Uncoupling Neocortical Neuron Fate and Migration via a Let-7-RBX2 Axis

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Neuronal fate and migration are crucial for central nervous system development.
• In the mammalian neocortex, precise laminar positioning of projection neurons is essential.
• The independent or coordinated regulation of neuronal fate and migration remains unclear.

Purpose of the Study:

• To investigate the role of microRNA let-7 in regulating pyramidal neuron migration and positioning.
• To elucidate the molecular mechanisms by which let-7 influences neuronal migration.

Main Methods:

• Investigated let-7's role in pyramidal neuron migration and positioning.
• Identified RBX2 as a direct target of let-7.
• Assessed the impact of RBX2 restoration on neuronal positioning.
• Analyzed let-7's effects on pyramidal neuron migration speed and duration.

Main Results:

• let-7 directly targets RBX2, a component of CRL5, reducing its translation and CRL5 activity.
• Restoring RBX2 levels rescues pyramidal neuron positioning without affecting neuronal fate.
• let-7 enhances pyramidal neuron migration by increasing locomotion speed and prolonging activity.

Conclusions:

• let-7 coordinates neuronal fate specification and migration through distinct molecular pathways.
• This coordination ensures the proper laminar positioning of late-born pyramidal neurons in the neocortex.