Rbm8a haploinsufficiency disrupts embryonic cortical development resulting in microcephaly

Area of Science:

• Developmental Neuroscience
• Genetics
• Molecular Biology

Background:

• Embryonic neurogenesis forms the cerebral cortex, with defects causing neurodevelopmental disorders like microcephaly.
• The 1q21.1 locus is linked to neurodevelopmental issues, but the roles of its genes in neurogenesis are unclear.
• Rbm8a, an exon junction complex (EJC) component at 1q21.1, is investigated for its role in neurogenesis.

Purpose of the Study:

• To investigate the function of Rbm8a in embryonic neurogenesis and its contribution to neurodevelopmental disorders.
• To determine the impact of Rbm8a haploinsufficiency and overexpression on brain development.

Main Methods:

• Utilized a mouse model to study the effects of Rbm8a haploinsufficiency on neurogenesis.
• Assessed radial glia proliferation, neuronal differentiation, apoptosis, and cortical lamination.
• Employed in utero electroporation in mouse neocortices and zebrafish models to examine RBM8A overexpression.

Main Results:

• Rbm8a haploinsufficiency in mice led to severe microcephaly and defective neurogenesis.
• Reduced Rbm8a levels impaired radial glia proliferation, promoted premature neuronal differentiation, and caused apoptosis.
• RBM8A overexpression did not significantly alter progenitor numbers or head size in mouse and zebrafish models.

Conclusions:

• Rbm8a is essential for regulating embryonic neurogenesis, controlling progenitor proliferation and neuronal differentiation.
• Disruption of Rbm8a function contributes to microcephaly and defective cortical development.
• These findings link EJC components to cortical development and neurodevelopmental pathologies, particularly those associated with 1q21.1 microdeletions.