biostudies-literatureUnknownZheng YNEI NIH HHSHomeodomain transcription factors (HD TFs) are instrumental to vertebrate development. Mutations in HD TFs have been linked to human diseases, but their pathogenic mechanisms remain elusive. Here we use Cone-Rod Homeobox (CRX) as a model to decipher the disease-causing mechanisms of two HD mutations, p.E80A and p.K88N, that produce severe dominant retinopathies. Through integrated analysis of molecular and functional evidence in vitro and in knock-in mouse models, we uncover two novel gain-of-function mechanisms: p.E80A increases CRX-mediated transactivation of canonical CRX target genes in developing photoreceptors; p.K88N alters CRX DNA-binding specificity resulting in binding at ectopic sites and severe perturbation of CRX target gene expressionbioRxiv : the preprint server for biology2023.02.01.526652https://www.ebi.ac.uk/biostudies/studies/S-EPMC9915647biostudies-literatureMissense mutations in CRX homeodomain cause dominant retinopathies through two distinct mechanisms.PMC9915647R01 EY012543R01 EY025272R01 EY032136P30 EY002687Ruzycki PAZheng YSun CZhang XChen SfalseMissense mutations in CRX homeodomain cause dominant retinopathies through two distinct mechanisms.Homeodomain transcription factors (HD TFs) are instrumental to vertebrate development. Mutations in HD TFs have been linked to human diseases, but their pathogenic mechanisms remain elusive. Here we use Cone-Rod Homeobox (CRX) as a model to decipher the disease-causing mechanisms of two HD mutations, p.E80A and p.K88N, that produce severe dominant retinopathies. Through integrated analysis of molecular and functional evidence in vitro and in knock-in mouse models, we uncover two novel gain-of-function mechanisms: p.E80A increases CRX-mediated transactivation of canonical CRX target genes in developing photoreceptors; p.K88N alters CRX DNA-binding specificity resulting in binding at ectopic sites and severe perturbation of CRX target gene expression2023-01-01T00:00:00Z2023 Jun2026-06-27T03:20:20.105Z2025-02-19T02:23:53.845ZS-EPMC99156473677840810.1101/2023.02.01.526652