Increased platelet-derived growth factor A-chain expression in human uterine smooth muscle cells during the physiologic hypertrophy of pregnancy.

Abstract

Platelet-derived growth factor (PDGF) has been implicated in the cell proliferation and directed cell movement in various physiologic and pathologic processes. To explore the role of PDGF in a reversible physiologic process, adaptation of the uterus to pregnancy, expression of PDGF in tissue sections of human gestational myometrium was demonstrated by immunohistochemical techniques and confirmed by nuclease protection analysis. Commensurate with an increase in immunoreactive PDGF expression in the myometrial smooth muscle cells, increased levels of PDGF A-chain mRNA, but not PDGF B-chain or PDGF B-type receptor transcripts, were seen in the gravid uterus relative to the nongravid uterus. The amount of A-chain transcript increased during gestation and diminished during the puerperium. These observations demonstrate PDGF polypeptide expression in situ and implicate PDGF in a normal physiologic process-uterine expansion during pregnancy.Platelet-derived growth factor (PDGF) is a growth factor which is mitogenic and chemotactic for smooth muscle cells and fibroblasts (1-3). PDGF is a dimer of two chains, designated A and B, that acts upon cells by binding to specific cell-surface receptors. All three dimeric isotypes of PDGF, PDGF-AA, -AB, and -BB, have been shown to be biologically active (4-7). The A and B chains of PDGF are the products of separate but related genes. The B chain is the product of the c-sis gene and is located on chromosome 22 (8-10). The homologous A-chain gene is found on chromosome 7 (11). Unlike the B-chain gene (12-16), two different A-chain precursors can be generated from the A-chain gene as a result of alternative splicing events that include or exclude the 69-base-pair (bp) sixth exon of the A-chain gene (17,18 (30 min). Each incubation was followed by a wash with buffered saline and a 15-min incubation with 0.5 M Tris HCl (pH 7.4) supplemented with 1% goat serum. Antibody localization was effected by a 5-min incubation with a freshly prepared solution of0.0006% 3,3-diaminobenzidine tetrahydrochloride in 0.1 M Tris HCI (pH 7.4) supplemented with 1% goat serum and 0.0003% hydrogen peroxide. After washing in tap water, the sections were counterstained with hematoxylin.RNA Isolation. Total RNA was prepared by the guanidine isothiocyanate/CsCl method (23). Briefly, the tissue was disrupted in 4 M guanidine isothiocyanate using a tissue homogenizer (Tekmar, Cinncinati) and the lysate was layered onto 5.7 M CsCl. After ultracentrifugation, the RNA pellet was harvested, phenol extracted, and ethanol precipitated. The concentration of RNA was determined from the absorbance at 260 nm. Seven and one-halfmicrograms ofRNA was dissolved in 12 Al [50%o formamide/5% formaldehyde/40 mM morpholinepropane sulfonic acid (Mops)/10 mM sodium acetate/1 mM EDTA, pH 7.0], heated for 15 min at 68°C, and size fractionated by electrophoresis on 1% agarose gels containing 5% formaldehyde in 40 mM Mops/10 mM sodium acetate/1 mM EDTA. Following electrophoresis, the gels were rinsed in distilled water, stain...

Genital Tract Smooth Muscle Tumors Are Common in Zoo Felids but Are Not Associated with Melengestrol Acetate Contraceptive Treatment

“…39 Progestin regulation of smooth muscle growth would be predicted because of the extensive physiologic myometrial hypertrophy and hyperplasia that occurs during pregnancy. 19 However, tumor volumes also have been reduced in women receiving high doses of progesterone, indicating complex hormonal regulation of smooth muscle tumor growth. 4 Because felids are induced ovulators, the tumors in control animals would have arisen in most cases in a progesterone-poor environment, indicating either growth promotion by estrogens or autonomous growth in these species.…”

Identification of a Cell Type-specific Enhancer in the Distal 5′-Region of the Platelet-derived Growth Factor A-chain Gene

“…A-chain null mice exhibit abnormalities in early embryonic development and formation of lung alveolar myofibroblasts (10,11), whereas expression of the A-chain and the PDGF ␣-receptor also appear to critical for development of the cardiovascular and nervous systems in mice (12)(13)(14). PDGF also appears to be critical for placental development, with high expression of A-chain observed in multiple cell types of the placenta including trophoblasts (2,15), as well as extraembryonic membranes and uterine smooth muscle cells during pregnancy (15,16). Inappropriate expression of the PDGF genes has also been implicated in many disease states involving abnormal cell proliferation, including atherosclerosis, pulmonary fibrosis, and neoplasia (17)(18)(19).…”

Intraglomerular expressions of IL-1α and platelet-derived growth factor (PDGF-B) mRNA in experimental immune complex-mediated glomerulonephritis

“…In platelets, PDGF is stored in a granules and is released following platelet activation by a variety of substances. PDGF is also synthesized and released by various other cell types [1], and it has mitogenic effects on cells of mesenebymal origin, including glotnerular mesangial cells [2][3][4][5][6][7][8][9][10][11][12][13], Studies of cultured mesangial cells demonstrated that these cells proliferated in response to PDGF, released PDGF and expressed PDGF mRNA [14.15].…”