Functional analysis and regulation of purified connexin hemichannels
Gap-junction channels (GJCs) are aqueous channels that communicate adjacent cells. They are formed by head-to-head association of two hemichannels (HCs), one from each of the adjacent cells. Functional HCs are connexin hexamers composed of one or more connexin isoforms. Deafness is the most frequent...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2014-02-01
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| Series: | Frontiers in Physiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fphys.2014.00071/full |
| _version_ | 1818000937729392640 |
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| author | Mariana C Fiori Luis eReuss Luis G Cuello Guillermo A Altenberg |
| author_facet | Mariana C Fiori Luis eReuss Luis G Cuello Guillermo A Altenberg |
| author_sort | Mariana C Fiori |
| collection | DOAJ |
| description | Gap-junction channels (GJCs) are aqueous channels that communicate adjacent cells. They are formed by head-to-head association of two hemichannels (HCs), one from each of the adjacent cells. Functional HCs are connexin hexamers composed of one or more connexin isoforms. Deafness is the most frequent sensineural disorder, and mutations of Cx26 are the most common cause of genetic deafness. Cx43 is the most ubiquitous connexin, expressed in many organs, tissues and cell types, including heart, brain and kidney. Alterations in its expression and function play important roles in the pathophysiology of very frequent medical problems such as those related to cardiac and brain ischemia. There is extensive information on the relationship between phosphorylation and Cx43 targeting, location and function from experiments in cells and organs in normal and pathological conditions. However, the molecular mechanisms of Cx43 regulation by phosphorylation are hard to tackle in complex systems. Here, we present the use of purified HCs as a model for functional and structural studies. Cx26 and Cx43 are the only isoforms that have been purified, reconstituted, and subjected to functional and structural analysis. Purified Cx26 and Cx43 HCs have properties compatible with those demonstrated in cells, and present methodologies for the functional analysis of purified HCs reconstituted in liposomes. We show that phosphorylation of serine 368 by PKC produces a partial closure of the Cx43 HCs, changing solute selectivity. We also present evidence that the effect of phosphorylation is highly cooperative, requiring modification of several connexin subunits, and that phosphorylation of serine 368 elicits conformational changes in the purified HCs. The use of purified HCs is starting to provide critical data to understand the regulation of HCs at the molecular level. |
| first_indexed | 2024-04-14T03:27:28Z |
| format | Article |
| id | doaj.art-99a1497d5cf249a3aca3577b3cef4f5a |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-04-14T03:27:28Z |
| publishDate | 2014-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physiology |
| spelling | doaj.art-99a1497d5cf249a3aca3577b3cef4f5a2022-12-22T02:15:06ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2014-02-01510.3389/fphys.2014.0007176219Functional analysis and regulation of purified connexin hemichannelsMariana C Fiori0Luis eReuss1Luis G Cuello2Guillermo A Altenberg3Texas Tech University Health Sciences CenterTexas Tech University Health Sciences CenterTexas Tech University Health Sciences CenterTexas Tech University Health Sciences CenterGap-junction channels (GJCs) are aqueous channels that communicate adjacent cells. They are formed by head-to-head association of two hemichannels (HCs), one from each of the adjacent cells. Functional HCs are connexin hexamers composed of one or more connexin isoforms. Deafness is the most frequent sensineural disorder, and mutations of Cx26 are the most common cause of genetic deafness. Cx43 is the most ubiquitous connexin, expressed in many organs, tissues and cell types, including heart, brain and kidney. Alterations in its expression and function play important roles in the pathophysiology of very frequent medical problems such as those related to cardiac and brain ischemia. There is extensive information on the relationship between phosphorylation and Cx43 targeting, location and function from experiments in cells and organs in normal and pathological conditions. However, the molecular mechanisms of Cx43 regulation by phosphorylation are hard to tackle in complex systems. Here, we present the use of purified HCs as a model for functional and structural studies. Cx26 and Cx43 are the only isoforms that have been purified, reconstituted, and subjected to functional and structural analysis. Purified Cx26 and Cx43 HCs have properties compatible with those demonstrated in cells, and present methodologies for the functional analysis of purified HCs reconstituted in liposomes. We show that phosphorylation of serine 368 by PKC produces a partial closure of the Cx43 HCs, changing solute selectivity. We also present evidence that the effect of phosphorylation is highly cooperative, requiring modification of several connexin subunits, and that phosphorylation of serine 368 elicits conformational changes in the purified HCs. The use of purified HCs is starting to provide critical data to understand the regulation of HCs at the molecular level.http://journal.frontiersin.org/Journal/10.3389/fphys.2014.00071/fullCalciumPermeabilityPhosphorylationATPgap junctionMethod |
| spellingShingle | Mariana C Fiori Luis eReuss Luis G Cuello Guillermo A Altenberg Functional analysis and regulation of purified connexin hemichannels Frontiers in Physiology Calcium Permeability Phosphorylation ATP gap junction Method |
| title | Functional analysis and regulation of purified connexin hemichannels |
| title_full | Functional analysis and regulation of purified connexin hemichannels |
| title_fullStr | Functional analysis and regulation of purified connexin hemichannels |
| title_full_unstemmed | Functional analysis and regulation of purified connexin hemichannels |
| title_short | Functional analysis and regulation of purified connexin hemichannels |
| title_sort | functional analysis and regulation of purified connexin hemichannels |
| topic | Calcium Permeability Phosphorylation ATP gap junction Method |
| url | http://journal.frontiersin.org/Journal/10.3389/fphys.2014.00071/full |
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