Cx46 hemichannel modulation by nitric oxide

Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation

Mauricio A. Retamal, Viviana P. Orellana, Nicolás J. Arévalo, Cristóbal G. Rojas, Rodolfo J. Arjona, Constanza A. Alcaíno, Wendy González, Jonathan G. Canan, Rodrigo Moraga-Amaro, Jimmy Stehberg, Luis Reuss, Guillermo A. Altenberg

Resultado de la investigación: Article

Resumen

Under normal conditions, connexin (Cx) hemichannels have a low open probability, which can increase under pathological conditions. Since hemichannels are permeable to relatively large molecules, their exacerbated activity has been linked to cell damage. Cx46 is highly expressed in the lens and its mutations have been associated to cataract formation, but it is unknown whether Cx46 has a role in non-genetic cataract formation (i.e. aging and diabetes). Nitric oxide (NO) is a key element in non-genetic cataract formation and Cx46 hemichannels have been shown to be sensitive to NO. The molecular mechanisms of the effects of NO on Cx46 are unknown, but are likely to result from Cx46 S-nitrosation (also known as S-nitrosylation). In this work, we found that lens opacity was correlated with Cx46 S-nitrosation in an animal model of cataract. Consistent with this result, a NO donor increased Cx46 S-nitrosation and hemichannel opening in HLE-B3 cells (cell line derived from human lens epithelial cells). Mutagenesis studies point to the cysteine located in the fourth transmembrane helix (TM4; human C212, rat C218) as the NO sensor. Electrophysiological studies performed in Xenopus oocytes revealed that rat Cx46 hemichannels are sensitive to different NO donors, and that the presence of C218 is necessary to observe the NO donors’ effects. Unexpectedly, gap junctions formed by Cx46 were insensitive to NO or the reducing agent dithiothreitol. We propose that increased hemichannel opening and/or changes in their electrophysiological properties of human Cx46 due to S-nitrosation of the cysteine in TM4 could be an important factor in cataract formation.

Idioma originalEnglish
Páginas (desde-hasta)54-62
Número de páginas9
PublicaciónNitric Oxide - Biology and Chemistry
Volumen86
DOI
EstadoPublished - 1 may 2019

Huella dactilar

Cataract
Cysteine
Nitric Oxide
Modulation
Nitric Oxide Donors
Lenses
Cells
Mutagenesis
Connexins
Dithiothreitol
Reducing Agents
Opacity
Medical problems
Gap Junctions
Rats
Xenopus
Animals
Aging of materials
Oocytes
connexin 46

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Clinical Biochemistry
  • Cancer Research

Citar esto

Retamal, Mauricio A. ; Orellana, Viviana P. ; Arévalo, Nicolás J. ; Rojas, Cristóbal G. ; Arjona, Rodolfo J. ; Alcaíno, Constanza A. ; González, Wendy ; Canan, Jonathan G. ; Moraga-Amaro, Rodrigo ; Stehberg, Jimmy ; Reuss, Luis ; Altenberg, Guillermo A. / Cx46 hemichannel modulation by nitric oxide : Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation. En: Nitric Oxide - Biology and Chemistry. 2019 ; Vol. 86. pp. 54-62.
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title = "Cx46 hemichannel modulation by nitric oxide: Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation",
abstract = "Under normal conditions, connexin (Cx) hemichannels have a low open probability, which can increase under pathological conditions. Since hemichannels are permeable to relatively large molecules, their exacerbated activity has been linked to cell damage. Cx46 is highly expressed in the lens and its mutations have been associated to cataract formation, but it is unknown whether Cx46 has a role in non-genetic cataract formation (i.e. aging and diabetes). Nitric oxide (NO) is a key element in non-genetic cataract formation and Cx46 hemichannels have been shown to be sensitive to NO. The molecular mechanisms of the effects of NO on Cx46 are unknown, but are likely to result from Cx46 S-nitrosation (also known as S-nitrosylation). In this work, we found that lens opacity was correlated with Cx46 S-nitrosation in an animal model of cataract. Consistent with this result, a NO donor increased Cx46 S-nitrosation and hemichannel opening in HLE-B3 cells (cell line derived from human lens epithelial cells). Mutagenesis studies point to the cysteine located in the fourth transmembrane helix (TM4; human C212, rat C218) as the NO sensor. Electrophysiological studies performed in Xenopus oocytes revealed that rat Cx46 hemichannels are sensitive to different NO donors, and that the presence of C218 is necessary to observe the NO donors’ effects. Unexpectedly, gap junctions formed by Cx46 were insensitive to NO or the reducing agent dithiothreitol. We propose that increased hemichannel opening and/or changes in their electrophysiological properties of human Cx46 due to S-nitrosation of the cysteine in TM4 could be an important factor in cataract formation.",
keywords = "Cataract, Connexins, Hemichannels, Nitric oxide, Redox regulation",
author = "Retamal, {Mauricio A.} and Orellana, {Viviana P.} and Ar{\'e}valo, {Nicol{\'a}s J.} and Rojas, {Crist{\'o}bal G.} and Arjona, {Rodolfo J.} and Alca{\'i}no, {Constanza A.} and Wendy Gonz{\'a}lez and Canan, {Jonathan G.} and Rodrigo Moraga-Amaro and Jimmy Stehberg and Luis Reuss and Altenberg, {Guillermo A.}",
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Retamal, MA, Orellana, VP, Arévalo, NJ, Rojas, CG, Arjona, RJ, Alcaíno, CA, González, W, Canan, JG, Moraga-Amaro, R, Stehberg, J, Reuss, L & Altenberg, GA 2019, 'Cx46 hemichannel modulation by nitric oxide: Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation', Nitric Oxide - Biology and Chemistry, vol. 86, pp. 54-62. https://doi.org/10.1016/j.niox.2019.02.007

Cx46 hemichannel modulation by nitric oxide : Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation. / Retamal, Mauricio A.; Orellana, Viviana P.; Arévalo, Nicolás J.; Rojas, Cristóbal G.; Arjona, Rodolfo J.; Alcaíno, Constanza A.; González, Wendy; Canan, Jonathan G.; Moraga-Amaro, Rodrigo; Stehberg, Jimmy; Reuss, Luis; Altenberg, Guillermo A.

En: Nitric Oxide - Biology and Chemistry, Vol. 86, 01.05.2019, p. 54-62.

Resultado de la investigación: Article

TY - JOUR

T1 - Cx46 hemichannel modulation by nitric oxide

T2 - Role of the fourth transmembrane helix cysteine and its possible involvement in cataract formation

AU - Retamal, Mauricio A.

AU - Orellana, Viviana P.

AU - Arévalo, Nicolás J.

AU - Rojas, Cristóbal G.

AU - Arjona, Rodolfo J.

AU - Alcaíno, Constanza A.

AU - González, Wendy

AU - Canan, Jonathan G.

AU - Moraga-Amaro, Rodrigo

AU - Stehberg, Jimmy

AU - Reuss, Luis

AU - Altenberg, Guillermo A.

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Under normal conditions, connexin (Cx) hemichannels have a low open probability, which can increase under pathological conditions. Since hemichannels are permeable to relatively large molecules, their exacerbated activity has been linked to cell damage. Cx46 is highly expressed in the lens and its mutations have been associated to cataract formation, but it is unknown whether Cx46 has a role in non-genetic cataract formation (i.e. aging and diabetes). Nitric oxide (NO) is a key element in non-genetic cataract formation and Cx46 hemichannels have been shown to be sensitive to NO. The molecular mechanisms of the effects of NO on Cx46 are unknown, but are likely to result from Cx46 S-nitrosation (also known as S-nitrosylation). In this work, we found that lens opacity was correlated with Cx46 S-nitrosation in an animal model of cataract. Consistent with this result, a NO donor increased Cx46 S-nitrosation and hemichannel opening in HLE-B3 cells (cell line derived from human lens epithelial cells). Mutagenesis studies point to the cysteine located in the fourth transmembrane helix (TM4; human C212, rat C218) as the NO sensor. Electrophysiological studies performed in Xenopus oocytes revealed that rat Cx46 hemichannels are sensitive to different NO donors, and that the presence of C218 is necessary to observe the NO donors’ effects. Unexpectedly, gap junctions formed by Cx46 were insensitive to NO or the reducing agent dithiothreitol. We propose that increased hemichannel opening and/or changes in their electrophysiological properties of human Cx46 due to S-nitrosation of the cysteine in TM4 could be an important factor in cataract formation.

AB - Under normal conditions, connexin (Cx) hemichannels have a low open probability, which can increase under pathological conditions. Since hemichannels are permeable to relatively large molecules, their exacerbated activity has been linked to cell damage. Cx46 is highly expressed in the lens and its mutations have been associated to cataract formation, but it is unknown whether Cx46 has a role in non-genetic cataract formation (i.e. aging and diabetes). Nitric oxide (NO) is a key element in non-genetic cataract formation and Cx46 hemichannels have been shown to be sensitive to NO. The molecular mechanisms of the effects of NO on Cx46 are unknown, but are likely to result from Cx46 S-nitrosation (also known as S-nitrosylation). In this work, we found that lens opacity was correlated with Cx46 S-nitrosation in an animal model of cataract. Consistent with this result, a NO donor increased Cx46 S-nitrosation and hemichannel opening in HLE-B3 cells (cell line derived from human lens epithelial cells). Mutagenesis studies point to the cysteine located in the fourth transmembrane helix (TM4; human C212, rat C218) as the NO sensor. Electrophysiological studies performed in Xenopus oocytes revealed that rat Cx46 hemichannels are sensitive to different NO donors, and that the presence of C218 is necessary to observe the NO donors’ effects. Unexpectedly, gap junctions formed by Cx46 were insensitive to NO or the reducing agent dithiothreitol. We propose that increased hemichannel opening and/or changes in their electrophysiological properties of human Cx46 due to S-nitrosation of the cysteine in TM4 could be an important factor in cataract formation.

KW - Cataract

KW - Connexins

KW - Hemichannels

KW - Nitric oxide

KW - Redox regulation

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U2 - 10.1016/j.niox.2019.02.007

DO - 10.1016/j.niox.2019.02.007

M3 - Article

VL - 86

SP - 54

EP - 62

JO - Nitric Oxide - Biology and Chemistry

JF - Nitric Oxide - Biology and Chemistry

SN - 1089-8603

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