Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis

article Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis Regina Huber author Bettina Krueger author 494280000-0001-5351-1785 Alexei Diakov author Judit Korbmacher author Silke Haerteis author Jürgen Einsiedel author Peter Gmeiner author Abul Azad author Harry Cuppens author Jean-Jaques Cassiman author Christoph Korbmacher author Robert Rauh author 35 department 22 department Loss-of-function mutations of the epithelial sodium channel (ENaC) may contribute to pulmonary symptoms resembling those of patients with atypical cystic fibrosis (CF). Recently, we identified a loss-of-function mutation in the alpha-subunit of ENaC (alphaF61L) in an atypical CF patient without mutations in CFTR. To investigate the functional effect of this mutation, we expressed human wild-type alpha beta gamma-ENaC or mutant alpha(F61L) beta gamma-ENaC in Xenopus laevis oocytes. The alphaF61L mutation reduced the ENaC mediated whole-cell currents by approximately 90%. In contrast, the mutation decreased channel surface expression only by approximately 40% and did not alter the single-channel conductance. These findings indicate that the major effect of the mutation is a reduction of the average channel open probability (P(o)). This was confirmed by experiments using the betaS520C mutant ENaC which can be converted to a channel with a P(o) of nearly one, and by experiments using chymotrypsin to proteolytically activate the channel. These experiments revealed that the mutation reduced the average P(o) of ENaC by approximately 75%. Na(+) self inhibition of the mutant channel was significantly enhanced, but the observed effect was too small to account for the large reduction in average channel P(o). The ENaC-activator S3969 partially rescued the loss-of-function phenotype of the alphaF61L mutation. We conclude that the alphaF61L mutation may contribute to respiratory symptoms in atypical CF patients. S. Karger AG2010 eng Cellular Physiology and Biochemistry10.1159/000272059 25001145–158 Huber, Regina, Bettina Krueger, Alexei Diakov, Judit Korbmacher, Silke Haerteis, Jürgen Einsiedel, Peter Gmeiner, et al. “Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis.” Cellular Physiology and Biochemistry 25, no. 001 (2010): 145–158. <a href="https://doi.org/10.1159/000272059">https://doi.org/10.1159/000272059</a>. R. Huber et al., “Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis,” Cellular Physiology and Biochemistry, vol. 25, no. 001, pp. 145–158, 2010, doi: <a href="https://doi.org/10.1159/000272059">10.1159/000272059</a>. Huber R, Krueger B, Diakov A, et al. Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis. Cellular Physiology and Biochemistry. 2010;25(001):145–158. doi:<a href="https://doi.org/10.1159/000272059">10.1159/000272059</a> R. Huber, B. Krueger, A. Diakov, J. Korbmacher, S. Haerteis, J. Einsiedel, P. Gmeiner, A. Azad, H. Cuppens, J.-J. Cassiman, C. Korbmacher, R. Rauh, Cellular Physiology and Biochemistry 25 (2010) 145–158. @article{Huber_Krueger_Diakov_Korbmacher_Haerteis_Einsiedel_Gmeiner_Azad_Cuppens_Cassiman_et al._2010, title={Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis}, volume={25}, DOI={<a href="https://doi.org/10.1159/000272059">10.1159/000272059</a>}, number={001}, journal={Cellular Physiology and Biochemistry}, publisher={S. Karger AG}, author={Huber, Regina and Krueger, Bettina and Diakov, Alexei and Korbmacher, Judit and Haerteis, Silke and Einsiedel, Jürgen and Gmeiner, Peter and Azad, Abul and Cuppens, Harry and Cassiman, Jean-Jaques and et al.}, year={2010}, pages={145–158} } Huber, Regina, et al. “Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis.” Cellular Physiology and Biochemistry, vol. 25, no. 001, S. Karger AG, 2010, pp. 145–158, doi:<a href="https://doi.org/10.1159/000272059">10.1159/000272059</a>. Huber, R., Krueger, B., Diakov, A., Korbmacher, J., Haerteis, S., Einsiedel, J., Gmeiner, P., Azad, A., Cuppens, H., Cassiman, J.-J., Korbmacher, C., & Rauh, R. (2010). Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis. Cellular Physiology and Biochemistry, 25(001), 145–158. <a href="https://doi.org/10.1159/000272059">https://doi.org/10.1159/000272059</a> 549422024-06-30T13:56:57Z2024-06-30T13:57:07Z