טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAlisa Fuchs
SubjectCellular Localization and Expression Pattern of the Amino
Terminus of L-VEGF in Normal and Tumor Tissues
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Full Professors Levi Ben-Zion


Abstract

Angiogenesis is the process of new blood vessels formation from pre-existing network of capillaries. Vascular Endothelial Growth Factor (VEGF) has a central role in pathological and physiological angiogenesis. Therefore, VEGF is subjected to multilevel regulation to ensure proper expression during embryogenesis and adulthood.

VEGF has a very long (1038bp) 5' untranslated region (5' UTR), which contains two IRES elements (A and B). Our laboratory was the first to show that 5'UTR of the VEGF harbors an open reading frame (ORF) initiated by a CUG which can add 180 amino acids to the following VEGF. This lengthened isoform was termed Long VEGF (L-VEGF).

Cytolocalization of the amino-terminal fragment of L-VEGF and its presence in various angiogenic and non-angiogenic tissues could elucidate its biological function, which still remains unclear. Immunohistochemical analysis of ORF and VEGF proteins in normal and tumor tissue has shown that ORF is localized in the nucleus, while VEGF is found in cytoplasm. VEGF expression is highly stimulated in angiogenic tissues and tumors and the localization of ORF in the nucleus was in most cases highly correlated with the presence of VEGF in the cytoplasm. Two bands were recognized by Western blot analysis with aORF antibodies, 30kDa and 60kDa, both in nuclear fractions of the cell. Although amino acid sequencing of the purified proteins did not confirm them to contain ORF, the antibodies proved to be very specific.

Our results suggest that the ORF has an important role in VEGF mediated angiogenic processes. Its presence in the nucleus might imply its involvement in VEGF regulated expression.