FIGURE 1.

FGFRL1 is expressed in insulin-secreting pancreatic islet beta-cells. A, Fgfrl1 mRNA was amplified by RT-PCR in islet samples (I) and insulin-secreting beta-cells (β = βTC3) but not α-cells (α = αTC1) or a DNA-deficient sample (−). The Gapdh housekeeping gene was amplified as a loading control. B, FGFRL1 protein bands of ∼53 and 65–70 kDa were visualized in βTC3 cell lysates by Western immunoblotting. Molecular mass markers (kDa) are indicated at left. C, polyclonal antibody co-immunofluorescent detection positively identified FGFRL1 expression (red) in insulin-positive cells (green) dispersed from whole mouse islets. FGFRL1 was not detected in insulin-negative cells (arrow). D, FGFRL1-associated immunofluorescence (red) was primarily associated with discrete intracellular punctate regions in βTC3 cells but was excluded from nuclei (DRAQ5 counterstain; blue). FGFRL1 was frequently observed to co-localize with insulin-rich regions (green; arrow). The inset reveals R5-immunofluorescence control. Scale bars, 10 μm.