Bone morphogenetic proteins, eye patterning, and retinocollicular map formation in the mouse

Area of Science:

• Neuroscience
• Developmental Biology
• Ophthalmology

Background:

• Early eye formation involves patterning events that determine retinal cell fate and guide retinal ganglion cell (RGC) axon navigation.
• Bone morphogenetic proteins (BMPs) and their receptors are crucial for initiating gene expression cascades that differentiate retinal regions, particularly along the dorsoventral axis.

Purpose of the Study:

• To investigate the roles of BMP signaling and its downstream effector, EphB, in retinotopic map formation in the lateral geniculate nucleus (LGN) and superior colliculus (SC).
• To compare RGC axon behaviors in wild-type mice with those in mice engineered with defects in BMP and EphB signaling.

Main Methods:

• Comparative analysis of RGC axon sorting and targeting in wild-type mice versus mice with genetically modified BMP and EphB signaling.
• Examination of axon order in the optic tract and map formation in the LGN and SC.

Main Results:

• Disruption of BMP signaling led to significant missorting of RGC axons at the optic chiasm, independent of EphB.
• Genetic modification of BMP signaling in the developing eye resulted in disrupted RGC order in the optic tract and aberrant targeting in the LGN and SC.

Conclusions:

• BMP signaling is essential for regulating dorsoventral RGC cell fate and RGC axon behavior in the optic tract.
• BMP signaling influences retinotopic map formation in the LGN and SC through mechanisms partially distinct from EphB signaling.