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Type 2 diabetes (T2D) is associated with compromised identity of insulin-producing pancreatic islet β cells, characterized by inappropriate production of other islet cell-enriched hormones. Here, we examined how hormone misexpression was influenced by the MAFA and MAFB transcription factors, closely related proteins that maintain islet cell function. Mice specifically lacking MafA in β cells demonstrated broad, population-wide changes in hormone gene expression with an overall gene signature closely resembling islet gastrin+ (Gast+) cells generated under conditions of chronic hyperglycemia and obesity. A human β cell line deficient in MAFB, but not one lacking MAFA, also produced a GAST+ gene expression pattern. In addition, GAST was detected in human T2D β cells with low levels of MAFB. Moreover, evidence is provided that human MAFB can directly repress GAST gene transcription. These results support a potentially novel, species-specific role for MafA and MAFB in maintaining adult mouse and human β cell identity, respectively. Here, we discuss the possibility that induction of Gast/GAST and other non-β cell hormones, by reduction in the levels of these transcription factors, represents a dysfunctional β cell signature.

BackgroundThe pancreatic β cell, as the sole source of the vital hormone insulin, has been under intensive study for more than a century. Given the potential of newly created insulin-producing cells as a treatment or even cure of type 1 diabetes (T1D) and possibly in severe cases of type 2 diabetes (T2D), multiple academic and commercial laboratories are working to derive surrogate glucose-responsive, insulin-producing cells.Scope of reviewThe recent development of advanced phenotyping technologies, including molecular, epigenomic, histological, or functional, have greatly improved our understanding of the critical properties of human β cells. Using this information, here we summarize the salient features of normal, fully functional adult human β cells, and propose minimal criteria for what should rightfully be termed 'β cells' as opposed to insulin-producing but not fully-functional surrogates that we propose should be referred to as 'β-like' cells or insulin-producing cells.Major conclusionsClear criteria can be established to differentiate fully functional, mature β cells from 'β-like' surrogates. In addition, we outline important knowledge gaps that must be addressed to enable a greater understanding of the β cell.

BACKGROUND. Accurate detection of graft-versus-host disease (GVHD) is a major challenge in the management of patients undergoing hematopoietic stem cell transplantation (HCT). Here, we demonstrated the use of circulating cell-free DNA (cfDNA) for detection of tissue turnover and chronic GVHD (cGVHD) in specific organs. METHODS. We established a cocktail of tissue-specific DNA methylation markers and used it to determine the concentration of cfDNA molecules derived from the liver, skin, lungs, colon, and specific immune cells in 101 patients undergoing HCT. RESULTS. Patients with active cGVHD showed elevated concentrations of cfDNA, as well as tissue-specific methylation markers that agreed with clinical scores. Strikingly, transplanted patients with no clinical symptoms had abnormally high levels of tissue-specific markers, suggesting hidden tissue turnover even in the absence of evident clinical pathology. An integrative model taking into account total cfDNA concentration, monocyte/macrophage cfDNA levels and alanine transaminase was able to correctly identify GVHD with a specificity of 86% and precision of 89% (AUC of 0.8). CONCLUSION. cfDNA markers can be used for the detection of cGVHD, opening a window into underlying tissue dynamics in patients that receive allogeneic stem cell transplants. FUNDING. This work was supported by grants from the Ernest and Bonnie Beutler Research Program of Excellence in Genomic Medicine, The Israel Science Foundation, the Waldholtz/Pakula family, the Robert M. and Marilyn Sternberg Family Charitable Foundation and the Helmsley Charitable Trust (to YD)., Introduction Hematopoietic stem cell transplantation (HCT) is an essential and often the sole curative treatment strategy for high risk hematologic malignancies (1). Graft-versus-host disease (GVHD), the foremost complication of allogeneic [...]

This article has been retracted; see accompanying Retraction Note, which can be accessed via a link at the top of the paper.

Pancreatic beta cells (β-cells) differentiate during fetal life, but only postnatally acquire the capacity for glucose-stimulated insulin secretion (GSIS). How this happens is not clear. In exploring what molecular mechanisms drive the maturation of β-cell function, we found that the control of cellular signaling in β-cells fundamentally switched from the nutrient sensor target of rapamycin (mTORC1) to the energy sensor 5'-adenosine monophosphate-activated protein kinase (AMPK), and that this was critical for functional maturation. Moreover, AMPK was activated by the dietary transition taking place during weaning, and this in turn inhibited mTORC1 activity to drive the adult β-cell phenotype. While forcing constitutive mTORC1 signaling in adult β-cells relegated them to a functionally immature phenotype with characteristic transcriptional and metabolic profiles, engineering the switch from mTORC1 to AMPK signaling was sufficient to promote β-cell mitochondrial biogenesis, a shift to oxidative metabolism, and functional maturation. We also found that type 2 diabetes, a condition marked by both mitochondrial degeneration and dysregulated GSIS, was associated with a remarkable reversion of the normal AMPK-dependent adult β-cell signature to a more neonatal one characterized by mTORC1 activation. Manipulating the way in which cellular nutrient signaling pathways regulate β-cell metabolism may thus offer new targets to improve β-cell function in diabetes.

Assessment of pancreas cell type composition is crucial to the understanding of the genesis of diabetes. Current approaches use immunodetection of protein markers, for example, insulin as a marker of b-cells. A major limitation of thesemethods is that protein content varies in physiological and pathological conditions, complicating the extrapolation to actual cell number. Here, we demonstrate the use of cell type-specific DNAmethylationmarkers for determining the fraction of specific cell types in human islet and pancreas specimens. We identified genomic loci that are uniquely demethylated in specific pancreatic cell types and applied targeted PCR to assess the methylation status of these loci in tissue samples, enabling inference of cell type composition. In islet preparations, normalization of insulin secretion to b-cell DNA revealed similar b-cell function in pre-type 1 diabetes (T1D), T1D, and type 2 diabetes (T2D), which was significantly lower than in donors without diabetes. In histological pancreas specimens from recent-onset T1D, this assay showed b-cell fraction within the normal range, suggesting a significant contribution of b-cell dysfunction. In T2D pancreata, we observed increased a-cell fraction and normal b-cell fraction. Methylation-based analysis provides an accurate molecular alternative to immune detection of cell types in the human pancreas, with utility in the interpretation of insulin secretion assays and the assessment of pancreas cell composition in health and disease. [ABSTRACT FROM AUTHOR]

Pancreatic [beta] cells differentiate during fetal life, but only postnatally acquire the capacity for glucose- stimulated insulin secretion (GSIS). How this happens is not clear. In exploring what molecular mechanisms drive the maturation of [beta] cell function, we found that the control of cellular signaling in [beta] cells fundamentally switched from the nutrient sensor target of rapamycin (mTORC1) to the energy sensor 5'-adenosine monophosphate- activated protein kinase (AMPK), and that this was critical for functional maturation. Moreover, AMPK was activated by the dietary transition taking place during weaning, and this in turn inhibited mTORC1 activity to drive the adult [beta] cell phenotype. While forcing constitutive mTORC1 signaling in adult [beta] cells relegated them to a functionally immature phenotype with characteristic transcriptional and metabolic profiles, engineering the switch from mTORC1 to AMPK signaling was sufficient to promote [beta] cell mitochondrial biogenesis, a shift to oxidative metabolism, and functional maturation. We also found that type 2 diabetes, a condition marked by both mitochondrial degeneration and dysregulated GSIS, was associated with a remarkable reversion of the normal AMPK-dependent adult [beta] cell signature to a more neonatal one characterized by mTORC1 activation. Manipulating the way in which cellular nutrient signaling pathways regulate [beta] cell metabolism may thus offer new targets to improve [beta] cell function in diabetes., Introduction During the neonatal period, pancreatic islets progressively lose their proliferative capacity and develop instead the capacity for highly sensitive and robust glucose-stimulated insulin secretion (GSIS) (1). This functional maturation [...]

During the first wave of COVID‐19 worldwide pandemic, the number of testing in Israel was severely affected by the shortage of reagents and consumables required to operate the instrument performing the sample extraction before the reverse transcription‐polymerase chain reaction (RT‐PCR), namely QIAsymphony instrument (Qiagen, Hilden, Germany). We aimed to develop an assay to clean used plastic ware parts while maintaining the reliability and reproducibility of the RT‐PCR testing. Wells, rods cover, and tips used by the QIAsymphony instrument were washed using distilled water, 3% sodium hypochlorite or sodium hydroxide 0.01 M solutions, followed by an additional wash using distilled water and eventually using 3% hydrogen peroxide or ethanol solution. Following overnight drying, the cleaned parts were installed in the QIAsymphony instrument, and the reliability of the results was compared to the set of samples that were analyzed using a new plastic ware. The results of reusing the cleaned sets of consumables were comparable to those of the new sets. [ABSTRACT FROM AUTHOR]