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Gap Junction Channels and Hemichannels in Health and Disease 2.0
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Gap Junction Channels and Hemichannels in Health and Disease 2.0

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Biochemistry".

Deadline for manuscript submissions: 20 September 2024 | Viewed by 1945

Special Issue Editors

Prof. Dr. Camillo Peracchia

E-Mail Website
Guest Editor
School of Medicine and Dentistry 601 Elmwood Ave, University of Rochester Medical Center, Rochester, NY 14642, USA
Interests: Gap junctions; connexins; cell communication; calmodulin; calcium; channel gating
Special Issues, Collections and Topics in MDPI journals
Dr. Mario Bortolozzi

E-Mail Website
Guest Editor
1. Department of Physics and Astronomy "G. Galilei", University of Padua, 35131 Padova, Italy
2. Veneto Institute of Molecular Medicine (VIMM), 35129 Padova, Italy
Interests: biophysics; neuropathies; Charcot-Marie-Tooth; connexin 32; brain organoids; electrophysiology; live imaging; systems biology

Special Issue Information

Dear Colleagues,

Neighboring cells directly exchange small cytosolic molecules via cell–cell channels clustered at gap junctions. Gap junction-mediated cell communication is a very important mechanism that allows cells to coordinate numerous functions. Conversely, impaired cell–cell communication is known to cause many diseases.

Each gap junction channel is formed by the interaction of two hemichannels that create a hydrophilic pathway spanning the two plasma membranes and a narrow extracellular space (gap). In turn, each hemichannel is an oligomer of six proteins (connexins/innexins). Gap junction channels are regulated by a gating mechanism sensitive to changes in cytosolic calcium (Ca2+i) and pHi.

In the mid-1980s, the cloning of connexin/innexin cDNAs opened the way to the field of gap junction channelopathies. Thus far, at least thirty-five genetic diseases caused by mutations of eleven different connexins genes are known to cause numerous structural and functional defects in the central and peripheral nervous system as well as in the heart, skin, eyes, teeth, ears, bone, hair, nails, and lymphatic system.

While all of these diseases are due to connexin mutations, minimal attention has thus far been addressed to potential diseases caused by mutations of connexin-associated molecules. An important accessory of gap junctions is the protein calmodulin (CaM), which plays a role in channel gating and is relevant to gap junction formation as well. Recently, diseases caused by CaM mutations (calmodulinopathies) have been identified, but thus far, calmodulinopathy studies have not considered the potential effect of CaM mutations on gap junction function. Therefore, it is important to also raise awareness on the likely role of CaM mutations in defects of gap-junction-mediated cell communication.

Prof. Dr. Camillo Peracchia
Dr. Mario Bortolozzi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • gap junction channel
  • hemichannel
  • CaM
  • calmodulin

Published Papers (2 papers)

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Review

28 pages, 7108 KiB  
Review
Gap Junction Channel Regulation: A Tale of Two Gates—Voltage Sensitivity of the Chemical Gate and Chemical Sensitivity of the Fast Voltage Gate
by Camillo Peracchia
Int. J. Mol. Sci. 2024, 25(2), 982; https://doi.org/10.3390/ijms25020982 - 12 Jan 2024
Cited by 1 | Viewed by 604
Abstract
Gap junction channels are regulated by gates sensitive to cytosolic acidification and trans-junctional voltage (Vj). We propose that the chemical gate is a calmodulin (CaM) lobe. The fast-Vj gate is made primarily by the connexin’s NH2-terminus domain (NT). The chemical gate [...] Read more.
Gap junction channels are regulated by gates sensitive to cytosolic acidification and trans-junctional voltage (Vj). We propose that the chemical gate is a calmodulin (CaM) lobe. The fast-Vj gate is made primarily by the connexin’s NH2-terminus domain (NT). The chemical gate closes the channel slowly and completely, while the fast-Vj gate closes the channel rapidly but incompletely. The chemical gate closes with increased cytosolic calcium concentration [Ca2+]i and with Vj gradients at Vj’s negative side. In contrast, the fast-Vj gate closes at the positive or negative side of Vj depending on the connexin (Cx) type. Cxs with positively charged NT close at Vj’s negative side, while those with negatively charged NT close at Vj’s positive side. Cytosolic acidification alters in opposite ways the sensitivity of the fast-Vj gate: it increases the Vj sensitivity of negative gaters and decreases that of positive gaters. While the fast-Vj gate closes and opens instantaneously, the chemical gate often shows fluctuations, likely to reflect the shifting of the gate (CaM’s N-lobe) in and out of the channel’s pore. Full article
(This article belongs to the Special Issue Gap Junction Channels and Hemichannels in Health and Disease 2.0)
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18 pages, 1203 KiB  
Review
Connexins Control Glial Inflammation in Various Neurological Diseases
by Ryo Yamasaki
Int. J. Mol. Sci. 2023, 24(23), 16879; https://doi.org/10.3390/ijms242316879 - 28 Nov 2023
Viewed by 891
Abstract
Connexins (Cxs) form gap junctions through homotypic/heterotypic oligomerization. Cxs are initially synthesized in the endoplasmic reticulum, then assembled as hexamers in the Golgi apparatus before being integrated into the cell membrane as hemichannels. These hemichannels remain closed until they combine to create gap [...] Read more.
Connexins (Cxs) form gap junctions through homotypic/heterotypic oligomerization. Cxs are initially synthesized in the endoplasmic reticulum, then assembled as hexamers in the Golgi apparatus before being integrated into the cell membrane as hemichannels. These hemichannels remain closed until they combine to create gap junctions, directly connecting neighboring cells. Changes in the intracellular or extracellular environment are believed to trigger the opening of hemichannels, creating a passage between the inside and outside of the cell. The size of the channel pore depends on the Cx isoform and cellular context-specific effects such as posttranslational modifications. Hemichannels allow various bioactive molecules, under ~1 kDa, to move in and out of the host cell in the direction of the electrochemical gradient. In this review, we explore the fundamental roles of Cxs and their clinical implications in various neurological dysfunctions, including hereditary diseases, ischemic brain disorders, degenerative conditions, demyelinating disorders, and psychiatric illnesses. The influence of Cxs on the pathomechanisms of different neurological disorders varies depending on the circumstances. Hemichannels are hypothesized to contribute to proinflammatory effects by releasing ATP, adenosine, glutamate, and other bioactive molecules, leading to neuroglial inflammation. Modulating Cxs’ hemichannels has emerged as a promising therapeutic approach. Full article
(This article belongs to the Special Issue Gap Junction Channels and Hemichannels in Health and Disease 2.0)
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