Chajek T, Stein O, Stein Y
Biochim Biophys Acta. 1978 Mar 30;528(3):456-65. doi: 10.1016/0005-2760(78)90035-8.
Cell suspensions prepared from rat hearts were separated by replating into F1, F2 and M cultures, and cultured for 3--11 days. Lipoprotein lipase activity was highest in the F1 cultures which consisted mainly of non-beating, mesenchymal cells. The enzyme activity was released into the medium only after addition of heparin. The release occurred by an initial rapid phase and a continuous slow phase. Both the rapid and the slow release of enzyme activity by heparin were inhibited by about 70% after a 4 h pretreatment with colchicine. Thus, it seems that the vesicular transport is responsible for the translocation of lipoprotein lipase to the cell surface also during the slow process of release. The residual activity in the colchicine treated cultures was higher than in the controls indicating that no inhibition of enzyme synthesis occurred. The slow phase of enzyme release continued also after removal of heparin from the medium but was reduced markedly when protein synthesis was inhibited by cycloheximide. Thus the increase in total enzyme activity encountered after exposure to heparin resulted from stimulation of new enzyme synthesis. The half-time of lipoprotein lipase in the F1 cultures was 35 min and full restoration of enzyme activity was found 60 min after complete removal of cycloheximide from the system. These data indicate that the culture system can be used to study regulation of new enzyme synthesis and its turnover.
将从大鼠心脏制备的细胞悬液通过再次接种分离到F1、F2和M培养物中，并培养3 - 11天。脂蛋白脂肪酶活性在主要由非搏动性间充质细胞组成的F1培养物中最高。该酶活性仅在添加肝素后才释放到培养基中。释放过程分为初始快速阶段和持续缓慢阶段。用秋水仙碱预处理4小时后，肝素引起的酶活性快速和缓慢释放均被抑制约70%。因此，似乎在缓慢释放过程中，囊泡运输也负责脂蛋白脂肪酶向细胞表面的转运。秋水仙碱处理的培养物中的残留活性高于对照，表明未发生酶合成的抑制。从培养基中去除肝素后，酶释放的缓慢阶段仍继续，但当蛋白质合成被放线菌酮抑制时，该阶段明显减少。因此，暴露于肝素后总酶活性的增加是由于新酶合成的刺激。F1培养物中脂蛋白脂肪酶的半衰期为35分钟，从系统中完全去除放线菌酮60分钟后发现酶活性完全恢复。这些数据表明该培养系统可用于研究新酶合成的调节及其周转。
