Browsing by Author "Morava, Eva"

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    Impaired mitochondrial complex I function as a candidate driver in the biological stress response and a concomitant stress-induced brain metabolic reprogramming in male mice
    (Nature, 2020-06-01) Emmerzaal, Tim L.; Preston, Graeme; Geenen, Bram; Verweij, Vivienne; Wiesmann, Maximilian; Vasileiou, Elisavet; Grüter, Femke; de Groot, Corné; Schoorl, Jeroen; de Veer, Renske; Roelofs, Monica; Arts, Martijn; Hendriksen, Yara; Klimars, Eva; Donti, Taraka R.; Graham, Brett H.; Morava, Eva; Rodenburg, Richard J.; Kozicz, Tamas; Medical and Molecular Genetics, School of Medicine
    Mitochondria play a critical role in bioenergetics, enabling stress adaptation, and therefore, are central in biological stress responses and stress-related complex psychopathologies. To investigate the effect of mitochondrial dysfunction on the stress response and the impact on various biological domains linked to the pathobiology of depression, a novel mouse model was created. These mice harbor a gene trap in the first intron of the Ndufs4 gene (Ndufs4GT/GT mice), encoding the NDUFS4 protein, a structural component of complex I (CI), the first enzyme of the mitochondrial electron transport chain. We performed a comprehensive behavioral screening with a broad range of behavioral, physiological, and endocrine markers, high-resolution ex vivo brain imaging, brain immunohistochemistry, and multi-platform targeted mass spectrometry-based metabolomics. Ndufs4GT/GT mice presented with a 25% reduction of CI activity in the hippocampus, resulting in a relatively mild phenotype of reduced body weight, increased physical activity, decreased neurogenesis and neuroinflammation compared to WT littermates. Brain metabolite profiling revealed characteristic biosignatures discriminating Ndufs4GT/GT from WT mice. Specifically, we observed a reversed TCA cycle flux and rewiring of amino acid metabolism in the prefrontal cortex. Next, exposing mice to chronic variable stress (a model for depression-like behavior), we found that Ndufs4GT/GT mice showed altered stress response and coping strategies with a robust stress-associated reprogramming of amino acid metabolism. Our data suggest that impaired mitochondrial CI function is a candidate driver for altered stress reactivity and stress-induced brain metabolic reprogramming. These changes result in unique phenomic and metabolomic signatures distinguishing groups based on their mitochondrial genotype.
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    TNPO2 variants associate with human developmental delays, neurologic deficits, and dysmorphic features and alter TNPO2 activity in Drosophila
    (Elsevier, 2021) Goodman, Lindsey D.; Cope, Heidi; Nil, Zelha; Ravenscroft, Thomas A.; Charng, Wu-Lin; Lu, Shenzhao; Tien, An-Chi; Pfundt, Rolph; Koolen, David A.; Haaxma, Charlotte A.; Veenstra-Knol, Hermine E.; Klein Wassink-Ruiter, Jolien S.; Wevers, Marijke R.; Jones, Melissa; Walsh, Laurence E.; Klee, Victoria H.; Theunis, Miel; Legius, Eric; Steel, Dora; Barwick, Katy E.S.; Kurian, Manju A.; Mohammad, Shekeeb. S.; Dale, Russell C.; Terhal, Paulien A.; van Binsbergen, Ellen; Kirmse, Brian; Robinette, Bethany; Cogné, Benjamin; Isidor, Bertrand; Grebe, Theresa A.; Kulch, Peggy; Hainline, Bryan E.; Sapp, Katherine; Morava, Eva; Klee, Eric W.; Macke, Erica L.; Trapane, Pamela; Spencer, Christopher; Si, Yue; Begtrup, Amber; Moulton, Matthew J.; Dutta, Debdeep; Kanca, Oguz; Undiagnosed Diseases Network; Wangler, Michael F.; Yamamoto, Shinya; Bellen, Hugo J.; Tan, Queenie K.G.; Pediatrics, School of Medicine
    Transportin-2 (TNPO2) mediates multiple pathways including non-classical nucleocytoplasmic shuttling of >60 cargoes, such as developmental and neuronal proteins. We identified 15 individuals carrying de novo coding variants in TNPO2 who presented with global developmental delay (GDD), dysmorphic features, ophthalmologic abnormalities, and neurological features. To assess the nature of these variants, functional studies were performed in Drosophila. We found that fly dTnpo (orthologous to TNPO2) is expressed in a subset of neurons. dTnpo is critical for neuronal maintenance and function as downregulating dTnpo in mature neurons using RNAi disrupts neuronal activity and survival. Altering the activity and expression of dTnpo using mutant alleles or RNAi causes developmental defects, including eye and wing deformities and lethality. These effects are dosage dependent as more severe phenotypes are associated with stronger dTnpo loss. Interestingly, similar phenotypes are observed with dTnpo upregulation and ectopic expression of TNPO2, showing that loss and gain of Transportin activity causes developmental defects. Further, proband-associated variants can cause more or less severe developmental abnormalities compared to wild-type TNPO2 when ectopically expressed. The impact of the variants tested seems to correlate with their position within the protein. Specifically, those that fall within the RAN binding domain cause more severe toxicity and those in the acidic loop are less toxic. Variants within the cargo binding domain show tissue-dependent effects. In summary, dTnpo is an essential gene in flies during development and in neurons. Further, proband-associated de novo variants within TNPO2 disrupt the function of the encoded protein. Hence, TNPO2 variants are causative for neurodevelopmental abnormalities.