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Updated: Aug 11, 2026
Electrophysiological Methods for Measuring Photopigment Levels in Drosophila Photoreceptors
Published on: June 2, 2022
Domain-specific early and late function of Dpatj in Drosophila photoreceptor cells
Sang-Chul Nam1, Kwang-Wook Choi
1Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas.
Insights
Drosophila Patj (Dpatj) protein has dual roles in eye development and maintenance. Its N-terminal region is vital for photoreceptor development, while the C-terminal region prevents age-related degeneration.
Area of Science:
- Cell Biology
- Developmental Biology
- Genetics
Background:
- Epithelial morphogenesis relies on cell polarity.
- Dpatj, a multi-PDZ domain protein, interacts with Crumbs (Crb) and Stardust (Sdt) cell polarity proteins.
- The in vivo function of Dpatj in eye development was previously unclear due to limited genetic data.
Purpose of the Study:
- To elucidate the in vivo functions of Dpatj in the developing and mature Drosophila eye.
- To investigate the domain-specific roles of Dpatj in photoreceptor development and maintenance.
- To understand Dpatj's contribution to the Crb-Sdt complex stability and localization.
Main Methods:
- Genetic analysis using hypomorph, null, and RNA interference mutations of dpatj.
- Examination of photoreceptor morphogenesis and cell polarity.
- Assessment of adherens junction positioning and photoreceptor integrity.
Main Results:
- Dpatj exhibits distinct N-terminal (developmental viability, morphogenesis) and C-terminal (prevention of degeneration) functions.
- Reduced Dpatj levels disrupt Crb and Sdt localization and stability.
- Dpatj is crucial for adherens junction positioning and photoreceptor integrity during development and maintenance.
Conclusions:
- Dpatj plays essential, domain-specific roles in both early photoreceptor development and late-onset degeneration prevention.
- Dpatj is critical for regulating the localization and stability of the Crb-Sdt complex in photoreceptor cells.
- This study clarifies Dpatj's dual functions in maintaining retinal integrity throughout the organism's life.
Abstract:
The formation and maintenance of cell polarity is essential for epithelial morphogenesis. Dpatj (Drosophila homolog of mammalian Patj) is a multi-PDZ domain protein that localizes to the apical cell membrane and forms a protein complex with cell polarity proteins, Crumbs (Crb) and Stardust (Sdt). Whereas Crb and Sdt are known to be required for the organization of adherens junctions (AJs) and rhabdomeres in differentiating photoreceptors, the in vivo function of Dpatj as a member of the Crb complex in developing eye has been unclear due to the lack of loss-of-function mutations specifically affecting the dpatj gene. Our genetic analysis of hypomorph, null, and RNA interference reveals distinct dual functions of Dpatj in developing and mature photoreceptors. The C-terminal region (PDZ domains 2-4) of Dpatj is not essential for development of the animal but is required to prevent late-onset photoreceptor degeneration. In contrast, the N-terminal region of Dpatj is essential for animal viability and photoreceptor morphogenesis during development. The localization and maintenance of Crb and Sdt in the apical photoreceptor membrane are strongly affected by reduced levels of Dpatj. Dpatj is necessary for proper positioning of AJs and the integrity of photoreceptors in the developing retina as well as for the maintenance of adult photoreceptors. Our study provides evidence that Dpatj has domain-specific early and late functions in regulating the localization and stability of the Crb-Sdt complex in photoreceptor cells.
