Isolation from lactalbumin hydrolysate of a high molecular weight mitogenic factor.
A new mitogenic factor has been isolated from tissue culture grade lactalbumin hydrolysate. Incubation of postconfluent Swiss 3T3 cells in serum-free medium containing lactalbumin hydrolysate resulted in enhanced synthesis and release of plasminogen activator. Sephadex G-100 gel filtration of concentrated, dialyzed lactalbumin hydrolysate revealed two fractions, LH-FI and LH-FII. LH-FI elutes at the void volume, indicative of high molecular weight, and contains all plasminogen activator stimulatory activity of the original lactalbumin hydrolysate, whereas LH-FII has no activity. In addition, LH-FI also induces DNA synthesis in Swiss 3T3 cells in a dose-dependent fashion, 1 to 2 microgram/ml being equivalent to 10% fetal calf serum. Again, LH-FII is without effect. Induction of DNA synthesis in LH-FI or serum-stimulated quiescent sparse cells followed essentially identical kinetics at least through the first 20 h. Furthermore, LH-FI also enhances 3T3 cell growth. Preliminary results of Sepharose 4B filtration of LH-FI reveal the presence of five subfractions each with plasminogen activator stimulatory as well as mitogenic activity.
D000818:Animals; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication / Q000187:drug effects; D006868:Hydrolysis; D007376:Interleukin-2 / Q000302:isolation & purification* / Q000494:pharmacology; D007768:Lactalbumin; D008222:Lymphokines / Q000302:isolation & purification*; D051379:Mice; D008970:Molecular Weight; D010960:Plasminogen Activators / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism
D007376:Interleukin-2; D008222:Lymphokines; D004247:DNA; D007768:Lactalbumin; D010960:Plasminogen Activators; D013936:Thymidine