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- Title
A framework to identify functional interactors that contribute to disrupted early retinal development in Vsx2 ocular retardation J mice.
- Authors
Leung, Amanda M.; Rao, Mahesh B.; Raju, Nathan; Chung, Minh; Klinger, Allison; Rowe, DiAnna J.; Li, Xiaodong; Levine, Edward M.
- Abstract
Background: A goal of developmental genetics is to identify functional interactions that underlie phenotypes caused by mutations. We sought to identify functional interactors of Vsx2, which when mutated, disrupts early retinal development. We utilized the Vsx2 loss‐of‐function mouse, ocular retardation J (orJ), to assess interactions based on principles of positive and negative epistasis as applied to bulk transcriptome data. This was first tested in vivo with Mitf, a target of Vsx2 repression, and then to cultures of orJ retina treated with inhibitors of Retinoid‐X Receptors (RXR) to target Rxrg, an up‐regulated gene in the orJ retina, and gamma‐Secretase, an enzyme required for Notch signaling, a key mediator of retinal proliferation and neurogenesis. Results: Whereas Mitf exhibited robust positive epistasis with Vsx2, it only partially accounts for the orJ phenotype, suggesting other functional interactors. RXR inhibition yielded minimal evidence for epistasis between Vsx2 and Rxrg. In contrast, gamma‐Secretase inhibition caused hundreds of Vsx2‐dependent genes associated with proliferation to deviate further from wild‐type, providing evidence for convergent negative epistasis with Vsx2 in regulating tissue growth. Conclusions: Combining in vivo and ex vivo testing with transcriptome analysis revealed quantitative and qualitative characteristics of functional interaction between Vsx2, Mitf, RXR, and gamma‐Secretase activities. Key Findings: The MItf‐mi allele exhibits positive epistasis with the Vsx2‐orJ allele, but Mitf activity only partially accounts for disrupted early retinal development in Vsx2 mutant mice.Rxrg is highly upregulated in the Vsx2 mutant retina, but RXR activity is not a strong driver of the early retinal phenotype.Gamma secretase activity regulates a large cohort of Vsx2‐dependent genes associated with proliferation, providing evidence for convergent negative epistasis, and could account for the continued but slow rate of proliferation in Vsx2 mutant retinal progenitor cells.Bulk RNA sequencing combined with tests of functional interaction can provide sufficient resolution to assess phenotypic changes and epistasis of complex developmental phenotypes
- Subjects
DEVELOPMENTAL genetics; RNA sequencing; RETINOID X receptors; PHENOTYPIC plasticity; PHENOTYPES
- Publication
Developmental Dynamics, 2023, Vol 252, Issue 11, p1338
- ISSN
1058-8388
- Publication type
Article
- DOI
10.1002/dvdy.629