| 1. |
- Kalis, Martins, et al.
(författare)
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Beta-cell specific deletion of dicer1 leads to defective insulin secretion and diabetes mellitus
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:12, s. e29166-
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Tidskriftsartikel (refereegranskat)abstract
- Mature microRNAs (miRNAs), derived through cleavage of pre-miRNAs by the Dicer1 enzyme, regulate protein expression in many cell-types including cells in the pancreatic islets of Langerhans. To investigate the importance of miRNAs in mouse insulin secreting beta-cells, we have generated mice with a beta-cells specific disruption of the Dicer1 gene using the Cre-lox system controlled by the rat insulin promoter (RIP). In contrast to their normoglycaemic control littermates (RIP-Cre(+/-) Dicer1(Delta/wt)), RIP-Cre(+/-) Dicer1(flox/flox) mice (RIP-Cre Dicer1(Delta/Delta)) developed progressive hyperglycaemia and full-blown diabetes mellitus in adulthood that recapitulated the natural history of the spontaneous disease in mice. Reduced insulin gene expression and concomitant reduced insulin secretion preceded the hyperglycaemic state and diabetes development. Immunohistochemical, flow cytometric and ultrastructural analyses revealed altered islet morphology, marked decreased beta-cell mass, reduced numbers of granules within the beta-cells and reduced granule docking in adult RIP-Cre Dicer1(Delta/Delta) mice. beta-cell specific Dicer1 deletion did not appear to disrupt fetal and neonatal beta-cell development as 2-week old RIP-Cre Dicer1(Delta/Delta) mice showed ultrastructurally normal beta-cells and intact insulin secretion. In conclusion, we have demonstrated that a beta-cell specific disruption of the miRNAs network, although allowing for apparently normal beta-cell development, leads to progressive impairment of insulin secretion, glucose homeostasis and diabetes development.
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| 2. |
- Mendu, Suresh Kumar, et al.
(författare)
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Increased GABA(A) channel subunits expression in CD8(+) but not in CD4(+) T cells in BB rats developing diabetes compared to their congenic littermates
- 2011
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 48:4, s. 399-407
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Tidskriftsartikel (refereegranskat)abstract
- GABA (γ-aminobutyric acid), the main inhibitory neurotransmitter in the central nervous system is also present in the pancreatic islet β cells where it may function as a paracrine molecule and perhaps as an immunomodulator of lymphocytes infiltrating the pancreatic islet. We examined CD4(+) and CD8(+) T cells from diabetes prone (DR(lyp/lyp)) or resistant (DR(+/+)) congenic biobreeding (BB) rats for expression of GABA(A) channels. Our results show that BB rat CD4(+) and CD8(+) T cells express α1, α2, α3, α4, α6, β3, γ1, δ, ρ1 and ρ2 GABA(A) channel subunits. In CD8(+) T cells from DR(lyp/lyp) animals the subunits were significantly upregulated relative to expression levels in the CD8(+) T cells from DR(+/+) rats as well as from CD4(+) T cells from both DR(lyp/lyp) and DR(+/+) rats. Functional channels were formed in the T cells and physiological concentrations of GABA (100 nM) decreased T cell proliferation. Our results are consistent with the hypothesis that GABA in the islets of Langerhans may diminish inflammation by inhibition of activated T lymphocytes.
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