Transgenic expression of constitutively active RAC1 disrupts mouse rod morphogenesis
Hongman Song1, Ronald A Bush, Camasamudram Vijayasarathy
1Section for Translational Research in Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States.
Investigative Ophthalmology & Visual Science
|March 22, 2014
Summary
Constitutively active RAC1 disrupts mouse rod photoreceptor development, causing polarity defects and degeneration. This suggests RAC1 is crucial for normal retinal morphogenesis and cell viability.
Area of Science:
- Molecular biology
- Developmental biology
- Neuroscience
Background:
- Rac1 is a small GTPase involved in cell polarity and morphogenesis.
- Previous studies in Drosophila suggest Rac1 plays a role in photoreceptor development.
Purpose of the Study:
- To investigate the role of constitutively active (CA) Rac1 in mammalian rod photoreceptor development.
- To assess the morphogenetic effects of CA Rac1 during mouse rod photoreceptor development.
Main Methods:
- Generated transgenic mice expressing CA Rac1 under the Rhodopsin promoter.
- Evaluated photoreceptor morphology using histology, immunohistochemistry, and electron microscopy.
- Assessed retinal function with electroretinography and identified protein partners via co-immunoprecipitation.
Main Results:
- CA Rac1 expression disrupted retinal lamination and photoreceptor nuclear positioning.
- Photoreceptors showed abnormal inner/outer segment development and synaptic element placement.
- CA Rac1 formed complexes with PAR6 and dynein, disrupting normal PAR6 localization and leading to photoreceptor degeneration.
Conclusions:
- CA Rac1 expression severely impairs mouse rod photoreceptor viability and development.
- Defects in polarity and migration were observed in CA Rac1-expressing rods.
- PAR6 and dynein may mediate CA Rac1's negative effects on photoreceptor morphogenesis.
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