Myelin proteome alterations upon oligodendroglial deletion of CDC42 and its effector proteins CDC42EP1/CDC42EP2

ABSTRACT: The regular structure of healthy CNS myelin sheaths requires specialized structural proteins, including septin filaments composed of subunits SEPTIN2, SEPTIN4, SEPTIN7, and SEPTIN8. Their assembly scaffolds the innermost non-compacted myelin layer as a late step of CNS myelin maturation and their disruption causes pathological myelin outfoldings. To gain insights into the mechanisms that control myelin septin assembly, we deleted CDC42 from oligodendrocytes of adult mice and compared the myelin proteome of Cdc42 icKO mice with that of Ctrl mice by quantitative mass spectrometry. We utilized a data-independent acquisition (DIA) workflow with alternating low and elevated energy (MSE) and an ion mobility-enhanced version thereof (referred to as UDMSE) to achieve both, a correct quantification of exceptionally abundant myelin proteins and a comprehensive coverage of the myelin proteome. Label-free protein quantification revealed a depletion of myelin septins and the CDC42-effector proteins CDC42EP1 and CDC42EP2. We thus tested the functional relevance of the CDC42-effector proteins by deleting both the Cdc42ep1 and Cdc42ep2-genes in oligodendrocytes, followed by myelin proteome analysis and superresolution microscopy imaging. In CDCEP1/2 dcKO mice, the abundance of myelin septins was markedly reduced, coinciding with impaired septin filaments and myelin outfoldings as a very specific pathology. Together, our data reveal a critical function for CDC42 and CDC42EP1/CDC42EP2 in regulating myelin septin filaments, which facilitate structural integrity of mature CNS myelin.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Brain, Oligodendrocyte, Myelin Sheath

SUBMITTER: Olaf Jahn  

LAB HEAD: Prof. Dr. Olaf Jahn

PROVIDER: PXD066943 | Pride | 2025-12-30

REPOSITORIES: Pride