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Chronic β-Cell Depolarization Impairs β-Cell Identity by Disrupting a Network of Ca-Regulated Genes.
Stancill JS, Cartailler JP, Clayton HW, O'Connor JT, Dickerson MT, Dadi PK, Osipovich AB, Jacobson DA, Magnuson MA
(2017) Diabetes 66: 2175-2187
MeSH Terms: Animals, Basic Helix-Loop-Helix Transcription Factors, Calcium, Calcium Signaling, Cell Adhesion, Cell Cycle Proteins, Cell Lineage, Cell Polarity, Gene Expression, Gene Expression Regulation, Insulin-Secreting Cells, KATP Channels, Mice, Pancreatic Polypeptide-Secreting Cells, S100 Calcium Binding Protein A6, S100 Calcium-Binding Protein A4, S100 Proteins, Sulfonylurea Receptors
Show Abstract · Added June 2, 2017
We used mice lacking , a key component of the β-cell K-channel, to analyze the effects of a sustained elevation in the intracellular Ca concentration ([Ca]) on β-cell identity and gene expression. Lineage tracing analysis revealed the conversion of β-cells lacking into pancreatic polypeptide cells but not to α- or δ-cells. RNA-sequencing analysis of FACS-purified β-cells confirmed an increase in gene expression and revealed altered expression of more than 4,200 genes, many of which are involved in Ca signaling, the maintenance of β-cell identity, and cell adhesion. The expression of and , two highly upregulated genes, is closely correlated with membrane depolarization, suggesting their use as markers for an increase in [Ca] Moreover, a bioinformatics analysis predicts that many of the dysregulated genes are regulated by common transcription factors, one of which, , was confirmed to be directly controlled by Ca influx in β-cells. Interestingly, among the upregulated genes is , a putative marker of β-cell dedifferentiation, and other genes associated with β-cell failure. Taken together, our results suggest that chronically elevated β-cell [Ca] in islets contributes to the alteration of β-cell identity, islet cell numbers and morphology, and gene expression by disrupting a network of Ca-regulated genes.
© 2017 by the American Diabetes Association.
4 Communities
4 Members
0 Resources
18 MeSH Terms
Metabolic responses to exogenous ghrelin in obesity and early after Roux-en-Y gastric bypass in humans.
Tamboli RA, Antoun J, Sidani RM, Clements A, Harmata EE, Marks-Shulman P, Gaylinn BD, Williams B, Clements RH, Albaugh VL, Abumrad NN
(2017) Diabetes Obes Metab 19: 1267-1275
MeSH Terms: Acylation, Anti-Obesity Agents, Cohort Studies, Combined Modality Therapy, Cross-Over Studies, Energy Metabolism, Gastric Bypass, Ghrelin, Gluconeogenesis, Glucose Clamp Technique, Human Growth Hormone, Humans, Infusions, Intravenous, Insulin Resistance, Liver, Muscle, Skeletal, Obesity, Morbid, Pancreatic Polypeptide, Pancreatic Polypeptide-Secreting Cells, Pituitary Gland, Anterior, Postoperative Care, Preoperative Care, Protein Precursors, Single-Blind Method
Show Abstract · Added April 3, 2017
AIMS - Ghrelin is a gastric-derived hormone that stimulates growth hormone (GH) secretion and has a multi-faceted role in the regulation of energy homeostasis, including glucose metabolism. Circulating ghrelin concentrations are modulated in response to nutritional status, but responses to ghrelin in altered metabolic states are poorly understood. We investigated the metabolic effects of ghrelin in obesity and early after Roux-en-Y gastric bypass (RYGB).
MATERIALS AND METHODS - We assessed central and peripheral metabolic responses to acyl ghrelin infusion (1 pmol kg  min ) in healthy, lean subjects (n = 9) and non-diabetic, obese subjects (n = 9) before and 2 weeks after RYGB. Central responses were assessed by GH and pancreatic polypeptide (surrogate for vagal activity) secretion. Peripheral responses were assessed by hepatic and skeletal muscle insulin sensitivity during a hyperinsulinaemic-euglycaemic clamp.
RESULTS - Ghrelin-stimulated GH secretion was attenuated in obese subjects, but was restored by RYGB to a response similar to that of lean subjects. The heightened pancreatic polypeptide response to ghrelin infusion in the obese was attenuated after RYGB. Hepatic glucose production and hepatic insulin sensitivity were not altered by ghrelin infusion in RYGB subjects. Skeletal muscle insulin sensitivity was impaired to a similar degree in lean, obese and post-RYGB individuals in response to ghrelin infusion.
CONCLUSIONS - These data suggest that obesity is characterized by abnormal central, but not peripheral, responsiveness to ghrelin that can be restored early after RYGB before significant weight loss. Further work is necessary to fully elucidate the role of ghrelin in the metabolic changes that occur in obesity and following RYGB.
© 2017 John Wiley & Sons Ltd.
0 Communities
3 Members
0 Resources
24 MeSH Terms
Ptf1a-mediated control of Dll1 reveals an alternative to the lateral inhibition mechanism.
Ahnfelt-Rønne J, Jørgensen MC, Klinck R, Jensen JN, Füchtbauer EM, Deering T, MacDonald RJ, Wright CV, Madsen OD, Serup P
(2012) Development 139: 33-45
MeSH Terms: Animals, Basic Helix-Loop-Helix Transcription Factors, Bromodeoxyuridine, Chromatin Immunoprecipitation, Galactosides, Gene Expression Regulation, Homeodomain Proteins, Immunohistochemistry, Indoles, Intercellular Signaling Peptides and Proteins, Mice, Mice, Transgenic, Nerve Tissue Proteins, Pancreas, Pancreatic Polypeptide-Secreting Cells, Stem Cells, Transcription Factor HES-1, Transcription Factors
Show Abstract · Added November 6, 2013
Neurog3-induced Dll1 expression in pancreatic endocrine progenitors ostensibly activates Hes1 expression via Notch and thereby represses Neurog3 and endocrine differentiation in neighboring cells by lateral inhibition. Here we show in mouse that Dll1 and Hes1 expression deviate during regionalization of early endoderm, and later during early pancreas morphogenesis. At that time, Ptf1a activates Dll1 in multipotent pancreatic progenitor cells (MPCs), and Hes1 expression becomes Dll1 dependent over a brief time window. Moreover, Dll1, Hes1 and Dll1/Hes1 mutant phenotypes diverge during organ regionalization, become congruent at early bud stages, and then diverge again at late bud stages. Persistent pancreatic hypoplasia in Dll1 mutants after eliminating Neurog3 expression and endocrine development, together with reduced proliferation of MPCs in both Dll1 and Hes1 mutants, reveals that the hypoplasia is caused by a growth defect rather than by progenitor depletion. Unexpectedly, we find that Hes1 is required to sustain Ptf1a expression, and in turn Dll1 expression in early MPCs. Our results show that Ptf1a-induced Dll1 expression stimulates MPC proliferation and pancreatic growth by maintaining Hes1 expression and Ptf1a protein levels.
2 Communities
2 Members
5 Resources
18 MeSH Terms