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Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in
Mailin Sotolongo-Lopez1, Karen Alvarez-Delfin1, Carole J Saade1,2
1Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America.
Plos Genetics
|April 9, 2016
Summary
The sine oculis homeobox homolog 7 (six7) gene regulates photoreceptor development in zebrafish. Mutations in six7 impact rod and cone cell numbers, revealing new insights into visual system evolution.
Area of Science:
- Developmental Biology
- Genetics
- Neuroscience
Background:
- Visual system adaptations are crucial for survival, with opsin mutations well-studied.
- Little is known about how gene regulatory networks influence cone subtypes and rod/cone ratios across species.
Purpose of the Study:
- Investigate the role of the sine oculis homeobox homolog 7 (six7) in photoreceptor development.
- Understand how alterations in gene regulatory networks impact photoreceptor diversity.
Main Methods:
- Utilized zebrafish as a model for photoreceptor patterning.
- Isolated and analyzed the lots-of-rods-junior (ljrp23ahub) mutation using genetic screens, sequence analysis, TALENs, and knockdown.
- Employed EdU, PH3, and TUNEL labeling to study cell proliferation and death.
Main Results:
- Identified ljrp23ahub as a hypomorphic allele of six7, linked to a cis-regulatory mutation.
- Demonstrated two independent roles for six7 in photoreceptor development: promoting rod mitosis and preventing cone precursor cell death.
- Observed increased rod numbers and a lack of green-sensitive cones in six7 mutants.
Conclusions:
- six7 is essential for photoreceptor specification and patterning in non-mammalian vertebrates.
- Transcriptional regulation alterations can drive photoreceptor variation across species.
- This study adds six7 to the list of key genes involved in visual system development.
