Analysis of the mitochondrial proteome in multiple sclerosis cortex.

Area of Science:

• Neuroscience
• Biochemistry
• Genetics

Background:

• Mitochondrial dysfunction is implicated in multiple sclerosis (MS) neuropathology.
• Previous studies revealed altered transcription and translation of electron transport chain components in MS.

Purpose of the Study:

• To investigate alterations in mitochondrial and related protein expression in postmortem MS and control brain cortex.
• To identify specific proteins differentially expressed in MS brain tissue.

Main Methods:

• Surface-Enhanced Laser Desorption Ionization Time of Flight Mass Spectrometry (SELDI-TOF-MS) was used to analyze the mitochondrial proteome.
• Principal Component Analysis (PCA) and hierarchical clustering identified distinguishing protein patterns.
• Peptide fingerprint mapping identified differentially expressed proteins.

Main Results:

• SELDI-TOF-MS analysis revealed distinct proteomic profiles differentiating MS from control cortex.
• Four key proteins were identified: cytochrome c oxidase subunit 5b (COX5b), brain-specific creatine kinase, hemoglobin β-chain, and myelin basic protein (MBP).
• While MBP alterations were observed in the EAE mouse model, the respiratory proteins were not, indicating model limitations.

Conclusions:

• MS neuropathology involves significant alterations in mitochondrial respiratory proteins and MBP.
• The EAE mouse model partially mimics MS but does not fully capture the mitochondrial dysfunction observed in MS gray matter.
• Distinct mechanisms contribute to gray matter mitochondrial dysfunction in MS beyond inflammatory demyelination.