Imbalanced mitochondrial function provokes heterotaxy via aberrant ciliogenesis
Martin D. Burkhalter, … , Stephanie M. Ware, Melanie Philipp
Martin D. Burkhalter, … , Stephanie M. Ware, Melanie Philipp
Published May 16, 2019
Citation Information: J Clin Invest. 2019;129(7):2841-2855. https://doi.org/10.1172/JCI98890.
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Research Article Cardiology Development

Imbalanced mitochondrial function provokes heterotaxy via aberrant ciliogenesis

Abstract

About 1% of all newborns are affected by congenital heart disease (CHD). Recent findings identify aberrantly functioning cilia as a possible source for CHD. Faulty cilia also prevent the development of proper left-right asymmetry and cause heterotaxy, the incorrect placement of visceral organs. Intriguingly, signaling cascades such as mTOR that influence mitochondrial biogenesis also affect ciliogenesis, and can cause heterotaxy-like phenotypes in zebrafish. Here, we identify levels of mitochondrial function as a determinant for ciliogenesis and a cause for heterotaxy. We detected reduced mitochondrial DNA content in biopsies of heterotaxy patients. Manipulation of mitochondrial function revealed a reciprocal influence on ciliogenesis and affected cilia-dependent processes in zebrafish, human fibroblasts and Tetrahymena thermophila. Exome analysis of heterotaxy patients revealed an increased burden of rare damaging variants in mitochondria-associated genes as compared with 1000 Genome controls. Knock down of such candidate genes caused cilia elongation and ciliopathy-like phenotypes in zebrafish, which could not be rescued by RNA encoding damaging rare variants identified in heterotaxy patients. Our findings suggest that ciliogenesis is coupled to the abundance and function of mitochondria. Our data further reveal disturbed mitochondrial function as an underlying cause for heterotaxy-linked CHD and provide a mechanism for unexplained phenotypes of mitochondrial disease.

Authors

Martin D. Burkhalter, Arthi Sridhar, Pedro Sampaio, Raquel Jacinto, Martina S. Burczyk, Cornelia Donow, Max Angenendt, Competence Network for Congenital Heart Defects Investigators, Maja Hempel, Paul Walther, Petra Pennekamp, Heymut Omran, Susana S. Lopes, Stephanie M. Ware, Melanie Philipp

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Figure 3

Dosage of mitochondrial function reciprocally influences length and function of primary cilia in human fibroblasts.

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Dosage of mitochondrial function reciprocally influences length and func...
(A, B) Increased mitochondrial function causes shortening of primary cilia of human fibroblasts. Representative images of cells treated with DMSO or DCHC. Cilia are visualized by staining for acetylated Tubulin (acTub, green), while COX IV (red) stains mitochondria. (C, D) DCHC or rotenone treatment does not change the number of ciliated cells. Paired 2-tailed t test; DMSO versus DCHC, N = 3, n = 248/246, P = 0.3517; DMSO versus rotenone, N = 3, n = 253/249, P = 0.1361. Shown are mean ± SEM. (E, F) DCHC or rotenone treatment alters the length of cilia. Two-tailed Mann-Whitney test; DMSO versus DCHC, N = 3, n = 96/105, ****P < 0.0001; DMSO versus rotenone, N = 3, n = 106/103, **P = 0.0011. Red line indicates median. (G, H) DCHC or rotenone treatment reduces the cellular ability to induce the Hedgehog-target gene GLI1 upon stimulation with an agonist of the Hh pathway. Paired, 2-tailed t test; DMSO versus DCHC, n = 4, *P = 0.0155; DMSO versus rotenone, N = 3, **P = 0.0277. Shown are mean ± SEM. (I, J) Patient-derived human fibroblasts carrying mutations in MPV17 or NFU1 extend longer primary cilia as compared with control cells (WT). Acetylated Tubulin (acTUB, red) stains cilia, while γTubulin (γTUB, green) stains centrioles. Kruskal-Wallis test with Dunn’s multiple comparison test, N = 3, n = 104/95/107, WT versus MPV17, **P = 0.0028; WT versus NFU1, ***P = 0.0002. Red line indicated median. In A, B, and I, scale bars: 10 μm.