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

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.

Download Full-text

Follow-up Study of the Revascularization Process of Purified Rat Islet Beta-Cell Grafts

Cell Transplantation ◽

10.1177/096368979700600609 ◽

1997 ◽

Vol 6 (6) ◽

pp. 603-612 ◽

Cited By ~ 7

Author(s):

José F. Mendola ◽

Ignacio Conget ◽

José María Manzanares ◽

Helena Corominola ◽

Odette Viñas ◽

...

Keyword(s):

Endothelial Cells ◽

Beta Cell ◽

Beta Cells ◽

Islet Cell ◽

Follow Up Study ◽

Major Process ◽

Indirect Immunofluorescence Technique ◽

Capillary Endothelial Cells ◽

Cells Cultured

The revascularization of islets of Langerhans transplanted in heterotopic sites like the liver by portal vein embolization or the renal subcapsular space is a major process necessary for the viability of grafted cells. This process has been extensively studied by different techniques and the results have shown that islet revascularization is an early phenomenon that takes place soon after transplantation. In this report we have analyzed by a double indirect immunofluorescence technique, the revascularization process of purified endocrine islet beta-cells transplanted in the renal subcapsular space of syngeneic rats. Lewis rats were grafted with islets cultured for 24 h, with a suspension of purified beta-cells cultured for 24 h, and with a suspension of purified beta plus nonbeta-cells cultured for 24 h. Rats were killed at different days after implantation and the kidney bearing the grafts were snap frozen and immunohistochemically stained with a rabbit anti factor VIII antiserum (which labels endothelial cells). Immunocytochemical analysis revealed that cultured islets completed revascularization by days 3-5 after transplantation, as shown by the detection of capillary endothelial cells within and surrounding the islets. Within purified endocrine beta-cell grafts, the presence of numerous endothelial cells was not observed until days 10-14, indicating that revascularization of beta-cells with host vessels is not such an early phenomenon as it takes place in whole isolated islets. Conversely, the addition of a population of endocrine nonbeta-cells to the purified islet cell grafts, partially accelerated the revascularization of pure beta-cell grafts, which showed the presence of abundant capillary endothelial cells already at day 7 after transplantation, indicating that some other unidentified factors besides the absence of endothelial cells may explain the retardation of beta-cell grafts revascularization.

Download Full-text

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 ◽

10.1007/s40828-021-00140-3 ◽

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.

Download Full-text

An ultrastructural study of isolated small vessel endothelial and choroid plexus epithelial cells of ovine brain

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100085113 ◽

1991 ◽

Vol 49 ◽

pp. 162-163

Author(s):

L. Faso ◽

R.S. Trowbridge ◽

R.C. Moretz ◽

H.M. Wisniewski

Keyword(s):

Endothelial Cells ◽

Epithelial Cells ◽

Choroid Plexus ◽

Cell Types ◽

Small Vessel ◽

Selective Permeability ◽

Capillary Endothelial Cells ◽

Pinocytotic Vesicles ◽

Choroid Plexus Epithelial

Homeostasis in the central nervous system is maintained by two selective permeability barriers: the blood brain barrier (BBB), made up of capillary endothelial cells (ECs) and the blood cerebral spinal fluid barrier composed of specialized cuboidal epithelial (Ep) cells. The ECs of the BBB contain few profiles of trans-cellular pinocytotic vesicles and form a band of intercellular zonular occludens (ZO) sealing adjacent cells. Choroid plexus Ep cells have on their free surfaces microvilli that are irregularly oriented and expanded at the tips. They also contain juxtaluminal ZO which seal the intercellular spaces. Two cell types, small vessel endothelial cells (ECl) and choroid plexus epithelial cells (SCP), were isolated from ovine brain and established as cell strains. These cells were examined with scanning (SEM) and transmission electron microscopy (TEM) to determine if they retain the features characteristic of the cells in vivo.

Download Full-text

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

Journal of Histochemistry & Cytochemistry ◽

10.1369/0022155420961361 ◽

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:

Download Full-text

Expression of murine STF-1, a putative insulin gene transcription factor, in beta cells of pancreas, duodenal epithelium and pancreatic exocrine and endocrine progenitors during ontogeny

Development ◽

10.1242/dev.121.1.11 ◽

1995 ◽

Vol 121 (1) ◽

pp. 11-18 ◽

Cited By ~ 10

Author(s):

Y. Guz ◽

M.R. Montminy ◽

R. Stein ◽

J. Leonard ◽

L.W. Gamer ◽

...

Keyword(s):

Epithelial Cells ◽

Beta Cell ◽

Cell Fate ◽

Beta Cells ◽

Protein S ◽

Cell Types ◽

Homeodomain Protein ◽

Pancreatic Cell ◽

Precursor Pool ◽

Islet Cell Types

The XlHbox 8 homeodomain protein of Xenopus and STF-1, its mammalian homolog, are selectively expressed by beta cells of adult mouse pancreatic islets, where they are likely to regulate insulin expression. We sought to determine whether the expression of the homeobox protein/s during mouse embryonic development was specific to beta cells or, alternatively, whether XlHbox 8/STF-1 protein/s were initially expressed by multipotential precursors and only later became restricted to the insulin-containing cells. With two antibodies, we studied the localization of STF-1 during murine pancreatic development. In embryos, as in adults, STF-1 was expressed by most beta cells, by subsets of the other islet cell types and by mucosal epithelial cells of the duodenum. In addition, most epithelial cells of the pancreatic duct and exocrine cells of the pancreas transiently contained STF-1. We conclude that in mouse, STF-1 not only labels a domain of intestinal epithelial cells but also provides a spatial and temporal marker of endodermal commitment to a pancreatic and subsequently, to an endocrine beta cell fate. We propose a model of pancreatic cell development that suggests that exocrine and endocrine (alpha, beta, delta and PP) cells arise from a common precursor pool of STF-1+ cells and that progression towards a defined monospecific non-beta cell type is correlated with loss of STF-1 expression.

Download Full-text

Kallikrein in rat pancreatic tissue after beta cell destruction or acinar cell atrophy.

Journal of Histochemistry & Cytochemistry ◽

10.1177/29.12.6798105 ◽

1981 ◽

Vol 29 (12) ◽

pp. 1431-1436 ◽

Cited By ~ 5

Author(s):

T B Orstavik ◽

I B Brekke ◽

J Alumets ◽

O A Carretero

Keyword(s):

Beta Cell ◽

Beta Cells ◽

Acinar Cell ◽

Pancreatic Beta Cells ◽

Exocrine Pancreas ◽

Acinar Cells ◽

Beta Cell Destruction ◽

Cell Destruction ◽

Duct Occlusion ◽

Cell Atrophy

The purpose of this study was to determine whether glandular kallikrein in rat pancreas is located in the beta cells of the endocrine pancreas or in the acinar cells of the exocrine pancreas. Kallikrein was measured by radial immunodiffusion and a direct radioimmunoassay in homogenates of pancreas obtained from 1) control rats, 2) rats with pancreatic beta cells selectively destroyed by streptozotocin, and 3) rats with acinar cell atrophy induced by pancreatic duct occlusion. Beta cell destruction was confirmed by the presence of hyperglycemia and by an almost total depletion of insulin-producing cells as demonstrated immunohistochemically. Acinar cell atrophy was confirmed histologically and by an almost total depletion of trypsin-like enzymes in pancreatic homogenates. The concentration of kallikrein in pancreatic homogenates was unchanged after beta cell destruction, whereas it was greatly decreased following acinar cell atrophy. Kallikrein was, by immunohistochemistry, demonstrated in the acinar cell only. The immunohistochemical localization of kallikrein agrees with the above results. These studies strongly indicate that kallikrein is predominantly located in the acinar cells of the exocrine pancreas.

Download Full-text

Stronger control of ATP/ADP by proton leak in pancreatic β-cells than skeletal muscle mitochondria

Biochemical Journal ◽

10.1042/bj20051280 ◽

2005 ◽

Vol 393 (1) ◽

pp. 151-159 ◽

Cited By ~ 43

Author(s):

Charles Affourtit ◽

Martin D. Brand

Keyword(s):

Skeletal Muscle ◽

Membrane Potential ◽

Beta Cell ◽

Beta Cells ◽

Pancreatic Beta Cells ◽

Respiratory Activity ◽

Cell Types ◽

Proton Leak ◽

Control Analysis ◽

Β Cells

Pancreatic beta cells respond to rising blood glucose concentrations by increasing their oxidative metabolism, which leads to an increased ATP/ADP ratio, closure of KATP channels, depolarization of the plasma membrane potential, influx of calcium and the eventual secretion of insulin. Such a signalling mechanism implies that the ATP/ADP ratio is flexible in beta cells (β-cells), which is in contrast with other cell types (e.g. muscle and liver) that maintain a stable ATP/ADP poise while respiring at widely varying rates. To determine whether this difference in flexibility is accounted for by mitochondrial peculiarities, we performed a top-down metabolic control analysis to quantitatively assess how ATP/ADP is controlled in mitochondria isolated from rat skeletal muscle and cultured beta cells. We show that the ATP/ADP ratio is more strongly controlled (approx. 7.5-fold) by proton leak in beta cells than in muscle. The comparatively high importance of proton leak in beta cell mitochondria (relative to phosphorylation) is evidenced furthermore by its relatively high level of control over membrane potential and overall respiratory activity. Modular-kinetic analysis of oxidative phosphorylation reveals that these control differences can be fully explained by a higher relative leak activity in beta cell mitochondria, which results in a comparatively high contribution of proton leak to the overall respiratory activity in this system.

Download Full-text

Tetraethylammonium modifies gap junctions between pancreatic beta-cells

AJP Cell Physiology ◽

10.1152/ajpcell.1981.240.3.c116 ◽

1981 ◽

Vol 240 (3) ◽

pp. C116-C120 ◽

Cited By ~ 12

Author(s):

M. S. Sheppard ◽

P. Meda

Keyword(s):

Beta Cell ◽

Gap Junctions ◽

Beta Cells ◽

Insulin Release ◽

Pancreatic Beta Cells ◽

Freeze Fracture ◽

Potassium Conductance ◽

Median Number ◽

Rat Islets Of Langerhans ◽

Gap Junctional

Gap junctions between pancreatic beta-cells were quantitatively assessed in freeze-fracture replicas of isolated rat islets of Langerhans incubated for 90 min with or without the potassium conductance blocker tetraethylammonium (TEA). The results show that TEA increases the median number of particles per beta-cell gap junction but not the frequency of gap junctions at both nonstimulating and threshold-stimulating concentrations of glucose. TEA increased the relative gap junctional area at both concentrations of glucose. TEA had no effect on insulin release at a basal concentration of glucose but potentiated that release at the threshold glucose level. Thus TEA modifies beta-cell gap junctions independently of its effect on insulin release. However, the junctional changes observed were greater when insulin release was also elevated.

Download Full-text

Multi-Organ Crosstalk with Endocrine Pancreas: A Focus on How Gut Microbiota Shapes Pancreatic Beta-Cells

Biomolecules ◽

10.3390/biom12010104 ◽

2022 ◽

Vol 12 (1) ◽

pp. 104

Author(s):

Elisa Fernández-Millán ◽

Carlos Guillén

Keyword(s):

Beta Cell ◽

Beta Cells ◽

Cell Biology ◽

Pancreatic Beta Cells ◽

Metabolic Diseases ◽

Cell Function ◽

Cell Mass ◽

Beta Cell Mass ◽

Short Chain Fatty Acids

Type 2 diabetes (T2D) results from impaired beta-cell function and insufficient beta-cell mass compensation in the setting of insulin resistance. Current therapeutic strategies focus their efforts on promoting the maintenance of functional beta-cell mass to ensure appropriate glycemic control. Thus, understanding how beta-cells communicate with metabolic and non-metabolic tissues provides a novel area for investigation and implicates the importance of inter-organ communication in the pathology of metabolic diseases such as T2D. In this review, we provide an overview of secreted factors from diverse organs and tissues that have been shown to impact beta-cell biology. Specifically, we discuss experimental and clinical evidence in support for a role of gut to beta-cell crosstalk, paying particular attention to bacteria-derived factors including short-chain fatty acids, lipopolysaccharide, and factors contained within extracellular vesicles that influence the function and/or the survival of beta cells under normal or diabetogenic conditions.

Download Full-text

Bergenin protects pancreatic beta cells against cytokine-induced apoptosis in INS-1E cells

PLoS ONE ◽

10.1371/journal.pone.0241349 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0241349

Author(s):

Sajid Ali Rajput ◽

Munazza Raza Mirza ◽

M. Iqbal Choudhary

Keyword(s):

Insulin Secretion ◽

Beta Cell ◽

Beta Cells ◽

Proinflammatory Cytokines ◽

Cell Apoptosis ◽

Pancreatic Beta Cells ◽

Cell Function ◽

Beta Cell Apoptosis ◽

Atp Levels ◽

Induced Apoptosis

Beta cell apoptosis induced by proinflammatory cytokines is one of the hallmarks of diabetes. Small molecules which can inhibit the cytokine-induced apoptosis could lead to new drug candidates that can be used in combination with existing therapeutic interventions against diabetes. The current study evaluated several effects of bergenin, an isocoumarin derivative, in beta cells in the presence of cytokines. These included (i) increase in beta cell viability (by measuring cellular ATP levels) (ii) suppression of beta cell apoptosis (by measuring caspase activity), (iii) improvement in beta cell function (by measuring glucose-stimulated insulin secretion), and (iv) improvement of beta cells mitochondrial physiological functions. The experiments were carried out using rat beta INS-1E cell line in the presence or absence of bergenin and a cocktail of proinflammatory cytokines (interleukin-1beta, tumor necrosis factor-alpha, and interferon- gamma) for 48 hr. Bergenin significantly inhibited beta cell apoptosis, as inferred from the reduction in the caspase-3 activity (IC50 = 7.29 ± 2.45 μM), and concurrently increased cellular ATP Levels (EC50 = 1.97 ± 0.47 μM). Bergenin also significantly enhanced insulin secretion (EC50 = 6.73 ± 2.15 μM) in INS-1E cells, presumably because of the decreased nitric oxide production (IC50 = 6.82 ± 2.83 μM). Bergenin restored mitochondrial membrane potential (EC50 = 2.27 ± 0.83 μM), decreased ROS production (IC50 = 14.63 ± 3.18 μM), and improved mitochondrial dehydrogenase activity (EC50 = 1.39 ± 0.62 μM). This study shows for the first time that bergenin protected beta cells from cytokine-induced apoptosis and restored insulin secretory function by virtue of its anti-inflammatory, antioxidant and anti-apoptotic properties. To sum up, the above mentioned data highlight bergenin as a promising anti-apoptotic agent in the context of diabetes.

Download Full-text