Gap junction is the aggregate of some intercellular channels, which allows ions and small molecules to transport or transfer between cells. There are about 20 proposed members of the connexin family found in mammalian tissues now, and more than 10 reported are expressed in the nervous system. The astrocytes and oligodendrocytes express some specific connexins. In the present article, we review the recent literatures to illustrate the importance of gap junction for the intercellular communication between glial cells, astrocytes and neurons, and neuronal cells, which is crucial for brain functions.
Brain ; metabolism ; physiology ; Connexins ; metabolism ; Gap Junctions ; metabolism ; physiology ; Humans ; Neuroglia ; metabolism ; physiology ; Neurons ; metabolism ; physiology

OBJECTIVEThis review discusses the experimental and clinical studies those show the expression of connexin 36 in the central nervous system and the possible role of connexin 36 in epileptic seizure.

DATA SOURCESAll articles used in this review were mainly searched from PubMed published in English from 1996 to 2012.

STUDY SELECTIONOriginal articles and reviews were selected if they were related to the expression of connexin 36 in the central nervous system and its role in epilepsy.

RESULTSThe distribution of connexin 36 is developmentally regulated, cell-specific and region-specific. Connexin 36 is involved in some neuronal functions and epileptic synchronization. Changes in the connexin 36 gene and protein were accompanied by seizures. Selective gap junction blockers have exerted anticonvulsant actions in a variety of experiments examined in both humans and experimental animals.

CONCLUSIONSConnexin 36 plays an important role in both physiological and pathological conditions in the central nervous system. A better understanding of the role of connexin 36 in seizure activity may contribute to the development of new therapeutic approaches to treating epilepsy.

Animals ; Central Nervous System ; metabolism ; Connexins ; metabolism ; Gap Junctions ; metabolism ; Humans ; Seizures ; metabolism

Gap junctions (GJ), as a special membrane structure between adjacent cells, are composed of connexins (Cx) and regulate the proliferation and differentiation of cells. Studies show that gap junctional intercellular communication is weakened or lost in most tumor cells and this abnormality is often accompanied by changed expression of Cxs. Cx43 is a major connexin in the testis tissue. This review focuses on the latest progress in the studies of Cx43 in testicular tumors.
Animals ; Cell Communication ; Cell Differentiation ; Connexin 43 ; metabolism ; Gap Junctions ; metabolism ; Male ; Testicular Neoplasms ; metabolism

Gap junctions play a critical role in electrical synchronization and exchange of small molecules between neighboring cells; connexins are a family of structurally related transmembrane proteins that assemble to form vertebrate gap junctions. Hyperglycemia changes the structure gap junction proteins and their expression, resulting in obstruction of neural regeneration, vascular function and wound healing, and also promoting vascular atherosclerosis. These pathogenic factors would cause diabetic foot ulcers. This article reviews the involvement of connexins in pathogenesis of diabetic foot.
Atherosclerosis ; Connexins ; metabolism ; Diabetic Foot ; pathology ; Gap Junctions ; metabolism ; Humans ; Hyperglycemia ; physiopathology ; Regeneration ; Wound Healing

OBJECTIVETo probe into expression of connexin 43 (Cx43) in the meridians of the normal healthy rats and the relation among connexin, gap junction and meridian.

METHODSPowerVision two step immunohistochemical technique and ASIAS-2000 automatical image-scan analyzing system were used to detect Cx43 level and distribution in the Kidney and Bladder Meridians of the rat.

RESULTSCx43 expressed mainly in skin epithelia, fibroblasts and mast cells of the subcutaneous layer. And expression of Cx43 in the Kidney and Bladder Meridians was significantly more than that in the control lines (P < 0.01).

CONCLUSIONConnexins and gap junctions have close relation with the meridians, and the gap junctional intercellular communication may play an important role in the function of meridians.

Animals ; Cell Communication ; Connexin 43 ; metabolism ; Connexins ; Gap Junctions ; metabolism ; Meridians ; Rats

OBJECTIVETo investigate the role of gap junction in ischemic preconditioning (IPC).

METHODSSprague-Dawley rats were subjected to a 30 min coronary artery occlusion followed by 4 h of reperfusion (I/R). Rats were divided into seven groups: I/R, IPC/R, IPC/R + 5-hydroxydecanoic acid (mitochondrial ATP sensitive potassium channel antagonist), I/R + diazoxide (mitochondrial ATP sensitive potassium channel agonist), I/R + 5-hydroxydecanoic acid + diazoxide, I/R + 18beta-glycyrrhetinic acid (gap junction blocker) and I/R + 18beta-glycyrrhetinic acid + 5-hydroxydecanoic acid. Hemodynamics and myocardial infarct size were measured and connexin43 phosphorylation and subcellular distribution were determined by quantitative immunoblotting and confocal immunofluorescence.

RESULTSInfarct size was reduced in IPC/R, I/R + diazoxide and I/R + 18beta-glycyrrhetinic acid group (13.34% +/- 7.87%, 11.02% +/- 2.24%, and 15.03% +/- 11.35%, respectively; P < 0.001 vs. I/R group: 45.81% +/- 7.91%). 5-hydroxydecanoic acid abolished the cardioprotective effects of IPC and diazoxide (46.57% +/- 5.36% and 47.36% +/- 3.17%; P > 0.05 vs. I/R) but not the effects of glycyrrhetinic acid (14.60% +/- 7.36%; P < 0.001 vs. I/R). Phosphorylation of connexin43 was significantly increased, dephosphorylation and connexin43 intracellular redistribution significantly decreased (Cx43 size in the cellular membrane 1.00% +/- 0.35% and 0.83% +/- 0.31%, P < 0.001 vs. I/R: 0.19% +/- 0.06%) by IPC and diazoxide and these effects could be abolished by 5-hydroxydecanoic acid.

CONCLUSIONIschemic preconditioning could reduce myocardial infarction size by activating mitochondrial ATP sensitive potassium channel and modulating connexin43 phosphorylation and internalization.

Animals ; Connexin 43 ; metabolism ; Gap Junctions ; physiology ; Ischemic Preconditioning, Myocardial ; Male ; Myocardial Infarction ; metabolism ; pathology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley

Homoeostasis depends on the close connection and intimate molecular exchange between extracellular, intracellular and intercellular networks. Intercellular communication is largely mediated by gap junctions (GJs), a type of specialized membrane contact composed of variable number of channels that enable direct communication between cells by allowing small molecules to pass directly into the cytoplasm of neighbouring cells. Although considerable evidence indicates that gap junctions contribute to the functions of many organs, such as the bone, intestine, kidney, heart, brain and nerve, less is known about their role in oral development and disease. In this review, the current progress in understanding the background of connexins and the functions of gap junctions in oral development and diseases is discussed. The homoeostasis of tooth and periodontal tissues, normal tooth and maxillofacial development, saliva secretion and the integrity of the oral mucosa depend on the proper function of gap junctions. Knowledge of this pattern of cell-cell communication is required for a better understanding of oral diseases. With the ever-increasing understanding of connexins in oral diseases, therapeutic strategies could be developed to target these membrane channels in various oral diseases and maxillofacial dysplasia.
Bone and Bones ; Cell Communication ; Connexins ; metabolism ; physiology ; Gap Junctions ; metabolism ; pathology ; Homeostasis ; physiology ; Humans ; Mouth Diseases ; Phosphorylation

Gap junctions construct hydrophilic trans-membrane channels which adjust the intercellular communication of chemistry and electricity. In the heart, individual cardiac myocytes are linked by gap junctions. These junctions form low resistance pathways along which the electrical impulse flows rapidly and repeatedly between all the myocardium, ensuring their synchronous contraction. In recent years, some researchers have found that connexins, the protein molecules of gap junction channels, are reduced in number or redistributed from intercalated disks (ID) to lateral cell borders in a variety of cardiac disease, especially in ischemic heart disease. The gap junction remodeling is considered to be arrhythmogenic. These findings will lead us to a new realm in the diagnostic of sudden death caused by coronary heart disease.
Animals ; Cell Communication/physiology* ; Connexins/metabolism* ; Coronary Disease/complications* ; Death, Sudden/etiology* ; Gap Junctions/metabolism* ; Humans ; Immunohistochemistry ; Myocardium/pathology*

OBJECTIVETo observe the influence of Cx26/Cx32 gap junction channel on the antineoplastic effect of etoposide in Hela cervical cancer cells.

METHODSFluorescence trace was used to assay the gap junction intercellular communication mediated by Cx26/Cx32 in Hela cells and its functional modulation by the pharmacological agents (oleamide, retinoid acid). A standard colony-forming assay was applied to determine the cell growth-inhibiting effect of etoposide in Hela cells with functional modulation of the gap junction. Hoechst 33258 staining was used to assess the changes in etoposide-induced apoptosis of Hela cells with altered gap junction functions.

RESULTSOleamide markedly decreased while retinoid acid obviously increased the gap junction function in Hela cells. Standard colony-forming assay showed that etoposide produced a lowered antiproliferative effect in Hela cells with reduced gap junction and an increased antiproliferative effect in cells with enhanced gap junction function. In cells with a reduced gap junction function, etoposide induced a lowered apoptosis rate, which increased obviously in cells with an enhanced gap junction function.

CONCLUSIONThe antineoplastic effect of etoposide is reduced in Hela cells with a decreased gap junction intercellular communication mediated by Cx26/Cx32 and is enhanced in cells with an increased gap junction intercellular communication.

Antineoplastic Agents, Phytogenic ; pharmacology ; Connexin 26 ; Connexins ; genetics ; metabolism ; physiology ; Etoposide ; pharmacology ; Gap Junctions ; physiology ; HeLa Cells ; Humans ; Transfection

BACKGROUNDClinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effect remain largely unknown. The present study investigated the effect of berberine on apoptosis induced by X-rays irradiation and the relation between this effect and gap junction intercellular communication (GJIC).

METHODSThe role of gap junctions in the modulation of X-rays irradiation-induced apoptosis was explored by manipulation of connexin (Cx) expression, and gap junction function, using oleamide, a GJIC inhibitor, and berberine.

RESULTSIn transfected HeLa cells, Cx32 expression increased apoptosis induced by X-rays irradiation, while inhibition of gap junction by oleamide reduced the irradiation responses, indicating the dependence of X-rays irradiation-induced apoptosis on GJIC. Berberine, at the concentrations without cytotoxicity, enhanced apoptosis induced by irradiation only in the presence of functional gap junctions.

CONCLUSIONSThese results suggest that berberine potentizes cell apoptosis induced by X-rays irradiation, probably through enhancement of gap junction activity.

Apoptosis ; drug effects ; Berberine ; pharmacology ; Gap Junctions ; drug effects ; metabolism ; radiation effects ; HeLa Cells ; Humans ; Oleic Acids ; pharmacology ; X-Rays