Structure And Function Of L-periaxin Protein

Periaxin is an important scaffolding protein that is expressed in Schwann cells. Periaxin is necessary for the stabilization and regeneration of the Schwann cell-axon unit and connection of the myelin sheath to the surrounding extracellular matrix. In Schwann cells, loss or mutation of the PRX(periaxin) gene disrupts compact peripheral myelin and causes severe demyelination CMT4F neuropathy. Periaxin has been also reported in cytoskeleton complexes of lens fibers. L-periaxin plays a key role in cell adhesive interactions, transmembrane signal transduction, and nutrient transport.The PRX gene encodes two protein isoforms, namely, L-periaxin and S-periaxin. L-periaxin contains an N-terminal PDZ domain, a nuclear localization signal (NLS) domain, a repeat domain, and an acidic domain, S-periaxin has an N-terminal PDZ domain.In this paper, the subcellular localizations of L-periaxin, and its interaction proteins network were further investigated by recombinant protein, transfection of liposome, fluorescence spectrum, bimolecular fluorescence complementation (BiFC), and Co-IP. The results were shown as followed:1, The recombinant plasmid of WT-PRX and different domains have been constructed. The intracellular location of L-periaxin was affected by the protein domain and phosphorylase, which is an important precondition to the form and stabilization of myelin sheath. The localization of L-periaxin in the cytoplasm is mediated by PDZ domain and the localization of L-periaxin in the nuclear is mediated by NLS domain. Mutant of PDZ deletion (EGFP-L-periaxin delPDZ) mainly localized in the cell nucleus, and EGFP-L-periaxindelNLS localized in the cytoplasm. The results of cell proliferation about L-periaxin+/1, pEGFP-L-periaxindelDZ, and pEGFP-L-periaxindelNLS have also been shown. These results indicated that L-periaxin and EGFP-L-periaxinddlPDZ were effected the proliferation of Schwann cells. At the same time, acidic domain of L-periaxin also affected its cellular localization, which was correlated with the phosphorylation of L-periaxin induced by Akt kinase. And L-periaxin-1439 (S/D) has a large number of localized in the cell membrane than WT-L-periaxin. Subcellular localizations of L-periaxin are related to different domains of L-periaxin.2, DRP2 is the only reported protein to interact with L-periaxin with 954 amino acid residues. DRP2 protein comprises two spectrin-like repeats (1 and 2) and WW domain in the N-terminal region and EF domain, as well as ZZ and coiled-coil domain in the C-terminal region. Results demonstrated that NLS domain of L-periaxin played a critical role in the complex of DRP2 and L-periaxin. L-periaxin has an unusual tripartite-type NLS that is composed of NLS1 (118-139 aa), NLS2 (162-175 aa), and NLS3 (183-194 aa), that only the NLS2 and NLS3 sub-domains in L-periaxin interacted with DRP2 spectrin-like domain 2 and WW (180-384 aa). NLS1 sub-domains of L-periaxin was found to be involved in nucleo-cytoplasmic shuttling of L-periaxin. These data revealed a previously unknown binding model between DRP2 and L-periaxin.3, Zwint-1 is a kinetochore-associated protein that interacts with the dynein accessory protein complex. The interaction between DRP2 and Zwint-1 has been found by yeast two-hybrid experiments and Co-IP assay. Further, the spectrin domains of DRP2 (1-349 aa) have been identified to bind of Zwint-1 protein. Over-expression of L-periaxin-NLS has greatly weakened the interaction of DRP2 and Zwint-1 protein. The interaction model of periaxin, Zwint-1, and DRP2 provides an idea for the growth of Schwann cells and the pathogenesis of neurogenic muscular atrophy.4, CMT disease is a hereditary motor and sensory neuropathies. Mutations about 30 genes which influencing myelin sheath and/or nerve cell are relevant to different forms of CMT. To identify the enriched pathways or the combined effects of mutated genes in the specific pathways, we employed a mutation dataset to analysis of CMT disease genes, which retrieved 49 genes from OMIM database and 22 genes from PubMed. By the DAVID and GO analysis, the signaling pathway of aminoacyl-tRNA biosynthesis (has 00970) was significantly associated with CMT disease.The results of cell location of periaxin protein, protein interaction network and metabolic pathways about CMT mutation gene will provide an important role to understand the development of Schwann cell and the pathogenesis of CMT 4F disease.