Mus musculus
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA296080 | ENA |
REPOSITORIES: ENA
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Project description:Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that regulates basic cell functions through metabolic and signaling pathways. Intracellular metabolism of S1P is controlled, in part, by two homologous S1P phosphatases, 1 and 2, which are encoded by Sgpp1 and Sgpp2, respectively. S1P phosphatase activity is needed for efficient recycling of sphingosine into the sphingolipid synthesis pathway. S1P phosphatase 1 is important for skin homeostasis, but little is known about the functional role of S1P phosphatase 2. To identify the functions of S1P phosphatase 2 in vivo, we studied mice with the Sgpp2 gene deleted. In contrast to Sgpp1-/- mice, Sgpp2-/- mice had normal skin and were viable into adulthood. Unexpectedly, WT mice expressed Sgpp2 mRNA at high levels in pancreatic islets when compared with other tissues. Sgpp2-/- mice had normal blood insulin levels and pancreatic islet size; however, Sgpp2-/- mice treated with a high-fat diet (HFD) had significantly lower blood insulin levels and smaller pancreatic islets compared with WT mice. The smaller islets in the HFD-treated Sgpp2-/- mice had a significantly lower adaptive β-cell proliferation rate in response to the diet compared with HFD-treated WT mice. Importantly, β-cells from Sgpp2-/- mice fed a normal diet showed significantly increased expression of proteins characteristic of the endoplasmic reticulum (ER) stress response compared with β-cells from WT mice. Our results suggest that Sgpp2 deletion causes β-cell ER stress, which is a known cause of β-cell dysfunction, and reveal a novel juncture in the sphingolipid recycling pathway that could impact the development of diabetes.
2016-07-25 | GSE73131 | GEO
Project description:Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that regulates basic cell functions through metabolic and signaling pathways. Intracellular metabolism of S1P is controlled, in part, by two homologous S1P phosphatases, 1 and 2, which are encoded by Sgpp1 and Sgpp2, respectively. S1P phosphatase activity is needed for efficient recycling of sphingosine into the sphingolipid synthesis pathway. S1P phosphatase 1 is important for skin homeostasis, but little is known about the functional role of S1P phosphatase 2. To identify the functions of S1P phosphatase 2 in vivo, we studied mice with the Sgpp2 gene deleted. In contrast to Sgpp1-/- mice, Sgpp2-/- mice had normal skin and were viable into adulthood. Unexpectedly, WT mice expressed Sgpp2 mRNA at high levels in pancreatic islets when compared with other tissues. Sgpp2-/- mice had normal blood insulin levels and pancreatic islet size; however, Sgpp2-/- mice treated with a high-fat diet (HFD) had significantly lower blood insulin levels and smaller pancreatic islets compared with WT mice. The smaller islets in the HFD-treated Sgpp2-/- mice had a significantly lower adaptive B-cell proliferation rate in response to the diet compared with HFD-treated WT mice. Importantly, B-cells from Sgpp2-/- mice fed a normal diet showed significantly increased expression of proteins characteristic of the endoplasmic reticulum (ER) stress response compared with B-cells from WT mice. Our results suggest that Sgpp2 deletion causes B-cell ER stress, which is a known cause of B-cell dysfunction, and reveal a novel juncture in the sphingolipid recycling pathway that could impact the development of diabetes. Three replications of Mouse (WT vs KO) that were treated with with Normal and HFD foods.
2016-07-25 | E-GEOD-73131 | biostudies-arrayexpress
Project description:The maintenance of pancreatic islet architecture is crucial for proper β-cell function. We previously reported that disruption of human islet integrity could result in altered β-cell identity. Here we combine β-cell lineage tracing and single-cell transcriptomics to investigate the mechanisms underlying this process in primary human islet cells. Using drug-induced ER stress and cytoskeleton modification models, we demonstrate that altering the islet structure triggers an unfolding protein response that causes the downregulation of β-cell maturity genes. Collectively, our findings illustrate the close relationship between endoplasmic reticulum homeostasis and β-cell phenotype, and strengthen the concept of altered β-cell identity as a mechanism underlying the loss of functional β-cell mass.
2024-04-13 | GSE263565 | GEO
Project description:The IL-22RA1 receptor is highly expressed in the pancreas, and exogenous IL-22 has been shown to reduce endoplasmic reticulum and oxidative stress in human pancreatic islets and promote secretion of high-quality insulin from beta-cells. However, the endogenous role of IL-22RA1 signaling on these cells remains unclear. Here, we show that antibody neutralisation of IL-22RA1 in cultured human islets leads to impaired insulin quality and increased cellular stress. Through the generation of mice lacking IL-22ra1 specifically on pancreatic alpha- or beta-cells, we demonstrate that ablation of murine beta-cell IL-22ra1 leads to similar decreases in insulin secretion, quality and islet regeneration, whilst increasing islet cellular stress, inflammation and MHC II expression. These changes in insulin secretion led to impaired glucose tolerance, a finding more pronounced in female animals compared to males. Our findings attribute a regulatory role for endogenous pancreatic beta-cell IL-22ra1 in insulin secretion, islet regeneration, inflammation/cellular stress and appropriate systemic metabolic regulation.
2024-04-16 | GSE262867 | GEO
Project description:Sirtuin 1 (Sirt1) has been reported to be a critical positive regulator of glucose-stimulated insulin secretion in pancreatic beta-cells. The effects on islet cells and blood glucose levels when Sirt1 is deleted specifically in the pancreas are still unclear.This study examined islet glucose responsiveness, blood glucose levels, pancreatic islet histology and gene expression in Pdx1-Cre;Sirt1(ex4F/F) mice that have loss of function and loss of expression of Sirt1 specifically in the pancreas. We found that in the Pdx1-Cre;Sirt1(ex4F/F) mice, the relative insulin positive area and the islet size distribution were unchanged. However, beta-cells were functionally impaired, presenting with lower glucose-stimulated insulin secretion. This defect was not due to a reduced expression of insulin but was associated with a decreased expression of the glucose transporter Slc2A2/Glut2 and of the Glucagon like peptide-1 receptor (Glp1r) as well as with a marked down regulation of endoplasmic reticulum (ER) chaperones that participate in the Unfolded Protein Response (UPR) pathway. Counter intuitively, the Sirt1-deficient mice did not develop hyperglycemia. Pancreatic polypeptide (PP) cells were the only other islet cells affected, with reduced numbers in the Sirt1-deficient pancreas. This study provides new mechanistic insights showing that beta-cell function in Sirt1-deficient pancreas is affected due to altered glucose sensing and deregulation of the UPR pathway. Interestingly, we uncover a context in which impaired beta-cell function is not accompanied by increased glycemia. This points to a unique compensatory mechanism. Given the reduction in PP, investigation of its role in the control of blood glucose is warranted. To uncover other Sirt1-regulated mechanisms, we performed a gene expression microarray analysis comparing pancreata from the 6 month old Sirt1âdeficient mice to their controls (n=3 per group).
2016-03-01 | E-GEOD-67239 | biostudies-arrayexpress
Project description:Individual organisms age at different rates, however, it remains unclear how aging alters the properties of individual cells. Here we show that zebrafish pancreatic beta-cells exhibit heterogeneity in both gene expression and proliferation with age. Individual beta-cells show marked variability in transcripts involved in endoplasmic reticulum stress, inhibition of growth factor signaling and inflammation, including NF-kB signaling. Using a reporter line, we show that NF-kB signaling is indeed activated heterogeneously with age. Notably, beta-cells with higher NF-kB activity proliferate less compared to neighbors with lower activity. Furthermore, NF-kB-signalinghigh beta-cells from younger islets upregulate socs2, a gene naturally expressed in beta-cells from older islets. In turn, socs2 can inhibit proliferation cell-autonomously. NF-kB activation correlates with the recruitment of tnfα-expressing immune cells, pointing towards a role for the islet microenvironment in this activity. We propose that aging is heterogeneous across individual beta-cells and identify NF-kB signaling as a marker of heterogeneity.
2018-05-04 | GSE106938 | GEO
Project description:Sphingosine-1-phosphate phosphatase 1 regulates keratinocyte differentiation and epidermal homeostasis
| PRJNA173774 | ENA
Project description:Pancreatic beta-cell dysfunction and death are central in the pathogenesis of type 2 diabetes. Saturated fatty acids cause beta-cell failure and contribute to diabetes development in genetically predisposed individuals. Here we used RNA-sequencing to map transcripts expressed in five palmitate-treated human islet preparations, observing 1,325 modified genes. Palmitate induced fatty acid metabolism and endoplasmic reticulum (ER) stress. Functional studies identified novel mediators of adaptive ER stress signaling. Palmitate modified genes regulating ubiquitin and proteasome function, autophagy and apoptosis. Inhibition of autophagic flux and lysosome function contributed to lipotoxicity. Palmitate inhibited transcription factors controlling beta-cell phenotype including PAX4 and GATA6. 59 type 2 diabetes candidate genes were expressed in human islets, and 11 were modified by palmitate. Palmitate modified expression of 17 splicing factors and shifted alternative splicing of 3,525 transcripts. Ingenuity Pathway Analysis of modified transcripts and genes confirmed that top changed functions related to cell death. DAVID analysis of transcription binding sites in palmitate-modified transcripts revealed a role for PAX4, GATA and the ER stress response regulators XBP1 and ATF6. This human islet transcriptome study identified novel mechanisms of palmitate-induced beta-cell dysfunction and death. The data point to crosstalk between metabolic stress and candidate genes at the beta-cell level. 5 human islet of Langerhans preparations examined under 2 conditions (control and palmitate treatment)
2014-01-09 | E-GEOD-53949 | biostudies-arrayexpress
Project description:Protein phosphatase 2A (PP2A) is one of the most common serine/threonine phosphatases in mammalian cells and primarily functions to regulate cell signaling, glycolipid metabolism, and apoptosis. Its PP2A catalytic subunit (PP2Ac) plays an important role in its function. Nonetheless, at present, there are only a few reports on the regulatory role of PP2Ac in pancreatic β-cells under lipotoxicity. Mouse pancreatic insulinoma (MIN6) cells were transfected by lentiviruses to generate PP2Ac knockdown cells and incubated with palmitate (PA) to establish the lipotoxicity model. Serine/Threonine Phosphatase Assay System kit, Cell Counting Kit-8 (CCK-8), flow cytometry, enzyme-linked immunosorbent assay (ELISA), Western Blotting (WB) and other techniques were used to measure PP2A activity, cell viability, apoptosis, oxidative stress, and insulin secretion. An animal model of lipotoxicity with knockdown of PP2Ac was established by a high-fat diet (HFD) after using adeno-associated viruses (AAV) to interfere with PP2Ac expression in mouse pancreatic tissues. Serine/Threonine Phosphatase Assay System kit, ELISA, pancreatic tissue immunofluorescence and other techniques were used to measure PP2A activity in pancreatic tissue, serum insulin level and the proliferation of mouse pancreatic β-cells. We found that PP2Ac knockdown inhibited lipotoxicity-induced PP2A hyperactivation, increased the resistance of pancreatic β-cells to lipotoxicity, decreased PA-induced apoptosis in MIN6 cells, protected the function of both the endoplasmic reticulum (ER) and mitochondria, and improved insulin secretion. By mRNA sequencing and Western blotting analysis, we hypothesized that the protective effects of PP2Ac knockdown in MIN6 cells may be mediated by the MAPK pathway. Moreover, the results obtained from animal experiments suggest that the specific knockdown of pancreatic PP2Ac could effectively attenuate HFD-induced insulin resistance and reduce the compensatory proliferation of pancreatic β-cells in mice. The present study revealed the effects and mechanisms of interfering with PP2Ac gene expression on pancreatic β-cells in vivo and in vitro, which might provide insights for the treatment of type 2 diabetes in the clinic.
2023-09-13 | GSE242538 | GEO
Project description:Pancreatic islet endocrine cell and endothelial cell (EC) interactions mediated by vascular endothelial growth factor-A (VEGF-A) signaling are important for islet endocrine cell differentiation and the formation of highly vascularized islets. To dissect how VEGF-A signaling modulates intra-islet vasculature and innervation, islet microenvironment, and β cell mass, we transiently increased VEGF-A production by β cells. VEGF-A induction dramatically increased the number of intra-islet ECs but led to β cell loss. After withdrawal of the VEGF-A stimulus, β cell mass, function, and islet structure normalized as a result of a robust, but transient, burst in proliferation of pre-existing β cells. Bone marrow-derived macrophages (MΦs) recruited to the site of β cell injury were crucial for the β cell proliferation, which was independent of pancreatic location and circulating factors such as glucose. Identification of the signals responsible for the proliferation of adult, terminally differentiated β cells will improve strategies aimed at β cell regeneration and expansion. Examination of RNA profiles from isolated whole islets from RIP-rtTA; TetO-VEGF-A mice with no doxycycline (Dox) treatment (3 samples) and after 1 week of Dox (3 sample); and islet-derived macrophages (3 samples) and endothelial cells (3 samples) isolated from dispersed purified islets from RIP-rtTA; TetO-VEGF-A mice after 1 week Dox treatment by fluorescence-activated cell sorting using antibodies against CD11b and CD31, respectively.
2015-09-01 | E-GEOD-72546 | biostudies-arrayexpress