Figure 5. Nkx6.1 is necessary for insulin biosynthesis.

(A) qRT-PCR analysis of islets reveals reduced expression of genes involved in insulin biosynthesis in Nkx6.1 ^Δadultβ compared to control mice at 6 wks (n=3). (B–E) Immunofluorescence staining of pancreata from Nkx6.1 ^Δadultβ and control mice at 6 wks. Dashed lines represent islet area. (F) qRT-PCR analysis of Nkx6.1 ^Δadultβ and control islets from mice at 6 wks shows no significant difference in ins1 or ins2 expression (n=3). (G) Proinsulin content normalized to protein concentration of whole pancreatic lysates (n=6). (H) The pancreatic insulin to proinsulin ratio is reduced in Nkx6.1^{Δ adultβ} mice (n=6). (I,J) Transmission electron microscopy of pancreatic sections reveals smaller vesicle size and an increase in immature vesicles (red arrowheads) in Nkx6.1 ^Δadultβ compared to control mice. Dashed boxes indicate area of magnification in I′ and J′. Blue arrowheads point to vesicles containing mature insulin dense core granules. Insets framed red show a representation of a typical immature vesicle and insets framed blue a typical mature vesicle. (K–M) Quantification of vesicle numbers (K), vesicle diameter (L), and the percentage of mature and immature vesicles (M) in Nkx6.1^{Δ adultβ} and control mice (n=10). In G–M, mice were analyzed at 7 wks. PC1, prohormone convertase 1/3; Wk, week. Data are shown as mean ± SEM for A,F,G,H and ± SD for K–M. *p<0.05, **p<0.01, ***p<0.001.