Hypermyelination and demyelinating peripheral neuropathy in Pmp22-deficient mice
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K Adlkofer1, R Martini, A Aguzzi
1Department of Cell Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, Zürich, Switzerland.
Abstract:
Peripheral myelin protein PMP22 has been suggested to have a role in peripheral nerve myelination and cell proliferation. Defects at the PMP22 locus are associated with peripheral neuropathies such as Charcot-Marie-Tooth disease type 1A. We now demonstrate that mice devoid of Pmp22 are retarded in the onset of myelination and develop abundant sausage-like hypermyelination structures (tomacula) at a young age followed by severe demyelination, axonal loss and functional impairment. Mice carrying one functional copy of Pmp22 are less affected but they also exhibit focal tomacula comparable to the morphological features in hereditary neuropathy with liability to pressure palsies (HNPP). We conclude that Pmp22 is required for the correct development of peripheral nerves, the maintenance of axons and the determination of myelin thickness and stability.
Insights
Peripheral myelin protein 22 (PMP22) is crucial for peripheral nerve development. Mice lacking PMP22 show myelination defects, leading to nerve damage and functional impairment, highlighting its role in myelin stability.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Peripheral myelin protein 22 (PMP22) is implicated in peripheral nerve myelination and cell proliferation.
- PMP22 gene defects are linked to peripheral neuropathies, including Charcot-Marie-Tooth disease type 1A.
Purpose of the Study:
- To investigate the precise role of Pmp22 in peripheral nerve development and function.
- To elucidate the consequences of Pmp22 deficiency on myelination, axonal integrity, and nerve function.
Main Methods:
- Generation and analysis of Pmp22-deficient mice.
- Histological examination of peripheral nerves to assess myelination, tomacula formation, and axonal loss.
- Functional assessment of nerve performance in Pmp22 mutant mice.
Main Results:
- Mice lacking Pmp22 exhibited delayed myelination onset and developed numerous tomacula (sausage-like hypermyelination).
- Pmp22-deficient mice showed severe demyelination, axonal degeneration, and significant functional deficits.
- Mice with one functional Pmp22 copy displayed focal tomacula, similar to hereditary neuropathy with liability to pressure palsies (HNPP).
Conclusions:
- Pmp22 is essential for proper peripheral nerve development and maturation.
- Pmp22 plays a critical role in maintaining myelin thickness, stability, and axonal integrity.
- Disruptions in Pmp22 function lead to peripheral neuropathies characterized by hypermyelination and subsequent demyelination.