期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1980
卷号：77
期号：1
页码：137-141
DOI：10.1073/pnas.77.1.137
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Sera from mouse, rat, and calf sources stimulate cellular phospholipase A2 activity (PLase; phosphatide 2-acylhydrolase, EC 3.1.1.4 ) and prostaglandin synthesis in 3T3 Swiss mouse fibroblasts, releasing up to 33% of biosynthetically incorporated [3H]arachidonic acid as hydrolysis products in 1 hr. The PLase stimulated by mouse serum exhibits specificity for arachidonic acid residues on phospholipids. It is stimulated 2.5-fold by 1.8 mM Ca2+ in the presence of 5 microM divalent cation ionophore A23187, consistent with a Ca2+-dependent enzyme possessing a cytoplasmic Ca2+ binding site. The percentage maximal PLase- and growth-stimulating activities of the three sera exhibit similar concentration dependencies, with the homologous (mouse) serum exhibiting the highest specific activities. Confluent 3T3 cells deplete PLase-stimulating activity from medium containing calf serum at a rate similar to the depletion of cell growth-stimulus activity. The PLase-stimulating activity in rat and mouse sera is derived from the leukocyte fraction of blood, presumably from platelets. In rat leukocyte lysates the PLase-stimulating activity exhibits properties similar to those reported for platelet-derived cell growth factors from rat and human sources--i.e., stability to exposure to 100 degrees C for 2 min or to pH 2 or pH 11, and cationic properties. Purified preparations of human platelet-derived growth factor also exhibit 3T3 PLase-stimulating activity.
