Capturing the pathomechanisms of different disease severities in a human cerebral organoid model of LIS1-lissencephaly
Lissencephaly is a malformation of cortical development (MCD) characterized by reduced to absent gyri and a disorganized cortex, leading to severe neurological consequences in affected individuals, including epilepsy, intellectual disability, and reduced life expectancy. Treatments are purely symptomatic, and patients often remain refractory to them. Heterozygous mutations in the LIS1 gene, encoding a regulator of the microtubule motor dynein, cause LIS1-lissencephaly. For unknown reasons, LIS1-lissencephaly patients show marked differences in disease severity despite each carrying a heterozygous LIS1 mutation. We leveraged forebrain-type organoids from patients diagnosed with mild, moderate, or severe LIS1-lissencephaly to investigate, in a cytoarchitecture and multi-omics approach, disease and severity grade associated phenotypes, mechanisms, and rescue approaches. We identified alterations of the cytoarchitecture, progenitor cell homeostasis, and neurogenesis often with a severity-dependent gradient. Identified disease-linked molecular mechanisms were microtubule destabilization, WNT-signaling, protein metabolism, and perturbed cadherin- and unfolded protein-binding. Some mechanisms exhibited a severity-dependent gradient or were specific to a severe grade. We present strategies to reverse phenotypic changes in LIS1-patient organoids and identify mTOR pathway inhibitors in in silico drug repurposing analysis as potential novel therapeutic strategy. By probing the top hit drug, the mTOR inhibitor everolimus, we could indeed rescue severity-dependent phenotypic changes in LIS1-patient organoids. This study demonstrates that organoid-based modeling is sensitive in recapitulating disease severity, which presents an important step in patient stratification, and allows the development of novel personalized rescue strategies with therapeutic potential.