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Sökning: WFRF:(Krus Ulrika)

  • Resultat 1-10 av 27
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  • Bennet, Hedvig, et al. (författare)
  • Altered serotonin (5-HT) 1D and 2A receptor expression may contribute to defective insulin and glucagon secretion in human type 2 diabetes.
  • 2015
  • Ingår i: Peptides. - : Elsevier. - 1873-5169. ; 71, s. 113-120
  • Tidskriftsartikel (refereegranskat)abstract
    • Islet produced 5-hydroxy tryptamine (5-HT) is suggested to regulate islet hormone secretion in a paracrine and autocrine manner in rodents. Hitherto, no studies demonstrate a role for this amine in human islet function, nor is it known if 5-HT signaling is involved in the development of beta cell dysfunction in type 2 diabetes (T2D). To clarify this, we performed a complete transcriptional mapping of 5-HT receptors and processing enzymes in human islets and investigated differential expression of these genes in non-diabetic and T2D human islet donors. We show the expression of fourteen 5-HT receptors as well as processing enzymes involved in the biosynthesis of 5-HT at the mRNA level in human islets. Two 5-HT receptors (HTR1D and HTR2A) were over-expressed in T2D islet donors. Both receptors (5-HT1d and 5-HT2a) were localized to human alpha, beta and delta cells. 5-HT inhibited both insulin and glucagon secretion in non-diabetic islet donors. In islets isolated from T2D donors the amine significantly increased release of insulin in response to glucose. Our results suggest that 5-HT signaling participates in regulation of overall islet hormone secretion in non- diabetic individuals and over-expression of HTR1D and HTR2A may either contribute to islet dysfunction in T2D or arise as a consequence of an already dysfunctional islet.
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  • Dwivedi, Om Prakash, et al. (författare)
  • Loss of ZnT8 function protects against diabetes by enhanced insulin secretion
  • Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036. ; , s. 1-22
  • Tidskriftsartikel (refereegranskat)abstract
    • A rare loss-of-function allele p.Arg138* in SLC30A8 encoding the zinc transporter 8 (ZnT8), which is enriched in Western Finland, protects against type 2 diabetes (T2D). We recruited relatives of the identified carriers and showed that protection was associated with better insulin secretion due to enhanced glucose responsiveness and proinsulin conversion, particularly when compared with individuals matched for the genotype of a common T2D-risk allele in SLC30A8, p.Arg325. In genome-edited human induced pluripotent stem cell (iPSC)-derived β-like cells, we establish that the p.Arg138* allele results in reduced SLC30A8 expression due to haploinsufficiency. In human β cells, loss of SLC30A8 leads to increased glucose responsiveness and reduced KATP channel function similar to isolated islets from carriers of the T2D-protective allele p.Trp325. These data position ZnT8 as an appealing target for treatment aimed at maintaining insulin secretion capacity in T2D.
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  • Fadista, Joao, et al. (författare)
  • Global genomic and transcriptomic analysis of human pancreatic islets reveals novel genes influencing glucose metabolism.
  • 2014
  • Ingår i: Proceedings of the National Academy of Sciences. - : National Acad Sciences. - 1091-6490. ; 111:38, s. 13924-13929
  • Tidskriftsartikel (refereegranskat)abstract
    • Genetic variation can modulate gene expression, and thereby phenotypic variation and susceptibility to complex diseases such as type 2 diabetes (T2D). Here we harnessed the potential of DNA and RNA sequencing in human pancreatic islets from 89 deceased donors to identify genes of potential importance in the pathogenesis of T2D. We present a catalog of genetic variants regulating gene expression (eQTL) and exon use (sQTL), including many long noncoding RNAs, which are enriched in known T2D-associated loci. Of 35 eQTL genes, whose expression differed between normoglycemic and hyperglycemic individuals, siRNA of tetraspanin 33 (TSPAN33), 5'-nucleotidase, ecto (NT5E), transmembrane emp24 protein transport domain containing 6 (TMED6), and p21 protein activated kinase 7 (PAK7) in INS1 cells resulted in reduced glucose-stimulated insulin secretion. In addition, we provide a genome-wide catalog of allelic expression imbalance, which is also enriched in known T2D-associated loci. Notably, allelic imbalance in paternally expressed gene 3 (PEG3) was associated with its promoter methylation and T2D status. Finally, RNA editing events were less common in islets than previously suggested in other tissues. Taken together, this study provides new insights into the complexity of gene regulation in human pancreatic islets and better understanding of how genetic variation can influence glucose metabolism.
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  • Fernandez, Celine, et al. (författare)
  • Metabolomic and proteomic analysis of a clonal insulin-producing beta-cell line (INS-1 832/13).
  • 2008
  • Ingår i: Journal of Proteome Research. - : The American Chemical Society (ACS). - 1535-3893. ; 7:1, s. 400-411
  • Tidskriftsartikel (refereegranskat)abstract
    • Metabolites generated from fuel metabolism in pancreatic beta-cells control exocytosis of insulin, a process which fails in type 2 diabetes. To identify and quantify these metabolites, global and unbiased analysis of cellular metabolism is required. To this end, polar metabolites, extracted from the clonal 832/13 beta-cell line cultured at 2.8 and 16.7 mM glucose for 48 h, were derivatized followed by identification and quantification, using gas chromatography (GC) and mass spectrometry (MS). After culture at 16.7 mM glucose for 48 h, 832/13 beta-cells exhibited a phenotype reminiscent of glucotoxicity with decreased content and secretion of insulin. The metabolomic analysis revealed alterations in the levels of 7 metabolites derived from glycolysis, the TCA cycle and pentose phosphate shunt, and 4 amino acids. Principal component analysis of the metabolite data showed two clusters, corresponding to the cells cultured at 2.8 and 16.7 mM glucose, respectively. Concurrent changes in protein expression were analyzed by 2-D gel electrophoresis followed by LC-MS/MS. The identities of 86 spots corresponding to 75 unique proteins that were significantly different in 832/13 beta-cells cultured at 16.7 mM glucose were established. Only 5 of these were found to be metabolic enzymes that could be involved in the metabolomic alterations observed. Anticipated changes in metabolite levels in cells exposed to increased glucose were observed, while changes in enzyme levels were much less profound. This suggests that substrate availability, allosteric regulation, and/or post-translational modifications are more important determinants of metabolite levels than enzyme expression at the protein level.
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  • Jonsson, Anna, et al. (författare)
  • Effect of Common Genetic Variants Associated with Type 2 Diabetes and Glycemic Traits on α- and β-cell Function and Insulin Action in Man.
  • 2013
  • Ingår i: Diabetes. - : American Diabetes Association Inc.. - 1939-327X. ; 62:8, s. 2978-2983
  • Tidskriftsartikel (refereegranskat)abstract
    • Although meta-analyses of genome-wide association studies have identified more than 60 single nucleotide polymorphisms (SNPs) associated with type 2 diabetes and/or glycemic traits, there is little information whether these variants also affect α-cell function. The aim of the present study was to evaluate the effects of glycemia-associated genetic loci on islet function in vivo and in vitro. We studied 43 SNPs in 4,654 normoglycemic participants from the Finnish population-based PPP-Botnia study. Islet function was assessed, in vivo, by measuring insulin and glucagon concentrations during OGTT, and, in vitro, by measuring glucose stimulated insulin and glucagon secretion from human pancreatic islets. Carriers of risk variants in BCL11A, HHEX, ZBED3, HNF1A, IGF1 and NOTCH2 showed elevated, while those in CRY2, IGF2BP2, TSPAN8 and KCNJ11 decreased fasting and/or 2hr glucagon concentrations in vivo. Variants in BCL11A, TSPAN8, and NOTCH2 affected glucagon secretion both in vivo and in vitro. The MTNR1B variant was a clear outlier in the relationship analysis between insulin secretion and action, as well as between insulin, glucose and glucagon. Many of the genetic variants shown to be associated with type 2 diabetes or glycemic traits also exert pleiotropic in vivo and in vitro effects on islet function.
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  • Resultat 1-10 av 27
  • [1]23Nästa
 
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