Limits...
Optix defines a neuroepithelial compartment in the optic lobe of the Drosophila brain.

Gold KS, Brand AH - Neural Dev (2014)

Bottom Line: Neuroepithelia are regionalised by the expression of transcription factors and signalling molecules, resulting in the formation of distinct developmental, and ultimately functional, domains.Six3 and Six6 are required for mammalian eye and forebrain development, and mutations in humans are associated with severe eye and brain malformation.Our findings provide insight into the spatial patterning of a complex region of the brain, and suggest an evolutionarily conserved principle of visual system development.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Gurdon Institute and Department of Physiology, Development & Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK. a.brand@gurdon.cam.ac.uk.

ABSTRACT

Background: During early brain development, the organisation of neural progenitors into a neuroepithelial sheet maintains tissue integrity during growth. Neuroepithelial cohesion and patterning is essential for orderly proliferation and neural fate specification. Neuroepithelia are regionalised by the expression of transcription factors and signalling molecules, resulting in the formation of distinct developmental, and ultimately functional, domains.

Results: We have discovered that the Six3/6 family orthologue Optix is an essential regulator of neuroepithelial maintenance and patterning in the Drosophila brain. Six3 and Six6 are required for mammalian eye and forebrain development, and mutations in humans are associated with severe eye and brain malformation. In Drosophila, Optix is expressed in a sharply defined region of the larval optic lobe, and its expression is reciprocal to that of the transcription factor Vsx1. Optix gain- and loss-of-function affects neuroepithelial adhesion, integrity and polarity. We find restricted cell lineage boundaries that correspond to transcription factor expression domains.

Conclusion: We propose that the optic lobe is compartmentalised by expression of Optix and Vsx1. Our findings provide insight into the spatial patterning of a complex region of the brain, and suggest an evolutionarily conserved principle of visual system development.

Show MeSH

Related in: MedlinePlus

Optix expression is maintained throughout optic lobe development. (A-F) We detected Optix protein in the optic lobe from 0 to 96 hours after larval hatching (ALH). Optix expression was detected in the medial neuroepithelium with a sharp boundary of expression throughout neuroepithelial expansion (white arrowhead). Posterior cross-sectional views of the optic lobe are presented throughout. (A-D) The early optic lobe is outlined by dotted white box. (A-C, D) Cells are outlined by Discs large (Dlg) or Fasciclin II (Fas II) staining. (D) Deadpan (Dpn) is expressed in all neuroblasts. (F) Dachshund (Dac) is expressed in lamina precursor cells and lamina neurons. Scale bars: 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4127074&req=5

Figure 2: Optix expression is maintained throughout optic lobe development. (A-F) We detected Optix protein in the optic lobe from 0 to 96 hours after larval hatching (ALH). Optix expression was detected in the medial neuroepithelium with a sharp boundary of expression throughout neuroepithelial expansion (white arrowhead). Posterior cross-sectional views of the optic lobe are presented throughout. (A-D) The early optic lobe is outlined by dotted white box. (A-C, D) Cells are outlined by Discs large (Dlg) or Fasciclin II (Fas II) staining. (D) Deadpan (Dpn) is expressed in all neuroblasts. (F) Dachshund (Dac) is expressed in lamina precursor cells and lamina neurons. Scale bars: 20 μm.

Mentions: In order to determine when Optix expression is established, we analysed Optix expression at different time points during larval development (Figure 2). The optic lobe arises from a small placode of cells in the embryo [35,50,51]. During embryogenesis these cells are quiescent, and they begin to proliferate just after larval hatching. The region expands and separates into two neuroepithelia, the outer and inner proliferation centres (OPC and IPC) [34,52]. We detect Optix expression in the optic lobe just after larval hatching (Figure 2A). Its expression persists in the same domain (roughly half of the neuroepithelium) as the neuroepithelium expands throughout larval development (Figure 2A-F). Its posterior expression boundary (Figure 1E) remains sharp during neuroepithelial expansion and differentiation. These results demonstrate that Optix expression is established and maintained from the beginning of larval development.


Optix defines a neuroepithelial compartment in the optic lobe of the Drosophila brain.

Gold KS, Brand AH - Neural Dev (2014)

Optix expression is maintained throughout optic lobe development. (A-F) We detected Optix protein in the optic lobe from 0 to 96 hours after larval hatching (ALH). Optix expression was detected in the medial neuroepithelium with a sharp boundary of expression throughout neuroepithelial expansion (white arrowhead). Posterior cross-sectional views of the optic lobe are presented throughout. (A-D) The early optic lobe is outlined by dotted white box. (A-C, D) Cells are outlined by Discs large (Dlg) or Fasciclin II (Fas II) staining. (D) Deadpan (Dpn) is expressed in all neuroblasts. (F) Dachshund (Dac) is expressed in lamina precursor cells and lamina neurons. Scale bars: 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4127074&req=5

Figure 2: Optix expression is maintained throughout optic lobe development. (A-F) We detected Optix protein in the optic lobe from 0 to 96 hours after larval hatching (ALH). Optix expression was detected in the medial neuroepithelium with a sharp boundary of expression throughout neuroepithelial expansion (white arrowhead). Posterior cross-sectional views of the optic lobe are presented throughout. (A-D) The early optic lobe is outlined by dotted white box. (A-C, D) Cells are outlined by Discs large (Dlg) or Fasciclin II (Fas II) staining. (D) Deadpan (Dpn) is expressed in all neuroblasts. (F) Dachshund (Dac) is expressed in lamina precursor cells and lamina neurons. Scale bars: 20 μm.
Mentions: In order to determine when Optix expression is established, we analysed Optix expression at different time points during larval development (Figure 2). The optic lobe arises from a small placode of cells in the embryo [35,50,51]. During embryogenesis these cells are quiescent, and they begin to proliferate just after larval hatching. The region expands and separates into two neuroepithelia, the outer and inner proliferation centres (OPC and IPC) [34,52]. We detect Optix expression in the optic lobe just after larval hatching (Figure 2A). Its expression persists in the same domain (roughly half of the neuroepithelium) as the neuroepithelium expands throughout larval development (Figure 2A-F). Its posterior expression boundary (Figure 1E) remains sharp during neuroepithelial expansion and differentiation. These results demonstrate that Optix expression is established and maintained from the beginning of larval development.

Bottom Line: Neuroepithelia are regionalised by the expression of transcription factors and signalling molecules, resulting in the formation of distinct developmental, and ultimately functional, domains.Six3 and Six6 are required for mammalian eye and forebrain development, and mutations in humans are associated with severe eye and brain malformation.Our findings provide insight into the spatial patterning of a complex region of the brain, and suggest an evolutionarily conserved principle of visual system development.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Gurdon Institute and Department of Physiology, Development & Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK. a.brand@gurdon.cam.ac.uk.

ABSTRACT

Background: During early brain development, the organisation of neural progenitors into a neuroepithelial sheet maintains tissue integrity during growth. Neuroepithelial cohesion and patterning is essential for orderly proliferation and neural fate specification. Neuroepithelia are regionalised by the expression of transcription factors and signalling molecules, resulting in the formation of distinct developmental, and ultimately functional, domains.

Results: We have discovered that the Six3/6 family orthologue Optix is an essential regulator of neuroepithelial maintenance and patterning in the Drosophila brain. Six3 and Six6 are required for mammalian eye and forebrain development, and mutations in humans are associated with severe eye and brain malformation. In Drosophila, Optix is expressed in a sharply defined region of the larval optic lobe, and its expression is reciprocal to that of the transcription factor Vsx1. Optix gain- and loss-of-function affects neuroepithelial adhesion, integrity and polarity. We find restricted cell lineage boundaries that correspond to transcription factor expression domains.

Conclusion: We propose that the optic lobe is compartmentalised by expression of Optix and Vsx1. Our findings provide insight into the spatial patterning of a complex region of the brain, and suggest an evolutionarily conserved principle of visual system development.

Show MeSH
Related in: MedlinePlus