Potentiation of Calcium Influx and Insulin Secretion in Pancreatic Beta Cell by the Specific TREK-1 Blocker Spadin

Figure 1

TREK-1 channels are expressed in insulin-containing cells. Immunofluorescent labeling of TREK-1 channels endogenously expressed in mouse pancreatic islets ((a) and (b)) and MIN6-B1 β-cells (c). (a) Immunohistochemistry of mouse pancreas sections stained for TREK-1 channels (Alexa-594) and insulin (Alexa-488) as described in Section 2. The merged image indicated colocalization of TREK-1 and insulin (yellow arrows), some peripheral cells were labeled only with TREK-1 antibodies (white arrows). (b) Immunohistochemistry of mouse pancreas sections from TREK-1 KO mice stained for TREK-1 channels (Alexa-594) and insulin (Alexa-488) clearly showed the absence of TREK-1 labeling. (c) Immunocytochemistry of MIN6-B1 cells was performed using anti-chromogranin A (labeling of secretory granules) and anti-TREK-1 antibodies followed by anti-mouse Alexa-488 and anti-rabbit Alexa-594 secondary antibodies and DAPI for nucleus labeling. Merged image showed the expression of TREK-1 at the plasma membrane (white arrows) (scale bar: 100 μm). (d) Immunoblotting of membrane homogenates from islets from WT and KO-TREK-1 mice, with anti-sortilin and anti-TREK-1, reveals a protein of 50 kDa for TREK-1 and 95 kDa for sortilin, respectively.

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