Faulty neuronal determination and cell polarization are reverted by modulating HD early phenotypes

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Early neurodevelopmental defects are increasingly linked to the adult neurodegenerative phenotype in Huntington's disease (HD).
• Understanding these early defects is crucial for developing effective therapeutic strategies for HD.

Purpose of the Study:

• To investigate the impact of Huntington's disease mutations on early neurodevelopment using patient-derived stem cells.
• To explore potential rescue strategies for neurodevelopmental abnormalities in Huntington's disease models.

Main Methods:

• Utilized Huntington's disease-derived induced pluripotent stem cell (iPSC) lines.
• Generated and analyzed cortical organoids to assess telencephalic induction and neural identity.
• Performed gene-expression analysis to compare Huntington's disease organoids with control and fetal brain development stages.
• Investigated molecular and pharmacological approaches for rescuing developmental defects.

Main Results:

• Observed affected telencephalic induction and neural identity in cortical and striatal populations derived from HD iPSCs.
• Demonstrated that large CAG expansions cause complete failure of neuroectodermal acquisition, while shorter expansions lead to abnormal neural rosette formation and cytoarchitecture.
• Gene-expression analysis revealed that HD organoids resemble immature developmental zones (ventricular/subventricular) compared to mature cortical areas in controls.
• Successfully rescued neuroectodermal and rosette formation defects, restoring striatal identity using specific interventions.

Conclusions:

• Mutant huntingtin protein disrupts normal neuronal fate acquisition during early development.
• Abnormal neural development is a key feature of Huntington's disease, potentially linking mutant huntingtin to developmental deficits.
• The identified rescue strategies offer promising avenues for therapeutic development in Huntington's disease.