Coordinate control of 3T3 cell proliferation by platelet-derived growth factor and plasma components.

Abstract

DNA synthesis and cell division were measured in Swiss mouse 3T3 cells cultured in different concentrations of cell-free plasma-derived serum and increasing amounts of a platelet-derived growth factor. In plasma-derived serum alone, the cells were quiescent and they were arrested in the Go/GI phase of the cell cycle. Addition of a platelet-derived growth factor to quiescent cells maintained in plasma-derived serum stimulated both DNA synthesis and cell division. When plasma components were present at hig concentration (5%, vol/vol), the amount of platelet factor added to the cultures determined the number of cell doublings. Plasma-derived molecules were required for the platelet factor to stimulate DNA synthesis and cell division in the maximal number of cells. In addition, plasma components had to be present for recently divided cells to respond to the platelet factor. When 3T3 cells were cultured in excess platelet factor and limiting amounts of plasma-derived serum (0.5%, vol/vol), the cells underwent one doubling and then ceased to proliferate. Addition of fresh plasma-derived serum to these cells induced a second round of cell division. Plasma components and the platelet-derived growth factor acted in a coordinate fashion to regulate the proliferation of Swiss 3T3 cells.

Distinct functions of down‐regulation‐sensitive and ‐resistant types of protein kinase C in rabbit aortic smooth muscle cells

“…TPA and PDBu were from CCR Inc. and 4a,-PDD was from Sigma. WBS and PDS were prepared from the Japanese White rabbits as described [16]. H1 histone and a phospholipid mixture were prepared from calf thymus and bovine brain, respectively, as described [17].…”

Serum stimulation of phospholipase A2 and prostaglandin release in 3T3 cells is associated with platelet-derived growth-promoting activity.

“…Ionophore A23187 was obtained from Calbiochem. [5,6,8,9,11,12,14,15(n)-3H]Arachidonic acid (135 Ci/mmol; 1 Ci = 3.7 X 1010 becquerels), [8,9,11,12,14,15 (12).…”

“…Fraction BG2, purified from human platelet lysate (11), was the gift of R. Ross (University of Washington). PGE2 and PGF2a were the gifts of J. Pike (Upjohn).…”

“…Some of the treatments resulted in precipitation of other proteins, giving a partial purification of the activator. § Obtained from R. Ross, and prepared as described (11).…”

Human platelet-derived growth factor stimulates amino acid transport and protein synthesis by human diploid fibroblasts in plasma-free media.

“…Serum can be divided into components released from platelets during clotting and components circulating in plasma (2)(3)(4)(5). Platelet-derived components and circulating plasma components interact synergistically to stimulate DNA synthesis in quiescent cells (6,7). In light of this information, the question that arises is which of the metabolic events occurring prior to the entry ofquiescent cells into S phase requires the presence ofplatelet-derived factors, plasma factors, or both.…”