Enhanced photosensitivity in VEGF164 transgenic mice. (A) VEGF164 is the most strongly expressed VEGF isoform in healthy skin compared with moderate expression of VEGF120 and VEGF188, as studied by reverse transcription–polymerase chain reaction (RT-PCR). Expression of all VEGF isoforms was induced at 2 and 4 days after exposure to a single dose of 200 mJ UVB, but VEGF164 was the most strongly expressed isoform at all time points studied. VEGF mRNA expression levels returned to preirradiation levels 8 days after UVB irradiation. (B) Dorsal skin was exposed to graded doses of a single UVB irradiation, ranging from 1.8 × 10-2 J/cm2 to 1.26 × 10-1 J/cm2 or to sham irradiation. In wild-type (WT; n = 5) mice, we found an MED of 7.2 × 102 J/cm2, whereas VEGF-overexpressing mice (VEGF-TG; n = 5) had an MED of 3.6 × 10-2 J/cm2. MED was determined 48 hours after UVB irradiation.
