Figure 2: JB253 binding and concentration–response studies.
From: Optical control of insulin release using a photoswitchable sulfonylurea
(a) Binding affinity of glimepiride (Glim) (red, IC50=8.3 nM), trans-JB253 (black, IC50=17.6 μM) and cis-JB253 (blue, IC50=14.8 μM) were indirectly determined in SUR1-expressing HEK293t cells using displacement of [3H]-glibenclamide (data points fitted using the Hill equation) (n=3 independent repeats). Note that, due to the potential for thermal dark-relaxation during the harvesting and washing steps, effects of photoswitching on JB253 binding affinity could not be excluded. Values represent the mean±s.d. (b) cis-JB253 and glimepiride (Glim) possess similar concentration–response curves for the stimulation of [Ca2+]i in mouse islets, while trans-JB253 is largely ineffective. The concentration–response for glimepiride is right-shifted in the presence of a saturating concentration (100 μM) of trans-JB253 (data points fitted using nonlinear regression) (n=3 recordings). (c) HEK293t cells expressing a full-length Epac2-camps probe respond to glimepiride with decreases in Förster resonance energy transfer (FRET) (represented here as an increase in R/Ro) (n=28 cells from 4 recordings). (d) As in c, but cis-JB253. Values represent the mean±s.e.m. for (b–d).
