Abstract
Purpose:
Investigation of single and combined UV-A (360 nm), (UV-B 320 nm) and blue light (470 nm) stress on porcine lens epithelial cell growth, formation α-tubulin and vimentin cytoskeletal elements (stress fibers) and the distribution of β-integrin as well as pan-cadherin as trans-membrane proteins (cell coupling).
Methods:
Primary porcine lens epithelial cells were obtained from ScienCell (p6550) USA, cultured in six well plates in the appropriate medium (EpiCM + 2% FCS, ScienCell 4101) at 37°C and 5% CO2. Routinely third passage was used for experiments. The following irradiation scheme was applied: UV-A 1 h, UV-B 5 min, blue light 6 h/12 h, 6 h blue light followed by UV-B 5 min. Six, 24 and 48 hours after the end of irradiation, cells were fixed and processed for immune staining using antibodies against α-tubulin (Abcam ab18247), vimentin (Dako M7020), β-integrin (Millipore MAB2000) and pan-cadherin (GeneTex GTX26528). Microscopy was done on a Leica fluorescence microscope using ImageJ® 1.46r for image analytical evaluation.
Results:
UV-A irradiation showed a stimulating effect both on cell growth (cell count) and cell size which persisted up to 48 hours, whereas blue light irradiation alone had little effects on these parameters. UV-B irradiation rapidly and continuously decreased cell count and size. Stress fiber induction was primarily caused by UV-B more prominently for α-tubulin than for vimentin. Blue light alone had little effect on the formation of stress fibers. However pretreatment with blue light before UV-B irradiation was applied, markedly increased the sensitivity of the cell to UV-B stress. Different effects could be demonstrated for trans-membrane proteins. Cell communication was intensified by UV-B irradiation for 24 h before cells started to shut off damaged cells. Again for this parameter blue light seemed to sensitize lens epithelial cells for the UV-B effect.
Conclusions:
Blue light seems to be a sensitizer for lens epithelial cells to UV-B stress in relation to cell growth and formation of stress fibers, whereas UV-A irradiation stimulates cell growth and defense mechanisms in porcine lens epithelial cells. Expression of trans-membrane proteins is less prominently affected by UV-B. Blue light alone has little effect on the parameters investigated.
Keywords: 670 radiation damage: light/UV •
449 cell survival •
599 microscopy: light/fluorescence/immunohistochemistry