Limits...
Compensatory Response by Late Embryonic Tubular Epithelium to the Reduction in Pancreatic Progenitors.

Nishimura W, Kapoor A, El Khattabi I, Jin W, Yasuda K, Bonner-Weir S, Sharma A - PLoS ONE (2015)

Bottom Line: Previously we reported that in Pdx1tTA/+;tetOMafA (bigenic) mice inducing expression of transcription factor MafA in Pdx1-expressing (Pdx1+) cells throughout embryonic development inhibited the proliferation and differentiation of 1°MPC cells, resulting in reduced pancreatic mass and endocrine cells by embryonic day (E) 17.5.However, by birth (P0), as we now report, such bigenic pups had significantly increased pancreatic and endocrine volumes with endocrine clusters containing all pancreatic endocrine cell types.Thus, these bigenic mice provide a novel way to characterize the competency of 1°MPC for their ability to specify endocrine progenitors, a critical limitation in our understanding of endocrine differentiation.

View Article: PubMed Central - PubMed

Affiliation: Section of Islet Cell & Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, United States of America.

ABSTRACT
Early in pancreatic development, epithelial cells of pancreatic buds function as primary multipotent progenitor cells (1°MPC) that specify all three pancreatic cell lineages, i.e., endocrine, acinar and duct. Bipotent "Trunk" progenitors derived from 1°MPC are implicated in directly regulating the specification of endocrine progenitors. It is unclear if this specification process is initiated in the 1°MPC where some 1°MPC become competent for later specification of endocrine progenitors. Previously we reported that in Pdx1tTA/+;tetOMafA (bigenic) mice inducing expression of transcription factor MafA in Pdx1-expressing (Pdx1+) cells throughout embryonic development inhibited the proliferation and differentiation of 1°MPC cells, resulting in reduced pancreatic mass and endocrine cells by embryonic day (E) 17.5. Induction of the transgene only until E12.5 in Pdx1+ 1°MPC was sufficient for this inhibition of endocrine cells and pancreatic mass at E17.5. However, by birth (P0), as we now report, such bigenic pups had significantly increased pancreatic and endocrine volumes with endocrine clusters containing all pancreatic endocrine cell types. The increase in endocrine cells resulted from a higher proliferation of tubular epithelial cells expressing the progenitor marker Glut2 in E17.5 bigenic embryos and increased number of Neurog3-expressing cells at E19.5. A BrdU-labeling study demonstrated that inhibiting proliferation of 1°MPC by forced MafA-expression did not lead to retention of those progenitors in E17.5 tubular epithelium. Our data suggest that the forced MafA expression in the 1°MPC inhibits their competency to specify endocrine progenitors only until E17.5, and after that compensatory proliferation of tubular epithelium gives rise to a distinct pool of endocrine progenitors. Thus, these bigenic mice provide a novel way to characterize the competency of 1°MPC for their ability to specify endocrine progenitors, a critical limitation in our understanding of endocrine differentiation.

No MeSH data available.


Related in: MedlinePlus

Normal-appearing acinar and tubular epithelial cells in E17.5 bigenic pancreas.H& E stained pancreatic sections from the E17.5 control and bigenic Pdx1tTA/+;tetOMafA mice (AB) show tubular epithelium and surrounding endocrine area (dashed line) with a lack of endocrine cells in the bigenic pancreas. Amylase (green, CD), insulin (red C-J), E-cadherin (green, GH), β-catenin (green, IJ), and DBA lectin (green EF) staining show a reduction in insulin+ cells in the bigenic pancreas but normal appearance of acinar and tubular epithelium. DAPI (blue). Bars: 50 μm.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4635002&req=5

pone.0142286.g002: Normal-appearing acinar and tubular epithelial cells in E17.5 bigenic pancreas.H& E stained pancreatic sections from the E17.5 control and bigenic Pdx1tTA/+;tetOMafA mice (AB) show tubular epithelium and surrounding endocrine area (dashed line) with a lack of endocrine cells in the bigenic pancreas. Amylase (green, CD), insulin (red C-J), E-cadherin (green, GH), β-catenin (green, IJ), and DBA lectin (green EF) staining show a reduction in insulin+ cells in the bigenic pancreas but normal appearance of acinar and tubular epithelium. DAPI (blue). Bars: 50 μm.

Mentions: Since cells in the embryonic Trunk/tubular epithelium are primarily responsible for the specification of pancreatic endocrine cells, we first examined whether the inhibitory effects of MafAMyc expression on endocrine differentiation of 1°MPCs persisted in E17.5 pancreas. In controls, Pdx1Hi-expressing cells had low E-cadherin expression at E17.5 (Fig 1), while the high E-cadherin-expressing tubular epithelial cells showed Pdx1Lo expression (Fig 1B and 1D). In the bigenic pancreas Pdx1Hi-expressing cells were dramatically reduced in number, with most cells in the tubular epithelium having Pdx1Lo expression and lacking MafAMyc expression (Fig 1A, 1C and 1E). The E17.5 tubular epithelium in the bigenic pancreas, like E15.5 epithelium [17], did not express MafAMyc. These observations that only the cells having higher Pdx1 expression were capable of inducing MafAMyc expression (Fig 1E) are consistent with the 1°MPCs being the only progenitor population during the pancreatic development expressing the transgene MafAMyc [17] and, therefore, likely responsible for the MafAMyc-dependent reduced number of endocrine progenitors and hormone-producing cells. The expression of MafAMyc in the 1°MPC did not alter the morphology of E17.5 tubular epithelial cells or their expression of E-cadherin and β-catenin nor that of the acinar cells (Fig 2) or DBA+ cells. The main difference in the bigenic mice was the lack of endocrine clusters surrounding the embryonic tubules.


Compensatory Response by Late Embryonic Tubular Epithelium to the Reduction in Pancreatic Progenitors.

Nishimura W, Kapoor A, El Khattabi I, Jin W, Yasuda K, Bonner-Weir S, Sharma A - PLoS ONE (2015)

Normal-appearing acinar and tubular epithelial cells in E17.5 bigenic pancreas.H& E stained pancreatic sections from the E17.5 control and bigenic Pdx1tTA/+;tetOMafA mice (AB) show tubular epithelium and surrounding endocrine area (dashed line) with a lack of endocrine cells in the bigenic pancreas. Amylase (green, CD), insulin (red C-J), E-cadherin (green, GH), β-catenin (green, IJ), and DBA lectin (green EF) staining show a reduction in insulin+ cells in the bigenic pancreas but normal appearance of acinar and tubular epithelium. DAPI (blue). Bars: 50 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4635002&req=5

pone.0142286.g002: Normal-appearing acinar and tubular epithelial cells in E17.5 bigenic pancreas.H& E stained pancreatic sections from the E17.5 control and bigenic Pdx1tTA/+;tetOMafA mice (AB) show tubular epithelium and surrounding endocrine area (dashed line) with a lack of endocrine cells in the bigenic pancreas. Amylase (green, CD), insulin (red C-J), E-cadherin (green, GH), β-catenin (green, IJ), and DBA lectin (green EF) staining show a reduction in insulin+ cells in the bigenic pancreas but normal appearance of acinar and tubular epithelium. DAPI (blue). Bars: 50 μm.
Mentions: Since cells in the embryonic Trunk/tubular epithelium are primarily responsible for the specification of pancreatic endocrine cells, we first examined whether the inhibitory effects of MafAMyc expression on endocrine differentiation of 1°MPCs persisted in E17.5 pancreas. In controls, Pdx1Hi-expressing cells had low E-cadherin expression at E17.5 (Fig 1), while the high E-cadherin-expressing tubular epithelial cells showed Pdx1Lo expression (Fig 1B and 1D). In the bigenic pancreas Pdx1Hi-expressing cells were dramatically reduced in number, with most cells in the tubular epithelium having Pdx1Lo expression and lacking MafAMyc expression (Fig 1A, 1C and 1E). The E17.5 tubular epithelium in the bigenic pancreas, like E15.5 epithelium [17], did not express MafAMyc. These observations that only the cells having higher Pdx1 expression were capable of inducing MafAMyc expression (Fig 1E) are consistent with the 1°MPCs being the only progenitor population during the pancreatic development expressing the transgene MafAMyc [17] and, therefore, likely responsible for the MafAMyc-dependent reduced number of endocrine progenitors and hormone-producing cells. The expression of MafAMyc in the 1°MPC did not alter the morphology of E17.5 tubular epithelial cells or their expression of E-cadherin and β-catenin nor that of the acinar cells (Fig 2) or DBA+ cells. The main difference in the bigenic mice was the lack of endocrine clusters surrounding the embryonic tubules.

Bottom Line: Previously we reported that in Pdx1tTA/+;tetOMafA (bigenic) mice inducing expression of transcription factor MafA in Pdx1-expressing (Pdx1+) cells throughout embryonic development inhibited the proliferation and differentiation of 1°MPC cells, resulting in reduced pancreatic mass and endocrine cells by embryonic day (E) 17.5.However, by birth (P0), as we now report, such bigenic pups had significantly increased pancreatic and endocrine volumes with endocrine clusters containing all pancreatic endocrine cell types.Thus, these bigenic mice provide a novel way to characterize the competency of 1°MPC for their ability to specify endocrine progenitors, a critical limitation in our understanding of endocrine differentiation.

View Article: PubMed Central - PubMed

Affiliation: Section of Islet Cell & Regenerative Biology, Joslin Diabetes Center, Boston, Massachusetts, United States of America.

ABSTRACT
Early in pancreatic development, epithelial cells of pancreatic buds function as primary multipotent progenitor cells (1°MPC) that specify all three pancreatic cell lineages, i.e., endocrine, acinar and duct. Bipotent "Trunk" progenitors derived from 1°MPC are implicated in directly regulating the specification of endocrine progenitors. It is unclear if this specification process is initiated in the 1°MPC where some 1°MPC become competent for later specification of endocrine progenitors. Previously we reported that in Pdx1tTA/+;tetOMafA (bigenic) mice inducing expression of transcription factor MafA in Pdx1-expressing (Pdx1+) cells throughout embryonic development inhibited the proliferation and differentiation of 1°MPC cells, resulting in reduced pancreatic mass and endocrine cells by embryonic day (E) 17.5. Induction of the transgene only until E12.5 in Pdx1+ 1°MPC was sufficient for this inhibition of endocrine cells and pancreatic mass at E17.5. However, by birth (P0), as we now report, such bigenic pups had significantly increased pancreatic and endocrine volumes with endocrine clusters containing all pancreatic endocrine cell types. The increase in endocrine cells resulted from a higher proliferation of tubular epithelial cells expressing the progenitor marker Glut2 in E17.5 bigenic embryos and increased number of Neurog3-expressing cells at E19.5. A BrdU-labeling study demonstrated that inhibiting proliferation of 1°MPC by forced MafA-expression did not lead to retention of those progenitors in E17.5 tubular epithelium. Our data suggest that the forced MafA expression in the 1°MPC inhibits their competency to specify endocrine progenitors only until E17.5, and after that compensatory proliferation of tubular epithelium gives rise to a distinct pool of endocrine progenitors. Thus, these bigenic mice provide a novel way to characterize the competency of 1°MPC for their ability to specify endocrine progenitors, a critical limitation in our understanding of endocrine differentiation.

No MeSH data available.


Related in: MedlinePlus