ANTISENSE OLIGONUCLEOTIDE TO THE 70-KDA HEAT-SHOCK COGNATE PROTEIN INHIBITS SYNTHESIS OF MYELIN BASIC-PROTEIN

Transfection of rat oligodendrocytes with an oligonucleotide sequence complementary to the mRNA encoding the initial ten amino acids of the rat 70-kDa heat shock cognate protein (HSC70) resulted in a rapid (wit hin 24 h) and significant reduction in HSC70 synthesis (69% of control cells transfected with sense oligonucleotide). A further decrease to approximately 44% of controls was detected after 2 days. At that time, HSC70 protein content fell to approximately 49% of controls, and a si gnificant reduction in the synthesis of myelin basic protein (MBP) was first detected (66% of controls). After 5 days, HSC70 synthesis retur ned to control levels. As HSC70 protein content recovered, so did the synthesis of MBP. Throughout the 5-day experimental period, only minor changes were detected in cell morphology, overall pattern of protein synthesis and the synthesis and content of proteolipid protein (PLP) a nd the pi isoenzyme of glutathione-S-transferase (pi). These data show that when HSC70 protein content is sufficiently reduced by antisense oligonucleotide, synthesis of MBP (but not PLP or pi) is corresponding ly down-regulated, and provide evidence consistent with the role of HS C70 as a chaperone for MBP.