scholarly journals A Pdx-1-Regulated Soluble Factor Activates Rat and Human Islet Cell Proliferation

2016 ◽  
Vol 36 (23) ◽  
pp. 2918-2930 ◽  
Author(s):  
Heather L. Hayes ◽  
Lu Zhang ◽  
Thomas C. Becker ◽  
Jonathan M. Haldeman ◽  
Samuel B. Stephens ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Islet Cell ◽  
Transforming Growth Factor ◽  
Cell Function ◽  
Transforming Growth Factor Β ◽  
Human Islet ◽  
Soluble Factor ◽  
Β Cells ◽  
Β Cell ◽  
Insulin Promoter

The homeodomain transcription factor Pdx-1 has important roles in pancreas and islet development as well as in β-cell function and survival. We previously reported that Pdx-1 overexpression stimulates islet cell proliferation, but the mechanism remains unclear. Here, we demonstrate that overexpression of Pdx-1 triggers proliferation largely by a non-cell-autonomous mechanism mediated by soluble factors. Consistent with this idea, overexpression of Pdx-1 under the control of a β-cell-specific promoter (rat insulin promoter [RIP]) stimulates proliferation of both α and β cells, and overexpression of Pdx-1 in islets separated by a Transwell membrane from islets lacking Pdx-1 overexpression activates proliferation in the untreated islets. Microarray and gene ontology (GO) analysis identified inhibin beta-B (Inhbb), an activin subunit and member of the transforming growth factor β (TGF-β) superfamily, as a Pdx-1-responsive gene. Overexpression of Inhbb or addition of activin B stimulates rat islet cell and β-cell proliferation, and the activin receptors RIIA and RIIB are required for the full proliferative effects of Pdx-1 in rat islets. In human islets, Inhbb overexpression stimulates total islet cell proliferation and potentiates Pdx-1-stimulated proliferation of total islet cells and β cells. In sum, this study identifies a mechanism by which Pdx-1 induces a soluble factor that is sufficient to stimulate both rat and human islet cell proliferation.

scholarly journals SMAD7 enhances adult β-cell proliferation without significantly affecting β-cell function in mice

2020 ◽  
Vol 295 (15) ◽  
pp. 4858-4869 ◽  
Author(s):  
Anuradha Sehrawat ◽  
Chiyo Shiota ◽  
Nada Mohamed ◽  
Julia DiNicola ◽  
Mohamed Saleh ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transforming Growth Factor ◽  
Cell Function ◽  
Therapeutic Option ◽  
Transforming Growth Factor Β ◽  
Vital Role ◽  
Negative Effects ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function

The interplay between the transforming growth factor β (TGF-β) signaling proteins, SMAD family member 2 (SMAD2) and 3 (SMAD3), and the TGF-β–inhibiting SMAD, SMAD7, seems to play a vital role in proper pancreatic endocrine development and also in normal β-cell function in adult pancreatic islets. Here, we generated conditional SMAD7 knockout mice by crossing insulin1Cre mice with SMAD7fx/fx mice. We also created a β cell–specific SMAD7-overexpressing mouse line by crossing insulin1Dre mice with HPRT-SMAD7/RosaGFP mice. We analyzed β-cell function in adult islets when SMAD7 was either absent or overexpressed in β cells. Loss of SMAD7 in β cells inhibited proliferation, and SMAD7 overexpression enhanced cell proliferation. However, alterations in basic glucose homeostasis were not detectable following either SMAD7 deletion or overexpression in β cells. Our results show that both the absence and overexpression of SMAD7 affect TGF-β signaling and modulates β-cell proliferation but does not appear to alter β-cell function. Reversible SMAD7 overexpression may represent an attractive therapeutic option to enhance β-cell proliferation without negative effects on β-cell function.

scholarly journals Identification of a small molecule that stimulates human β-cell proliferation and insulin secretion, and protects against cytotoxic stress in rat insulinoma cells

2019 ◽  
Author(s):  
Hans E. Hohmeier ◽  
Lu Zhang ◽  
Brandon Taylor ◽  
Samuel Stephens ◽  
Peter McNamara ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Insulin Secretion ◽  
Small Molecule ◽  
Islet Cell ◽  
Human Islet ◽  
Luciferase Reporter ◽  
Β Cell ◽  
Cytotoxic Stress ◽  
Insulinoma Cells ◽  
Rat Insulinoma

AbstractA key event in the development of both major forms of diabetes is the loss of functional pancreatic islet β-cell mass. Strategies aimed at enhancing β-cell regeneration have long been pursued, but methods for reliably inducing human β-cell proliferation with full retention of key functions such as glucose-stimulated insulin secretion (GSIS) are still very limited. We have previously reported that overexpression of the homeobox transcription factor Nkx6.1 stimulates β-cell proliferation, while also enhancing GSIS and providing protection against β-cell cytotoxicity through induction of the VGF prohormone. We developed an Nkx6.1 pathway screen by stably transfecting 832/13 rat insulinoma cells with a VGF promoter-luciferase reporter construct, using the resultant cell line to screen a 630,000 compound chemical library. We isolated three compounds with consistent effects to stimulate human islet cell proliferation. Further studies of the most potent of these compounds, GNF-9228, revealed that it selectively activates human β-cell relative to α-cell proliferation and has no effect on δ-cell replication. In addition, pre-treatment, but not short term exposure of human islets to GNF-9228 enhances GSIS. GNF-9228 also protects 832/13 insulinoma cells against ER stress- and inflammatory cytokine-induced cytotoxicity. In contrast to recently emergent Dyrk1a inhibitors that stimulate human islet cell proliferation, GNF-9228 does not activate NFAT translocation. These studies have led to identification of a small molecule with pleiotropic positive effects on islet biology, including stimulation of human β-cell proliferation and insulin secretion, and protection against multiple agents of cytotoxic stress.

scholarly journals MicroRNA-224 Is Involved in Transforming Growth Factor-β-Mediated Mouse Granulosa Cell Proliferation and Granulosa Cell Function by Targeting Smad4

2010 ◽  
Vol 24 (3) ◽  
pp. 540-551 ◽  
Author(s):  
Guidong Yao ◽  
Mianmian Yin ◽  
Jie Lian ◽  
Hui Tian ◽  
Lin Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Granulosa Cell ◽  
Transforming Growth Factor ◽  
Cell Function ◽  
Ectopic Expression ◽  
Follicular Development ◽  
Transforming Growth Factor Β ◽  
Type I ◽  
Mrna Levels ◽  
Tgf Β1

Abstract Many members of the TGF-β superfamily are indicated to play important roles in ovarian follicular development, such as affecting granulosa cell function and oocyte maturation. Abnormalities associated with TGF-β1 signaling transduction could result in female infertility. MicroRNAs (miRNAs), as small noncoding RNAs, were recently found to regulate gene expression at posttranscriptional levels. However, little is known about the role of miRNAs in TGF-β-mediated granulosa cell proliferation and granulosa cell function. In this study, the miRNA expression profiling was identified from TGF-β1-treated mouse preantral granulosa cells (GCs), and three miRNAs were found to be significantly up-regulated and 13 miRNAs were down-regulated. Among up-regulated miRNAs, miR-224 was the second most significantly elevated miRNA. This up-regulation was attenuated by treatment of GCs with SB431542 (an inhibitor of TGFβ superfamily type I receptors, thus blocking phosphorylation of the downstream effectors Smad2/3), indicating that miR-224 expression was regulated by TGF-β1/Smads pathway. The ectopic expression of miR-224 can enhance TGF-β1-induced GC proliferation through targeting Smad4. Inhibition of endogenous miR-224 partially suppressed GC proliferation induced by TGF-β1. In addition, both miR-224 and TGF-β1 can promote estradiol release from GC, at least in part, through increasing CYP19A1 mRNA levels. This is the first demonstration that miRNAs can control reproductive functions resulting in promoting TGF-β1-induced GC proliferation and ovarian estrogen release. Such miRNA-mediated effects could be potentially used for regulation of reproductive processes or for treatment of reproductive disorders.

scholarly journals Three-dimensional analysis of β-cell proliferation by a novel mouse model

2019 ◽  
Author(s):  
Shinsuke Tokumoto ◽  
Daisuke Yabe ◽  
Hisato Tatsuoka ◽  
Ryota Usui ◽  
Muhammad Fauzi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Cycle Progression ◽  
Three Dimensional ◽  
Spatiotemporal Analysis ◽  
Mouse Line ◽  
Β Cells ◽  
Β Cell ◽  
Insulin Promoter ◽  
Novel Method

SummaryInducing β-cell proliferation could inhibit diabetes progression. Many factors have been suggested as potential β-cell mitogens, but their impact on β-cell replication has not been confirmed due to the lack of a standardized β-cell proliferation assay. In this study, we developed a novel method that specifically labels replicating β cells and yields more reproducible results than current immunohistochemical assays. We established a mouse line expressing the fluorescent ubiquitination-based cell cycle indicator (Fucci2a) reporter only in β cells through Cre-mediated recombination under the control of the rat insulin promoter (RIP-Cre;Fucci2aR). Three-dimensional imaging of optically cleared pancreas tissue from these mice enabled the quantification of replicating β cells in islets and morphometric analysis of islets following mitogen treatment. Intravital imaging of RIP-Cre;Fucci2aR mice revealed cell cycle progression of β cells. Thus, this novel mouse line is a powerful tool for spatiotemporal analysis of β-cell proliferation in response to mitogen stimulation.

scholarly journals Lactation improves pancreatic β cell mass and function through serotonin production

2020 ◽  
Vol 12 (541) ◽  
pp. eaay0455
Author(s):  
Joon Ho Moon ◽  
Hyeongseok Kim ◽  
Hyunki Kim ◽  
Jungsun Park ◽  
Wonsuk Choi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Proliferation ◽  
Glucose Tolerance ◽  
Serotonin Receptor ◽  
Cell Function ◽  
Cell Mass ◽  
Β Cells ◽  
Β Cell ◽  
Beneficial Effects

Pregnancy imposes a substantial metabolic burden on women through weight gain and insulin resistance. Lactation reduces the risk of maternal postpartum diabetes, but the mechanisms underlying this benefit are unknown. Here, we identified long-term beneficial effects of lactation on β cell function, which last for years after the cessation of lactation. We analyzed metabolic phenotypes including β cell characteristics in lactating and non-lactating humans and mice. Lactating and non-lactating women showed comparable glucose tolerance at 2 months after delivery, but after a mean of 3.6 years, glucose tolerance in lactated women had improved compared to non-lactated women. In humans, the disposition index, a measure of insulin secretory function of β cells considering the degree of insulin sensitivity, was higher in lactated women at 3.6 years after delivery. In mice, lactation improved glucose tolerance and increased β cell mass at 3 weeks after delivery. Amelioration of glucose tolerance and insulin secretion were maintained up to 4 months after delivery in lactated mice. During lactation, prolactin induced serotonin production in β cells. Secreted serotonin stimulated β cell proliferation through serotonin receptor 2B in an autocrine and paracrine manner. In addition, intracellular serotonin acted as an antioxidant to mitigate oxidative stress and improved β cell survival. Together, our results suggest that serotonin mediates the long-term beneficial effects of lactation on female metabolic health by increasing β cell proliferation and reducing oxidative stress in β cells.

scholarly journals GLP-1 signaling suppresses menin’s transcriptional block by phosphorylation in β cells

2019 ◽  
Vol 218 (3) ◽  
pp. 855-870 ◽  
Author(s):  
Bowen Xing ◽  
Jian Ma ◽  
Zongzhe Jiang ◽  
Zijie Feng ◽  
Sunbin Ling ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Gene Transcription ◽  
Histone Deacetylases ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Histone Modifiers ◽  
Β Cell Function ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Both menin and glucagon-like peptide 1 (GLP-1) pathways play central yet opposing role in regulating β cell function, with menin suppressing, and GLP-1 promoting, β cell function. However, little is known as to whether or how GLP-1 pathway represses menin function. Here, we show that GLP-1 signaling–activated protein kinase A (PKA) directly phosphorylates menin at the serine 487 residue, relieving menin-mediated suppression of insulin expression and cell proliferation. Mechanistically, Ser487-phosphorylated menin gains increased binding affinity to nuclear actin/myosin IIa proteins and gets sequestrated from the Ins1 promoter. This event leads to reduced binding of repressive epigenetic histone modifiers suppressor variegation 3–9 homologue protein 1 (SUV39H1) and histone deacetylases 1 (HDAC1) at the locus and subsequently increased Ins1 gene transcription. Ser487 phosphorylation of menin also increases expression of proproliferative cyclin D2 and β cell proliferation. Our results have uncovered a previously unappreciated physiological link in which GLP-1 signaling suppresses menin function through phosphorylation-triggered and actin/myosin cytoskeletal protein–mediated derepression of gene transcription.

Comparison of cellular and medium insulin and GABA content as markers for living β-cells

2005 ◽  
Vol 288 (2) ◽  
pp. E307-E313 ◽  
Author(s):  
Chen Wang ◽  
Zhidong Ling ◽  
Daniel Pipeleers
Keyword(s):  
Cell Death ◽  
Islet Cell ◽  
Cellular Localization ◽  
Gaba Release ◽  
Human Islet ◽  
Nitric Oxide Donor ◽  
Cell Phenotype ◽  
Β Cells ◽  
Β Cell ◽  
Gaba Content

Experimental and therapeutic use of islet cell preparations could benefit from assays that measure variations in the mass of living β-cells. Because processes of cell death can be followed by depletion and/or discharge of cell-specific substances, we examined whether in vitro conditions of β-cell death resulted in changes in tissue and medium content of insulin and of γ-aminobutyric acid (GABA), two β-cell-specific compounds with different cellular localization and turnover. Exposure of rat purified β-cells to streptozotocin (5 mM, 120 min) or to the nitric oxide donor GEA-3162 (GEA; 50 μM, 120 min) caused 80% necrosis within 24 h; at the end of this period, cellular insulin content was not significantly decreased, but cellular GABA content was reduced by 70%; when cultured at basal glucose (6 mM), the toxin-exposed cells did not discharge less insulin but released 80% less GABA in the period 8–24 h. As in rat β-cell purification, GABA comigrated with insulin during human islet cell isolation. Twenty-four hours after GEA (500 μM, 120 min), human islet cell preparations exhibited 90% dead cells and a 45 and 90% reduction, respectively, in tissue insulin and GABA content; in the period 9–24 h, insulin discharge in the medium was not reduced, but GABA release was decreased by 90%. When rat β-cells were cultured for 24 h with nontoxic interleukin (IL)-1β concentrations that suppressed glucose-induced insulin release, cellular GABA content was not decreased and GABA release increased by 90% in the period 8–24 h. These data indicate that a reduction in cellular and medium GABA levels is more sensitive than insulin as a marker for the presence of dead β-cells in isolated preparations. Pancreatic GABA content also rapidly decreased after streptozotocin injection and remained unaffected by 12 h of hyperglycemia. At further variance with insulin, GABA release from living β-cells depends little on its cellular content but increases with IL-1β-induced alterations in β-cell phenotype.

scholarly journals Connective tissue growth factor is critical for proper β-cell function and pregnancy-induced β-cell hyperplasia in adult mice

2016 ◽  
Vol 311 (3) ◽  
pp. E564-E574 ◽  
Author(s):  
Raymond C. Pasek ◽  
Jennifer C. Dunn ◽  
Joseph M. Elsakr ◽  
Mounika Aramandla ◽  
Anveetha R. Matta ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Insulin Secretion ◽  
Growth Factor ◽  
Gestational Diabetes ◽  
Cell Function ◽  
Tissue Growth ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Stimulated Insulin Secretion

During pregnancy, maternal β-cells undergo compensatory changes, including increased β-cell mass and enhanced glucose-stimulated insulin secretion. Failure of these adaptations to occur results in gestational diabetes mellitus. The secreted protein connective tissue growth factor (CTGF) is critical for normal β-cell development and promotes regeneration after partial β-cell ablation. During embryogenesis, CTGF is expressed in pancreatic ducts, vasculature, and β-cells. In adult pancreas, CTGF is expressed only in the vasculature. Here we show that pregnant mice with global Ctgf haploinsufficiency (CtgfLacZ/+) have an impairment in maternal β-cell proliferation; no difference was observed in virgin CtgfLacZ/+ females. Using a conditional CTGF allele, we found that mice with a specific inactivation of CTGF in endocrine cells (CtgfΔEndo) develop gestational diabetes during pregnancy, but this is due to a reduction in glucose-stimulated insulin secretion rather than impaired maternal β-cell proliferation. Moreover, virgin CtgfΔEndo females also display impaired GSIS with glucose intolerance, indicating that underlying β-cell dysfunction precedes the development of gestational diabetes in this animal model. This is the first time a role for CTGF in β-cell function has been reported.

scholarly journals Extracellular CADM1 interactions influence insulin secretion by rat and human islet β-cells and promote clustering of syntaxin-1

2016 ◽  
Vol 310 (11) ◽  
pp. E874-E885 ◽  
Author(s):  
Charles Zhang ◽  
Thomas A. Caldwell ◽  
M. Reza Mirbolooki ◽  
Diana Duong ◽  
Eun Jee Park ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Protein Interactions ◽  
Network Formation ◽  
Cell Function ◽  
Human Islet ◽  
Cell Contact ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Insulinoma Cells

Contact between β-cells is necessary for their normal function. Identification of the proteins mediating the effects of β-cell-to-β-cell contact is a necessary step toward gaining a full understanding of the determinants of β-cell function and insulin secretion. The secretory machinery of the β-cells is nearly identical to that of central nervous system (CNS) synapses, and we hypothesize that the transcellular protein interactions that drive maturation of the two secretory machineries upon contact of one cell (or neural process) with another are also highly similar. Two such transcellular interactions, important for both synaptic and β-cell function, have been identified: EphA/ephrin-A and neuroligin/neurexin. Here, we tested the role of another synaptic cleft protein, CADM1, in insulinoma cells and in rat and human islet β-cells. We found that CADM1 is a predominant CADM isoform in β-cells. In INS-1 cells and primary β-cells, CADM1 constrains insulin secretion, and its expression decreases after prolonged glucose stimulation. Using a coculture model, we found that CADM1 also influences insulin secretion in a transcellular manner. We asked whether extracellular CADM1 interactions exert their influence via the same mechanisms by which they influence neurotransmitter exocytosis. Our results suggest that, as in the CNS, CADM1 interactions drive exocytic site assembly and promote actin network formation. These results support the broader hypothesis that the effects of cell-cell contact on β-cell maturation and function are mediated by the same extracellular protein interactions that drive the formation of the presynaptic exocytic machinery. These interactions may be therapeutic targets for reversing β-cell dysfunction in diabetes.

Sign in / Sign up

Export Citation Format

Share Document