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Title: Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells

Abstract

Hormonal regulation of glycogen synthase, an enzyme that can be phosphorylated on multiple sites, is often associated with changes in its phosphorylation state. Enzyme activation is conventionally monitored by determining the synthase activity ratio ((activity in the absence of glucose 6-P)/(activity in the presence of glucose 6-P)). Insulin causes an activation of glycogen synthase with a concomitant decrease in its phosphate content. In a previous report, the authors showed that epidermal growth factor (EGF) increases the glycogen synthase activity ratio in Swiss 3T3 cells. The time and dose-dependency of this response was similar to that of insulin. Their recent results indicate that PDGF also stimulates glycogen synthase activity. Enzyme activation was maximal after 30 min. of incubation with PDGF; the time course observed was very similar to that with insulin and EGF. At 1 ng/ml (0.03nM), PDGF caused a maximal stimulation of 4-fold in synthase activity ratio. Half-maximal stimulation was observed at 0.2 ng/ml (6 pM). The time course of changes in enzyme activity ratio closely followed that of /sup 125/I-PDGF binding. The authors data suggest that PDGF, as well as EFG and insulin, may be important in regulating glycogen synthesis through phosphorylation/dephosphorylation mechanisms.

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of Washington, Seattle
OSTI Identifier:
6899102
Report Number(s):
CONF-8606151-
Journal ID: CODEN: FEPRA; TRN: 87-006987
Resource Type:
Conference
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; LIGASES; ENZYME ACTIVITY; ENZYME REACTIVATION; PHOSPHORYLATION; PROTEINS; BIOCHEMICAL REACTION KINETICS; FIBROBLASTS; GLYCOGEN; IODINE 125; PEPTIDE HORMONES; TRACER TECHNIQUES; ANIMAL CELLS; BETA DECAY RADIOISOTOPES; CARBOHYDRATES; CHEMICAL REACTIONS; CONNECTIVE TISSUE CELLS; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; ENZYMES; HORMONES; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPE APPLICATIONS; ISOTOPES; KINETICS; NUCLEI; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; POLYSACCHARIDES; RADIOISOTOPES; REACTION KINETICS; SACCHARIDES; SOMATIC CELLS 550201* -- Biochemistry-- Tracer Techniques

Citation Formats

Chan, C.P., Bowen-Pope, D.F., Ross, R., and Krebs, E.G. Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells. United States: N. p., 1986. Web.
Chan, C.P., Bowen-Pope, D.F., Ross, R., & Krebs, E.G. Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells. United States.
Chan, C.P., Bowen-Pope, D.F., Ross, R., and Krebs, E.G. 1986. "Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells". United States. doi:.
@article{osti_6899102,
title = {Platelet-derived growth factor (PDGF) stimulates glycogen synthase activity in 3T3 cells},
author = {Chan, C.P. and Bowen-Pope, D.F. and Ross, R. and Krebs, E.G.},
abstractNote = {Hormonal regulation of glycogen synthase, an enzyme that can be phosphorylated on multiple sites, is often associated with changes in its phosphorylation state. Enzyme activation is conventionally monitored by determining the synthase activity ratio ((activity in the absence of glucose 6-P)/(activity in the presence of glucose 6-P)). Insulin causes an activation of glycogen synthase with a concomitant decrease in its phosphate content. In a previous report, the authors showed that epidermal growth factor (EGF) increases the glycogen synthase activity ratio in Swiss 3T3 cells. The time and dose-dependency of this response was similar to that of insulin. Their recent results indicate that PDGF also stimulates glycogen synthase activity. Enzyme activation was maximal after 30 min. of incubation with PDGF; the time course observed was very similar to that with insulin and EGF. At 1 ng/ml (0.03nM), PDGF caused a maximal stimulation of 4-fold in synthase activity ratio. Half-maximal stimulation was observed at 0.2 ng/ml (6 pM). The time course of changes in enzyme activity ratio closely followed that of /sup 125/I-PDGF binding. The authors data suggest that PDGF, as well as EFG and insulin, may be important in regulating glycogen synthesis through phosphorylation/dephosphorylation mechanisms.},
doi = {},
journal = {Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)},
number = ,
volume = 45:6,
place = {United States},
year = 1986,
month = 5
}

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  • Suspensions rich in pancreatic {beta} cells were transfected by means of electroporation or by using the liposome technique with DNA constructs coding for the {beta} chain of platelet-derived growth factor (PDGF) and the PDGF {alpha} and {beta} receptors to induce a mitotic response in this slowly replicating cell type. Transfection with the B-chain construct induced synthesis of the PDGF B-chain homodimer (PDGF-BB) as assessed by the presence of {sup 125}I-labeled PDGF-BB competing activity in the conditioned medium of the transfected islet cells. Moreover, islet cells transfected with the PDGF {beta}-receptor construct exhibited increased immunofluorescence staining with a PDGF {beta}-receptor antibody.more » These cells also displayed increased {sup 125}I-labeled PDGF-BB binding compared with control transfected cells. The {beta} cells exhibited elevated levels of ({sup 3}H)inositol trisphosphate after transfection with the B-chain and {beta}-receptor constructs, indicating activation of phospholipase C. Islet cells transfected with the different receptor constructs exhibited different patterns of tyrosine phosphorylation upon ligand activation. The results demonstrate that pancreatic islet cells can be stimulated to increase DNA synthesis by transfection with the PDGF {beta}-receptor gene, whereas cotransfection with the {alpha}-receptor gene may attenuate the growth response.« less
  • Platelet-derived growth factor (PDGF) stimulates many of the processes important in tissue repair, including proliferation of fibroblasts and synthesis of extracellular matrices. In this study, the authors have demonstrated with in situ hydridization and immunocytochemistry the reversible expression of 3-sis/PDGF-2 and PDGF receptor (PDGF-R) b mRNAs and their respective protein products in epithelial cells and fibroblasts following cutaneous injury in pigs. Epithelial cells in control, unwounded skin did not express c-sis and PDGF-R mRNAs, and fibroblasts expressed only PDGF-R mRNA. The expression levels in the injured site were correlated with the stage of tissue repair, being highest during the initialmore » stages of the repair process and declining at the time of complete re-epithelialization and tissue remodeling. These studies provide a mulecular basis for understanding the mechanisms contributing to normal tissue repair. They suggest the possibility that a defect in these mechanisms may be associated with defective wound healing. It is also conceivable that chronic injury may induce irreversible gene expression leading to pathologic, unregulated cell growth.« less
  • When activated, normal human blood monocytes are known to express the c-sis proto-oncogene coding for PDGF B-chain. Since normal human platelet PDGF molecules are dimers of A and B chains and platelets and monocytes are derived from the same marrow precursors, activated blood monocytes were simultaneously evaluated for their expression of PDGF A and B chain genes. Human blood monocytes were purified by adherence, cultured with or without activation by lipopolysaccharide and poly(A)+ RNA evaluated using Northern analysis and /sup 32/P-labeled A-chain and B-chain (human c-sis) probes. Unstimulated blood monocytes did not express either A-chain or B-chain genes. In contrast,more » activated monocytes expressed a 4.2 kb mRNA B-chain transcript at 4 hr, but the B-chain mRNA levels declined significantly over the next 18 hr. In comparison, activated monocytes expressed very little A-chain mRNA at 4 hr, but at 12 hr 1.9, 2.3, and 2.8 kb transcripts were observed and persisted through 24 hr. Thus, activation of blood monocytes is followed by PDGF B-chain gene expression preceding PDGF A-chain gene expression, suggesting a difference in the regulation of the expression of the genes for these two chains by these cells.« less
  • Platelet-derived growth factor (PDGF) is a potent mitogen for cells of mesenchymal origin and is released and/or synthesized by platelets, macrophages, endothelial cells and rat mesangial cells. In the present investigation, the authors found that human glomerular mesangial cells in culture release a PDGF-like protein which competes for {sup 125}I-PDGF binding to human foreskin fibroblasts and is mitogenic for these fibroblasts. The competing and to a lesser extent the mitogenic activities present in the conditioned medium are partially recognized by an anti-PDGF antibody. Northern blot analysis of poly(A){sup +} RNA from human mesangial cells demonstrates the expression of both PDGFmore » A- and B-chain mRNAs. PDGF also binds to mesangial cells in a specific manner and stimulates DNA synthesis and cell proliferation. These data suggest that a PDGF-like protein secreted by mesangial cells or released from platelets, monocytes, or endothelial cells during glomerular inflammation may function as an autocrine or a paracrine growth factor for these cells. The biological role of PDGF in mediating proliferative and other inflammatory events in the glomerulus remains to be identified.« less
  • The authors have examined the effects of transfection of rat-1 fibroblasts with the ras oncogene on the metabolism of phosphatidylinositol (PI). Incubation of (/sup 3/H)inositol-labeled rat-1 cells with PDGF resulted in a 2- to 3-fold increase in (/sup 3/H)IP3 levels within 90 s. In the presence of 25 mM Li+, (/sup 3/H)IP1 levels were increased 8-fold after 30 min. In contrast, incubation of ras-transfected fibroblasts (EJ-2 line) with PDGF had little or no effect on the level of either (/sup 3/H)IP3 or (/sup 3/H)IP1. Similar stimulations by PDGF were observed in NIH 3T3 cells, but not in Kirsten virus-transformed ormore » Harvey ras-transfected cell lines. On the other hand, NIH 3T3 cells transfected with v-src responded to PDGF by stimulation of PI turnover similar to the parent cell line. In NIH 3T3 cells transfected with an expression vector containing the v-Ha-ras gene under transcriptional control of the glucocorticoid-inducible mouse mammary tumor virus promoter, the PDGF stimulation of (/sup 3/H)inositol incorporation into PI was reduced from 10-fold in the absence of dexamethasone to 1.8-fold when the cells were pretreated for 26 h with 2 ..mu..M dexamethasone. In the parental 3T3 cells PDGF stimulation was reduced by about 40% in the presence of dexamethasone. In the absence of PDGF the rate of PI turnover (i.e., the kinetics of (/sup 3/H)IP1 accumulation in the presence of Li+) in EJ-2 cells was similar to that in rat-1 cells. Thus, in the presence of PDGF, the rate of PI turnover in rat-1 cells was several fold higher than in the transfected cells. These results suggest that the ras gene product (p21) may exert an inhibitory effect on PDGF-stimulated phosphoinositide metabolism.« less