Faculty Opinions recommendation of Conversion of adult pancreatic alpha-cells to beta-cells after extreme beta-cell loss.

Background/Aims: The lack of available beta cells greatly limits the use of beta cell transplantation as a therapy for diabetes. Thus, generation of beta cells from other sources is substantially required. Pax4 has been shown to induce reprograming of alpha cells into beta cells during embryogenesis. Nevertheless, whether expression of Pax4 in adult alpha cells could trigger this alpha-to-beta cell reprogramming is unknown. Methods: Here we generated an adeno-associated virus carrying Pax4 and GFP under a CMV promoter (AAV-Pax4). We used AAV-Pax4 to transduce a mouse alpha cell line in vitro, and to transduce primary alpha cells in diabetic mice. Reprogramming was examined by double immunostaining and by changes in beta cell number. The effects on blood glucose were evaluated by fasting blood glucose and glucose response. Results: In vitro, Pax4 overexpression neither induced insulin expression, nor suppressed glucagon expression in alpha cells. In vivo, Pax4 overexpression failed to increase beta cell number, and did not alter hyperglycemia and glucose response in diabetic mice. Conclusion: Pax4 expression is not sufficient to transduce pancreatic alpha cells into beta cells. Overexpression of Pax4 in alpha cells may not increase functional beta cell number in diabetic patients.

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Up-regulation of clusterin (sulfated glycoprotein-2) in pancreatic islet cells upon streptozotocin injection to rats

Journal of Endocrinology ◽

10.1677/joe.0.1620057 ◽

1999 ◽

Vol 162 (1) ◽

pp. 57-65 ◽

Cited By ~ 15

Author(s):

IS Park ◽

YZ Che ◽

M Bendayan ◽

SW Kang ◽

BH Min

Keyword(s):

Cell Death ◽

Embryonic Development ◽

Beta Cell ◽

Beta Cells ◽

Endocrine Cells ◽

Morphological Alteration ◽

Alpha Cells ◽

Pancreatic Alpha Cells ◽

Tissue Reorganization ◽

Clusterin Expression

Clusterin is a heterodimeric glycoprotein which has been shown to play important roles in programmed cell death and/or in tissue reorganization not only during embryonic development but also in damaged tissues. Recently, we reported the transient induction of clusterin in pancreatic endocrine cells during early developmental stages of islet formation. In the present study, we have investigated the expression of clusterin in pancreatic tissue of streptozotocin-treated rats which were undergoing extensive islet tissue reorganization due to degeneration of insulin beta cells. Clusterin was found in endocrine cells identified as glucagon-secreting alpha cells at the periphery of the islet. Using immunoelectron microscopy, clusterin-positive cells showed the typical ultrastructural features of pancreatic alpha cells. In addition, colocalization of clusterin and glucagon in the same secretory granules was shown by double immunogold labeling. These results imply that clusterin is a secretory molecule having endocrine and/or paracrine actions in parallel with glucagon. Further, we noted that clusterin expression was increased in pancreatic alpha cells during the process of beta cell death upon streptozotocin injection. The increase was significant as early as 1-3 h after streptozotocin treatment prior to any morphological alteration of islet beta cell and any manifestation of hyperglycemia. The expression of clusterin was steady-stately up-regulated during the process of islet reorganization caused by streptozotocin-induced cytotoxic injury. Therefore, we suggest that clusterin might be considered as a molecule induced by both embryonic development and drug-induced reorganization of the endocrine pancreas. Since clusterin expression is up-regulated in alpha cells, but not in beta cells undergoing degeneration, it may play a protective role against the cytotoxic insult.

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Mitochondrial and insulin gene expression in single cells shape pancreatic beta cells’ population divergence

10.1101/2020.07.21.213801 ◽

2020 ◽

Author(s):

H. Medini ◽

T. Cohen ◽

D. Mishmar

Keyword(s):

Gene Expression ◽

Beta Cell ◽

Beta Cells ◽

Pancreatic Beta Cells ◽

Single Cells ◽

Insulin Gene ◽

Population Divergence ◽

Cell Populations ◽

Alpha Cells ◽

Insulin Gene Expression

AbstractMitochondrial gene expression is pivotal to cell metabolism. Nevertheless, it is unknown whether it diverges within a given cell type. Here, we analysed single-cell RNA-seq experiments from ∼4600 human pancreatic alpha and beta cells, as well as ∼900 mouse beta cells. Cluster analysis revealed two distinct human beta cells populations, which diverged by mitochondrial (mtDNA) and nuclear DNA (nDNA)-encoded oxidative phosphorylation (OXPHOS) gene expression in healthy and diabetic individuals, and in newborn but not in adult mice. Insulin gene expression was elevated in beta cells with higher mtDNA gene expression in humans and in young mice. Such human beta cell populations also diverged in mt-RNA mutational repertoire, and in their selective signature, thus implying the existence of two previously overlooked distinct and conserved beta cell populations. While applying our approach to alpha cells, two sub-populations of cells were identified which diverged in mtDNA gene expression, yet these cellular populations did not consistently diverge in nDNA OXPHOS genes expression, nor did they correlate with the expression of glucagon, the hallmark of alpha cells. Thus, pancreatic beta cells within an individual are divided into distinct groups with unique metabolic-mitochondrial signature.

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Efficient induction of pancreatic alpha cells from human induced pluripotent stem cells by controlling the timing for BMP antagonism and activation of retinoic acid signaling

PLoS ONE ◽

10.1371/journal.pone.0245204 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0245204

Author(s):

Shigeharu G. Yabe ◽

Satsuki Fukuda ◽

Junko Nishida ◽

Fujie Takeda ◽

Kiyoko Nashiro ◽

...

Keyword(s):

Stem Cells ◽

Retinoic Acid ◽

Cell Fate ◽

Beta Cells ◽

Pluripotent Stem Cells ◽

Pancreatic Beta Cells ◽

Alpha Cells ◽

Retinoic Acid Signaling ◽

Pancreatic Alpha Cells ◽

Efficient Induction

Diabetes mellitus is caused by breakdown of blood glucose homeostasis, which is maintained by an exquisite balance between insulin and glucagon produced respectively by pancreatic beta cells and alpha cells. However, little is known about the mechanism of inducing glucagon secretion from human alpha cells. Many methods for generating pancreatic beta cells from human pluripotent stem cells (hPSCs) have been reported, but only two papers have reported generation of pancreatic alpha cells from hPSCs. Because NKX6.1 has been suggested as a very important gene for determining cell fate between pancreatic beta and alpha cells, we searched for the factors affecting expression of NKX6.1 in our beta cell differentiation protocols. We found that BMP antagonism and activation of retinoic acid signaling at stage 2 (from definitive endoderm to primitive gut tube) effectively suppressed NKX6.1 expression at later stages. Using two different hPSCs lines, treatment with BMP signaling inhibitor (LDN193189) and retinoic acid agonist (EC23) at Stage 2 reduced NKX6.1 expression and allowed differentiation of almost all cells into pancreatic alpha cells in vivo after transplantation under a kidney capsule. Our study demonstrated that the cell fate of pancreatic cells can be controlled by adjusting the expression level of NKX6.1 with proper timing of BMP antagonism and activation of retinoic acid signaling during the pancreatic differentiation process. Our method is useful for efficient induction of pancreatic alpha cells from hPSCs.

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In vitro reprogramming of pancreatic alpha cells towards a beta cell phenotype following ectopic HNF4α expression

Molecular and Cellular Endocrinology ◽

10.1016/j.mce.2014.09.009 ◽

2015 ◽

Vol 399 ◽

pp. 50-59 ◽

Cited By ~ 14

Author(s):

Caroline B. Sangan ◽

Ramiro Jover ◽

Harry Heimberg ◽

David Tosh

Keyword(s):

Beta Cell ◽

Cell Phenotype ◽

Alpha Cells ◽

Pancreatic Alpha Cells

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Alpha cell regulation of beta cell function

Diabetologia ◽

10.1007/s00125-020-05196-3 ◽

2020 ◽

Vol 63 (10) ◽

pp. 2064-2075

Author(s):

Tilo Moede ◽

Ingo B. Leibiger ◽

Per-Olof Berggren

Keyword(s):

Blood Glucose ◽

Beta Cell ◽

Beta Cells ◽

Endocrine Cell ◽

Beta Cell Function ◽

Cell Function ◽

Cell Types ◽

Alpha Cell ◽

Alpha Cells

Abstract The islet of Langerhans is a complex endocrine micro-organ consisting of a multitude of endocrine and non-endocrine cell types. The two most abundant and prominent endocrine cell types, the beta and the alpha cells, are essential for the maintenance of blood glucose homeostasis. While the beta cell produces insulin, the only blood glucose-lowering hormone of the body, the alpha cell releases glucagon, which elevates blood glucose. Under physiological conditions, these two cell types affect each other in a paracrine manner. While the release products of the beta cell inhibit alpha cell function, the alpha cell releases factors that are stimulatory for beta cell function and increase glucose-stimulated insulin secretion. The aim of this review is to provide a comprehensive overview of recent research into the regulation of beta cell function by alpha cells, focusing on the effect of alpha cell-secreted factors, such as glucagon and acetylcholine. The consequences of differences in islet architecture between species on the interplay between alpha and beta cells is also discussed. Finally, we give a perspective on the possibility of using an in vivo imaging approach to study the interactions between human alpha and beta cells under in vivo conditions.

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Inherent Beta Cell Dysfunction Contributes to Autoimmune Susceptibility

Biomolecules ◽

10.3390/biom11040512 ◽

2021 ◽

Vol 11 (4) ◽

pp. 512

Author(s):

Yong Kyung Kim ◽

Lori Sussel ◽

Howard W. Davidson

Keyword(s):

Insulin Secretion ◽

Beta Cell ◽

Beta Cells ◽

Pancreatic Beta Cell ◽

Cell Loss ◽

The Body ◽

Beta Cell Dysfunction ◽

Metabolic Characteristics ◽

Cell Dysfunction ◽

Glucose Stimulated Insulin Secretion

The pancreatic beta cell is a highly specialized cell type whose primary function is to secrete insulin in response to nutrients to maintain glucose homeostasis in the body. As such, the beta cell has developed unique metabolic characteristics to achieve functionality; in healthy beta cells, the majority of glucose-derived carbons are oxidized and enter the mitochondria in the form of pyruvate. The pyruvate is subsequently metabolized to induce mitochondrial ATP and trigger the downstream insulin secretion response. Thus, in beta cells, mitochondria play a pivotal role in regulating glucose stimulated insulin secretion (GSIS). In type 2 diabetes (T2D), mitochondrial impairment has been shown to play an important role in beta cell dysfunction and loss. In type 1 diabetes (T1D), autoimmunity is the primary trigger of beta cell loss; however, there is accumulating evidence that intrinsic mitochondrial defects could contribute to beta cell susceptibility during proinflammatory conditions. Furthermore, there is speculation that dysfunctional mitochondrial responses could contribute to the formation of autoantigens. In this review, we provide an overview of mitochondrial function in the beta cells, and discuss potential mechanisms by which mitochondrial dysfunction may contribute to T1D pathogenesis.

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Characterization of the endocrine pancreas in Type 1 Diabetes: islet size is maintained but islet number is markedly reduced

10.1101/480509 ◽

2018 ◽

Cited By ~ 2

Author(s):

Peter Seiron ◽

Anna Wiberg ◽

Lars Krogvold ◽

Frode Lars Jahnsen ◽

Knut Dahl-Jørgensen ◽

...

Keyword(s):

Type 1 Diabetes ◽

Beta Cell ◽

Beta Cells ◽

Cell Mass ◽

Beta Cell Mass ◽

Cell Loss ◽

Recent Onset ◽

Islet Size ◽

Pancreas Volume

AbstractInsulin deficiency in type 1 diabetes (T1D) is generally considered a consequence of specific beta-cell loss. Since healthy pancreatic islets consist of ~65% beta cells, this would lead to reduced islet size if the beta cells are not replaced by other cells or tissue. The number of islets per pancreas volume (islet density) would not be affected.In this study, we compared the islet density, size, and size distribution in subjects with recent-onset or long-standing T1D, with that in matched non-diabetic subjects. Results show that subjects with T1D, regardless of disease duration, had a dramatically reduced islet number per mm2, while the islet size was similar in all groups. Insulin-negative islets in T1D subjects were dominated by glucagon-positive cells that frequently had lost the alpha-cell transcription factor ARX while instead expressing PDX1, normally expressed in beta cells.Based on our findings, we propose that failure during childhood to establish a sufficient islet number to reach the beta-cell mass needed to cope with episodes of increased insulin demand contributes to T1D susceptibility. Exhaustion induced by relative lack of beta cells could then potentially drive beta-cell dedifferentiation to alpha-cells, explaining the preserved islet size observed in T1D compared to controls.

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Serum miR-204 is an early biomarker of type 1 diabetes-associated pancreatic beta-cell loss

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00122.2019 ◽

2019 ◽

Vol 317 (4) ◽

pp. E723-E730 ◽

Cited By ~ 6

Author(s):

Guanlan Xu ◽

Lance A. Thielen ◽

Junqin Chen ◽

Truman B. Grayson ◽

Tiffany Grimes ◽

...

Keyword(s):

Type 1 Diabetes ◽

Beta Cell ◽

Beta Cells ◽

Cell Function ◽

Pancreatic Beta Cell ◽

Cell Loss ◽

Human Islets ◽

Serum Samples ◽

Early Biomarker

Pancreatic beta-cell death is a major factor in the pathogenesis of type 1 diabetes (T1D), but straightforward methods to measure beta-cell loss in humans are lacking, underlining the need for novel biomarkers. Using studies in INS-1 cells, human islets, diabetic mice, and serum samples of subjects with T1D at different stages, we have identified serum miR-204 as an early biomarker of T1D-associated beta-cell loss in humans. MiR-204 is a highly enriched microRNA in human beta-cells, and we found that it is released from dying beta-cells and detectable in human serum. We further discovered that serum miR-204 was elevated in children and adults with T1D and in autoantibody-positive at-risk subjects but not in type 2 diabetes or other autoimmune diseases and was inversely correlated with remaining beta-cell function in recent-onset T1D. Thus, serum miR-204 may provide a much needed novel approach to assess early T1D-associated human beta-cell loss even before onset of overt disease.

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