Distribution of insulin and proinsulin in pancreatic islets of pre-diabetic mice.

<p>Sections of paraffin embedded pancreata were immunostained with anti-insulin antibodies (red), anti-proinsulin antibodies (green) and anti-BIP (blue). The endogenous GFP fluorescence was quenched prior immunostaining. A. Endogenous insulin and proinsulin in pre-diabetic hProC(A7)Y-CpepGFP male compared to hProCpepGFP control. B. Endogenous insulin and proinsulin in pre-diabetic LepR^db/db male compare to LepR^db/+ control. C. β-cell BIP in pre-diabetic hProC(A7)Y-CpepGFP and LepR^db/db males. In genetically predisposed pre-diabetic mice, maturation of proinsulin to insulin is heterogeneously compromised, likely in β-cells more affected by the ER insult (white arrowheads). Red arrow denotes autofluorescence deriving from red blood cells.