Islet Specific Wnt Activation in Human Type II Diabetes
Figure 4
Wnt signaling is induced in islets in
vitro. Western blot analysis (a) indicates that β-catenin
is expressed in both cultured purified islets
and cultured purified nonendocrine pancreatic
clusters (NEPCs). Islets were dithizone picked to 99% purity, verified by qPCR as previously reported (23). As
expected, the duct marker CK 19 is expressed at
higher levels in NEPCs than in purified islets. Actin
expression confirmed equivalent sample loading.
(b) and (c) β-catenin (green in (b) and (c)) and somatostatin (red
to visualize islets) staining demonstrate a low or
absent β-catenin expression in islets of pancreatic
tissue removed and fixed immediately postmortem
(b) compared with high β-catenin
expression in islets of pancreas tissue removed
and fixed after the entire pancreas was shipped
using the bilayer method to an islet isolation center
(c). β-catenin is downregulated in cultured human
islets following transplantation under the kidney
capsule of Scid mice (d) and (e). Scale bars for (b)–(e):
50 m. Islets isolated from nondiabetic individuals
() were cultured for 48 hours in the absence
(f), (h), and (k) or presence (g), (i), and (l) of 500 ng/mL of the Wnt
inhibitor sFRP. Immunohistochemical analysis of
insulin (green) and anti-sFRP (red in (f) and (g)) detects
sFRP on islet cells only when sFRP has been
added to the culture media. sFRP exposure led to
inhibition of β-catenin ((h) versus (i), quantitated in (j)) and
c-myc ((k) versus (l), quantitated in (m)). Error bars = mean
+/−s.e.m. *. Scale bars in (f)–(m): 25 m.
