Recovery of normal protein synthesis in heat-shocked chicken myotubes by liposome-mediated transfer of mRNAs.
Exposure of chicken myotube culture to 45 degrees C induced the synthesis of three heat-shock polypeptides of 25 000, 65 000, and 81 000 daltons. Recovery to the normal pattern of protein synthesis was judged by the decrease in the synthesis of heat-shock polypeptides. This recovery to normal protein synthesis required de novo synthesis of mRNAs for normal cellular proteins. Inhibition of RNA synthesis by actinomycin D during recovery at 37 degrees C blocked the recovery process and resulted in the continued synthesis of heat-shock polypeptides. Large unilamellar vesicles were used to examine the effect of delivery of mRNAs isolated from both normal and heat-shocked myotubes on the recovery of these cells from heat-shock treatment. The results presented here show that liposome-mediated delivery of normal mRNAs to heat-shocked cells relieved the block of recovery by actinomycin. On the other hand, when mRNAs from heat-shocked cells were used during recovery, the synthesis of heat-shock polypeptides was stimulated. These observations suggest that the relative abundance of mRNAs in the cytoplasm plays a critical role in regulating protein synthesis in chicken myotube cultures.
D000818:Animals; D002645:Chickens; D046508:Culture Techniques; D003609:Dactinomycin / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D008081:Liposomes; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D012333:RNA, Messenger / Q000008:administration & dosage / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
D006360:Heat-Shock Proteins; D008081:Liposomes; D012333:RNA, Messenger; D003609:Dactinomycin