The Lnk/Sh2b3 adaptor protein functions as a regulatory molecule for cytokine signaling in lymphohematopoiesis. A missense variant of the LNK/SH2B3 gene is reportedly a risk variant common to several ...

β-cell dysfunction and dedifferentiation towards an α-cell-like phenotype are hallmarks of type 2 diabetes. Her,e the authors detect five α-cell subpopulations, find differences between healthy and diabetic donors, and identify SMOC1 as an inducer of human β-cell dysfunction and dedifferentiation.

Aims/hypothesis The bromodomain and extra-terminal (BET) protein family acts as ‘epigenetic readers’ to identify the acetylation marks on histones that convert the acetylated lysine residues into observable phenotypes. BET proteins have gained attention due to their ability to modulate the transcription of pathology-related genes involved in cancer and autoimmune diseases, including type 1 diabetes mellitus. However, targeting BET proteins may have secondary effects on other host cells. We aimed to elucidate possible secondary effects of BET inhibition on pancreatic beta cell function. Methods We studied the effect of the small-molecule BET inhibitor I-BET151 on pancreatic beta cells in vitro, ex vivo and in vivo. GTTs, ITTs and glucose-stimulated insulin secretion assays were performed in healthy mice and a mouse model of diabetes following daily i.p. injections of I-BET151 for 2 weeks. Transcriptomic analysis was carried out on primary mouse islets, which were subjected to ex vivo I-BET151 treatment. Changes in expression were further validated in primary human islets. Results Administration of I-BET151 modestly but significantly increased glucose excursions and reduced insulin responses in both healthy mice and diabetic mice. We found that I-BET151 exposure significantly reduced the expression of Hnf4α (also known as Hnf4a; MODY1), Gck (MODY2), Hnf1α (also known as Hnf1a; MODY3), Glut2 and other genes essential for beta cell function in rat INS-1E insulinoma cells and in mouse primary islets and human islets. Global gene expression analysis in cells treated with I-BET151 showed a downregulation of the phosphoinositide-3-kinase (PI3K)–Akt pathway. Downregulation of forkhead box protein O1, a downstream transcriptional factor of the PI3K–Akt pathway, partially rescued I-BET151-driven downregulation of Gck and insulin secretion. Likewise, islets from I-BET151-treated mice showed a modest reduction in glucose-stimulated insulin secretion. Conclusions/interpretation The results presented here suggest that BET inhibition therapy should be used with caution due to possible bimodal effects at high concentrations at the detriment of pancreatic beta cell function. Graphical Abstract

The pancreas plays a central role in major human diseases, yet our understanding of its cellular diversity and plasticity remains incomplete. Here, we present a single-cell multiomics atlas of the hum...

In young people with recent-onset, clinical type 1 diabetes, 2·5 mg/kg and 0·5 mg/kg ATG reduced loss of β-cell function, showing the potential of an affordable, repurposed agent, ATG, in a low and sa...

Type 1 diabetes mellitus (T1DM) is the most common severe chronic disease in children and adolescents and requires life-long exogenous insulin treatment. Investigating key differences between the panc...

Aims/hypothesis Previous studies have indicated that 29-amino-acid glucagon (i.e. ‘pancreatic’ glucagon) circulates in totally pancreatectomised individuals and that a postprandial glucagon response can be detected. Using a glucagon receptor antagonist (GRA), we investigated the possible role of extrapancreatic glucagon on glucose, lipid and amino acid metabolism in totally pancreatectomised individuals. Method In a randomised, crossover study, nine totally pancreatectomised individuals and nine matched healthy control individuals were given, in randomised order (planned on the website www.random.org ), 300 mg GRA (LY2409021; Eli Lilly) or placebo 10 h before two 3 h OGTTs. The experiment was double-masked (i.e. both participants and investigator were masked for the type of the experimental day [day A vs day B]). The key inclusion criteria for the healthy control participants were age >18 years, normal fasting plasma glucose and HbA1c 31–44 mmol/mol (6.0–7.2%), haemoglobin >7.0 mmol/l (men) / >6.5 mmol/l (women) and informed consent. Key inclusion criteria for the pancreatectomised individuals were age >18 years, haemoglobin in the normal range and informed consent. The primary endpoint was the difference in plasma glucose excursions between study days. Results Glucagon concentrations remained unchanged from fasting concentrations during the OGTT in the totally pancreatectomised individuals on both study days and circulating glucose, lipids and amino acid levels were unaffected by treatment with LY2409021 compared with placebo. In the control group, LY2409021 resulted in relevant pharmacodynamic effects, including lower fasting plasma glucose (4.7 [0.1] vs 5.2 [0.1] mmol/l, p=0.001) and augmented concentrations of amino acids in plasma, compared with placebo. Conclusions/interpretation We conclude that inhibition of the glucagon receptor using LY2409021 during OGTT in totally pancreatectomised individuals does not produce detectable effects on glucose, lipid or amino acid metabolism, ruling out metabolic effects of extrapancreatic glucagon. Trial registration ClinicalTrials.gov (NCT02944110). Funding This study was supported by grants from the Aase and Ejnar Danielsen’s Foundation and the Novo Nordisk Foundation. Graphical Abstract

α cells can generate and secrete both glucagon and GLP-1 with distinct processing enzymes to control metabolism.

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Over 1,000 genetic variants have been associated with diabetes by genome-wide association studies (GWASs), but for most, their functional impact is un…

This study demonstrates that hyperglycemia in diabetes activates ChREBP, which epigenetically represses SCAMP5 expression in pancreatic β-cells. This SCAMP5 deficiency impairs insulin secretion by do...

The present findings provide a better understanding of the dynamics of STAT1 activation in human beta cells and will be useful to develop new and targeted (i.e. favouring individuals with particular p...