The authors have derived a new β-cell line
(βIns2−/−lacZ) from Ins2−/− mice that carry the lacZ
reporter gene under control of the Ins2 promoter.
βIns2−/−lacZ cells stained positively using anti-insulin
antibody, expressed β-cell–specific genes encoding the
transcription factor PDX-1, glucokinase, and Glut-2, retained
glucose-responsiveness for insulin secretion, and expressed
the lacZ gene. Analysis of Ins1 expression by reverse
transcriptase–polymerase chain reaction (RT-PCR)
showed that Ins1 transcripts were significantly raised to
compensate for the lack of Ins2 transcripts in βIns2−/−lacZ
cells, as compared to those found in βTC1 cells expressing
both Ins1/Ins2. Thus, transcriptional up-regulation of the
remaining functional insulin gene in Ins2−/− mice could
potentially contribute to the β-cell adaptation exhibited by
these mutants, in addition to the increase in β-cell mass
that we previously reported.We have also shown that lacZ
expression, as analyzed by determining β-galactosidase
activity, was up-regulated by incubating βIns2−/−lacZ cells
with GLP-1 and/or IBMX, 2 known stimulators of insulin
gene expression. These cells thus represent a new tool for
testing of molecules capable of stimulating Ins2 promoter
activity
