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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 586/17/4137    most recent jphysiol.2008.154906v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Jarecki, B. W. Articles by Cummins, T. R. PubMed PubMed Citation Articles by Jarecki, B. W. Articles by Cummins, T. R. Related Collections Neuroscience

¹ Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA

Single-point missense mutations in the peripheral neuronal voltage-gated sodium channel Nav1.7 are implicated in the painful inherited neuropathy paroxysmal extreme pain disorder (PEPD). The Nav1.7 PEPD mutations are located in regions of the channel suggested to play important roles in fast inactivation. PEPD mutations in the putative inactivation gate have been reported to significantly impair fast inactivation, resulting in pronounced persistent currents. However, PEPD mutations in the S4–S5 linker of domain 3 (D3/S4–S5) had not been characterized and the roles of specific residues in this linker in channel gating are unclear. We functionally characterized two of the D3/S4–S5 PEPD mutations (V1298F and V1299F) and compared their effects on gating to an adjacent non-PEPD mutation (V1300F) and the I1461T PEPD mutation, located in the putative inactivation gate. The primary effect of the V1298F and V1299F mutations is to shift the voltage dependence of fast inactivation by 20 mV in the depolarizing direction. We observed a similar effect with the PEPD mutation I1461T. Interestingly, while all three PEPD mutations increased persistent currents, the relative amplitudes (6% of peak) were much smaller than previously reported for the I1461T mutation. In contrast, the main effect of the V1300F mutation was a depolarizing shift in the voltage dependence of activation. These data demonstrate that (1) mutations within D3/S4–S5 affect inactivation of Nav1.7 in a residue-specific manner and (2) disruption of the fast-inactivated state by PEPD mutations can be more moderate than previously indicated, which has important implications for the pathophysiology of PEPD.

(Received 7 April 2008; accepted after revision 1 July 2008; first published online 3 July 2008)
Corresponding author T. Cummins: Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, 950 West Walnut Street, R2468, Indianapolis, IN 46202, USA. Email: trcummin{at}iupui.edu

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