Retinoic acid is a cofactor for translational regulation of vascular endothelial growth factor in human endometrial stromal cells.
Vascular endothelial growth factor (VEGF) and endometrial angiogenesis play a critical role in successful embryonic implantation. Despite many studies of the effects of estrogen and progesterone on VEGF expression, its focal regulation at the site of implantation is unknown. Retinoic acid (RA) has been reported to regulate VEGF in a variety of cell types. Because localized RA synthesis occurs within the periimplantation endometrium, we tested the possibility that RA regulates VEGF production in endometrial stromal cells. Using primary and telomerase-immortalized human endometrial stromal cells, we determined that RA alone did not alter constitutive levels of VEGF production, but markedly amplified secretion when the cells were cotreated with activators of VEGF gene transcription (12-O-tetradecanoyl phorbol-13-acetate, TPA; TGF-beta; and IL-1beta). Whereas TPA or TGF-beta alone stimulated VEGF promoter activity and up-regulated mRNA levels, significant protein secretion was detected only after RA was added to the culture systems. Analysis of retinoids in secretory phase endometrial biopsies indicated that endogenous RA accumulated at concentrations sufficient to induce VEGF secretion. Polyribosome profile analysis showed that the addition of RA to transcriptional activators of VEGF shifted the translational suppressed VEGF mRNA transcripts into larger polyribosome complexes engaged in active translation. Although the precise mechanism(s) of the RA effect remains to be defined, it appears to be mediated by reactive oxygen species; the antioxidant N-acetylcysteine inhibited RA+TPA-stimulated secretion of VEGF by more than 80%. Together, our results demonstrate that in human endometrial stromal cells, RA can combine with transcriptional activators of VEGF to augment VEGF secretion through a translational mechanism of action mediated by reactive oxygen species. These findings suggest a link between the spatiotemporal changes of retinoid synthesis in the periimplantation stroma and the capacity to quickly up-regulate focal VEGF secretion needed to induce early angiogenic events of pregnancy.
Sidell
Neil
N
Division of Research, Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA. nsidell@emory.edu
Feng
Yue
Y
Hao
Lijuan
L
Wu
Juanjuan
J
Yu
Jie
J
Kane
Maureen A
MA
Napoli
Joseph L
JL
Taylor
Robert N
RN
D000328:Adult; D002460:Cell Line; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D004717:Endometrium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D008183:Luteal Phase / Q000378:metabolism; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000378:metabolism*; D015854:Up-Regulation; D042442:Vascular Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism*
D016207:Cytokines; D020033:Protein Isoforms; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D042442:Vascular Endothelial Growth Factors; D014212:Tretinoin; D013755:Tetradecanoylphorbol Acetate