Defective metabolic programming impairs early neuronal morphogenesis in neural cultures and an organoid model of Leigh syndrome

Abstract

Leigh syndrome (LS) is a severe manifestation of mitochondrial disease in children and is currently incurable. The lack of effective models hampers our understanding of the mechanisms underlying the neuronal pathology of LS. Using patient-derived induced pluripotent stem cells and CRISPR/Cas9 engineering, we developed a human model of LS caused by mutations in the complex IV assembly gene SURF1. Single-cell RNA-sequencing and multi-omics analysis revealed compromised neuronal morphogenesis in mutant neural cultures and brain organoids. The defects emerged at the level of neural progenitor cells (NPCs), which retained a glycolytic proliferative state that failed to instruct neuronal morphogenesis. LS NPCs carrying mutations in the complex I gene NDUFS4 recapitulated morphogenesis defects. SURF1 gene augmentation and PGC1A induction via bezafibrate treatment supported the metabolic programming of LS NPCs, leading to restored neuronal morphogenesis. Our findings provide mechanistic insights and suggest potential interventional strategies for a rare mitochondrial disease.

Accessory Subunits of the Matrix Arm of Mitochondrial Complex I with a Focus on Subunit NDUFS4 and Its Role in Complex I Function and Assembly

“…It was recently demonstrated that hypoxic breathing normalizes a detrimental hyperoxia in brain tissue, while activation of the hypoxia-inducible factor (HIF) is not a crucial factor [95]. A new perspective on LS has recently been opened by the observation that switching from glycolytic metabolism to OXPHOS is critical for early neuronal morphogenesis [96]. Defective metabolic reprogramming due to mutations in OXPHOS complexes is thought to be incompatible with normal brain development and might lead to early termination of pregnancy in more cases than previously known.…”

Human iPSC-derived cerebral organoids model features of Leigh Syndrome and reveal abnormal corticogenesis

“…Inability to transition to neuronal oxidative phosphorylation causes apoptosis due to excessive conversion of pyruvate to lactate, and potentially a cell fate shift into GFAP-positive glial cells (Zheng et al, 2016b). Considering our observations that there is a marked deficit in MT-ATP6/PDH mutants to commit and generate neuronal subtypes and an increased signal in astroglial markers, these mutations may be impairing the ability to transition from aerobic glycolysis to OXPHOS as previously described with SURF mutations (Inak et al, 2019, 2021). The preferential switch to a glial fate may be promoted by astrocytes having low expression levels or lower active levels of the PDHα subunit (Bélanger et al, 2011; Halim et al, 2010; Itoh et al, 2003; Laughton et al, 2007).…”

“…The availability of animal models and brain tissue from biopsies has provided critical insight into this disease. However, our understanding of the etiology and pathology of complex neurological diseases like LS would benefit from human-derived platforms such as induced pluripotent stem cell-derived models (Inak et al, 2021; Lorenz et al, 2017; Quadrato et al, 2016). The ability to reprogram somatic cells into induced pluripotent stem cells (iPSCs), followed by differentiation into specific lineages has become a useful tool for complex disease modeling (Kelava and Lancaster, 2016; Di Lullo and Kriegstein, 2017; Pașca, 2018; Quadrato et al, 2016).…”

“…The ability to reprogram somatic cells into induced pluripotent stem cells (iPSCs), followed by differentiation into specific lineages has become a useful tool for complex disease modeling (Kelava and Lancaster, 2016; Di Lullo and Kriegstein, 2017; Pașca, 2018; Quadrato et al, 2016). In the context of LS, iPSCs have been successfully generated from patients with mutations in mitochondrially encoded ATP Synthase Membrane Subunit 6 (MT-ATP6) (Galera-Monge et al, 2016; Grace et al, 2019; Lorenz et al, 2017; Ma et al, 2015), mitochondrially encoded NADH:Ubiquinone Oxidoreductase Core Subunit 3 (MT-ND3) subunit (Hattori et al, 2016) and the nuclear-encoded gene Surfeit locus protein 1 (SURF1) (Inak et al, 2019, 2021). These iPSC-model systems have been proposed for drug discovery (Inak et al, 2017; Lorenz et al, 2017) as well as testing platforms for potential metabolic rescue treatments (Ma et al, 2015).…”

Modelling Mitochondrial Disease in Human Pluripotent Stem Cells: What Have We Learned?

“…The tissue specific nature of mitochondrial diseases means that mitochondrial function post-differentiation can be distinct to that from the undifferentiated stem cells or original fibroblast line, often greatly exaggerating any underlying defects [ 97 ]. Additionally, detailed transcriptomic and proteomic analyses can elucidate cellular compensation mechanisms and potential target pathways to inform downstream treatment studies [ 98 , 99 ]. Other approaches include microscopic visualization of key cellular features to determine a mutation’s impact on cell structure or function [ 100 ].…”