Significance Voltage-gated sodium (Na v ) channels contribute to physiological and pathophysiological electrical signaling in nerve and muscle cells. Because Na v channel isoforms exhibit tissue-specific expression, subtype selective modulation of this channel family provides important drug development opportunities. However, most available Na v channel modulators are unable to distinguish between Na v channel subtypes, which limits their therapeutic utility because of cardiac or nervous system toxicity. This study describes a new class of subtype selective Na v channel inhibitors that interact with a region of the channel that controls voltage sensitivity. This interaction site may enable development of selective therapeutic interventions with reduced potential for toxicity.

Estrogen receptor (ER) modulators produce distinct tissue-specific biological effects, but within the confines of the established models of ER action it is difficult to understand why. Previous studies have suggested that there might be a relationship between ER structure and activity. Different ER modulators may induce conformational changes in the receptor that result in a specific biological activity. To investigate the possibility of modulator-specific conformational changes, we have applied affinity selection of peptides to identify binding surfaces that are exposed on the apo-ERs ␣ and ␤ and on each receptor complexed with estradiol or 4-OH tamoxifen. These peptides are sensitive probes of receptor conformation. We show here that ER ligands, known to produce distinct biological effects, induce distinct conformational changes in the receptors, providing a strong correlation between ER conformation and biological activity. Furthermore, the ability of some of the peptides to discriminate between different ER ␣ and ER ␤ ligand complexes suggests that the biological effects of ER agonists and antagonists acting through these receptors are likely to be different.

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Autoantibodies to type VII collagen are characteristic of the blistering diseases epidermolysis bullosa acquisita and bullous systemic lupus erythematosus (SLE). Blisters in those diseases are due to defective adhesion of the lamina densa subregion of the epithelial basement membrane to the underlying dermis. Previous studies indicating that type VII collagen contributes to lamina densa-dermal adhesion by cross-linking lamina densa and dermal matrix proteins suggests that autoantibodies may contribute to blisters by interfering with type VII collagen function. That hypothesis is supported by previous studies showing autoantibodies from a small number of epidermolysis bullosa acquisita patients recognize proteolytic fragments containing the 145-kD noncollagenous domain of type VII collagen. In this study, we examined reactivity of autoantibodies from a large number of epidermolysis bullosa acquisita and bullous SLE patients with fusion proteins representing most of the noncollagenous domain of type VII collagen and that those regions are homologous to type III repeats of fibronectin. These results suggest autoantibodies binding to fibronectin homology regions within the 145-kD noncollagenous domain may interfere with the adhesion function of type VII collagen and contribute to lamina densa-dermal dysadhesion in epidermolysis bullous acquisita and bullous SLE.