ANALYZING THE PROLIFERATION DEFECTS CAUSED BY ALTERATIONS IN CDH2 AND AFADIN IN HUMAN BRAIN ORGANOIDS

The neocortex is the most recent evolutionary acquisition of the brain and is responsible for complex tasks such as cognition and sensory integration. The proper neocortical organization is highly regulated during development through precisely orchestrated mechanisms, from the generation of neural cells to the establishment of specific connections. Consequently, disruptions of this regulated process are associated with neurodevelopmental disorders, including schizophrenia and autism spectrum disorder (ASD). Among the numerous genes implicated in the regulation of neocortical development, cell-cell adhesion molecules such as Cdh2 and its associated protein Afadin play crucial roles. In mice, early inactivation of these genes in the dorsal telencephalon leads to defects in radial glial cell (RGC) proliferation and differentiation, giving rise to a disorganized neocortex with increased size due to an overproduction of neurons expressing upper-layer neuron (ULN) markers. Additionally, our behavioral studies revealed social deficits linked to this altered proliferation. Interestingly, downregulation of Cdh2 and Afadin expression have been recently found in organoids derived from ASD patients with macrocephaly and mutations in Cdh2 have been described in autism patients. Since ULNs are particularly susceptible to dysregulation in neurodevelopmental disorders and are significantly expanded in primates, especially humans, we plan to use human forebrain organoids derived from human iPSCs with altered expression of Cdh2 and Afadin using CRISPR-Cas9 to investigate potential defects in their proliferative activity. Human brain organoids provide a powerful platform to model disease, increasing biomedical relevance and fostering the development of alternatives to animal experimentation.