title: Ontogeny and regulation of platelet-derived growth factor gene expression in distal fetal rat lung epithelial cells.
abstract: Using flow cytometry, thymidine uptake into DNA, and expression of two growth-related genes, histone 3 and c-myc, we found an increase in the proportion of distal lung epithelial cells in the G0/G1 phase of the cell cycle with advancing gestation. Since our previous studies had demonstrated that platelet-derived growth factor (PDGF) is essential for the progression of these cells from the G0/G1 to the S phase of cell cycle, we investigated the gene and protein expression of PDGF-related genes (PDGF-A, PDGF-B, alpha-receptor, and beta-receptor) in distal fetal lung epithelial cells. The cells transcribed all the PDGF-related genes and translated the PDGF-A and PDGF-B mRNAs into protein, as demonstrated by immunocytochemistry and immunoprecipitation. To explore an autocrine role for PDGF in distal fetal lung epithelial cells, intervention studies using PDGF-A and -B chain-specific antisense oligodeoxynucleotides (ODN) were carried out. Antisense PDGF-B ODN, but not antisense PDGF-A ODN, significantly reduced the DNA synthesis of these cells. The inhibitory effect of antisense PDGF-B ODN on DNA synthesis was reversed by the addition of exogenous PDGF-BB, which supports an autocrine role in the DNA synthesis of these cells. We also examined the expression of PDGF genes in distal fetal lung epithelial cells during late gestation. PDGF-A chain and beta-receptor gene expressions declined with advancing gestation, whereas expression of message for PDGF-B chain and alpha-receptor increased. The increases in message for PDGF-B chain and alpha-receptor with advancing gestation were due to a greater rate of transcription, whereas the developmental decrease of PDGF-A chain and beta-receptor mRNAs was caused by a decrease in RNA stability. Taken together with the ODN data, these results suggest that the G0/G1 cell cycle arrest of distal lung epithelial cells during late fetal gestation is due to a decrease in PDGF beta-receptor expression by the cells.
authors.affiliation: MRC Group in Lung Development, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Buch
authors.forename: D
authors.initials: D
authors.lastname: Jassal
authors.forename: I
authors.initials: I
authors.lastname: Cannigia
authors.forename: J
authors.initials: J
authors.lastname: Edelson
authors.forename: R
authors.initials: R
authors.lastname: Han
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Tanswell
authors.forename: M
authors.initials: M
authors.lastname: Post
mesh_terms: D000818:Animals; D001483:Base Sequence; D000077214:Becaplermin; D004247:DNA / Q000096:biosynthesis; D016373:DNA, Antisense / Q000138:chemical synthesis / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D005865:Gestational Age; D006657:Histones / Q000235:genetics; D008081:Liposomes; D008168:Lung / Q000196:embryology* / Q000378:metabolism; D008969:Molecular Sequence Data; D010982:Platelet-Derived Growth Factor / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics
chemical_list: D016373:DNA, Antisense; D006657:Histones; D008081:Liposomes; D010982:Platelet-Derived Growth Factor; D016271:Proto-Oncogene Proteins c-myc; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; C075278:platelet-derived growth factor A; D000077214:Becaplermin; D004247:DNA; D017479:Receptors, Platelet-Derived Growth Factor