title: Overexpression of progesterone receptor B increases sensitivity of human colon muscle cells to progesterone.
abstract: Colon muscle strips and cells from female patients with slow-transit constipation (STC) exhibit impaired motility, signal transduction abnormalities characterized by downregulation of Gq/11 and upregulation of Gs proteins, decreased cyclooxygenase (COX)-1 and thromboxane (Tx)B2 levels, increased COX-2 and PGE2 levels, and overexpression of progesterone receptors (PGR). Progesterone (P4) treatment of normal cells reproduced these motility and signal transduction abnormalities. The purpose of the study was to examine whether overexpression of PGR-B reproduces these abnormalities by rendering the cells more sensitive to physiological concentrations of P4. Cultured human colon muscle was transfected with a plasmid DNA expressing PGR-B. The mRNAs of PGR, COX-1, COX-2, and Gq/11 were determined by quantitative real-time PCR. Their protein expression was determined by Western blot, and prostaglandins were measured by radioimmunoassay. Cultured muscle cells maintained their phenotypic features determined with myosin light chain (MLC) and h-caldesmon antibodies. Control and transfected muscle cells responded to 10(-6) M P4. In contrast, muscle cells transfected with PGR-B responded to lower P4 concentration (10(-7) M). This P4 concentration reduced MLC phosphorylation induced by CCK-8 (10(-8) M), downregulated Gq/11, and decreased COX-1 and TxB2 levels. It upregulated Gs proteins. It also increased COX-2 and PGE2 levels. We conclude that overexpression of PGR-B renders the cells more sensitive to physiological concentrations of P4. These results are consistent with the hypothesis that overexpression of PGR-B contributes to the motility and signal transduction abnormalities observed in female patients with STC and normal serum levels of P4.
authors.affiliation: Department of Medicine, Rhode Island Hospital and Warren Alpert Medical School, Brown University, Providence, RI 02903, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Cheng
authors.forename: Victor
authors.initials: V
authors.lastname: Pricolo
authors.forename: Piero
authors.initials: P
authors.lastname: Biancani
authors.forename: Jose
authors.initials: J
authors.lastname: Behar
mesh_terms: D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003106:Colon / Q000201:enzymology / Q000378:metabolism*; D003248:Constipation / Q000378:metabolism; D051545:Cyclooxygenase 1 / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D005260:Female; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000201:enzymology / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D011374:Progesterone / Q000378:metabolism*; D011453:Prostaglandins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012844:Sincalide / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D002148:Calmodulin-Binding Proteins; D018994:Myosin Light Chains; D011453:Prostaglandins; D012333:RNA, Messenger; D011980:Receptors, Progesterone; C101118:progesterone receptor A; C097314:progesterone receptor B; D011374:Progesterone; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D012844:Sincalide
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