Myelin basic protein gene dosage effects in the PNS.

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Myelin basic protein (MBP) is crucial for compact myelin formation in the central nervous system (CNS).
• Its role in the peripheral nervous system (PNS) is less understood, though it may influence Schmidt-Lanterman incisures (SLI).
• SLI are cytoplasmic channels within PNS myelin, containing proteins like connexin-32 (Cx32) and myelin-associated glycoprotein (MAG).

Purpose of the Study:

• To investigate the role of MBP in regulating the levels of Cx32 and MAG in PNS myelin.
• To determine if MBP affects the expression of Cx32 and MAG at the transcriptional or post-transcriptional level.
• To explore a potential new function for MBP in PNS gene expression regulation.

Main Methods:

• Analysis of protein and mRNA levels in sciatic nerves of shiverer (shi) mutant mice, which have reduced MBP levels.
• Quantification of MBP, Cx32, MAG, protein zero (P0), and peripheral membrane protein 22 (PMP22) in both protein and mRNA forms.
• Comparison of protein and mRNA levels to assess post-transcriptional regulation.

Main Results:

• MBP levels were inversely proportional to Cx32 and MAG levels in shi mutant mouse sciatic nerves.
• Levels of P0 and PMP22, structural components of compact myelin, remained constant.
• mRNA levels for P0, PMP22, Cx32, and MAG did not change in relation to MBP levels.

Conclusions:

• MBP influences Cx32 and MAG levels in the PNS at a post-transcriptional level.
• This suggests a novel function for MBP in regulating gene expression in the PNS, beyond its role in compact myelin adhesion.
• MBP's impact on SLI formation and composition is mediated post-transcriptionally.