| Autor: |
Quade BN; Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York., Marshall A; Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York., Parker MD; Department of Physiology and Biophysics, The State University of New York: The University at Buffalo, Buffalo, New York.; Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York, Buffalo, New York.; State University of New York Eye Institute, University at Buffalo: The State University of New York, Buffalo, New York. |
| Jazyk: |
angličtina |
| Zdroj: |
American journal of physiology. Cell physiology [Am J Physiol Cell Physiol] 2020 Aug 01; Vol. 319 (2), pp. C359-C370. Date of Electronic Publication: 2020 Jun 10. |
| DOI: |
10.1152/ajpcell.00128.2020 |
| Abstrakt: |
SLC4A11 is the only member of the SLC4 family that transports protons rather than bicarbonate. SLC4A11 is expressed in corneal endothelial cells, and its mutation causes corneal endothelial dystrophy, although the mechanism of pathogenesis is unknown. We previously demonstrated that the magnitude of the H + conductance ( G m ) mediated by SLC4A11 is increased by rises in intracellular as well as extracellular pH (pH i and pH e ). To better understand this feature and whether it is altered in disease, we studied the pH dependence of wild-type and mutant mouse Slc4a11 expressed in Xenopus oocytes. Using voltage-clamp circuitry in conjunction with a H + -selective microelectrode and a microinjector loaded with NaHCO 3 , we caused incremental rises in oocyte pH i and measured the effect on G m . We find that the rise of G m has a steeper pH i dependence at pH e =8.50 than at pH e =7.50. Data gathered at pH e =8.50 can be fit to the Hill equation enabling the calculation of a p K value that reports pH i dependence. We find that mutation of lysine residues that are close to the first transmembrane span (TM1) causes an alkaline shift in p K . Furthermore, two corneal-dystrophy-causing mutations close to the extracellular end of TM1, E399K and T401K (E368K and T370K in mouse), cause an acidic shift in p K , while a third mutation in the fourth intracellular loop, R804H (R774H in mouse), causes an alkaline shift in p K . This is the first description of determinants of SLC4A11 pH dependence and the first indication that a shift in pH dependence could modify disease expressivity in some cases of corneal dystrophy. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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