloroacetate (DCA), in fbxl-1(ok3741) C. elegans demonstrated its beneficial effects on fecundity, neuromotor activity, and mitochondrial function. Validation studies were performed in fbxl4sa12470 zebrafish larvae and in FBXL4–/– human fibroblasts; they showed DCA efficacy in preventing brain death, impairment of neurologic and/or muscular function, mitochondrial biochemical dysfunction, and stress-induced morphologic and ultrastructural mitochondrial defects. These data demonstrate that fbxl-1(ok3741) C. elegans and fbxl4sa12470 zebrafish provide robust translational models to study mechanisms and identify preclinical therapeutic candidates for FBXL4–/– disease. Furthermore, DCA is a lead therapeutic candidate with therapeutic benefit on diverse aspects of survival, neurologic and/or muscular function, and mitochondrial physiology that warrants rigorous clinical trial study in humans with FBXL4–/– disease.

Authors

Manuela Lavorato, Eiko Nakamaru-Ogiso, Neal D. Mathew, Elizabeth Herman, Nina Shah, Suraiya Haroon, Rui Xiao, Christoph Seiler, Marni J. Falk

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Figure 6

DCA rescued the gray brain phenotype, survival, and integrated neurologic and/or muscular function in CAP-stressed fbxl4sa12470 larval zebrafish.

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DCA rescued the gray brain phenotype, survival, and integrated neurologi...
(A–D) RC and CS enzyme activity detected in 7 dpf larvae (mean ± SEM). n = 3 each condition. (E–I) Representative images of 6 dpf age-matched fbxl4sa12470 and AB WT larvae at 6 dpf after 4 days (starting from 2 dpf) of incubation with 2.5 mM CAP alone or with DCA cotreatment. Morphological defects were obvious at 6 dpf, showing higher sensitivity of (F and H) fbxl4sa12470 larvae to 2.5 mM CAP compared with (E) AB WT larvae: gray brain phenotype (black arrows in F and bracket in H, Supplemental Figure 3), heart edema (generally not observed in WT, arrowheads in F and H), and overall body degeneration and slight bent tail (white arrow in H). (G and I) Coexposure of stressed fbxl4sa12470 larvae with 5 mM DCA improved the gray brain phenotype (clear brain in I indicated by a bracket; Supplemental Figure 3) but did not rescue the delay in swim bladder formation in either AB WT or fbxl4sa12470 larvae. Scale bar: 1 mm. (J–N) 2.5 mM CAP significantly affected development (percentage of swim bladder), survival, and neuromuscular response (percentage of tap response and touch response), and caused brain death in 7 dpf mutant larvae (Supplemental Table 2, A and B). (J and K and Supplemental Videos 6 and 7) 5 mM DCA significantly rescued the gray brain phenotype and survival and improved neuromuscular response. *P < 0.05, **P < 0.01, ***P < 0.001, Cochran-Mantel-Haenszel and χ2 test performed (Supplemental Table 2). Bar graphs are representative of the statistical analysis shown in the Supplemental Table 2, where all data details are shown.