Comparative analysis of Insulin-producing cells in pancreas, gallbladder and the brain (#105)
of pancreatic islets is a current therapy for treatment of diabetes; however it
is limited by the availability of cadaveric donors and yield from islet isolations. It is therefore important to identify alternate
sources of insulin-producing cells for treatment of diabetes. During our search for “lineage-committed”
islet progenitor cells, we identified pro-insulin expression and c-peptide
immuno-positive cells in rodent/human gallbladders and brain. We are the first to identify insulin-producing
cells in adult human gallbladder1. Although the level of pro-insulin transcripts in gallbladder is
thousand-fold less than in pancreatic islets, this is significantly higher than
the reported levels of differentiated stem cells. Insulin-producing cells have
been localized in brains of fruit-fly2,3, mice4
as well as in a clinical report of insulinoma5.
applied a range of molecular techniques including Next Generation Sequencing
(NGS), TaqMan-based real-time PCR, Confocal microscopy, Flowcytometry, single
cell PCR and Chromatin IP (ChIP) to identify
similarities and differences in the transcriptome, epigenome and protein expression
of rodent and human islets, gallbladder and brain cells.
analyses using a Pdx1-GFP reporter mouse model indicates that the developing
gallbladder contains comparable proportions of Pdx1 / insulin-expressing cells,
which are retained in the adult gallbladder epithelium. On the other hand, the brain shows a
significant reduction in the proportion of insulin-producing cells in adult
life as compared to the embryonic samples.
ChIP for H3K4me3 and H3acetylation at Pdx1 gene promoter confirmed that
open chromatin conformation was retained in the adult brain. I will discuss our findings demonstrating the
similarities in transcriptome and epigenome of human and rodent gallbladder and
pancreas samples, identified through NGS and single cell PCR technologies.
analysis using chromosomal-conformation-capture (3C) and “loopscape” analysis
of insulin promoter region in islets and gallbladder cells would identify molecules
that would aid in efficient differentiation of islet progenitor cells.