Limits...
Orthodenticle Is Required for the Expression of Principal Recognition Molecules That Control Axon Targeting in the Drosophila Retina.

Mencarelli C, Pichaud F - PLoS Genet. (2015)

Bottom Line: Our data indicate that otd function in these photoreceptors is largely mediated by the recognition molecules flamingo (fmi) and golden goal (gogo).In addition, we find that otd regulates synaptic-layer targeting of R8.Our work therefore demonstrates that otd is a main component of the gene regulatory network that regulates synaptic-column and layer targeting in the fly visual system.

View Article: PubMed Central - PubMed

Affiliation: MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom.

ABSTRACT
Parallel processing of neuronal inputs relies on assembling neural circuits into distinct synaptic-columns and layers. This is orchestrated by matching recognition molecules between afferent growth cones and target areas. Controlling the expression of these molecules during development is crucial but not well understood. The developing Drosophila visual system is a powerful genetic model for addressing this question. In this model system, the achromatic R1-6 photoreceptors project their axons in the lamina while the R7 and R8 photoreceptors, which are involved in colour detection, project their axons to two distinct synaptic-layers in the medulla. Here we show that the conserved homeodomain transcription factor Orthodenticle (Otd), which in the eye is a main regulator of rhodopsin expression, is also required for R1-6 photoreceptor synaptic-column specific innervation of the lamina. Our data indicate that otd function in these photoreceptors is largely mediated by the recognition molecules flamingo (fmi) and golden goal (gogo). In addition, we find that otd regulates synaptic-layer targeting of R8. We demonstrate that during this process, otd and the R8-specific transcription factor senseless/Gfi1 (sens) function as independent transcriptional inputs that are required for the expression of fmi, gogo and the adhesion molecule capricious (caps), which govern R8 synaptic-layer targeting. Our work therefore demonstrates that otd is a main component of the gene regulatory network that regulates synaptic-column and layer targeting in the fly visual system.

No MeSH data available.


Related in: MedlinePlus

The early pattern of photoreceptor axon projections is affected in otd mutants.Wild-type (A) and otduvi mutant (B) eye imaginal discs from third instar larvae stained for the neural marker Elav (blue) and for the R7- and R8-specific markers Pros (red) and Sens (green) respectively. Asterisks indicate the position of the bristle cell. Wild-type (C) and otduvi (D) photoreceptor axon projections in third-instar larva were visualized by expressing UAS-mCD8::GFP under the control of the GMR-Gal4 driver [43]. The growth cones of R1-R6 form a neural plexus (chevrons) at the lamina (L). R8 axons project to the medulla neuropile (M). bn stands for the Bolwig’s nerve.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4482733&req=5

pgen.1005303.g002: The early pattern of photoreceptor axon projections is affected in otd mutants.Wild-type (A) and otduvi mutant (B) eye imaginal discs from third instar larvae stained for the neural marker Elav (blue) and for the R7- and R8-specific markers Pros (red) and Sens (green) respectively. Asterisks indicate the position of the bristle cell. Wild-type (C) and otduvi (D) photoreceptor axon projections in third-instar larva were visualized by expressing UAS-mCD8::GFP under the control of the GMR-Gal4 driver [43]. The growth cones of R1-R6 form a neural plexus (chevrons) at the lamina (L). R8 axons project to the medulla neuropile (M). bn stands for the Bolwig’s nerve.

Mentions: otd is expressed in all differentiating photoreceptors, but all indications are that it is not required for cell fate specification [21,22]. This is supported by the fact that otd mutant ommatidia contain the full complement of photoreceptors including R1-6 and both R7 and R8 (Fig 2A and 2B).


Orthodenticle Is Required for the Expression of Principal Recognition Molecules That Control Axon Targeting in the Drosophila Retina.

Mencarelli C, Pichaud F - PLoS Genet. (2015)

The early pattern of photoreceptor axon projections is affected in otd mutants.Wild-type (A) and otduvi mutant (B) eye imaginal discs from third instar larvae stained for the neural marker Elav (blue) and for the R7- and R8-specific markers Pros (red) and Sens (green) respectively. Asterisks indicate the position of the bristle cell. Wild-type (C) and otduvi (D) photoreceptor axon projections in third-instar larva were visualized by expressing UAS-mCD8::GFP under the control of the GMR-Gal4 driver [43]. The growth cones of R1-R6 form a neural plexus (chevrons) at the lamina (L). R8 axons project to the medulla neuropile (M). bn stands for the Bolwig’s nerve.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482733&req=5

pgen.1005303.g002: The early pattern of photoreceptor axon projections is affected in otd mutants.Wild-type (A) and otduvi mutant (B) eye imaginal discs from third instar larvae stained for the neural marker Elav (blue) and for the R7- and R8-specific markers Pros (red) and Sens (green) respectively. Asterisks indicate the position of the bristle cell. Wild-type (C) and otduvi (D) photoreceptor axon projections in third-instar larva were visualized by expressing UAS-mCD8::GFP under the control of the GMR-Gal4 driver [43]. The growth cones of R1-R6 form a neural plexus (chevrons) at the lamina (L). R8 axons project to the medulla neuropile (M). bn stands for the Bolwig’s nerve.
Mentions: otd is expressed in all differentiating photoreceptors, but all indications are that it is not required for cell fate specification [21,22]. This is supported by the fact that otd mutant ommatidia contain the full complement of photoreceptors including R1-6 and both R7 and R8 (Fig 2A and 2B).

Bottom Line: Our data indicate that otd function in these photoreceptors is largely mediated by the recognition molecules flamingo (fmi) and golden goal (gogo).In addition, we find that otd regulates synaptic-layer targeting of R8.Our work therefore demonstrates that otd is a main component of the gene regulatory network that regulates synaptic-column and layer targeting in the fly visual system.

View Article: PubMed Central - PubMed

Affiliation: MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom.

ABSTRACT
Parallel processing of neuronal inputs relies on assembling neural circuits into distinct synaptic-columns and layers. This is orchestrated by matching recognition molecules between afferent growth cones and target areas. Controlling the expression of these molecules during development is crucial but not well understood. The developing Drosophila visual system is a powerful genetic model for addressing this question. In this model system, the achromatic R1-6 photoreceptors project their axons in the lamina while the R7 and R8 photoreceptors, which are involved in colour detection, project their axons to two distinct synaptic-layers in the medulla. Here we show that the conserved homeodomain transcription factor Orthodenticle (Otd), which in the eye is a main regulator of rhodopsin expression, is also required for R1-6 photoreceptor synaptic-column specific innervation of the lamina. Our data indicate that otd function in these photoreceptors is largely mediated by the recognition molecules flamingo (fmi) and golden goal (gogo). In addition, we find that otd regulates synaptic-layer targeting of R8. We demonstrate that during this process, otd and the R8-specific transcription factor senseless/Gfi1 (sens) function as independent transcriptional inputs that are required for the expression of fmi, gogo and the adhesion molecule capricious (caps), which govern R8 synaptic-layer targeting. Our work therefore demonstrates that otd is a main component of the gene regulatory network that regulates synaptic-column and layer targeting in the fly visual system.

No MeSH data available.


Related in: MedlinePlus