Expression of normal and mutant huntingtin in the developing brain

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Huntington's disease (HD) is a neurodegenerative disorder caused by a genetic mutation leading to polyglutamine expansion in the huntingtin protein.
• The precise timing of neuronal loss in HD, particularly before symptom onset, remains unclear.
• Understanding huntingtin's role during brain development is crucial for elucidating early pathological mechanisms.

Purpose of the Study:

• To investigate the expression pattern and developmental regulation of huntingtin in the brain.
• To determine if mutant huntingtin is present during early brain development in Huntington's disease.

Main Methods:

• Western blot analysis to detect huntingtin protein levels.
• Immunohistochemistry to visualize huntingtin distribution in developing mouse and human brains.
• Comparison of huntingtin expression in control and HD human brain samples.

Main Results:

• Huntingtin protein is detected throughout embryonic and postnatal brain development in mice.
• Huntingtin levels significantly increase between postnatal days 7 and 15, coinciding with active neuronal differentiation.
• Mutant huntingtin is expressed in the immature human brain of an infant with HD, detectable before complete neuronal maturation.

Conclusions:

• Huntingtin plays a vital constitutive role in neuronal development.
• The expression and distribution of huntingtin in neurons are developmentally regulated.
• The presence of mutant huntingtin in the developing brain suggests potential early neuronal vulnerability in Huntington's disease.