Analysis Tools
endocrine/exocrine glands
|
• at 6 weeks of age, islets exhibit increased levels of apoptosis, as shown by double immunofluorescence for caspase-3 and either insulin or glucagon
• TUNEL staining indicated increased levels of apoptosis in all islets by 52 weeks of age
|
|
• at 6 weeks of age, islets exhibit increased levels of apoptosis, as shown by double immunofluorescence for caspase-3 and insulin
|
|
• at 8 weeks of age, expression of several cell cycle and mitosis-associated genes is altered, consistent with increased mitosis rates
|
|
• at 6 weeks of age, mice show defects and heterogeneity in islet patterning
• PH3 immunofluorescence indicated that mitotic activity is 2-fold higher at P1 and 50-fold higher at 6 weeks of age
• phosphorylated AMPKA levels are significantly increased suggesting that beta cells are energy depleted
• ATP levels are reduced by ~2-fold in isolated islets relative to control islets
|
|
• at 6 weeks of age, many islets contain supernumerary glucagon-positive (GCG+) cells
|
|
• continued mitosis in islets results in a 3.6-fold expansion of the beta cell mass by 20 weeks of age
• however, beta cell mass differences are negligible at P1 and 6 weeks of age
|
|
• at 6 weeks of age, many islets contain supernumerary somatostatin-positive (SOM+) cells
|
|
• continued mitosis results in a 2-fold increase in median islet size by 20 weeks of age
|
|
• although early pancreas development is normal, progenitor differentiation is accelerated during the secondary transition, indicating premature lineage commitment
• the number of neurogenin 3-positive (NGN3+) endocrine progenitors is transiently increased at E13.5 and E14.5
• the number of C-peptide-positive (C-PEP+) cells, but not glucagon-positive (GCG+) cells, is increased at E14.5
• amylase complex-positive (AMY+) acinar cells and duct Dolichos biflorus agglutinin-positive (DBA+) cells appear earlier and are more numerous at E14.5 relative to wild-type controls
• the number of epithelial cells in mitosis (Phosphohistone-H3+/E-cadherin+ cells) is transiently increased at E14.5
• however, apoptosis levels remain very low and similar to those in wild-type controls
|
|
• transcriptome analyses of P1 islets revealed impaired islet patterning with misregulation of key beta cell transcription factors and genes critical for beta cell function
• defects and heterogeneity in islet patterning persist into adulthood, with the number of misregulated genes expanding >6-fold at 8 weeks of age
• at 8 weeks of age, affected beta cells contain 30% fewer type 1 (mature) secretory granules and 22% more type 2 (immature) granules than wild-type cells
• z score heat maps showed misregulated expression of several genes involved in secretory granule formation and exocytosis
|
|
• 2.6-fold increase in glucagon content in the pancreas at 8 weeks of age
• pancreas glucagon levels are increased at 52 weeks of age
|
|
• at 8 weeks of age, acute insulin secretion during IPGTT is impaired; first-phase response takes ~3 times as long to peak without reaching control levels while second-phase response is absent
• acute insulin secretion is weak by 20 weeks and monophasic at 52 weeks of age
• at 20 weeks of age, glucose-stimulated insulin secretion is reduced by 13-fold in isolated islets relative to control islets
• following stimulation with tolbutamide (a K+ channel antagonist) or BayK8644 (a specific L-type voltage-sensitive Ca2+ channel agonist), insulin release is reduced by 5-fold in isolated islets relative to control islets, indicating impaired stimulus-coupling secretion
|
|
• transient increase in insulin and proinsulin content in the pancreas at 8 weeks of age
• however, insulin-to-proinsulin ratio remains similar to that in controls until 20 weeks of age
|
homeostasis/metabolism
| N |
• at 20 weeks of age, mice show normal hepatic stores of glycogen, expression of liver G6Pase, and gluconeogenesis rates relative to controls
|
|
• 2.6-fold increase in glucagon content in the pancreas at 8 weeks of age
• pancreas glucagon levels are increased at 52 weeks of age
|
|
• at 8 weeks of age, acute insulin secretion during IPGTT is impaired; first-phase response takes ~3 times as long to peak without reaching control levels while second-phase response is absent
• acute insulin secretion is weak by 20 weeks and monophasic at 52 weeks of age
• at 20 weeks of age, glucose-stimulated insulin secretion is reduced by 13-fold in isolated islets relative to control islets
• following stimulation with tolbutamide (a K+ channel antagonist) or BayK8644 (a specific L-type voltage-sensitive Ca2+ channel agonist), insulin release is reduced by 5-fold in isolated islets relative to control islets, indicating impaired stimulus-coupling secretion
|
|
• transient increase in insulin and proinsulin content in the pancreas at 8 weeks of age
• however, insulin-to-proinsulin ratio remains similar to that in controls until 20 weeks of age
|
|
• mice develop age-dependent hyperglycemia from 12 weeks onwards
• onset of hyperglycemia is preceded by reduced glucose tolerance and significant delay in acute insulin secretion
|
|
• at 8 weeks of age, mice show a significant delay in blood glucose clearance during intraperitoneal glucose tolerance testing (IPGTT)
• glucose tolerance is further reduced by 20 weeks and deteriorated by 52 weeks of age
|
|
• at 52 weeks of age, mice show clear signs of insulin resistance during intraperitoneal insulin tolerance testing (IPITT)
• however, normal rates of glucose clearance are observed during IPITT at 8 and 20 weeks of age
|
|
• in response to glucose stimulation, increase in intracellular Ca2+ concentration is reduced in islets isolated from 20-week-old mice relative to control islets, due to a subset islets (14 of 59) with very low or negligible response
|
cellular
|
• at 6 weeks of age, islets exhibit increased levels of apoptosis, as shown by double immunofluorescence for caspase-3 and either insulin or glucagon
• TUNEL staining indicated increased levels of apoptosis in all islets by 52 weeks of age
|
|
• at 6 weeks of age, islets exhibit increased levels of apoptosis, as shown by double immunofluorescence for caspase-3 and insulin
|
|
• transcriptome analyses of P1 islets revealed impaired islet patterning with misregulation of key beta cell transcription factors and genes critical for beta cell function
• defects and heterogeneity in islet patterning persist into adulthood, with the number of misregulated genes expanding >6-fold at 8 weeks of age
• at 8 weeks of age, affected beta cells contain 30% fewer type 1 (mature) secretory granules and 22% more type 2 (immature) granules than wild-type cells
• z score heat maps showed misregulated expression of several genes involved in secretory granule formation and exocytosis
|
|
• at 8 weeks of age, expression of several cell cycle and mitosis-associated genes is altered, consistent with increased mitosis rates
|
|
• pancreatic islets fail to show induction of several genes involved in protection from and repair of oxidative damage from P1 to adulthood
• at 20 weeks of age, islets show high ROS content and markedly increased oxidation of unsaturated fatty acids, indicating oxidative stress
|
