Hyperglycemia-induced activation of the hexosamine biosynthetic pathway causes myocardial cell death
| Autor: | Rajamani, Uthra |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: | |
| Druh dokumentu: | Diplomová práce |
| Popis: | Thesis (PhD (Physiological Sciences))--University of Stellenbosch, 2009. ENGLISH ABSTRACT: OBJECTIVE – Oxidative stress increases flux through the hexosamine biosynthetic pathway (HBP) resulting in greater O-GlcNAcylation of target proteins. Since increased oxidative stress and HBP flux are associated with insulin resistance, we hypothesized that its activation leads to greater O-GlcNAcylation of BAD (pro-apoptotic) and increased myocardial apoptosis. RESEARCH DESIGN AND METHODS – To investigate our hypothesis, we employed two experimental models: 1) H9c2 cardiomyoblasts exposed to high glucose (33 mM glucose) ± HBP modulators ± antioxidant treatment vs. matched controls (5.5 mM glucose); and 2) a rat model of high fat diet-induced insulin resistance and hyperglycemia. We evaluated apoptosis in vitro by Hoechst nuclear staining, Annexin-V staining, caspase activity measurements and immunoblotting while in vivo apoptosis was assessed by immunoblotting. In vitro reactive oxygen species (ROS) levels were quantified by H2DCFDA staining (fluorescence microscopy, flow cytometry). We determined overall and BAD O-GlcNAcylation, both by immunoblotting and immunofluorescence microscopy. As BAD-Bcl-2 dimer formation enhances apoptosis, we performed immunoprecipitation analysis and immunofluorescence microscopy (co-localization) to determine BAD-cl-2 dimerization. In vivo overall O-GlcNAcylation, BAD O-GlcNAcylation and BAD-Bcl-2 dimerization was determined by immunoprecipitation and immunoblotting. 4 RESULTS – High glucose treatment of cells significantly increased the degree of apoptosis as revealed by Hoechst nuclear staining (54 ± 9%, p AFRIKAANSE OPSOMMING: DOELWIT – Oksidatiewe stres verhoog fluks deur die heksosamien biosintetiese weg (HBW) wat in „n groter O-GlcNAsetilering van teiken proteïene resulteer. Weens die feit dat verhoogde oksidatiewe stres en HBW fluks verband hou met insulienweerstandigheid, hipotetiseer ons dat die aktivering hiervan tot groter O-GlcNAsetilering van BAD (pro-aptoptoties) en verhoogde miokardiale apoptose lei. NAVORSINGS ONTWERP EN METODES – Om die hipotese te ondersoek het ons twee modelle ontplooi: 1) H9c2 kardiomioblaste is blootgestel aan hoë glukose konsentrasie (33mM glucose) ± HBW moduleerders ± antioksidant behandeling vs. gepaarde kontrole (5.5mM glucose); en 2) „n hoë vet dieetgeïnduseerde insulienweerstandige rotmodel en hiperglukemie. Ons het apoptose in vitro deur middel van Hoescht nukleuskleuring geëvalueer, kasapase aktiwiteit bepalings en immunoblotting terwyl apoptose in vivo getoets is deur immunoblotting. Reaktiewe suurstofspesie (RSS) vlakke is deur middel van H2DCFDA verkleuring (fluoresensie mikroskopie, vloeisitometrie) bepaal. Algehele en BAD O-GlcNAsetilering is beide deur immunoblotting en immunofluoresensie mikroskopie bepaal. BAD-Bcl-2 dimeervorming bevorder apoptose, om BAD-cl-2 dimerisasie te bepaal is daar van immunopresipitering analise en immunofluoresensie mikroskopie (ko-lokalisasie) gebruik gemaak. In vivo is algehele OGlcNAsetiliering, BAD O-GlcNAsetiliering en BAD-Bcl-2 dimerisasie deur immunopresipitasie en immunoblotting bepaal. 6 RESULTE – Hoë glukose behandeling van selle het die graad van apotpose betekenisvol verhoog soos blootgelê deur Hoechst nukleuskleuring (54 ± 9%, p |
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