scholarly journals Regulation of pancreatic islet gene expression in mouse islets by pregnancy

2010 ◽  
Vol 207 (3) ◽  
pp. 265-279 ◽  
Author(s):  
B T Layden ◽  
V Durai ◽  
M V Newman ◽  
A M Marinelarena ◽  
C W Ahn ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Global Gene Expression ◽  
Surfactant Protein ◽  
Surfactant Protein D ◽  
Mrna Levels ◽  
Β Cell ◽  
Expression Array ◽  
Follow Up Studies

Pancreatic β cells adapt to pregnancy-induced insulin resistance by unclear mechanisms. This study sought to identify genes involved in β cell adaptation during pregnancy. To examine changes in global RNA expression during pregnancy, murine islets were isolated at a time point of increased β cell proliferation (E13.5), and RNA levels were determined by two different assays (global gene expression array and G-protein-coupled receptor (GPCR) array). Follow-up studies confirmed the findings for select genes. Differential expression of 110 genes was identified and follow-up studies confirmed the changes in select genes at both the RNA and protein level. Surfactant protein D (SP-D) mRNA and protein levels exhibited large increases, which were confirmed in murine islets. Cytokine-induced expression of SP-D in islets was also demonstrated, suggesting a possible role as an anti-inflammatory molecule. Complementing these studies, an expression array was performed to define pregnancy-induced changes in expression of GPCRs that are known to impact islet cell function and proliferation. This assay, the results of which were confirmed using real-time reverse transcription-PCR assays, demonstrated that free fatty acid receptor 2 and cholecystokinin receptor A mRNA levels were increased at E13.5. This study has identified multiple novel targets that may be important for the adaptation of islets to pregnancy.

scholarly journals Influence of chronic hyperglycemia on the loss of the unfolded protein response in transplanted islets

2013 ◽  
Vol 51 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Stacey N Walters ◽  
Jude Luzuriaga ◽  
Jeng Yie Chan ◽  
Shane T Grey ◽  
D Ross Laybutt
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Mrna Levels ◽  
Diabetic Mice ◽  
Β Cell ◽  
Unfolded Protein ◽  
Chronic Hyperglycemia ◽  
Β Cell Function ◽  
The Unfolded Protein Response ◽  
Protein Response

Chronic hyperglycemia contributes to β-cell dysfunction in diabetes and with islet transplantation, but the mechanisms remain unclear. Recent studies demonstrate that the unfolded protein response (UPR) is critical for β-cell function. Here, we assessed the influence of hyperglycemia on UPR gene expression in transplanted islets. Streptozotocin-induced diabetic or control nondiabetic mice were transplanted under the kidney capsule with syngeneic islets either sufficient or not to normalize hyperglycemia. Twenty-one days after transplantation, islet grafts were excised and RT-PCR was used to assess gene expression. In islet grafts from diabetic mice, expression levels of many UPR genes of the IRE1/ATF6 pathways, which are important for adaptation to endoplasmic reticulum stress, were markedly reduced compared with that in islet grafts from control mice. UPR genes of the PERK pathway were also downregulated. The normalization of glycemia restored the changes in mRNA expression, suggesting that chronic hyperglycemia contributes to the downregulation of multiple arms of UPR gene expression. Similar correlations were observed between blood glucose and mRNA levels of transcription factors involved in the maintenance of β-cell phenotype and genes implicated in β-cell function, suggesting convergent regulation of UPR gene expression and β-cell differentiation by hyperglycemia. However, the normalization of glycemia was not accompanied by restoration of antioxidant or pro-inflammatory cytokine mRNA levels, which were increased in islet grafts from diabetic mice. These studies demonstrate that chronic hyperglycemia contributes to the downregulation of multiple arms of UPR gene expression in transplanted mouse islets. Failure of the adaptive UPR may contribute to β-cell dedifferentiation and dysfunction in diabetes.

scholarly journals Pericytes contribute to the islet basement membranes to promote beta-cell gene expression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lina Sakhneny ◽  
Alona Epshtein ◽  
Limor Landsman
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Basement Membranes ◽  
Cell Physiology ◽  
Β Cells ◽  
Β Cell ◽  
Cell Clustering ◽  
Β Cell Function ◽  
Cell Gene Expression ◽  
Glucose Stimulated Insulin Secretion

Abstractβ-Cells depend on the islet basement membrane (BM). While some islet BM components are produced by endothelial cells (ECs), the source of others remains unknown. Pancreatic pericytes directly support β-cells through mostly unidentified secreted factors. Thus, we hypothesized that pericytes regulate β-cells through the production of BM components. Here, we show that pericytes produce multiple components of the mouse pancreatic and islet interstitial and BM matrices. Several of the pericyte-produced ECM components were previously implicated in β-cell physiology, including collagen IV, laminins, proteoglycans, fibronectin, nidogen, and hyaluronan. Compared to ECs, pancreatic pericytes produce significantly higher levels of α2 and α4 laminin chains, which constitute the peri-islet and vascular BM. We further found that the pericytic laminin isoforms differentially regulate mouse β-cells. Whereas α2 laminins promoted islet cell clustering, they did not affect gene expression. In contrast, culturing on Laminin-421 induced the expression of β-cell genes, including Ins1, MafA, and Glut2, and significantly improved glucose-stimulated insulin secretion. Thus, alongside ECs, pericytes are a significant source of the islet BM, which is essential for proper β-cell function.

Effect of sitagliptin plus metformin on β-cell function, islet integrity and islet gene expression in Zucker diabetic fatty rats

2011 ◽  
Vol 92 (2) ◽  
pp. 213-222 ◽  
Author(s):  
Seung Jin Han ◽  
Sung-E. Choi ◽  
Yup Kang ◽  
Jong Gab Jung ◽  
Sang-A. Yi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Β Cell ◽  
Zucker Diabetic Fatty Rats ◽  
Β Cell Function

Nitric oxide decreases surfactant protein gene expression in primary cultures of type II pneumocytes

2005 ◽  
Vol 288 (5) ◽  
pp. L950-L957 ◽  
Author(s):  
Jae W. Lee ◽  
Robert F. Gonzalez ◽  
Cheryl J. Chapin ◽  
Justin Busch ◽  
Jeffrey R. Fineman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nitric Oxide ◽  
Protein Gene ◽  
Surfactant Protein ◽  
Model Systems ◽  
Cell Phenotype ◽  
Mrna Levels ◽  
Type Ii ◽  
Endothelin 1 ◽  
Type Ii Pneumocytes

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator effective in treating persistent pulmonary hypertension in newborns and in infants following congenital heart disease surgery. Recently, multiple in vivo and in vitro studies have shown a negative effect of NO on surfactant activity as well as surfactant protein gene expression. Although the relationship between NO and surfactant has been studied previously, the data has been hard to interpret due to the model systems used. The objective of the current study was to characterize the effect of NO on surfactant protein gene expression in primary rat type II pneumocytes cultured on a substratum that promoted the maintenance of type II cell phenotype. Exposure to a NO donor, S-nitroso-N-acetylpenicillamine (SNAP), decreased surfactant protein (SP)-A, (SP)-B, and (SP)-C mRNA levels in type II pneumocytes in a time- and dose-dependent manner. The effect was mediated in part by an increase in endothelin-1 secretion and a decrease in the intracellular messenger, phosphorylated ERK1/2 mitogen-activated protein kinases (MAPK). Exposing type II pneumocytes to endothelin-1 receptor antagonists PD-156707 or bosentan before exposure to SNAP partially prevented the decrease in surfactant protein gene expression. The results showed that NO mediated the decrease in surfactant protein gene expression at least in part through an increase in endothelin-1 secretion and a decrease in phosphorylated ERK1/2 MAPKs.

scholarly journals Eaf1 Links the NuA4 Histone Acetyltransferase Complex to Htz1 Incorporation and Regulation of Purine Biosynthesis

2015 ◽  
Vol 14 (6) ◽  
pp. 535-544 ◽  
Author(s):  
Xue Cheng ◽  
Andréanne Auger ◽  
Mohammed Altaf ◽  
Simon Drouin ◽  
Eric Paquet ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cross Talk ◽  
Global Gene Expression ◽  
Histone Variant ◽  
Purine Biosynthesis ◽  
Expression Array ◽  
Link Type ◽  
Molecular Events ◽  
Nucleosome Disassembly

ABSTRACT Proper modulation of promoter chromatin architecture is crucial for gene regulation in order to precisely and efficiently orchestrate various cellular activities. Previous studies have identified the stimulatory effect of the histone-modifying complex NuA4 on the incorporation of the histone variant H2A.Z (Htz1) at the PHO5 promoter (A. Auger, L. Galarneau, M. Altaf, A. Nourani, Y. Doyon, R. T. Utley, D. Cronier, S. Allard, and J. Côté, Mol Cell Biol 28:2257–2270, 2008, http://dx.doi.org/10.1128/MCB.01755-07 ). In vitro studies with a reconstituted system also indicated an intriguing cross talk between NuA4 and the H2A.Z-loading complex, SWR-C (M. Altaf, A. Auger, J. Monnet-Saksouk, J. Brodeur, S. Piquet, M. Cramet, N. Bouchard, N. Lacoste, R. T. Utley, L. Gaudreau, J. Côté, J Biol Chem 285:15966–15977, 2010, http://dx.doi.org/10.1074/jbc.M110.117069 ). In this work, we investigated the role of the NuA4 scaffold subunit Eaf1 in global gene expression and genome-wide incorporation of Htz1. We found that loss of Eaf1 affects Htz1 levels mostly at the promoters that are normally highly enriched in the histone variant. Analysis of eaf1 mutant cells by expression array unveiled a relationship between NuA4 and the gene network implicated in the purine biosynthesis pathway, as EAF1 deletion cripples induction of several ADE genes. NuA4 directly interacts with Bas1 activation domain, a key transcription factor of adenine genes. Chromatin immunoprecipitation (ChIP) experiments demonstrate that nucleosomes on the inactive ADE17 promoter are acetylated already by NuA4 and enriched in Htz1. Upon derepression, these poised nucleosomes respond rapidly to activate ADE gene expression in a mechanism likely reminiscent of the PHO5 promoter, leading to nucleosome disassembly. These detailed molecular events depict a specific case of cross talk between NuA4-dependent acetylation and incorporation of histone variant Htz1, presetting the chromatin structure over ADE promoters for subsequent chromatin remodeling and activated transcription.

scholarly journals Excess Testosterone Exposure Alters Hypothalamic-Pituitary-Testicular Axis Dynamics and Gene Expression in Sheep Fetuses

Endocrinology ◽  
2016 ◽  
Vol 157 (11) ◽  
pp. 4234-4245 ◽  
Author(s):  
Charles E. Roselli ◽  
Rebecka Amodei ◽  
Kyle P. Gribbin ◽  
Keely Corder ◽  
Fred Stormshak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
Testosterone Propionate ◽  
Mammalian Species ◽  
Mrna Levels ◽  
Negative Effects ◽  
Gonadotropin Secretion ◽  
Androgen Exposure ◽  
Hypothalamic Regulation ◽  
Maternal Testosterone

Prenatal exposure to excess androgen may result in impaired adult fertility in a variety of mammalian species. However, little is known about what feedback mechanisms regulate gonadotropin secretion during early gestation and how they respond to excess T exposure. The objective of this study was to determine the effect of exogenous exposure to T on key genes that regulate gonadotropin and GnRH secretion in fetal male lambs as compared with female cohorts. We found that biweekly maternal testosterone propionate (100 mg) treatment administered from day 30 to day 58 of gestation acutely decreased (P < .05) serum LH concentrations and reduced the expression of gonadotropin subunit mRNA in both sexes and the levels of GnRH receptor mRNA in males. These results are consistent with enhanced negative feedback at the level of the pituitary and were accompanied by reduced mRNA levels for testicular steroidogenic enzymes, suggesting that Leydig cell function was also suppressed. The expression of kisspeptin 1 mRNA, a key regulator of GnRH neurons, was significantly greater (P < .01) in control females than in males and reduced (P < .001) in females by T exposure, indicating that hypothalamic regulation of gonadotropin secretion was also affected by androgen exposure. Although endocrine homeostasis was reestablished 2 weeks after maternal testosterone propionate treatment ceased, additional differences in the gene expression of GnRH, estrogen receptor-β, and kisspeptin receptor (G protein coupled receptor 54) emerged between the treatment cohorts. These changes suggest the normal trajectory of hypothalamic-pituitary axis development was disrupted, which may, in turn, contribute to negative effects on fertility later in life.

Insulin Regulation of β-Cell Function Involves a Feedback Loop on SERCA Gene Expression, Ca2+Homeostasis, and Insulin Expression and Secretion†

Biochemistry ◽  
2000 ◽  
Vol 39 (48) ◽  
pp. 14912-14919 ◽  
Author(s):  
Gang G. Xu ◽  
Zhi-yong Gao ◽  
Prabhakar D. Borge ◽  
Patricia A. Jegier ◽  
Robert A. Young ◽  
...  
Keyword(s):  
Gene Expression ◽  
Feedback Loop ◽  
Cell Function ◽  
Β Cell ◽  
Insulin Regulation ◽  
Insulin Expression ◽  
Β Cell Function

Antisense inhibition of surfactant protein A decreases tubular myelin formation in human fetal lung in vitro

2002 ◽  
Vol 282 (3) ◽  
pp. L386-L393 ◽  
Author(s):  
Jonathan M. Klein ◽  
Troy A. McCarthy ◽  
John M. Dagle ◽  
Jeanne M. Snyder
Keyword(s):  
Gene Expression ◽  
Protein A ◽  
Fetal Lung ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Mrna Levels ◽  
Phosphorothioate Oligonucleotide ◽  
Myelin Formation ◽  
Surfactant Phospholipids ◽  
Human Fetal Lung

Surfactant protein A (SP-A) is the most abundant of the surfactant-associated proteins. SP-A is involved in the formation of tubular myelin, the modulation of the surface tension-reducing properties of surfactant phospholipids, the metabolism of surfactant phospholipids, and local pulmonary host defense. We hypothesized that elimination of SP-A would alter the regulation of SP-B gene expression and the formation of tubular myelin. Midtrimester human fetal lung explants were cultured for 3–5 days in the presence or absence of an antisense 18-mer phosphorothioate oligonucleotide (ON) complementary to SP-A mRNA. After 3 days in culture, SP-A mRNA was undetectable in antisense ON-treated explants. After 5 days in culture, levels of SP-A protein were also decreased by antisense treatment. SP-B mRNA levels were not affected by the antisense SP-A ON treatment. However, there was decreased tubular myelin formation in the antisense SP-A ON-treated tissue. We conclude that selective elimination of SP-A mRNA and protein results in a decrease in tubular myelin formation in human fetal lung without affecting SP-B mRNA. We speculate that SP-A is critical to the formation of tubular myelin during human lung development and that the regulation of SP-B gene expression is independent of SP-A gene expression.

scholarly journals VMP1-related autophagy induced by a fructose-rich diet in β-cells: its prevention by incretins

2017 ◽  
Vol 131 (8) ◽  
pp. 673-687 ◽  
Author(s):  
Bárbara Maiztegui ◽  
Verónica Boggio ◽  
Carolina L. Román ◽  
Luis E. Flores ◽  
Héctor Del Zotto ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Cell Function ◽  
Cell Damage ◽  
Cell Mass ◽  
Ultrastructural Changes ◽  
Mrna Levels ◽  
Model Assessment ◽  
Β Cells ◽  
Β Cell ◽  
Insulin Mrna

The aim of the present study was to demonstrate the role of autophagy and incretins in the fructose-induced alteration of β-cell mass and function. Normal Wistar rats were fed (3 weeks) with a commercial diet without (C) or with 10% fructose in drinking water (F) alone or plus sitagliptin (CS and FS) or exendin-4 (CE and FE). Serum levels of metabolic/endocrine parameters, β-cell mass, morphology/ultrastructure and apoptosis, vacuole membrane protein 1 (VMP1) expression and glucose-stimulated insulin secretion (GSIS) were studied. Complementary to this, islets isolated from normal rats were cultured (3 days) without (C) or with F and F + exendin-4 or chloroquine. Expression of autophagy-related proteins [VMP1 and microtubule-associated protein light chain 3 (LC3)], apoptotic/antiapoptotic markers (caspase-3 and Bcl-2), GSIS and insulin mRNA levels were measured. F rats developed impaired glucose tolerance (IGT) and a significant increase in plasma triacylglycerols, thiobarbituric acid-reactive substances, insulin levels, homoeostasis model assessment (HOMA) for insulin resistance (HOMA-IR) and β-cell function (HOMA-β) indices. A significant reduction in β-cell mass was associated with an increased apoptotic rate and morphological/ultrastructural changes indicative of autophagic activity. All these changes were prevented by either sitagliptin or exendin-4. In cultured islets, F significantly enhanced insulin mRNA and GSIS, decreased Bcl-2 mRNA levels and increased caspase-3 expression. Chloroquine reduced these changes, suggesting the participation of autophagy in this process. Indeed, F induced the increase of both VMP1 expression and LC3-II, suggesting that VMP1-related autophagy is activated in injured β-cells. Exendin-4 prevented islet-cell damage and autophagy development. VMP1-related autophagy is a reactive process against F-induced islet dysfunction, being prevented by exendin-4 treatment. This knowledge could help in the use of autophagy as a potential target for preventing progression from IGT to type 2 diabetes mellitus.

scholarly journals Antidepressant medication use and trajectories of fasting plasma glucose, glycated haemoglobin, β-cell function and insulin sensitivity: a 9-year longitudinal study of the D.E.S.I.R. cohort

2015 ◽  
Vol 44 (6) ◽  
pp. 1927-1940 ◽  
Author(s):  
Marine Azevedo Da Silva ◽  
Aline Dugravot ◽  
Beverley Balkau ◽  
Ronan Roussel ◽  
Frédéric Fumeron ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Plasma Glucose ◽  
Fasting Plasma Glucose ◽  
Cell Function ◽  
Glycated Haemoglobin ◽  
Β Cell ◽  
Fasting Plasma ◽  
Β Cell Function ◽  
Antidepressant Use

Abstract Background : Use of antidepressants is seen to be a risk factor for type 2 diabetes, even though the underlying mechanisms remain unclear. We examined whether antidepressant use was associated with change in fasting plasma glucose, glycated haemoglobin (HbA1c), β-cell function (HOMA2-%B) and insulin sensitivity (HOMA2-%S) over time. Methods : Participants in the French D.E.S.I.R. cohort study included over 4700 men (48.1%) and women, free of diabetes, aged 30–65 years at baseline in 1994–96 (D.E.S.I.R. 0), who were followed for 9 years at 3-yearly intervals (D.E.S.I.R. 3, 1997–99; 6, 2000–02; 9, 2003–05). Antidepressant use, fasting plasma glucose, HbA1c, HOMA2-%B and HOMA2-%S were assessed concurrently at four medical examinations. Linear mixed models were used to examine the cross-sectional and longitudinal associations of time-dependent antidepressant use with changes in these four biological parameters. Results : Mean fasting plasma glucose and HbA1c increased whereas HOMA2-%B and HOMA2-%S decreased over the follow-up. In a fully adjusted model, there were no differences in: mean fasting plasma glucose ( β  = 0.01 mmol/l, P  = 0.702); HbA1c ( β  = 0.01 %, P  = 0.738); HOMA2-%B ( β  = 0.00, P  = 0.812); or HOMA2-%S ( β  =−0.01, P  = 0.791) at baseline (1994–96) between antidepressant users and non-users. The interaction term with time also suggested no differences in the annual change in: fasting plasma glucose ( β  = 0.00 mmol/l, P  = 0.322); HbA1c ( β  = 0.00 %, P  = 0.496); HOMA2-%B ( β  = 0.00, P  = 0.609); or HOMA2-%S ( β  = 0.00, P  = 0.332) between antidepressant users and non-users. Similar associations were observed in analyses of type and cumulative use of antidepressants over follow-up. Conclusion : Our longitudinal data show that use of antidepressants is not associated with altered glucose metabolism, suggesting that the association between antidepressant use and diabetes reported by previous studies may not be causal. Detection bias or clinical ascertainment bias may account for much of this apparent association.

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