Diabetes, Vol 48, Issue 10 1962-1970, Copyright © 1999 by American Diabetes Association
Two novel immortal pancreatic beta-cell lines expressing and secreting human islet amyloid polypeptide do not spontaneously develop islet amyloid
S Andrikopoulos, CB Verchere, JC Teague, WM Howell, WY Fujimoto, TN Wight and SE Kahn
Department of Medicine, University of Washington, Seattle, USA.
Type 2 diabetes is characterized by islet amyloid deposits, which are
primarily composed of the amyloidogenic human form of islet amyloid
polypeptide (IAPP, amylin). The mechanism of islet amyloido-genesis is not
known, but other products (e.g., apolipoprotein E and perlecan) contained
within islet amyloid may be necessary. Because rodent IAPP does not form
islet amyloid, the currently available beta-cell lines are not useful for
studying processes involved in amyloid formation. To develop a suitable in
vitro cell system for the study of islet amyloid formation, we generated
two new beta-cell lines that express the amyloidogenic human IAPP. We did
this by crossbreeding human IAPP transgenic mice with RIP-Tag mice that
develop islet tumors and then culturing one of these islet tumors from two
separate offspring of this cross. The resultant 2350-2C0 and 2511 cell
lines produce human as well as mouse IAPP-like immunoreactivity (IAPP-LI)
and immunoreactive insulin (IRI). Incubation of both these cell lines with
16.7 mmol/l glucose resulted in a two- to fourfold increase in human
IAPP-LI, mouse IAPP-LI, and IRI secretion compared with 1.67 mmol/l glucose
and the combination of 16.7 mmol/l glucose and 10 mmol/l arginine, 0.1
mmol/l 3-isobutyl-1-methylxanthine (IBMX), and 5 micromol/l carbachol
induced a >50-fold increase in the release of these peptides. The
omission of calcium from the above secretagogue cocktail reduced secretion
of all three peptides to only two- to sixfold higher than the 16.7 mmol/l
glucose condition. Perifusion with 16.7 mmol/l glucose plus 0.1 mmol/l IBMX
caused a biphasic secretion of human IAPP-LI and mouse IAPP-LI, as well as
IRI, in both cell lines, with the peak of the first phase being five- to
sixfold higher than the prestimulated 1.67 mmol/l glucose condition.
Immunoelectron microscopic inspection of both 2350-2C0 and 2511 cells after
7 days of culture did not reveal the presence of amyloid fibrils,
suggesting the need for other critical components. We conclude that we have
established two novel beta-cell lines that produce and secrete human IAPP
in a regulated manner. These cell lines will be a useful tool to
investigate the secretion of human IAPP as well as the necessity of other
components for islet amyloid formation.