FULL-LENGTH CLONING, EXPRESSION AND CELLULAR-LOCALIZATION OF RAT PLASMOLIPIN MESSENGER-RNA, A PROTEOLIPID OF PNS AND CNS

We have isolated a 1.476 bp cDNA (NTII11) representing a transcript th at is differentially expressed during sciatic nerve development and re generation in the rat. Nucleotide sequence comparison indicates partia l identity with a recently isolated plasmolipin cDNA. However, our clo ne extends the published sequence by 234 bp at the 5' end and predicts a protein that contains an additional 25 amino acids at the N-terminu s. The open reading frame of the NTII11 transcript encodes a 19.4 kDa protein with four putative transmembrane domains. Northern blot analys es revealed a tissue-specific expression of the plasmolipin transcript that is restricted to sciatic nerve, brain and kidney. The neural exp ression was confirmed by in situ hybridization, and cellular localizat ion of plasmolipin mRNA was demonstrated in Schwann cells of the sciat ic nerve and in glial cells of myelinated brain structures. The steady -state levels of plasmolipin mRNA were markedly altered (i) during dev elopment of the sciatic nerve and brain, (ii) after sciatic nerve inju ry, and (iii) in cultured Schwann cells maintained under different con ditions of cell growth and arrest. Our data indicate a function of pla smolipin during myelination in the central as well as in the periphera l nervous system.