Sitagliptin and the Blood-Retina Barrier: Effects on Retinal Endothelial Cells Manifested Only after Prolonged Exposure

Figure 7

Prolonged treatment of iBREC with sitagliptin increased expression of claudin-1 and changed the plasma membrane localization of VEcadherin. (a) After exposure of confluent iBREC to 10-1000 nM sitagliptin for two days, cells were harvested for preparation of cell extracts, followed by Western blot analyses. Expression of claudin-1 was higher after treatment with sitagliptin at all concentrations used, but only 1 μM sitagliptin led to a significantly higher level of claudin-5; expression of VEcadherin was not changed. Signals were normalized as described in Materials and Methods; for each condition. (b) Immunofluorescence staining showed that plasma membrane-localized claudin-5 was not affected by the inhibitor of DPP-4, but staining of VEcadherin at the plasma membrane appeared more diffuse when cells had been exposed to sitagliptin. Scale bar: 10 μm.

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