Abstract
Purpose:
Ocular neovascularization is the hallmark of a wide variety of ophthalmic maladies such retinopathy of prematurity, wet AMD and diabetic retinopathy. All of these diseases can be associated with the overexpression of VEGF and subsequent aberrant vessel growth. TEAD4 is a transcription factor shown to bind MCAT and SP1 elements and is involved in development and cellular maturation. We have previously shown that ocular derived isoforms of TEAD4 can differentially modulate the VEGF promoter and regulate its expression using an in vitro promoter assay. To test whether an importable inhibitory peptide of TEAD4 can attenuate blood vessel development, a mouse aortic ring assay was employed.
Methods:
Aortas were harvested from mice ranging in age from 25 to 40 days old. Aortas were flushed using HBSS to remove blood from the interior of the aorta. The aortas were cut into approximately 3mm rings and washed 5 times in serum free EMEM media. Rings were placed into 24 well plates containing 500μl of Matrigel and allowed to solidify at 37°C. 500μl of serum free EMEM media containing the TEAD4 651-RMR peptide (.02mg/ml) or control was added to the rings. Media changes were performed every 2 days along with photography for 9 days. Images were assessed by tracing around the ring using ImageJ and Image Pro Plus was used to calculate the area of vessel outgrowth.
Results:
The TEAD4 treated group displayed a pronounced reduction in new vessel development and rate of growth. Vessel sprouting was observed in the control group as early as day 2 compared to day 6 in the treated group. Differences in the vessel sprout morphology were also apparent. The control group had profuse branching networks while the treated group’s vessels were more diffuse and spindly. Significant differences in vessel area were observed on days 4 and 9 (p=0.035 and p=0.01 respectively).
Conclusions:
The TEAD4 peptide containing the RMR importation signal significantly inhibits vessel growth in an aortic ring assay. It has been shown that endothelial cells grown in vitro regulate VEGF expression in what is presumably an autocrine fashion. The presence of the inhibitory isoform of TEAD4 may down-regulate the expression of VEGF and/or other angiogenic factors and may have therapeutic value.
Keywords: 609 neovascularization •
739 transcription factors •
748 vascular endothelial growth factor