Abstract
Purpose: :
RdCVF (Rod-derived cone viability factor) and RdCVF2 are proteins produced by rod photoreceptor cells that function to promote the survival of cone photoreceptors. RdCVF is specifically expressed in photoreceptor and bipolar (Reichman et al. ARVO 2008), cells and is not detected in any other tissue tested, whereas RdCVF2 is expressed in other tissues such as brain, mammary gland, and placenta. In an effort to understand the mechanisms regulating their expression, with interest in possible future therapeutic modulation of their expression in vivo, we have been studying DNA elements and protein factors involved in controlling their transcription.
Methods: :
A deletion series of murine (m) and human (h) RdCVF and RdCVF2 5’-upstream region/luciferase and GFP constructs were generated by Gateway technology. Resulting constructs were tested for promoter activity by transfection of human cell lines and by electroporation of murine retinal explants. Constructs are also being tested by Xenopus transgenesis.
Results: :
Regions with promoter activity were identified for hRdCVF (0.263 to 0.135 kb, relative to the initiation ATG), hRdCVF2 (0.420 to 0.340 kb), and mRdCVF2 (0.452 to 0.000 kb) contain promoter activity. More limited sequences within these regions that are required for activity have also been located. The identified promoter fragments have activity in photoreceptor cells, but also other cell types. Further analysis is underway to identify the elements responsible for photoreceptor-specific expression. In order to explore specificity in vivo, analogous studies with transgenic Xenopus experiments are underway.
Conclusions: :
We identified human RdCVF and murine and human RdCVF2 DNA regions with promoter activity. Using the results for these and ongoing studies, we will use yeast one-hybrid technology to identify transcription factors responsible for the expression of RdCVF and RdCVF2 in photoreceptor cells.
Keywords: transcription • neuroprotection • retinal degenerations: cell biology