TY - JOUR
T1 - Extracellular Cysteines Are Critical to Form Functional Cx46 Hemichannels
AU - Fernández-Olivares, Ainoa
AU - Durán-Jara, Eduardo
AU - Verdugo, Daniel A.
AU - Fiori, Mariana C.
AU - Altenberg, Guillermo A.
AU - Stehberg, Jimmy
AU - Alfaro, Iván
AU - Calderón, Juan Francisco
AU - Retamal, Mauricio A.
N1 - Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2022/7/1
Y1 - 2022/7/1
N2 - Connexin (Cxs) hemichannels participate in several physiological and pathological pro-cesses, but the molecular mechanisms that control their gating remain elusive. We aimed at deter-mining the role of extracellular cysteines (Cys) in the gating and function of Cx46 hemichannels. We studied Cx46 and mutated all of its extracellular Cys to alanine (Ala) (one at a time) and studied the effects of the Cys mutations on Cx46 expression, localization, and hemichannel activity. Wild-type Cx46 and Cys mutants were expressed at comparable levels, with similar cellular localization. However, functional experiments showed that hemichannels formed by the Cys mutants did not open either in response to membrane depolarization or removal of extracellular divalent cations. Molecular-dynamics simulations showed that Cys mutants may show a possible alteration in the electrostatic potential of the hemichannel pore and an altered disposition of important residues that could contribute to the selectivity and voltage dependency in the hemichannels. Replacement of extracellular Cys resulted in “permanently closed hemichannels”, which is congruent with the inhibition of the Cx46 hemichannel by lipid peroxides, through the oxidation of extracellular Cys. These results point to the modification of extracellular Cys as potential targets for the treatment of Cx46-hemichannel associated pathologies, such as cataracts and cancer, and may shed light into the gating mechanisms of other Cx hemichannels.
AB - Connexin (Cxs) hemichannels participate in several physiological and pathological pro-cesses, but the molecular mechanisms that control their gating remain elusive. We aimed at deter-mining the role of extracellular cysteines (Cys) in the gating and function of Cx46 hemichannels. We studied Cx46 and mutated all of its extracellular Cys to alanine (Ala) (one at a time) and studied the effects of the Cys mutations on Cx46 expression, localization, and hemichannel activity. Wild-type Cx46 and Cys mutants were expressed at comparable levels, with similar cellular localization. However, functional experiments showed that hemichannels formed by the Cys mutants did not open either in response to membrane depolarization or removal of extracellular divalent cations. Molecular-dynamics simulations showed that Cys mutants may show a possible alteration in the electrostatic potential of the hemichannel pore and an altered disposition of important residues that could contribute to the selectivity and voltage dependency in the hemichannels. Replacement of extracellular Cys resulted in “permanently closed hemichannels”, which is congruent with the inhibition of the Cx46 hemichannel by lipid peroxides, through the oxidation of extracellular Cys. These results point to the modification of extracellular Cys as potential targets for the treatment of Cx46-hemichannel associated pathologies, such as cataracts and cancer, and may shed light into the gating mechanisms of other Cx hemichannels.
KW - channel permeability
KW - connexins
KW - extracellular loops
KW - post-translational modification
KW - redox sensing
UR - http://www.scopus.com/inward/record.url?scp=85133120405&partnerID=8YFLogxK
U2 - 10.3390/ijms23137252
DO - 10.3390/ijms23137252
M3 - Article
C2 - 35806258
AN - SCOPUS:85133120405
SN - 1661-6596
VL - 23
JO - International Journal of Molecular Sciences
JF - International Journal of Molecular Sciences
IS - 13
M1 - 7252
ER -