PTCH1mutant human cerebellar organoids are associated with altered neural development and early pathways of medulloblastoma oncogenesis

Summary Patched 1 (PTCH1) is the primary receptor for Sonic Hedgehog (SHH) ligand and negatively regulates SHH signalling, an essential pathway in human embryogenesis. Loss-of-function mutations in PTCH1 are associated with altered neuronal development and the malignant brain tumour medulloblastoma (MB). As a result of differences between murine and human development, molecular and cellular perturbations that arise from human PTCH1 mutations remain poorly understood. Here, we employ cerebellar organoids differentiated from human induced pluripotent stem cells (iPSC) combined with CRISPR/Cas9 gene editing to investigate the earliest molecular and cellular consequences of PTCH1 mutations on human cerebellar development. Our findings support the occurrence of developmental mechanisms in cerebellar organoids that mirror in vivo processes of regionalisation and SHH signalling, and offer new insight into early pathophysiological events of MB tumorigenesis. Higlights Differentiation of human iPSC into cerebellar organoids Homozygous LOF of PTCH1 prevents cerebellar organoid differentiation PTCH1+/- cerebellar organoids display tissue-specific effects of SHH signalling Early altered gene expression relevant for MB in PTCH1+/- cerebellar organoids