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Bloch and Richard T. Lee P. Christian Schulze, Heling Liu, Elizabeth ...

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<strong>Schulze</strong> et al. NO regulates thioredoxin through Txnip-Supplemental Material - R1; page 3<br />

onto nitrocellulose membranes. Identical numbers of control <strong>and</strong> GSNO-treated cells were used for<br />

the isolation of nuclei <strong>and</strong> preparation of [ 32 P]UTP-radiolabeled transcripts. Signals were visualized<br />

by autoradiography. Specific radioactive signal intensity (as counts per minute) was determined for<br />

each probe individually using a scintillation counter <strong>and</strong> normalized over signal intensity of the<br />

housekeeping gene β-tubulin.<br />

mRNA stability. Cells were pretreated with actinomycin D (5 µg/mL for 30 min) before<br />

incubation with <strong>and</strong> without GSNO stimulation (100 µM) for varying durations. RNA was extracted,<br />

<strong>and</strong> Txnip gene expression was measured by quantitative PCR <strong>and</strong> normalized for expression of β-<br />

tubulin as described before. 3<br />

Plasmid construction <strong>and</strong> transient transfection experiments. The human Txnip promoter<br />

region including -1777 bp upstream of the ATG start codon was cloned from human genomic DNA<br />

using primers 1-6 (Table 1). To generate the Txnip promoter constructs, PCR products were<br />

extracted <strong>and</strong> cloned into a firefly luciferase reporter vector pGL3-Basic Vector (Promega). The<br />

transcriptional activity of the promoter constructs was assessed under stimulation with GSNO at 5.6<br />

mM <strong>and</strong> 22.4 mM glucose. Luciferase activity was determined using the Dual Light assay kit<br />

(Tropix). All experiments were repeated five times. Further, full-length human Txnip was cloned<br />

into a mammalian expression vector (pcDNA3.1, Invitrogen). Expression plasmids for human<br />

wildtype thioredoxin or mutant thioredoxin with a serine replacing cysteine 69 (C69S) were kindly<br />

provided by Dr. Judith Haendeler (Molecular Cardiology, University of Frankfurt, Germany). These<br />

vectors express a thioredoxin-Xpress-tag fusion protein. Complete sequence identity was confirmed<br />

by sequencing analysis. Cells were transfected using FUGENE transfection reagent (Roche Applied<br />

Biosystems) <strong>and</strong> were studied 48 hours later. Equal amounts of empty expression plasmids served<br />

as control vectors.<br />

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