Biochemical and biophysical research communications
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Biochem. Biophys. Res. Commun. · Dec 2009
Impaired TLR3/IFN-beta signaling in monocyte-derived dendritic cells from patients with acute-on-chronic hepatitis B liver failure: relevance to the severity of liver damage.
Toll-like receptors (TLRs) are a class of proteins that play key roles in innate immunity through recognition of microbial components. TLR3 is expressed abundantly in dendritic cells, and is responsible for recognizing viral pathogens and inducing interferon beta (IFN-beta) production. Although TLR3 has been reported to be involved in several diseases caused by viral infections, its role in hepatitis B virus (HBV)-induced hepatitis is still largely unknown. ⋯ Compared with surviving patients, TLR3 and IFN-beta expression was significantly lower in non-surviving ACHBLF patients, which strongly indicated a correlation between TLR3 signaling impairment in MoDCs and disease severity in ACHBLF patients. Further linear correlation analysis demonstrated significant correlations between expression of TLR3 signaling components (TLR3 and IFN-beta) and disease severity markers (prothrombin activity and total bilirubin) for individual ACHBLF patients. To the best of our knowledge, this is the first study to show that MoDC impairment is correlated with severe liver damage in ACHBLF patients, which suggests the potential of TLR3/IFN-beta expression in MoDCs as a diagnostic marker.
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Biochem. Biophys. Res. Commun. · Dec 2009
An aggregate-prone mutant of human glyceraldehyde-3-phosphate dehydrogenase augments oxidative stress-induced cell death in SH-SY5Y cells.
Glycerladehyde-3-phosphate dehydrogenase (GAPDH), a classic glycolytic enzyme, also has a role in mediating cell death under oxidative stress. Our previous reports suggest that oxidative stress-induced GAPDH aggregate formation is, at least in part, a mechanism to account for the death signaling. Here we show that substitution of cysteine for serine-284 of human GAPDH (S284C-GAPDH) leads to aggregate-prone GAPDH, and that its expression in SH-SY5Y human neuroblastoma results in greater dopamine-induced cell death than expression of wild type-GAPDH. ⋯ Several lines of structural analysis revealed that S284C-GAPDH was amyloidogenic. Overexpression of doxycycline-inducible S284C-GAPDH in SH-SY5Y cells accelerated dopamine treatment-induced death and increased formation of GAPDH aggregates, compared to cells expressing wild type-GAPDH. These results suggest that aggregate-prone mutations of GAPDH such as S284C-GAPDH may confer risk of oxidative stress-induced cell death.
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Biochem. Biophys. Res. Commun. · Dec 2009
Erythromelalgia mutation L823R shifts activation and inactivation of threshold sodium channel Nav1.7 to hyperpolarized potentials.
Erythromelalgia (also termed erythermalgia) is a neuropathic pain syndrome, characterized by severe burning pain combined with redness in the extremities, triggered by mild warmth. The inherited form of erythromelalgia (IEM) has recently been linked to mutations in voltage-gated sodium channel Nav1.7, which is expressed in peripheral nociceptors. Here, we used whole-cell voltage-clamp recordings in HEK293 cells to characterize the IEM mutation L823R, which introduces an additional positive charge into the S4 voltage sensor of domain II. ⋯ The L823R mutation induces a approximately 10mV hyperpolarizing shift in fast-inactivation. L823R is the only naturally-occurring IEM mutation studied thus far to shift fast-inactivation to more negative potentials. We conclude that introduction of an additional charge into the S4 segment of domain II of Nav1.7 leads to a pronounced hyperpolarizing shift of activation, a change that is expected to increase nociceptor excitability despite the hyperpolarizing shift in fast-inactivation, which is unique among the IEM mutations.
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Biochem. Biophys. Res. Commun. · Oct 2009
Effective neuropathic pain relief through sciatic nerve administration of GAD65-expressing rAAV2.
Recently, we demonstrated that the administration of GAD65-expressing rAAV2 to DRG attenuates peripheral neuropathy by inducing GABA release in the spinal cord. However, the direct injection to DRG is invasive and may therefore cause nerve injury and other side effects. To circumvent this surgical intervention, we explored the potential of a much simpler and less invasive route of sciatic nerve administration. ⋯ Both GFP and GAD65 expression indicated that effective transgene delivery to the DRG can be accomplished via sciatic nerve administration. Equally importantly, the GABA concentration in the spinal cord increased significantly after GAD65 introduction, and pain symptoms were dramatically reduced and persistently controlled. The implication is that the sciatic nerve is a highly promising route for delivering rAAV2 to the DRG, and thus represents a much less invasive, clinically viable gene therapy option.
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Biochem. Biophys. Res. Commun. · Aug 2009
Insights from investigating the interaction of oseltamivir (Tamiflu) with neuraminidase of the 2009 H1N1 swine flu virus.
The neuraminidase (NA) of influenza virus is the target of anti-flu drugs oseltamivir and zanamivir. Clinical practices showed that oseltamivir was effective to treat the 2009-H1N1 influenza but failed to the 2006-H5N1 avian influenza. To perform an in-depth analysis on such a drug-resistance problem, the 2009-H1N1-NA structure was developed. ⋯ It has been revealed that the hydrophobic residue Try347 in H5N1-NA does not match with the hydrophilic carboxyl group of oseltamivir as in the case of H1N1-NA. This may be the reason why H5N1 avian influenza virus is drug-resistant to oseltamivir. The finding provides useful insights for how to modify the existing drugs, such as oseltamivir and zanamivir, making them not only become more effective against H1N1 virus but also effective against H5N1 virus.