Expression and function of the neuronal gap junction protein connexin 36 in developing mammalian retina

2005 ◽  
Vol 493 (2) ◽  
pp. 309-320 ◽  
Author(s):  
Kristi A. Hansen ◽  
Christine L. Torborg ◽  
Justin Elstrott ◽  
Marla B. Feller
Keyword(s):  
Gap Junction ◽  
Connexin 36 ◽  
Junction Protein ◽  
Mammalian Retina ◽  
Gap Junction Protein ◽  
And Function

scholarly journals GJA1 Depletion Causes Ciliary Defects by Affecting Rab11 Trafficking to the Ciliary Base

2020 ◽  
Author(s):  
Dong Gil Jang ◽  
Keun Yeong Kwon ◽  
Yeong Cheon Kweon ◽  
Byung-gyu Kim ◽  
Kyungjae Myung ◽  
...  
Keyword(s):  
Gap Junction ◽  
Primary Cilium ◽  
Transport Channel ◽  
Junction Protein ◽  
Complex Functions ◽  
Mother Centriole ◽  
Pericentriolar Material ◽  
Gap Junction Protein ◽  
And Function ◽  
Distinct Distribution

AbstractThe gap junction complex functions as a transport channel across the membrane. Among gap junction subunits, gap junction protein alpha 1 (GJA1) is the most commonly expressed subunit. However, the roles of GJA1 in the formation and function of cilia remain unknown. Here, we examined GJA1 functions during ciliogenesis in vertebrates. GJA1 was localized to the motile ciliary axonemes or pericentriolar material (PCM) around the primary cilium. GJA1 depletion caused the severe malformation of both primary cilium and motile cilia. Interestingly, GJA1 depletion caused strong delocalization of BBS4 from the PCM and basal body and distinct distribution as cytosolic puncta. Further, CP110 removal from the mother centriole was significantly reduced by GJA1 depletion. Importantly, Rab11, key regulator during ciliogenesis, was immunoprecipitated with GJA1 and GJA1 knockdown caused the mis-localization and mis-accumulation of Rab11. These findings suggest that GJA1 is necessary for proper ciliogenesis by regulating the Rab11 pathway.

Sharp Wave-Like Activity in the Hippocampus In Vitro in Mice Lacking the Gap Junction Protein Connexin 36

2003 ◽  
Vol 89 (4) ◽  
pp. 2046-2054 ◽  
Author(s):  
Isabel Pais ◽  
Sheriar G. Hormuzdi ◽  
Hannah Monyer ◽  
Roger D. Traub ◽  
Ian C. Wood ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Frequency Oscillation ◽  
Connexin 36 ◽  
Sharp Wave ◽  
Bath Application ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Electrical Signaling

Bath application of kainate (100–300 nM) induced a persistent gamma-frequency (30–80 Hz) oscillation that could be recorded in stratum radiatum of the CA3 region in vitro. We have previously described that in knockout mice lacking the gap junction protein connexin 36 (Cx36KO), γ-frequency oscillations are reduced but still present. We now demonstrate that in the Cx36KO mice, but not in wild-type (WT), large population field excitatory postsynaptic potentials, or sharp wave-burst discharges, also occurred during the on-going γ-frequency oscillation. These spontaneous burst discharges were not seen in WT mice. Burst discharges in the Cx36KO mice occurred with a mean frequency of 0.23 ± 0.11 Hz and were accompanied by a series of fast (approximately 60–115 Hz) population spikes or “ripple” oscillations in many recordings. Intracellular recordings from CA3 pyramidal cells showed that the burst discharges consisted of a depolarizing response and presumed coupling potentials (spikelets) could occasionally be seen either before or during the burst discharge. The burst discharges occurring in Cx36KO mice were sensitive to gap junctions blockers as they were fully abolished by carbenoxolone (200 μM). In control mice we made several attempts to replicate this pattern of sharp wave activity/ripples occurring with the on-going kainate-evoked γ-frequency oscillation by manipulating synaptic and electrical signaling. Partial disruption of inhibition, in control slices, by bath application of the γ-aminobutyric acid-A (GABAA) receptor antagonist bicuculline (1–4 μM) completely abolished all γ-frequency activity before any burst discharges occurred. Increasing the number of open gap junctions in control slices by using trimethylamine (TMA; 2–10 mM), in conjunction with kainate, failed to elicit any sharp wave bursts or fast ripples. However, bath application of the potassium channel blocker 4-aminopyridine (4-AP; 20–80 μM) produced a pattern of activity in control mice (13/16 slices), consisting of burst discharges occurring in conjunction with kainate-evoked γ-frequency oscillations, that was similar to that seen in Cx36KO mice. In a few cases ( n = 9) the burst discharges were accompanied by fast ripple oscillations. Carbenoxolone also fully blocked the 4-AP-evoked burst discharges ( n = 5). Our results show that disruption of electrical signaling in the interneuronal network can, in the presence of kainate, lead to the spontaneous generation of sharp wave/ripple activity similar to that observed in vivo. This suggests a complex role for electrically coupled interneurons in the generation of hippocampal network activity.

scholarly journals Involvement of the Gap Junction Protein, Connexin43, in the Formation and Function of Invadopodia in the Human U251 Glioblastoma Cell Line

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 117 ◽  
Author(s):  
Amandine Chepied ◽  
Zeinaba Daoud-Omar ◽  
Annie-Claire Meunier-Balandre ◽  
Dale W. Laird ◽  
Marc Mesnil ◽  
...  
Keyword(s):  
Gap Junction ◽  
Molecular Mechanisms ◽  
Glioblastoma Cells ◽  
Dynamic Interactions ◽  
Cx43 Expression ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
And Function ◽  
Low Cell Density ◽  
Invadopodia Formation

The resistance of glioblastomas to treatments is mainly the consequence of their invasive capacities. Therefore, in order to better treat these tumors, it is important to understand the molecular mechanisms which are responsible for this behavior. Previous work suggested that gap junction proteins, the connexins, facilitate the aggressive nature of glioma cells. Here, we show that one of them—connexin43 (Cx43)—is implicated in the formation and function of invadopodia responsible for invasion capacity of U251 human glioblastoma cells. Immunofluorescent approaches—combined with confocal analyses—revealed that Cx43 was detected in all the formation stages of invadopodia exhibiting proteolytic activity. Clearly, Cx43 appeared to be localized in invadopodia at low cell density and less associated with the establishment of gap junctions. Accordingly, lower extracellular matrix degradation correlated with less mature invadopodia and MMP2 activity when Cx43 expression was decreased by shRNA strategies. Moreover, the kinetics of invadopodia formation could be dependent on Cx43 dynamic interactions with partners including Src and cortactin. Interestingly, it also appeared that invadopodia formation and MMP2 activity are dependent on Cx43 hemichannel activity. In conclusion, these results reveal that Cx43 might be involved in the formation and function of the invadopodia of U251 glioblastoma cells.

scholarly journals Amyloid-β regulates gap junction protein connexin 43 trafficking in cultured primary astrocytes

2020 ◽  
Vol 295 (44) ◽  
pp. 15097-15111
Author(s):  
Mahua Maulik ◽  
Lakshmy Vasan ◽  
Abhishek Bose ◽  
Saikat Dutta Chowdhury ◽  
Neelanjana Sengupta ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Connexin 43 ◽  
Cx43 Expression ◽  
Chemical Chaperone ◽  
Junction Protein ◽  
Gap Junction Coupling ◽  
Gap Junction Protein ◽  
Junction Coupling ◽  
And Function

Altered expression and function of astroglial gap junction protein connexin 43 (Cx43) has increasingly been associated to neurotoxicity in Alzheimer disease (AD). Although earlier studies have examined the effect of increased β-amyloid (Aβ) on Cx43 expression and function leading to neuronal damage, underlying mechanisms by which Aβ modulates Cx43 in astrocytes remain elusive. Here, using mouse primary astrocyte cultures, we have examined the cellular processes by which Aβ can alter Cx43 gap junctions. We show that Aβ25-35 impairs functional gap junction coupling yet increases hemichannel activity. Interestingly, Aβ25-35 increased the intracellular pool of Cx43 with a parallel decrease in gap junction assembly at the surface. Intracellular Cx43 was found to be partly retained in the endoplasmic reticulum-associated cell compartments. However, forward trafficking of the newly synthesized Cx43 that already reached the Golgi was not affected in Aβ25-35-exposed astrocytes. Supporting this, treatment with 4-phenylbutyrate, a well-known chemical chaperone that improves trafficking of several transmembrane proteins, restored Aβ-induced impaired gap junction coupling between astrocytes. We further show that interruption of Cx43 endocytosis in Aβ25-35-exposed astrocytes resulted in their retention at the cell surface in the form of functional gap junctions indicating that Aβ25-35 causes rapid internalization of Cx43 gap junctions. Additionally, in silico molecular docking suggests that Aβ can bind favorably to Cx43. Our study thus provides novel insights into the cellular mechanisms by which Aβ modulates Cx43 function in astrocytes, the basic understanding of which is vital for the development of alternative therapeutic strategy targeting connexin channels in AD.

scholarly journals The Roles of Calmodulin and CaMKII in Cx36 Plasticity

2021 ◽  
Vol 22 (9) ◽  
pp. 4473
Author(s):  
Georg R. Zoidl ◽  
David C. Spray
Keyword(s):  
Synaptic Transmission ◽  
Gap Junctions ◽  
Gap Junction ◽  
Network Activity ◽  
Adaptive Plasticity ◽  
Electrical Synapses ◽  
Connexin 36 ◽  
Neuronal Network Activity ◽  
Junction Protein ◽  
Gap Junction Protein

Anatomical and electrophysiological evidence that gap junctions and electrical coupling occur between neurons was initially confined to invertebrates and nonmammals and was thought to be a primitive form of synaptic transmission. More recent studies revealed that electrical communication is common in the mammalian central nervous system (CNS), often coexisting with chemical synaptic transmission. The subsequent progress indicated that electrical synapses formed by the gap junction protein connexin-36 (Cx36) and its paralogs in nonmammals constitute vital elements in mammalian and fish synaptic circuitry. They govern the collective activity of ensembles of coupled neurons, and Cx36 gap junctions endow them with enormous adaptive plasticity, like that seen at chemical synapses. Moreover, they orchestrate the synchronized neuronal network activity and rhythmic oscillations that underlie the fundamental integrative processes, such as memory and learning. Here, we review the available mechanistic evidence and models that argue for the essential roles of calcium, calmodulin, and the Ca2+/calmodulin-dependent protein kinase II in integrating calcium signals to modulate the strength of electrical synapses through interactions with the gap junction protein Cx36.

The effect of connexin 36 deletion on chemotherapy-induced peripheral neuropathy (CIPN).

2016 ◽  
Vol 34 (26_suppl) ◽  
pp. 1-1
Author(s):  
Adam Sterman ◽  
Regina Hanstein ◽  
David C. Spray
Keyword(s):  
Gap Junction ◽  
Sensory Neurons ◽  
Chemotherapeutic Agents ◽  
Satellite Glial Cells ◽  
Connexin 36 ◽  
Junction Protein ◽  
Tactile Threshold ◽  
Gap Junction Protein ◽  
Novel Target ◽  
Von Frey Filaments

1 Background: CIPN is a debilitating side effect and dose limiting toxicity of many chemotherapeutic agents. CIPN induces pathological changes in dorsal root ganglia (DRG), leading to increased cross-talk among the glia that surround sensory neurons (Satellite Glial Cells, SGC’s) and between sensory neurons and their adjacent SGCs via gap junctions. Since Connexin 36 (Cx36) is the main neuronal gap junction protein, we investigated CIPN in mice with deletion of Cx36. Methods: To induce CIPN, mice were given two i.p. oxaliplatin (oxa) injections 2 days apart. Controls received saline (sal). We used transgenic mice, which were either heterozygous for Cx36 or complete Cx36 knockouts (Cx36 Het or Cx36 KO), and littermate controls (Cx36 wildtype), 6-14 per group. Tactile sensitivity of the hindpaws was assessed prior to and every week after injections for 4 weeks using von Frey filaments. The number of paw withdrawals to 10 stimulations with each filament and pain thresholds (corresponding to filament that elicits 8/10 responses) were recorded. Results: Oxa-injected wildtype mice had higher response rates to filaments compared to sal-injected controls (p < 0.05), and lower tactile thresholds (at 9 days: sal 6.0±0.0g vs. oxa 1.9±0.5g, p < 0.0001), indicating hypersensitivity. Compared with wildtype, mice lacking Cx36 (Cx36 KO) displayed significantly less tactile hypersensitivity after oxa (tactile threshold at 9 days: WT 1.9±0.5g vs. KO 4.0±0.4g, p < 0.01), whereas oxa induced tactile hypersensitivity occurred in a similar fashion in Cx36 Het mice (tactile threshold at 9 days: WT 1.9±0.5g vs. Het 1.5±0.1g). At 9 days, there were fewer responses to filaments in oxa-injected Cx36 KO mice compared to oxa-injected wildtype mice (p < 0.05), but not in oxa-injected Cx36 Het mice. Conclusions: We found that oxaliplatin induces transient CIPN, represented by tactile hypersensitivity, in wildtype mice. Deletion of the gap junction protein Cx36, as displayed in the Cx36 KO mice, resulted in significantly less CIPN. This is the first report that a neuronal gap junction protein may modulate pain sensitivity, and points to a new molecule (Cx36) as a potential novel target for CIPN therapy.

scholarly journals The extracellular matrix controls gap junction protein expression and function in postnatal hippocampal neural progenitor cells

2009 ◽  
Vol 10 (1) ◽  
pp. 13 ◽  
Author(s):  
Sophie Imbeault ◽  
Lianne G Gauvin ◽  
Hadi D Toeg ◽  
Alexandra Pettit ◽  
Catherine D Sorbara ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Protein Expression ◽  
Gap Junction ◽  
Progenitor Cells ◽  
Neural Progenitor Cells ◽  
Neural Progenitor ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
And Function
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