Abstract
Glutathione-dependent formaldehyde dehydrogenase (GFD) from Taiwanofungus camphorata plays important roles in formaldehyde detoxification and antioxidation. The enzyme is bifunctional. In addition to the GFD activity, it also functions as an effective S-nitrosoglutathione reductase (GSNOR) against nitrosative stress. We investigated the modulation of HEK (human embryonic kidney) 293T cells under nitrosative stress by transfecting a codon optimized GFD cDNA from Taiwanofungus camphorata (Tc-GFD-O) to these cells. The parental and transfected HEK 293T cells were then subjected to S-nitrosoglutathione treatment to induce nitrosative stress. The results showed that in Tc-GFD-O-transfected 293T cells, the expression and activity of GFD increased. Additionally, these cells under the nitrosative stress induced by S-nitrosoglutathione showed both higher viability and less apoptosis than the parental 293T cells. This finding suggests that the Tc-GFD-O in HEK 293T cells may provide a protective function under nitrosative stress.
Highlights
The human ether-a-go-go related gene encodes the pore-forming subunit of the voltage-dependent potassium channel that conducts the rapidly activating delayed rectifier potassium current (IKr) [1,2]
(A–C) demonstrate the lack of contamination of the tail current by non-IKr currents under our experimental conditions; (D) Typical original IKr tail currents recorded over a 20-min period from a myocyte; (E,F) show the representative traces of time-dependence of the relative current and the I–V curve during myocyte superperfusion with control extracellular solution. (D–F) demonstrate that the IKr tail currents were stable within a timeframe of 20 min
The main findings of the present report are as follows: (1) acute activation of α1-adrenergic receptors (ARs) produce comparable effects on IKr tail current density to β1-adrenergic receptors (β1-ARs); (2) acute activation of α1-adrenergic receptors (α1-ARs) in the presence of β1-AR activation elicits a minor decrease in IKr tail current, which is statistically different from that achieved by α1-AR activation alone; (3) acute activation of β1-AR in the presence of α1-AR
Summary
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the voltage-dependent potassium channel that conducts the rapidly activating delayed rectifier potassium current (IKr) [1,2]. Acute activation of β1-adrenergic receptors (β1-ARs), classically coupling with Gs-proteins, results in adenylate cyclase and thereby increases cyclic AMP (cAMP). This promotes protein kinase A (PKA)-mediated phosphorylation of four recognized serine residues (S283, S890, S895, and S1137) on the hERG channel. The combined activation of both pathways in terms of IKr inhibition would not reflect the sum of the individual effects of stimulating either axis alone To address this hypothesis, we designed two experimental groups, which are referred to as Ppre + X and Xpre + P. PE-induced IKr reduction in the presence of Xamo, and Xamo-induced IKr reduction in the presence of PE, as well as shifts in the activation curve of IKr under varying conditions
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