title: Osmotic induction of placental growth factor in retinal pigment epithelial cells in vitro: contribution of NFAT5 activity.
abstract: One risk factor of neovascular age-related macular degeneration is systemic hypertension; hypertension is mainly caused by extracellular hyperosmolarity after consumption of dietary salt. In retinal pigment epithelial (RPE) cells, high extracellular osmolarity induces vascular endothelial growth factor (VEGF)-A (Hollborn et al. in Mol Vis 21:360-377, 2015). The aim of the present study was to determine whether extracellular hyperosmolarity and chemical hypoxia trigger the expression of further VEGF family members including placental growth factor (PlGF) in human RPE cells. Hyperosmotic media were made up by addition of 100 mM NaCl or sucrose. Chemical hypoxia was induced by CoCl2. Gene expression was quantified by real-time RT-PCR, and secretion of PlGF-2 was investigated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) was depleted using siRNA. Extracellular hyperosmolarity triggered expression of VEGF-A, VEGF-D, and PlGF genes, and secretion of PlGF-2. Hypoosmolarity decreased PlGF gene expression. Hypoxia induced expression of VEGF-A, VEGF-B, VEGF-D, and PlGF genes. Extracellular hyperosmolarity and hypoxia produced additive PlGF gene expression. Both hyperosmolarity and hypoxia induced expression of KDR and FLT-4 receptor genes, while hyperosmolarity caused neuropilin-2 and hypoxia neuropilin-1 gene expression. The hyperosmotic, but not the hypoxic, PlGF gene expression was in part mediated by NFAT5. The expression of PlGF in RPE cells depends on the extracellular osmolarity. The data suggest that high consumption of dietary salt may exacerbate the angiogenic response of RPE cells in the hypoxic retina via transcriptional activation of various VEGF family member genes.
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany. hollbm@medizin.uni-leipzig.de.
authors.forename: Margrit
authors.initials: M
authors.lastname: Hollborn
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Reichmuth
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Prager
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Wiedemann
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bringmann
authors.affiliation: Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.|Helios Klinikum Aue, Aue, Germany.
authors.forename: Leon
authors.initials: L
authors.lastname: Kohen
mesh_terms: D000328:Adult; D000368:Aged; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D008268:Macular Degeneration / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D000072483:Placenta Growth Factor / Q000235:genetics* / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000473:pathology; D015398:Signal Transduction; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: C118125:NFAT5 protein, human; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D000072483:Placenta Growth Factor
keywords: Hypoxia; NFAT5; Osmolarity; PlGF; Retinal pigment epithelium; VEGF