Biosynthesis of myelin-associated proteins in simian virus 40 (SV40)-transformed rat Schwann cell lines.

In order to study the biosynthesis of myelin-associated proteins in Schwann cells, we have induced proliferation of cultured Schwann cells from neonatal rat sciatic nerve by transformation with Simian Virus 40 (SV40). Homogeneous transformed Schwann cell lines were established by single cell cloning. The transformed phenotype of these Schwann cell lines was determined by both integration of SV40 viral DNA sequences into the cellular genome and active synthesis of the large T antigen of SV40. In addition, similar transformations with SV40 virus containing a temperature-sensitive mutation in the large T gene yielded Schwann cell lines with transformed phenotype which were temperature-sensitive. In this report, we demonstrate that these SV40-transformed Schwann cells actively synthesize myelin-specific sulfatide, myelin-associated glycoprotein (MAG) and the glial cell marker 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNPase). Despite the expression of MAG and CNPase, these Schwann cells did not synthesize PO the major protein of peripheral myelin. Since a substantial amount of normal size PO mRNA was present in these transformed Schwann cells, the lack of PO synthesis was apparently not the result of a deficiency of transcription. These results are consistent with the possibility that the regulation of PO synthesis differs from that of MAG and CNPase synthesis and that PO synthesis may be controlled at the post-transcriptional level.