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Functional analysis for peripheral myelin protein PASII/PMP22: is it a member of claudin superfamily?

Y Takeda1, T Notsu, K Kitamura

  • 1Department of Physiology, Keio University School of Medicine, Tokyo, Japan. yachan@center.tmig.or.jp

Neurochemical Research
|August 25, 2001
PubMed

Insights

Peripheral myelin glycoprotein PASII/PMP22, while structurally similar to oligodendrocyte-specific protein (OSP), does not exhibit homophilic cell adhesion. Its expression inhibits cell proliferation and neurite outgrowth, suggesting a role in Schwann cell differentiation.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Molecular Biology

Background:

  • Peripheral myelin contains major glycoproteins P0 and PASII/PMP22, crucial for nerve function.
  • Mutations or altered expression of these proteins are linked to hereditary peripheral neuropathies.
  • While P0's function as an adhesion molecule is known, PASII/PMP22's role remains unclear.

Purpose of the Study:

  • To investigate the function of the peripheral myelin glycoprotein PASII/PMP22.
  • To explore the potential classification of PASII/PMP22 within the claudin superfamily based on structural similarities to OSP.

Main Methods:

  • Comparative sequence analysis of PASII/PMP22 and OSP.
  • Exogenous expression of PASII/PMP22 in C6 cells to assess proliferation (BrdU incorporation).
  • Co-culture experiments with dorsal root ganglion (DRG) neurons to evaluate neurite extension and branching.

Main Results:

  • PASII/PMP22 shares significant sequence homology (48%) and identity (21%) with OSP.
  • Exogenous PASII/PMP22 expression inhibited BrdU incorporation in C6 cells, indicating reduced proliferation.
  • PASII/PMP22-expressing cells showed no homophilic cell adhesion and significantly inhibited DRG neurite extension and branching.

Conclusions:

  • PASII/PMP22 may regulate Schwann cell development, potentially acting at a transition point from proliferation to differentiation.
  • Functional data does not currently support PASII/PMP22's classification within the claudin superfamily, despite structural similarities.

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