Structure, chromosomal localization, and brain expression of human Cx36 gene

Kremer

Cell Communication & Adhesion

et al. 2008

Gap junctions are among the most widely distributed cell structures involved in cell-to-cell communication. Recently completed genome sequencing projects including species from all major phyla have demonstrated the existence of three distinct gene families, the connexins, pannexins, and innexins, as molecular building blocks of gap junctional communication. In the present study, the authors have addressed the molecular complexity of gap junction gene expression in the zebrafish retina, a remarkably complex sensory organ built by diverse neuronal subtypes. Using a combination of cDNA library and genomic DNA library screening and/or RACE technology, the authors have cloned, in addition to the four previously reported connexins, seven novel connexins and four pannexin transcripts resembling two pannexin genes. This result demonstrates the presence of two distinct gap junction type gene families and indicates a remarkable molecular and functional diversity of gap junction-mediated coupling in the fish retina.

Section: Comparison Of Connexin-specific Expression In Adult Zebrafissupporting

confidence: 90%

Section: Cloning Of Seven Novel Connexin Genes Expressed In the Adultmentioning

confidence: 92%

Molecular Diversity of Connexin and Pannexin Genes in the Retina of the ZebrafishDanio rerio

Kremer

Cell Communication & Adhesion

et al. 2008

Journal of Biological Chemistry

“…The identity of a single positive clone was first confirmed by Southern hybridization with the 269-bp rat Cx36 DNA probe (35). Four kilobases of the 5Ј-flanking sequence were sequenced.…”

Section: Methodsmentioning

confidence: 99%

Critical Role of the Transcriptional Repressor Neuron-restrictive Silencer Factor in the Specific Control of Connexin36 in Insulin-producing Cell Lines

Martín

Tawadros

Meylan

et al. 2003

Adjacent cells share ions, second messengers, small metabolites, and signaling molecules with a weight as high as 1000 Da (1) through intercellular channels that form gap junctions. This type of intercellular communication permits coordinated cellular activity and allows cells to review the functional state of their neighbors, a critical feature for the homeostasis of multicellular organisms (1-4). Intercellular channels result from the association of two half-channels named connexons, which are contributed to separately by each of two adjacent cells. Each connexon is an assembly of membrane proteins named connexins, which are encoded by a gene family consisting of at least 20 members (5, 6).It has been reported that Cx36 1 is the predominantly expressed connexin in rodent neuronal cells (7-9). Immunogold labeling using freeze-fracture replicas have shown that Cx36 was found only in neurons (10) and indicate that the specific expression of connexins by the different cell types of the nervous system may define separate pathways for neuronal versus glial gap junction communication (10 -12). We recently found that Cx36 is the predominant if not the sole connexin isoform expressed in insulin-producing ␤-cells of rat and mouse pancreatic islets (13,14). Recently, Cx36 content was modified in insulin-secreting cells by using an adenoviral gene transfer approach (15) or a lentivirus-mediated transduction of cx36 cDNA (16) in order to evaluate the contribution of Cx36 in the control of insulin secretion and content. These experiments have demonstrated that tight levels of Cx36 are crucial for proper function of insulin-producing cells. Moreover, stably transfected insulin-secreting MIN6 cells with a cx36 antisense cDNA impaired the synchronization of glucose-induced Ca( 2ϩ ) oscillations and insulin secretion in response to glucose (17). These data provided evidence that proper storage of insulin as well as the regulation of insulin release required that the levels of Cx36 be maintained within native values.The objective of the present study was to characterize the mechanisms of cell-specific expression of Cx36. The presence of several gene transcripts in pancreatic ␤-cells and neuronal cells was correlated with the absence in these cell types of a transcription factor named NRSF/REST (neuron-restrictive silencer factor/repressor element silencing transcription factor) (18). NRSF/REST binds to a 21-bp cis element named neuronal restrictive silencer element (NRSE). Through this NRSE, NRSF/REST has been identified as a negative regulatory system that silences neuronal gene expression in non-neuronal tissues, neuronal precursor cells, and certain differentiated

“…1) as well as neurons in the olivary nucleus and cerebellum. 15,16 This channel is highly expressed in the retina, with localization in AII amacrine cells (the interneurons of the retina), 17 cone photoreceptors, and OFF cone bipolar cells. 18,19 It is thought that Cx36 gap junctions play critical roles in coordinating network properties such as spike synchronization 15 and electrical coupling of hippocampal interneurons, 20 amacrine cells, 21 and striatal medium spiny neurons.…”

Section: Hemichannel Definedmentioning

confidence: 99%

Connexin and pannexin hemichannels of neurons and astrocytes

Thompson

MacVicar²

2008

Channels

Hemichannels are large pore ion channels that in the traditional view are formed when half a gap connexin junction opens to the extracellular space. It is now evident that other ion channel families, including the newly discovered pannexin family can form channels with all the nascent properties of hemichannels. This suggests that hemichannels should now be defined to include members of non-connexin families. Several connexin, and two pannexins are expressed in neurons and astrocytes where they may function in release of ATP and glutamate. Additionally, pannexin-1 appears to play a role in neuronal death. Hemichannels form a novel and unique class of ion channels that likely have diverse physiological and pathophysiological roles in the nervous system.