Dataset Information

Correlations between clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in the cardiac Na+ channel.

ABSTRACT:

Aim

We compared the clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in domain II (S5-S6) of human, hNa(v)1.5, cardiac Na(+) channels.

Methods

Full clinical evaluation of pedigree members through three generations of a Chinese family combined with SCN5A sequencing from genomic DNA was compared with patch and voltage-clamp results from two independent expression systems.

Results

The four mutation carriers showed bradycardia, and slowed sino-atrial, atrioventricular and intraventricular conduction. Two also showed sick sinus syndrome; two had ST elevation in leads V1 and V2. Unlike WT-hNa(v)1.5, whole-cell patch-clamped HEK293 cells expressing R878C-hNa(v)1.5 showed no detectable Na(+) currents (i(Na)), even with substitution of a similarly charged lysine residue. Voltage-clamped Xenopus oocytes injected with either 0.04 or 1.5 microg microL(-1) R878C-hNa(v)1.5 cRNA similarly showed no i(Na), yet WT-hNa(v)1.5 cRNA diluted to 0.0004-0.0008 ng microL(-1)resulted in expression of detectable i(Na). i(Na) was simply determined by the amount of injected WT-hNa(v)1.5: doubling the dose of WT-hNa(v)1.5 cRNA doubled i(Na). i(Na) amplitudes and activation and inactivation characteristics were similar irrespective of whether WT-hNa(v)1.5 cRNA was given alone or combined with equal doses of R878C-hNa(v)1.5 cRNA therefore excluding dominant negative phenotypic effects. Na(+) channel function in HEK293 cells transfected with R878C-hNa(v)1.5 was not restored by exposure to mexiletine (200 microM) and lidocaine (100 microM). Fluorescence confocal microscopy using E3-Nav1.5 antibody demonstrated persistent membrane expression of both WT and R878C-hNa(v)1.5. Modelling studies confirmed that such i(Na) reductions reproduced the SSS phenotype.

Conclusion

Clinical consequences of the novel R878C mutation correlate with results of physiological studies.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC2659387 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Publications

Correlations between clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in the cardiac Na+ channel.

Zhang Y Y Wang T T Ma A A Zhou X X Gui J J Wan H H Shi R R Huang C C Grace A A AA Huang C L-H CL Trump D D Zhang H H Zimmer T T Lei M M

Acta physiologica (Oxford, England) 20080724 4

<h4>Aim</h4>We compared the clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in domain II (S5-S6) of human, hNa(v)1.5, cardiac Na(+) channels.<h4>Methods</h4>Full clinical evaluation of pedigree members through three generations of a Chinese family combined with SCN5A sequencing from genomic DNA was compared with patch and voltage-clamp results from two independent expression systems.<h4>Results</h4>The four mutation carriers showed bradycard ...[more]

PMID: 18616619

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Project description:Previous studies have shown that highly conserved residues in the inner domain of gp120 are required for HIV-1 envelope glycoprotein (Env) transitions to the CD4-bound conformation (A. Finzi, S. H. Xiang, B. Pacheco, L. Wang, J. Haight, et al., Mol Cell 37:656-667, 2010, http://dx.doi.org/10.1016/j.molcel.2010.02.012; A. Desormeaux, M. Coutu, H. Medjahed, B. Pacheco, A. Herschhorn, et al., J Virol 87:2549-2562, 2013, http://dx.doi.org/10.1128/JVI.03104-12). Moreover, W69, a highly conserved residue located at the interface between layer 1 and layer 2 of the inner domain, was recently shown to be important for efficient Env recognition by CD4-induced (CD4i) antibodies capable of potent antibody-dependent cellular cytotoxicity (W. D. Tolbert, N. Gohain, M. Veillette, J. P. Chapleau, C. Orlandi, et al., 2016, Structure 24:697-709, http://dx.doi.org/10.1016/j.str.2016.03.005; S. Ding, M. Veillette, M. Coutu, J. Prevost, L. Scharf, et al., 2016, J Virol 90:2127-2134, http://dx.doi.org/10.1128/JVI.02779-15). We evaluated the contribution of the hydrophobicity of W69 to conformational changes of Env by replacing it with a series of residues with aliphatic or aromatic side chains of decreasing chain length. We have found that the hydrophobicity of residue 69 is important for Env processing, CD4 binding, and its transition to the CD4-bound conformation. The most deleterious effect was observed when W69 was replaced with alanine or glycine residues. However, the functions lost due to W69 mutations could be progressively restored with amino acids of increasing aliphatic chain length and fully recovered with residues bearing an aromatic ring. Interestingly, poor CD4 binding of W69A could be fully restored by introducing a compensatory mutation within layer 2 (S115W). Structural studies of HIV-1 gp120 coree W69A/S115W mutant bound to the CD4 peptide mimetic M48U1 and Fab of anti-cluster A antibody N60-i3 revealed no perturbations to the overall structure of the double mutant compared to the wild-type protein but identified higher mobility within the interface between layer 1 and layer 2, the bridging sheet region, and the CD4 binding site.IMPORTANCE HIV-1 Env transitions to the CD4-bound conformation are required for viral entry. Previous studies identified a highly conserved residue of the inner domain, W69, as being involved in these conformational transitions (A. Finzi, S. H. Xiang, B. Pacheco, L. Wang, J. Haight, et al., Mol Cell 37:656-667, 2010, http://dx.doi.org/10.1016/j.molcel.2010.02.012). Here, we show that W69, located at the interface between gp120 and gp41 in the PGT151-bound trimer, plays a critical role in the interprotomer signaling induced by CD4 binding. This new information might be useful in immunogen design.

Dataset Information

Correlations between clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in the cardiac Na+ channel.

Aim

Methods

Results

Conclusion

Publications

Correlations between clinical and physiological consequences of the novel mutation R878C in a highly conserved pore residue in the cardiac Na+ channel.

Similar Datasets

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