scholarly journals Involvement of connexin 43 in meiotic maturation of bovine oocytes

Reproduction ◽  
2001 ◽  
pp. 619-628 ◽  
Author(s):  
C Vozzi ◽  
A Formenton ◽  
A Chanson ◽  
A Senn ◽  
R Sahli ◽  
...  
Keyword(s):  
Gap Junction ◽  
Oocyte Maturation ◽  
Connexin 43 ◽  
Lucifer Yellow ◽  
Cumulus Cells ◽  
Lower Amount ◽  
Cx43 Expression ◽  
Gap Junction Channels ◽  
Junction Protein ◽  
Bovine Oocytes

In ovarian follicles, cumulus cells provide the oocyte with small molecules that permit growth and control maturation. These nutrients reach the germinal cell through gap junction channels, which are present between the cumulus cells and the oocyte, and between the cumulus cells. In this study the involvement of intercellular communication mediated by gap junction channels on oocyte maturation of in vitro cultured bovine cumulus-oocyte complexes (COCs) was investigated. The stages of oocyte maturation were determined by Hoechst 33342 staining, which showed that 90% of COCs placed in the maturation medium for 24 h progress to the metaphase II stage. Bovine COC gap junction communication was disrupted initially using n-alkanols, which inhibit any passage through gap junctions. In the presence of 1-heptanol (3 mmol l(-1)) or octanol (3.0 mmol l(-1) and 0.3 mmol l(-1)), only 29% of the COCs reached metaphase II. Removal of the uncoupling agent was associated with restoration of oocyte maturation, indicating that treatment with n-alkanols was neither cytotoxic nor irreversible. Concentrations of connexin 43 (Cx43), the major gap junction protein expressed in the COCs, were decreased specifically using a recombinant adenovirus expressing the antisense Cx43 cDNA (Ad-asCx43). The efficacy of adenoviral infection was > 95% in cumulus cells evaluated after infection with recombinant adenoviruses expressing the green fluorescence protein. RT-PCR performed on total RNA isolated from Ad-asCx43-infected COCs showed that the rat Cx43 cDNA was transcribed. Western blot analysis revealed a three-fold decrease in Cx43 expression in COCs expressing the antisense RNA for Cx43. Injection of cumulus cells with Lucifer yellow demonstrated further that the resulting lower amount of Cx43 in infected COCs is associated with a two-fold decrease in the extent of coupling between cumulus cells. In addition, oocyte maturation was decreased by 50% in the infected COC cultures. These results indicate that Cx43-mediated communication between cumulus cells plays a crucial role in maturation of bovine oocytes.

Phosphorylation of connexin 43 induced by traumatic brain injury promotes exosome release

2018 ◽  
Vol 119 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Wei Chen ◽  
Yijun Guo ◽  
Wenjin Yang ◽  
Lei Chen ◽  
Dabin Ren ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Gap Junction ◽  
Connexin 43 ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Cx43 Expression ◽  
Term Potentiation ◽  
Junction Protein

Traumatic brain injury (TBI) caused by the external force leads to the neuronal dysfunction and even death. TBI has been reported to significantly increase the phosphorylation of glial gap junction protein connexin 43 (Cx43), which in turn propagates damages into surrounding brain tissues. However, the neuroprotective and anti-apoptosis effects of glia-derived exosomes have also been implicated in recent studies. Therefore, we detected whether TBI-induced phosphorylation of Cx43 would promote exosome release in rat brain. To generate TBI model, adult male Sprague-Dawley rats were subjected to lateral fluid percussion injury. Phosphorylated Cx43 protein levels and exosome activities were quantified using Western blot analysis following TBI. Long-term potentiation (LTP) was also tested in rat hippocampal slices. TBI significantly increased the phosphorylated Cx43 and exosome markers expression in rat ipsilateral hippocampus, but not cortex. Blocking the activity of Cx43 or ERK, but not JNK, significantly suppressed TBI-induced exosome release in hippocampus. Furthermore, TBI significantly inhibited the induction of LTP in hippocampal slices, which could be partially but significantly restored by pretreatment with exosomes. The results imply that TBI-activated Cx43 could mediate a nociceptive effect by propagating the brain damages, as well as a neuroprotective effect by promoting exosome release. NEW & NOTEWORTHY We have demonstrated in rat traumatic brain injury (TBI) models that both phosphorylated connexin 43 (p-Cx43) expression and exosome release were elevated in the hippocampus following TBI. The promoted exosome release depends on the phosphorylation of Cx43 and requires ERK signaling activation. Exosome treatment could partially restore the attenuated long-term potentiation. Our results provide new insight for future therapeutic direction on the functional recovery of TBI by promoting p-Cx43-dependent exosome release but limiting the gap junction-mediated bystander effect.

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 Gap junction proteins and cell-cell communication in the three functional zones of the adrenal gland

2002 ◽  
Vol 173 (1) ◽  
pp. 13-21 ◽  
Author(s):  
KT Davis ◽  
N Prentice ◽  
VL Gay ◽  
SA Murray
Keyword(s):  
Adrenal Gland ◽  
Gap Junction ◽  
Adrenal Cortex ◽  
Adrenal Glands ◽  
Lucifer Yellow ◽  
Cx43 Expression ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Gap Junction Proteins ◽  
Junction Proteins

Mouse and monkey adrenal glands were used to study the relationships between gap junction protein expression, intercellular communication and adrenal zonation. Dye communication patterns were determined by incubating freshly excised and hemisected adrenal glands in Lucifer yellow, a gap junction permeable fluorescent dye. Immunohistochemical techniques were used to localize adrenal gap junction proteins. The combination of these two techniques permitted the correlation of gap junction proteins with dye transfer and hormone responses in specialized regions of the adrenal cortex. Lucifer yellow dye communication was most pronounced in the inner glucocorticoid/androgen-producing regions (zona fasciculata/zona reticularis), but was virtually absent in the outer mainly mineralocorticoid-producing region (zona glomerulosa). This pattern of dye communication was coincident with immunohistochemical localization of the gap junction protein, alpha(1)Cx43. The variations in communication and alpha(1)Cx43 expression within the adrenal cortex are thought to be relevant to normal physiological regulation of the adrenal gland.

scholarly journals Cdon deficiency causes cardiac remodeling through hyperactivation of WNT/β-catenin signaling

2017 ◽  
Vol 114 (8) ◽  
pp. E1345-E1354 ◽  
Author(s):  
Myong-Ho Jeong ◽  
Hyun-Ji Kim ◽  
Jung-Hoon Pyun ◽  
Kyu-Sil Choi ◽  
Dong I. Lee ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Gap Junction ◽  
Cardiac Remodeling ◽  
Connexin 43 ◽  
Cardiac Fibrosis ◽  
Critical Role ◽  
Cell Surface Receptor ◽  
Cx43 Expression ◽  
Rat Cardiomyocytes ◽  
Junction Protein

On pathological stress, Wnt signaling is reactivated and induces genes associated with cardiac remodeling and fibrosis. We have previously shown that a cell surface receptor Cdon (cell-adhesion associated, oncogene regulated) suppresses Wnt signaling to promote neuronal differentiation however its role in heart is unknown. Here, we demonstrate a critical role of Cdon in cardiac function and remodeling. Cdon is expressed and predominantly localized at intercalated disk in both mouse and human hearts. Cdon-deficient mice develop cardiac dysfunction including reduced ejection fraction and ECG abnormalities.Cdon−/−hearts exhibit increased fibrosis and up-regulation of genes associated with cardiac remodeling and fibrosis. Electrical remodeling was demonstrated by up-regulation and mislocalization of the gap junction protein, Connexin 43 (Cx43) inCdon−/−hearts. In agreement with altered Cx43 expression, functional analysis both usingCdon−/−cardiomyocytes and shRNA-mediated knockdown in rat cardiomyocytes shows aberrant gap junction activities. Analysis of the underlying mechanism reveals thatCdon−/−hearts exhibit hyperactive Wnt signaling as evident by β-catenin accumulation and Axin2 up-regulation. On the other hand, the treatment of rat cardiomyocytes with a Wnt activator TWS119 reduces Cdon levels and aberrant Cx43 activities, similarly to Cdon-deficient cardiomyocytes, suggesting a negative feedback between Cdon and Wnt signaling. Finally, inhibition of Wnt/β-catenin signaling by XAV939, IWP2 or dickkopf (DKK)1 prevented Cdon depletion-induced up-regulation of collagen 1a and Cx43. Taken together, these results demonstrate that Cdon deficiency causes hyperactive Wnt signaling leading to aberrant intercellular coupling and cardiac fibrosis. Cdon exhibits great potential as a target for the treatment of cardiac fibrosis and cardiomyopathy.

scholarly journals The connexin 43/ZO-1 complex regulates cerebral endothelial F-actin architecture and migration

2015 ◽  
Vol 309 (9) ◽  
pp. C600-C607 ◽  
Author(s):  
Cheng-Hung Chen ◽  
Jamie N. Mayo ◽  
Robert G. Gourdie ◽  
Scott R. Johnstone ◽  
Brant E. Isakson ◽  
...  
Keyword(s):  
Wound Healing ◽  
Endothelial Cell ◽  
Actin Cytoskeleton ◽  
Gap Junction ◽  
Connexin 43 ◽  
Cell Spreading ◽  
Endothelial Cell Migration ◽  
Cx43 Expression ◽  
Junction Protein

Endothelial cell migration is a fundamental process during angiogenesis and, therefore, a point of intervention for therapeutic strategies aimed at controlling pathologies involving blood vessel growth. We sought to determine the role of the gap junction protein connexin 43 (Cx43) in key features of angiogenesis in the central nervous system. We used an in vitro model to test the hypothesis that a complex of interacting proteins, including Cx43 and zonula occludens-1 (ZO-1), regulates the migratory behavior of cerebral endothelium. With knockdown and overexpression experiments, we demonstrate that the rate of healing following scrape-wounding of endothelium is regulated by the level of Cx43 protein expression. The effects on cell motility and proliferation were independent of gap junction communication as cells were sensitive to altered Cx43 expression in single plated cells. Coupling of Cx43/ZO-1 critically regulates this process as demonstrated with the use of a Cx43 α-carboxy terminus 1 peptide mimetic (αCT1) and overexpression of a mutant ZO-1 with the Cx43-binding PDZ2 domain deleted. Disrupting the Cx43/ZO-1 complex with these treatments resulted in collapse of the organized F-actin cytoskeleton and the appearance of actin nodes. Preincubation with the myosin 2 inhibitors blebbistatin or Y-27632 disrupted the Cx43/ZO-1 complex and inhibited cell spreading at the leading edge of migration. Cells studied individually in time-lapse open field locomotion assays wandered less when Cx43/ZO-1 interaction was disrupted without significant change in speed, suggesting that faster wound healing is a product of linearized migration. In contrast to the breakdown of F-actin architecture, microtubule architecture was not obviously affected by treatments. This study provides new insight into the fundamental regulatory mechanisms of cerebral endothelial cell locomotion. Cx43 tethers the F-actin cytoskeleton through a ZO-1 linker and supports cell spreading and exploration during locomotion. Here, we demonstrate that releasing this actin-coupled tether shifts the balance of directional migration control to a more linear movement that enhances the rate of wound healing.

scholarly journals Beyond Gap Junction Channel Function: the Expression of Cx43 Contributes to Aldosterone-Induced Mesangial Cell Proliferation via the ERK1/2 and PKC Pathways

2015 ◽  
Vol 36 (3) ◽  
pp. 1210-1222 ◽  
Author(s):  
Aiqing Zhang ◽  
Ying Han ◽  
Bin Wang ◽  
Shanwen Li ◽  
Weihua Gan
Keyword(s):  
Gap Junction ◽  
Connexin 43 ◽  
Mesangial Cell ◽  
Lucifer Yellow ◽  
Inverse Correlation ◽  
Dye Transfer ◽  
Cx43 Expression ◽  
Pi3k Inhibitor Ly294002 ◽  
Channel Function ◽  
Gap Junction Channel

Aims: This study aimed to explore the precise mechanism and signaling pathways of mesangial cell (MC) proliferation from a new point of view considering Connexin 43 (Cx43). Methods: MC proliferation was measured by the incorporation of 3H-thymidine (3H-TdR). Cx43 was over-expressed in MC cells using lipofectamine 2000, and the expression level was tested with reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses. The gap junction channel function was explored by Lucifer Yellow scrape loading and dye transfer (SLDT), and the intracellular calcium concentrations ([Ca2+]i) were characterized by confocal microscopy on cells loaded with Fura-3/AM. Results: There was an inverse correlation between Cx43 expression and MC proliferation (P<0.05). SLDT studies revealed that there was no difference in the gap junction channel function between the normal and Aldosterone (Aldo)-stimulated groups (P>0.05). Our data also showed that the mineralcorticoid receptor (MR) antagonist spironolactone, ERK1/2 inhibitor PD98059 and PKC inhibitor GF109203X could attenuate the down-regulation of Cx43 expression in Aldo-induced MC proliferation; however, the PI3K inhibitor LY294002 could block MC proliferation without affecting Cx43 expression at either the mRNA or protein level. In addition, Aldo promoted MC proliferation in parallel with increasing [Ca2+]i (P<0.05), suggesting that the classical PKC pathway might be activated. Conclusions: Our study provides preliminary evidence that Cx43 is an important regulator of Aldo-promoted MC proliferation. Furthermore, reduced Cx43 expression promoted MC proliferation independent of the gap junction channel function, and this process might be mediated through the ERK1/2- and PKC-dependent pathways.

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