scholarly journals Human Islets Contain a Beta Cell Type That Expresses Proinsulin But Not the Enzyme That Converts the Precursor to Insulin

2020 ◽  
Vol 68 (10) ◽  
pp. 691-702
Author(s):  
Gladys Teitelman
Keyword(s):  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Cell Types ◽  
Human Islets ◽  
Cell Type ◽  
Human Beta Cells ◽  
Human Beta Cell ◽  
Cell Phenotypes

In pancreatic beta cells, proinsulin (ProIN) undergoes folding in endoplasmic reticulum/Golgi system and is translocated to secretory vesicles for processing into insulin and C-peptide by the proprotein convertases (PC)1/3 and PC2, and carboxypeptidase E. Human beta cells show significant variation in the level of expression of PC1/3, the critical proconvertase involved in proinsulin processing. To ascertain whether this heterogeneity is correlated with the level of expression of the prohormone and mature hormone, the expression of proinsulin, insulin, and PC1/3 in human beta cells was examined. This analysis identified a human beta cell type that expressed proinsulin but lacked PC1/3 (ProIN+PC1/3−). This beta cell type is absent in rodent islets and is abundant in human islets of adults but scarce in islets from postnatal donors. Human islets also contained a beta cell type that expressed both proinsulin and variable levels of PC1/3 (ProIN+PC1/3+) and a less abundant cell type that lacked proinsulin but expressed the convertase (ProIN−PC1/3+). These cell phenotypes were altered by type 2 diabetes. These data suggest that these three cell types represent different stages of a dynamic process with proinsulin folding in ProIN+PC1/3− cells, proinsulin conversion into insulin in ProIN+PC1/3+cells, and replenishment of the proinsulin content in ProIN−PC1/3+ cells:

scholarly journals Disruption of Beta-Cell Mitochondrial Networks by the Orphan Nuclear Receptor Nor1/Nr4a3

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 168 ◽  
Author(s):  
Anne-Françoise Close ◽  
Nidheesh Dadheech ◽  
Hélène Lemieux ◽  
Qian Wang ◽  
Jean Buteau
Keyword(s):  
Beta Cell ◽  
Beta Cells ◽  
Nuclear Receptor ◽  
Pancreatic Beta Cells ◽  
Orphan Nuclear Receptor ◽  
Atp Production ◽  
Human Beta Cells ◽  
Glucose Stimulated Insulin Secretion ◽  
Mitochondrial Networks

Nor1, the third member of the Nr4a subfamily of nuclear receptor, is garnering increased interest in view of its role in the regulation of glucose homeostasis. Our previous study highlighted a proapoptotic role of Nor1 in pancreatic beta cells and showed that Nor1 expression was increased in islets isolated from type 2 diabetic individuals, suggesting that Nor1 could mediate the deterioration of islet function in type 2 diabetes. However, the mechanism remains incompletely understood. We herein investigated the subcellular localization of Nor1 in INS832/13 cells and dispersed human beta cells. We also examined the consequences of Nor1 overexpression on mitochondrial function and morphology. Our results show that, surprisingly, Nor1 is mostly cytoplasmic in beta cells and undergoes mitochondrial translocation upon activation by proinflammatory cytokines. Mitochondrial localization of Nor1 reduced glucose oxidation, lowered ATP production rates, and inhibited glucose-stimulated insulin secretion. Western blot and microscopy images revealed that Nor1 could provoke mitochondrial fragmentation via mitophagy. Our study unveils a new mode of action for Nor1, which affects beta-cell viability and function by disrupting mitochondrial networks.

scholarly journals Stearoyl CoA desaturase is a gatekeeper that protects human beta cells against lipotoxicity and maintains their identity

Diabetologia ◽  
2019 ◽  
Vol 63 (2) ◽  
pp. 395-409 ◽  
Author(s):  
Masaya Oshima ◽  
Séverine Pechberty ◽  
Lara Bellini ◽  
Sven O. Göpel ◽  
Mélanie Campana ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Beta Cell ◽  
Beta Cells ◽  
Cell Identity ◽  
Human Beta Cells ◽  
Human Beta Cell ◽  
Stearoyl Coa Desaturase

Abstract Aims/hypothesis During the onset of type 2 diabetes, excessive dietary intake of saturated NEFA and fructose lead to impaired insulin production and secretion by insulin-producing pancreatic beta cells. The majority of data on the deleterious effects of lipids on functional beta cell mass were obtained either in vivo in rodent models or in vitro using rodent islets and beta cell lines. Translating data from rodent to human beta cells remains challenging. Here, we used the human beta cell line EndoC-βH1 and analysed its sensitivity to a lipotoxic and glucolipotoxic (high palmitate with or without high glucose) insult, as a way to model human beta cells in a type 2 diabetes environment. Methods EndoC-βH1 cells were exposed to palmitate after knockdown of genes related to saturated NEFA metabolism. We analysed whether and how palmitate induces apoptosis, stress and inflammation and modulates beta cell identity. Results EndoC-βH1 cells were insensitive to the deleterious effects of saturated NEFA (palmitate and stearate) unless stearoyl CoA desaturase (SCD) was silenced. SCD was abundantly expressed in EndoC-βH1 cells, as well as in human islets and human induced pluripotent stem cell-derived beta cells. SCD silencing induced markers of inflammation and endoplasmic reticulum stress and also IAPP mRNA. Treatment with the SCD products oleate or palmitoleate reversed inflammation and endoplasmic reticulum stress. Upon SCD knockdown, palmitate induced expression of dedifferentiation markers such as SOX9, MYC and HES1. Interestingly, SCD knockdown by itself disrupted beta cell identity with a decrease in mature beta cell markers INS, MAFA and SLC30A8 and decreased insulin content and glucose-stimulated insulin secretion. Conclusions/interpretation The present study delineates an important role for SCD in the protection against lipotoxicity and in the maintenance of human beta cell identity. Data availability Microarray data and all experimental details that support the findings of this study have been deposited in in the GEO database with the GSE130208 accession code.

scholarly journals The absence of H-2 antigens from mouse pancreatic beta-cells demonstrated by immunoferritin labeling.

1979 ◽  
Vol 150 (1) ◽  
pp. 1-9 ◽  
Author(s):  
E L Parr
Keyword(s):  
Endothelial Cells ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Beta Cell ◽  
Pancreatic Duct ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Acinar Cells ◽  
Cell Types ◽  
Capillary Endothelial Cells

Islets of Langerhans were isolated from mouse pancreases and fixed in periodatelysine-paraformaldehyde. The fixed islets were then dissociated with trypsin and EDTA to yield cell suspensions that contained mainly four cell types; beta-cells, capillary endothelial cells, acinar cells, and pancreatic duct epithelial cells. The nonislet cells were probably associated wtih the surface of the isolated islets. The H-2 antigens of the dissociated pancreatic cells were labeled with an immunoferritin technique. Pancreatic duct epithelial cells showed specific ferritin labeling on their lateral cell membranes but not on apical microvillus membranes. Acinar cells were also labeled on lateral membranes, and the capillary endothelial cells were labeled on both the luminal and albuminal aspects of their surface membranes. In contrast, pancreatic beta-cells were unlabeled. The number of ferritin molecules per unit length of beta-cell membrane was essentially the same on cells from the antigenic strain and the congeneic control strain, and was about 200-fold less than on the labeled pancreatic duct epithelial cell lateral membranes. Pancreatic beta-cells are therefore one of six known epithelial cell types on which H-2 antigens can not be detected by immunoferritin labeling. The apparent absence of H-2 antigens from these cells suggests a study of the viability of beta-cells in allografts of dissociated islet cells, in which the beta-cell would not be in contact with antigenic cells. Such studies might lead to a new approach to the control of diabetes mellitus by transplantation.

scholarly journals Beta Cell Autophagy in the Pathogenesis of Type 1 Diabetes

2021 ◽  
Author(s):  
Charanya Muralidharan ◽  
Amelia K Linnemann
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Potential Role ◽  
Cell Dysfunction ◽  
Unconventional Secretion ◽  
Insulin Dependent

Type 1 diabetes is an insulin-dependent, autoimmune disease where the pancreatic beta cells are destroyed resulting in hyperglycemia. This multi-factorial disease involves multiple environmental and genetic factors, and has no clear etiology. Accumulating evidence suggests that early signaling defects within the beta cells may promote a change in the local immune mileu, contributing to autoimmunity. Therefore, many studies have been focused on intrinsic beta cell mechanisms that aid in restoration of cellular homeostasis under environmental conditions that cause dysfunction. One of these intrinsic mechanisms to promote homeostasis is autophagy, defects in which are clearly linked with beta cell dysfunction in the context of type 2 diabetes. Recent studies have now also pointed towards beta cell autophagy defects in the context of type 1 diabetes. In this perspectives review, we will discuss the evidence supporting a role for beta cell autophagy in the pathogenesis of type 1 diabetes, including a potential role for unconventional secretion of autophagosomes/lysosomes in the changing dialogue between the beta cell and immune cells.

scholarly journals The hepatokine fetuin-A disrupts functional maturation of pancreatic beta cells

Diabetologia ◽  
2021 ◽  
Author(s):  
Felicia Gerst ◽  
Elisabeth Kemter ◽  
Estela Lorza-Gil ◽  
Gabriele Kaiser ◽  
Ann-Kathrin Fritz ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Human Islets ◽  
Fetuin A ◽  
Adult Human ◽  
Functional Maturation ◽  
Glucose Responsiveness

Abstract Aims/hypothesis Neonatal beta cells carry out a programme of postnatal functional maturation to achieve full glucose responsiveness. A partial loss of the mature phenotype of adult beta cells may contribute to a reduction of functional beta cell mass and accelerate the onset of type 2 diabetes. We previously found that fetuin-A, a hepatokine increasingly secreted by the fatty liver and a determinant of type 2 diabetes, inhibits glucose-stimulated insulin secretion (GSIS) of human islets. Since fetuin-A is a ubiquitous fetal glycoprotein that declines peripartum, we examined here whether fetuin-A interferes with the functional maturity of beta cells. Methods The effects of fetuin-A were assessed during in vitro maturation of porcine neonatal islet cell clusters (NICCs) and in adult human islets. Expression alterations were examined via microarray, RNA sequencing and reverse transcription quantitative real-time PCR (qRT-PCR), proteins were analysed by western blotting and immunostaining, and insulin secretion was quantified in static incubations. Results NICC maturation was accompanied by the gain of glucose-responsive insulin secretion (twofold stimulation), backed up by mRNA upregulation of genes governing beta cell identity and function, such as NEUROD1, UCN3, ABCC8 and CASR (Log2 fold change [Log2FC] > 1.6). An active TGFβ receptor (TGFBR)–SMAD2/3 pathway facilitates NICC maturation, since the TGFBR inhibitor SB431542 counteracted the upregulation of aforementioned genes and de-repressed ALDOB, a gene disallowed in mature beta cells. In fetuin-A-treated NICCs, upregulation of beta cell markers and the onset of glucose responsiveness were suppressed. Concomitantly, SMAD2/3 phosphorylation was inhibited. Transcriptome analysis confirmed inhibitory effects of fetuin-A and SB431542 on TGFβ-1- and SMAD2/3-regulated transcription. However, contrary to SB431542 and regardless of cMYC upregulation, fetuin-A inhibited beta cell proliferation (0.27 ± 0.08% vs 1.0  ± 0.1% Ki67-positive cells in control NICCs). This effect was sustained by reduced expression (Log2FC ≤ −2.4) of FOXM1, CENPA, CDK1 or TOP2A. In agreement, the number of insulin-positive cells was lower in fetuin-A-treated NICCs than in control NICCs (14.4 ± 1.2% and 22.3 ± 1.1%, respectively). In adult human islets fetuin-A abolished glucose responsiveness, i.e. 1.7- and 1.1-fold change over 2.8 mmol/l glucose in control- and fetuin-A-cultured islets, respectively. In addition, fetuin-A reduced SMAD2/3 phosphorylation and suppressed expression of proliferative genes. Of note, in non-diabetic humans, plasma fetuin-A was negatively correlated (p = 0.013) with islet beta cell area. Conclusions/interpretation Our results suggest that the perinatal decline of fetuin-A relieves TGFBR signalling in islets, a process that facilitates functional maturation of neonatal beta cells. Functional maturity remains revocable in later life, and the occurrence of a metabolically unhealthy milieu, such as liver steatosis and elevated plasma fetuin-A, can impair both function and adaptive proliferation of beta cells. Data availability The RNAseq datasets and computer code produced in this study are available in the Gene Expression Omnibus (GEO): GSE144950; https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE144950 Graphical abstract

scholarly journals Pancreatic beta-cell-type-specific expression of the rat insulin II gene is controlled by positive and negative cellular transcriptional elements.

1989 ◽  
Vol 9 (8) ◽  
pp. 3253-3259 ◽  
Author(s):  
J Whelan ◽  
D Poon ◽  
P A Weil ◽  
R Stein
Keyword(s):  
Transcription Factors ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Pancreatic Beta Cell ◽  
Cell Type ◽  
Specific Expression ◽  
Cis Acting ◽  
Cell Type Specific Expression ◽  
Cell Type Specific

The insulin gene is expressed almost exclusively in pancreatic beta-cells. The DNA sequences that control cell-specific expression are located upstream of the transcription initiation site. To identify the cis-acting transcriptional control regions within the rat insulin II gene that are responsible for this tissue-specific expression pattern, we constructed a series of 5'-flanking deletion mutants and analyzed their expression in vivo in transfected insulin-producing and -nonproducing cell lines. Pancreatic beta-cell-specific expression was shown to be controlled by enhancer sequences lying between nucleotides -342 and -91 relative to the transcription start site. The rat insulin II enhancer appears to be a chimera, composed of a number of distinct cis-acting DNA elements. Both positive and negative transcriptional regulatory elements appear to be responsible for this cell-type-specific expression. We have shown that expression from one element within the enhancer, which is found between nucleotides -100 and -91, is regulated by both positive- and negative-acting cellular transcription factors. Expression from chimeras containing only the enhancer element sequences from -100 to -91 were active only in insulin-producing cells, indicating that the positive-acting factor(s) required for this activity may be active only in beta-cells. In contrast to the enhancer region, the rat insulin II gene promoter did not appear to require cell-specific transcription factors. Promoter mutants with 5'-flanking sequences extending to nucleotides -90 and -73 were constitutively active in both insulin-producing and -nonproducing cells. These results suggest that rat insulin II gene transcription in pancreatic beta-cells is imparted by a combination of both negative- and positive-acting cellular factors interacting with the gene enhancer.

scholarly journals Imaging of Human Insulin Secreting Cells with Gd-DOTA-P88, a Paramagnetic Contrast Agent Targeting the Beta Cell Biomarker FXYD2γa

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2100 ◽  
Author(s):  
Stéphane Demine ◽  
Alexander Balhuizen ◽  
Vinciane Debaille ◽  
Lieke Joosten ◽  
Maïté Fereau ◽  
...  
Keyword(s):  
Beta Cell ◽  
Contrast Agent ◽  
Beta Cells ◽  
Cell Mass ◽  
Beta Cell Mass ◽  
Paramagnetic Contrast Agent ◽  
Biodistribution Studies ◽  
Beta Cell Line ◽  
Human Beta Cells ◽  
Human Beta Cell

Non-invasive imaging and quantification of human beta cell mass remains a major challenge. We performed pre-clinical in vivo validation of a peptide previously discovered by our group, namely, P88 that targets a beta cell specific biomarker, FXYD2γa. We conjugated P88 with DOTA and then complexed it with GdCl3 to obtain the MRI (magnetic resonance imaging) contrast agent (CA) Gd-DOTA-P88. A scrambled peptide was used as a negative control CA, namely Gd-DOTA-Scramble. The CAs were injected in immunodeficient mice implanted with EndoC-βH1 cells, a human beta cell line that expresses FXYD2γa similarly to primary human beta cells. The xenograft-bearing mice were analyzed by MRI. At the end, the mice were euthanized and the CA biodistribution was evaluated on the excised tissues by measuring the Gd concentration with inductively coupled plasma mass spectrometry (ICP-MS). The MRI and biodistribution studies indicated that Gd-DOTA-P88 accumulates in EndoC-βH1 xenografts above the level observed in the background tissue, and that its uptake is significantly higher than that observed for Gd-DOTA-Scramble. In addition, the Gd-DOTA-P88 showed good xenograft-to-muscle and xenograft-to-liver uptake ratios, two potential sites of human islets transplantation. The CA shows good potential for future use to non-invasively image implanted human beta cells.

scholarly journals The pancreatic beta cell: an intricate relation between anatomical structure, the signalling mechanism of glucose-induced insulin secretion, the low antioxidative defence, the high vulnerability and sensitivity to diabetic stress

ChemTexts ◽  
2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Sigurd Lenzen
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Islet Cell ◽  
Pancreatic Beta Cell ◽  
Cell Types ◽  
Antioxidative Defence ◽  
Islet Cell Types ◽  
Low Expression

AbstractThe biosynthesis of insulin takes place in the insulin-producing beta cells that are organized in the form of islets of Langerhans together with a few other islet cell types in the pancreas organ. The signal for glucose-induced insulin secretion is generated in two pathways in the mitochondrial metabolism of the pancreatic beta cells. These pathways are also known as the triggering pathway and the amplifying pathway. Glucokinase, the low-affinity glucose-phosphorylating enzyme in beta cell glycolysis acts as the signal-generating enzyme in this process. ATP ultimately generated is the crucial second messenger in this process. Insulin-producing pancreatic beta cells are badly protected against oxidative stress resulting in a particular vulnerability of this islet cell type due to low expression of H2O2-inactivating enzymes in various subcellular locations, specifically in the cytosol, mitochondria, peroxisomes and endoplasmic reticulum. This is in contrast to the glucagon-producing alpha cells and other islet cell types in the islets that are well equipped with these H2O2-inactivating enzymes. On the other hand the membranes of the pancreatic beta cells are well protected against lipid peroxidation and ferroptosis through high level expression of glutathione peroxidase 4 (GPx4) and this again is at variance from the situation in the non-beta cells of the islets with a low expression level of GPx4. The weak antioxidative defence equipment of the pancreatic beta cells, in particular in states of disease, is very dangerous because the resulting particular vulnerability endangers the functionality of the beta cells, making people prone to the development of a diabetic metabolic state.

scholarly journals Investigation of the utility of the 1.1B4 cell as a model human beta cell line for study of persistent enteroviral infection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jessica R. Chaffey ◽  
Jay Young ◽  
Kaiyven A. Leslie ◽  
Katie Partridge ◽  
Pouria Akhbari ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Beta Cell ◽  
Cell Line ◽  
Beta Cells ◽  
Cell Cultures ◽  
Enteroviral Infection ◽  
Beta Cell Line ◽  
Human Beta Cells ◽  
Human Beta Cell

AbstractThe generation of a human pancreatic beta cell line which reproduces the responses seen in primary beta cells, but is amenable to propagation in culture, has long been an important goal in diabetes research. This is particularly true for studies focussing on the role of enteroviral infection as a potential cause of beta-cell autoimmunity in type 1 diabetes. In the present work we made use of a clonal beta cell line (1.1B4) available from the European Collection of Authenticated Cell Cultures, which had been generated by the fusion of primary human beta-cells with a pancreatic ductal carcinoma cell, PANC-1. Our goal was to study the factors allowing the development and persistence of a chronic enteroviral infection in human beta-cells. Since PANC-1 cells have been reported to support persistent enteroviral infection, the hybrid 1.1B4 cells appeared to offer an ideal vehicle for our studies. In support of this, infection of the cells with a Coxsackie virus isolated originally from the pancreas of a child with type 1 diabetes, CVB4.E2, at a low multiplicity of infection, resulted in the development of a state of persistent infection. Investigation of the molecular mechanisms suggested that this response was facilitated by a number of unexpected outcomes including an apparent failure of the cells to up-regulate certain anti-viral response gene products in response to interferons. However, more detailed exploration revealed that this lack of response was restricted to molecular targets that were either activated by, or detected with, human-selective reagents. By contrast, and to our surprise, the cells were much more responsive to rodent-selective reagents. Using multiple approaches, we then established that populations of 1.1B4 cells are not homogeneous but that they contain a mixture of rodent and human cells. This was true both of our own cell stocks and those held by the European Collection of Authenticated Cell Cultures. In view of this unexpected finding, we developed a strategy to harvest, isolate and expand single cell clones from the heterogeneous population, which allowed us to establish colonies of 1.1B4 cells that were uniquely human (h1.1.B4). However, extensive analysis of the gene expression profiles, immunoreactive insulin content, regulated secretory pathways and the electrophysiological properties of these cells demonstrated that they did not retain the principal characteristics expected of human beta cells. Our data suggest that stocks of 1.1B4 cells should be evaluated carefully prior to their use as a model human beta-cell since they may not retain the phenotype expected of human beta-cells.

scholarly journals Arginase 2 and Polyamines in Human Pancreatic Beta Cells: Possible Role in the Pathogenesis of Type 2 Diabetes

2021 ◽  
Vol 22 (22) ◽  
pp. 12099
Author(s):  
Lorella Marselli ◽  
Emanuele Bosi ◽  
Carmela De Luca ◽  
Silvia Del Guerra ◽  
Marta Tesi ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Beta Cell ◽  
Beta Cells ◽  
Beta Cell Function ◽  
Pancreatic Beta Cells ◽  
Cell Function ◽  
Pancreas Development ◽  
Tissue Specific

Arginase 2 (ARG2) is a manganese metalloenzyme involved in several tissue specific processes, from physiology to pathophysiology. It is variably expressed in extra-hepatic tissues and is located in the mitochondria. In human pancreatic beta cells, ARG2 is downregulated in type 2 diabetes. The enzyme regulates the synthesis of polyamines, that are involved in pancreas development and regulation of beta cell function. Here, we discuss several features of ARG2 and polyamines, which can be relevant to the pathophysiology of type 2 diabetes.

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