Retinoic acid-receptor activation of SP-B gene transcription in respiratory epithelial cells

Abstract

Retinoids are known to play important roles in organ development of the lung. Retinoids exert their activity by modulating the expression of numerous genes, generally influencing gene transcription, in target cells. In the present work, the mechanism by which retinoic acid (RA) regulates surfactant protein (SP) B expression was assessed in vitro. RA (9- cis-RA) enhanced SP-B mRNA in pulmonary adenocarcinoma cells (H441 cells) and increased transcriptional activity of the SP-B promoter in both H441 and mouse lung epithelial cells (MLE-15). Cotransfection of H441 cells with retinoid nuclear receptor (RAR)-α, -β, and -γ and retinoid X receptor (RXR)-γ further increased the response of the SP-B promoter to RA. Treatment of H441 cells with RA increased immunostaining for the SP-B proprotein and increased the number of cells in which the SP-B proprotein was detected. An RA responsive element mediating RA stimulation of the human SP-B promoter was identified. RAR-α and -γ and RXR-α but not RAR-β or RXR-β and -γ were detected by immunohistochemical analysis of H441 cells. RA, by activating RAR activity, stimulated the transcription and synthesis of SP-B in pulmonary adenocarcinoma cells.

9-cis retinoic acid induces insulin-like growth factor binding protein-3 through DR-8 Retinoic acid responsive elements

“…Selection for H1299 cells was based on a previous experiment that showed these cells to have lower levels of endogenous RAR-β and high transfection efficiency compared to other NSCLC cell lines. 20 As shown in Figure 5, pGL2-∆862 exhibited a 2.5-fold induction of promoter activity by 9cRA. When a unilateral deletion construct carrying the -534 to -64 region of the IGFBP-3 promoter (pGL2-∆1393) was introduced, the inductive effect of 9cRA was similar to that of pGL2-∆862, whereas further deletion of the promoter region to -445 bp (pGL2-∆1482) abolished the inductive effect of 9cRA.…”

“…[17][18][19] The retinoic acid receptors are ligand-dependent transcription factors that bind to cis-acting DNA sequences called retinoic acid responsive elements (RAREs) and retinoid X responsive elements (RXREs), located in the promoter region of their target genes. 20 In this study, we report that IGFBP-3 gene expression by 9cRA involves RAR-β and is mediated by a distinct DR-8 responsive element located in the proximal region of the IGFBP-3 promoter.…”

Retinoic Acid Stimulation of the Human Surfactant Protein B Promoter Is Thyroid Transcription Factor 1 Site-dependent

“…RA increased SP-B mRNA and pro-SP-B protein in H441 cells (16 -18) and lung explants in vitro (19,20). The responsiveness of RA stimulatory effect was identified within the enhancer region of the hSP-B promoter (16). Furthermore, a dominant negative RAR␣403 mutant inhibited the hSP-B promoter in H441 cells, indicating an essential role of RAR in hSP-B promoter activity in respiratory epithelial cells (21).…”

Peroxisome Proliferator-activated Receptor γ and Ligands Inhibit Surfactant Protein B Gene Expression in the Lung

“…This suggests that during lung development, both positive and negative regulation by nuclear receptors and coactivators are essential for proper SP-B gene expression. Previously, the glucocorticoid receptor has also been reported to inhibit hSP-B transcription (14), although the mechanism is unknown.…”

“…Total RNAs were isolated from cells using the RNA purification kit (Qiagen Co.), and RNA concentrations were determined. One g of total RNAs from each sample was subject to RT-PCR assay using a pair of primers corresponding to the SP-B coding region and the SuperScript One-Step RT-PCR kit (Invitrogen) as described previously (14). A pair of primers corresponding to the glyceraldehyde-3-phosphate dehydrogenase coding region was used as a control.…”