Abstract
Purpose: :
Our ongoing work on periaxin in lens fiber cells led us to hypothesize that lens fibers and myelinated neurons might share parallel molecular mechanisms in organization of the plasma membrane subdomains and stabilization. This study examines the biochemical evidence in support of this hypothesis.
Methods: :
Paraffin embedded lens sections derived from the post natal and adult mice were examined by immunofluorescence and confocal imaging for the distribution pattern of proteins known to regulate membrane microdomain organization and cytoskeletal scaffolding including NrCAM, ankyrin B, β-spectrin, βIV-spectrin, ezrin, contactin-1, Caspr2, periaxin, desmoyokin and PMP-22. Mouse lens cDNA microarray data were examined for the expression profile of genes involved in membrane organization and stabilization of channel proteins of myelinated neurons. The protein profile of the dystrophin-glycoprotein complex (DGC) regulating the membrane cytoskeletal scaffolding were determined in mouse lens by immunoblot, cDNA microarray and RT-PCR analysis. GPI-anchored contactins involved in cytoskeletal organization of myelinated neurons were characterized in detail in mouse lens fiber cells.
Results: :
Lens fibers of post natal and adult mice exhibit membrane distribution of several neuronal abundant proteins including NrCAM, ankyrin B, β-spectrin, βIV-spectrin, ezrin, contactin-1, periaxin, Caspr2, desmoyokin and PMP-22 as assessed by immunofluorescence and immunoblot analysis. Mouse lenses are confirmed to express various components of the dystrophin-glycoprotein complex including, dystrophin, dystroglycan, syntrophin, dystrobrevin and dystrophin-related protein involved in membrane cytoskeletal scaffolding and membrane organization by cDNA microarray, RT-PCR and immunoblot analyses.
Conclusions: :
Identification of several neuronal abundant proteins involved in membrane organization in lens fibers presents us with significant insight into fiber cell membrane organization and stability and raises exciting possibilities concerning the existence of parallel molecular mechanisms regulating the membrane organization and stability in long lived differentiated lens fibers and myelinated neurons.
Keywords: cytoskeleton • cell membrane/membrane specializations • differentiation