Multiple dose-dependent effects of Lis1 on cerebral cortical development

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Type I lissencephaly in humans results from heterozygous inactivating mutations in the LIS1 gene, causing cortical dysplasia due to abnormal neuronal migration.
• Previous studies established a cell-autonomous defect in neuronal migration upon LIS1 reduction.

Purpose of the Study:

• To systematically examine the effects of reduced LIS1 protein dosage on neocortical development in mice.
• To investigate the role of LIS1 in neuronal migration, proliferation, and survival during cerebral cortex formation.

Main Methods:

• Utilized wild-type, null heterozygous (45% LIS1), and compound null/hypomorphic (35% LIS1) mouse models.
• Conducted in vivo and in vitro analyses of neuronal migration and cortical development.
• Assessed effects on Cajal-Retzius cells, radial glial scaffold, subplate organization, and ventricular zone neuroblasts.

Main Results:

• LIS1 dosage reduction caused dose-dependent defects in neuronal migration and subplate disorganization.
• Abnormalities in interkinetic nuclear migration and neuroblast proliferation were observed with decreased LIS1 levels.
• Programmed cell death led to progressive thinning of the cortex and ventricular zone as LIS1 levels decreased.

Conclusions:

• LIS1 is crucial for cell-autonomous neuronal migration and also influences the generation and survival of cortical ventricular zone neuroblasts.
• LIS1 levels are critical for orderly cerebral cortical morphogenesis.
• These findings provide new insights into the pathogenesis of type I lissencephaly.