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Published on: July 16, 2013
Altered trafficking of mutant connexin32
S M Deschênes1, J L Walcott, T L Wexler
1Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
Summary
X-linked Charcot-Marie-Tooth disease (CMTX) mutations disrupt connexin32 (Cx32) protein trafficking. This leads to toxic Cx32 accumulation in the cytoplasm, suggesting a shared disease mechanism in myelin disorders.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- X-linked Charcot-Marie-Tooth disease (CMTX) is a genetic peripheral neuropathy.
- Connexin32 (Cx32) is a key protein in myelinating cells, and mutations are linked to CMTX.
- Understanding Cx32 protein trafficking is crucial for elucidating CMTX pathophysiology.
Purpose of the Study:
- To investigate the cellular localization of nine different Cx32 mutants associated with CMTX.
- To determine how CMTX mutations affect Cx32 protein trafficking and cellular distribution.
- To explore potential shared mechanisms in diseases affecting myelinating cells.
Main Methods:
- Utilized communication-incompetent mammalian cells.
- Examined the expression and localization of Cx32 mutants using immunofluorescence.
- Assessed colocalization with cellular markers, such as the Golgi apparatus.
Main Results:
- Identified three classes of Cx32 mutants based on cellular localization.
- One class showed minimal Cx32 protein despite detectable mRNA.
- Another class displayed Cx32 in the cytoplasm and at the cell surface (plaques/punctate staining).
- A third class showed Cx32 restricted to the cytoplasm, often colocalizing with the Golgi apparatus.
Conclusions:
- CMTX mutations predominantly impair Cx32 protein trafficking.
- Mutations can lead to potentially toxic cytoplasmic accumulation of Cx32.
- Shared pathophysiology may exist among diseases affecting myelinating cells, involving cytoplasmic accumulation of mutated proteins.
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