scholarly journals Ischemia Alters the Expression of Connexins in the Aged Human Brain

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Taizen Nakase ◽  
Tetsuya Maeda ◽  
Yasuji Yoshida ◽  
Ken Nagata
Keyword(s):  
Gap Junctions ◽  
Connexin 43 ◽  
Immunohistochemical Analysis ◽  
Analysis Data ◽  
Computer Assisted ◽  
Ischemic Insult ◽  
Cx43 Expression ◽  
Neuronal Marker ◽  
Neuronal Markers ◽  
Human Stroke

Although the function of astrocytic gap junctions under ischemia is still under debate, increased expression of connexin 43 (Cx43) has been observed in ischemic brain lesions, suggesting that astrocytic gap junctions could provide neuronal protection against ischemic insult. Moreover, different connexin subtypes may play different roles in pathological conditions. We used immunohistochemical analysis to investigate alterations in the expression of connexin subtypes in human stroke brains. Seven samples, sectioned after brain embolic stroke, were used for the analysis. Data, evaluated semiquantitatively by computer-assisted densitometry, was compared between the intact hemisphere and ischemic lesions. The results showed that the coexpression of Cx32 and Cx45 with neuronal markers was significantly increased in ischemic lesions. Cx43 expression was significantly increased in the colocalization with astrocytes and relatively increased in the colocalization with neuronal marker in ischemic lesions. Therefore, Cx32, Cx43, and Cx45 may respond differently to ischemic insult in terms of neuroprotection.

CX43 expression, phosphorylation, and distribution in the normal and autoimmune orchitic testis with a look at gap junctions joining germ cell to germ cell

2011 ◽  
Vol 300 (1) ◽  
pp. R121-R139 ◽  
Author(s):  
R.-Marc Pelletier ◽  
Casimir D. Akpovi ◽  
Li Chen ◽  
Robert Day ◽  
María L. Vitale
Keyword(s):  
Cell Differentiation ◽  
Gap Junctions ◽  
Germ Cell ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
Seminiferous Tubule ◽  
Connexin 43 ◽  
Cx43 Expression ◽  
Cx43 Protein ◽  
Cx43 Mrna

Spermatogenesis requires connexin 43 (Cx43).This study examines normal gene transcription, translation, and phosphorylation of Cx43 to define its role on germ cell growth and Sertoli cell's differentiation, and identifies abnormalities arising from spontaneous autoimmune orchitis (AIO) in mink, a seasonal breeder and a natural model for autoimmunity. Northern blot analysis detected 2.8- and a 3.7-kb Cx43 mRNA bands in seminiferous tubule-enriched fractions. Cx43 mRNA increased in seminiferous tubule-enriched fractions throughout development and then seasonally with the completion of spermatogenesis. Cx43 protein levels increased transiently during the colonization of the tubules by the early-stage spermatocytes. Cx43 phosphorylated (PCx43) and nonphosphorylated (NPCx43) in Ser368 decreased during the periods of completion of meiosis and Sertoli cell differentiation, while Cx43 mRNA remained elevated throughout. PCx43 labeled chiefly the plasma membrane except by stage VII when vesicles were also labeled in Sertoli cells. Vesicles and lysosomes in Sertoli cells and the Golgi apparatus in the round spermatids were NPCx43 positive. A decrease in Cx43 gene expression was matched by a Cx43 protein increase in the early, not the late, phase of AIO. Total Cx43 and PCx43 decreased with the advance of orchitis. The study makes a novel finding of gap junctions connecting germ cells. The data indicate that Cx43 protein expression and phosphorylation in Ser368 are stage-specific events that may locally influence the acquisition of meiotic competence and the Sertoli cell differentiation in normal testis. AIO modifies Cx43 levels, suggesting changes in Cx43-mediated intercommunication and spermatogenic activity in response to cytokines imbalances in Sertoli cells.

Expression of connexin 43 (Cx43) is critical for normal hematopoiesis

Blood ◽  
2000 ◽  
Vol 96 (3) ◽  
pp. 917-924 ◽  
Author(s):  
Encarnacion Montecino-Rodriguez ◽  
Hyosuk Leathers ◽  
Kenneth Dorshkind
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Blood Cell ◽  
Gap Junctions ◽  
Connexin 43 ◽  
Cell Formation ◽  
Cx43 Expression ◽  
Hematopoietic System ◽  
Blood Cell Formation

Abstract Gap junctions are intercellular channels, formed by individual structural units known as connexins (Cx), that allow the intercellular exchange of various messenger molecules. The finding that numbers of Cx43-type gap junctions in bone marrow are elevated during establishment and regeneration of the hematopoietic system has led to the hypothesis that expression of Cx43 is critical during the initiation of blood cell formation. To test this hypothesis, lymphoid and myeloid development were examined in mice with a targeted disruption of the gene encoding Cx43. Because Cx43−/− mice die perinatally, initial analyses were performed on Cx43−/−, Cx43+/−, and Cx43+/+ embryos and newborns. The data indicate that lack of Cx43 expression during embryogenesis compromises the terminal stages of primary T and B lymphopoiesis. Cx43−/− embryos and neonates had a reduced frequency of CD4+ and T-cell receptor-expressing thymocytes and surface IgM+cells compared to their Cx43+/+ littermates. Surprisingly, Cx43+/− embryos/neonates also showed defects in B- and T-cell development similar to those observed in Cx43−/− littermates, but their hematopoietic system was normal at 4 weeks of age. However, the regeneration of lymphoid and myeloid cells was severely impaired in the Cx43+/− mice after cytoablative treatment. Taken together, these data indicate that loss of a single Cx43 allele can affect blood cell formation. Finally, the results of reciprocal bone marrow transplants between Cx43+/+ and Cx43+/− mice and examination of hematopoietic progenitors and stromal cells in vitro indicates that the primary effects of Cx43 are mediated through its expression in the hematopoietic microenvironment.

scholarly journals Cx43 and Associated Cell Signaling Pathways Regulate Tunneling Nanotubes in Breast Cancer Cells

Cancers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2798
Author(s):  
Alexander Tishchenko ◽  
Daniel D. Azorín ◽  
Laia Vidal-Brime ◽  
María José Muñoz ◽  
Pol Jiménez Arenas ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gap Junctions ◽  
Small Molecules ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Connexin 43 ◽  
Breast Cancer Cell Lines ◽  
Tunneling Nanotubes ◽  
Cx43 Expression ◽  
Cancer Signaling

Connexin 43 (Cx43) forms gap junctions that mediate the direct intercellular diffusion of ions and small molecules between adjacent cells. Cx43 displays both pro- and anti-tumorigenic properties, but the mechanisms underlying these characteristics are not fully understood. Tunneling nanotubes (TNTs) are long and thin membrane projections that connect cells, facilitating the exchange of not only small molecules, but also larger proteins, organelles, bacteria, and viruses. Typically, TNTs exhibit increased formation under conditions of cellular stress and are more prominent in cancer cells, where they are generally thought to be pro-metastatic and to provide growth and survival advantages. Cx43 has been described in TNTs, where it is thought to regulate small molecule diffusion through gap junctions. Here, we developed a high-fidelity CRISPR/Cas9 system to knockout (KO) Cx43. We found that the loss of Cx43 expression was associated with significantly reduced TNT length and number in breast cancer cell lines. Notably, secreted factors present in conditioned medium stimulated TNTs more potently when derived from Cx43-expressing cells than from KO cells. Moreover, TNT formation was significantly induced by the inhibition of several key cancer signaling pathways that both regulate Cx43 and are regulated by Cx43, including RhoA kinase (ROCK), protein kinase A (PKA), focal adhesion kinase (FAK), and p38. Intriguingly, the drug-induced stimulation of TNTs was more potent in Cx43 KO cells than in wild-type (WT) cells. In conclusion, this work describes a novel non-canonical role for Cx43 in regulating TNTs, identifies key cancer signaling pathways that regulate TNTs in this setting, and provides mechanistic insight into a pro-tumorigenic role of Cx43 in cancer.

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 Myoendothelial gap junctions mediate regulation of angiopoietin-2-induced vascular hyporeactivity after hypoxia through connexin 43-gated cAMP transfer

2017 ◽  
Vol 313 (3) ◽  
pp. C262-C273 ◽  
Author(s):  
Jing Xu ◽  
Guangming Yang ◽  
Tao Li ◽  
Liangming Liu
Keyword(s):  
Gap Junctions ◽  
Connexin 43 ◽  
Vascular Endothelial Cell ◽  
Inos Expression ◽  
Glycyrrhetic Acid ◽  
Dependent Manner ◽  
Sprague Dawley ◽  
Cx43 Expression ◽  
Vascular Hyporeactivity ◽  
Angiopoietin 2

Angiopoietin-2 (Ang-2) contributes to vascular hyporeactivity after hemorrhagic shock and hypoxia through upregulation of inducible nitric oxide synthase (iNOS) in a vascular endothelial cell (VEC)-specific and Ang-2/Tie2 receptor-dependent manner. While iNOS is primarily expressed in vascular smooth muscle cells (VSMCs), the mechanisms of signal transfer from VECs to VSMCs are unknown. A double-sided coculture model with VECs and VSMCs from Sprague-Dawley rats was used to investigate the role of myoendothelial gap junctions (MEGJs), the connexin (Cx) isoforms involved, and other relevant mechanisms. After hypoxia, VSMCs treated with exogenous Ang-2 showed increased iNOS expression and hyporeactivity, as well as MEGJ formation and communication. These Ang-2 effects were suppressed by the MEGJ inhibitor 18α-glycyrrhetic acid (18-GA), Tie2 siRNA, or Cx43 siRNA. Reagents antagonizing cAMP or protein kinase A (PKA) in VECs inhibited Cx43 expression in MEGJs, decreasing MEGJ formation and associated communication, after hypoxia following Ang-2 treatment. The increased cAMP levels in VSMCs and transfer of Alexa Fluor 488-labeled cAMP from VECs to VSMCs, after hypoxia following Ang-2 treatment, was antagonized by Cx43 siRNA. A cAMP antagonist added to VECs or VSMCs inhibited both increased iNOS expression and hyporeactivity in VSMCs subjected to hypoxia following Ang-2 treatment. Based on these findings, we propose that Cx43 was the Cx isoform involved in MEGJ-mediated VEC-dependent regulation of Ang-2, which induces iNOS protein expression and vascular hyporeactivity after hypoxia. Cx43 was upregulated by cAMP and PKA, permitting cAMP transfer between cells.

scholarly journals Cx43 and Associated Cell Signaling Pathways Regulate Tunneling Nanotubes in Breast Cancer Cells

2020 ◽  
Author(s):  
Alexander Tishchenko ◽  
Daniel Domínguez Azorín ◽  
Laia Vidal-Brime ◽  
María José Muñoz ◽  
Pol Jiménez Arenas ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gap Junctions ◽  
Small Molecules ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Connexin 43 ◽  
Breast Cancer Cell Lines ◽  
Tunneling Nanotubes ◽  
Cx43 Expression ◽  
Cancer Signaling

Connexin 43 (Cx43) forms gap junctions that mediate the direct intercellular diffusion of ions and small molecules between adjacent cells. Cx43 displays both pro- and anti-tumorigenic properties, but the mechanisms underlying these characteristics are not fully understood. Tunneling nanotubes (TNTs) are long and thin membrane projections that connect cells, facilitating the exchange of not only small molecules, but also larger proteins, organelles, bacteria, and viruses. Typically, TNTs exhibit increased formation under conditions of cellular stress and are more prominent in cancer cells, where they are generally thought to be pro-metastatic and to provide growth and survival advantages. Cx43 has been described in TNTs, where it is thought to regulate small molecule diffusion through gap junctions. Here, we developed a high-fidelity CRISPR/Cas9 system to knockout (KO) Cx43. We found that loss of Cx43 expression was associated with significantly reduced TNT length and number in breast cancer cell lines. Notably, secreted factors present in conditioned medium stimulated TNTs more potently when derived from Cx43-expressing cells than from KO cells. Moreover, TNT formation was significantly induced by inhibition of several key cancer signaling pathways that both regulate Cx43 and are regulated by Cx43, including RhoA kinase (ROCK), protein kinase A (PKA), focal adhesion kinase (FAK), and p38. Intriguingly, drug-induced stimulation of TNTs was more potent in Cx43 KO cells than in wild-type cells. In conclusion, this work describes a novel non-canonical role for Cx43 in regulating TNTs, identifies key cancer signaling pathways that regulate TNTs in this setting, and provides mechanistic insight into a pro-tumorigenic role of Cx43 in cancer.

Connexin 43 mediates endothelium-derived hyperpolarizing factor-induced vasodilatation in subcutaneous resistance arteries from healthy pregnant women

2007 ◽  
Vol 292 (2) ◽  
pp. H1026-H1032 ◽  
Author(s):  
Ninian N. Lang ◽  
Leonid Luksha ◽  
David E. Newby ◽  
Karolina Kublickiene
Keyword(s):  
Gap Junctions ◽  
Pregnant Women ◽  
Connexin 43 ◽  
Subcutaneous Fat ◽  
Cyclooxygenase Inhibitors ◽  
Elective Cesarean Section ◽  
Resistance Arteries ◽  
Cx43 Expression ◽  
Elective Cesarean ◽  
Oxide Synthase

The role of gap junctions in endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation of human arteries was assessed using connexin mimetic peptides (CMPs) designated 37,43Gap27, 40Gap27, and 43Gap26 according to homology with the major vascular connexins (Cx37, Cx40, and Cx43). Resistance arteries were obtained from subcutaneous fat biopsies of healthy pregnant women undergoing elective cesarean section. Endothelium-dependent vasodilatation to bradykinin (BK) was assessed using wire myography. Nω-nitro-l-arginine methyl ester (l-NAME) and indomethacin (nitric oxide synthase and cyclooxygenase inhibitors, respectively) attenuated maximal relaxation to BK (Rmax) by ∼50%. Coincubation with l-NAME, indomethacin, and the combined CMPs (37,43Gap27, 40Gap27, and 43Gap26) almost abolished relaxation to BK (Rmax = 12.2 ± 3.7%). In arteries incubated with l-NAME and indomethacin, the addition of either 37,43Gap27 or 40Gap27 had no significant effect on Rmax, whereas 43Gap26 caused marked inhibition (Rmax = 21 ± 6.4%, P = 0.005 vs. l-NAME plus indomethacin alone) that was similar to that of the triple combination. Endothelium-independent vasorelaxation was unaffected by CMPs, l-NAME, or indomethacin. Immunohistochemistry demonstrated Cx37, Cx40, and Cx43 expression in the endothelium and vascular smooth muscle. In pregnant women, EDHF-mediated vasorelaxation of subcutaneous resistance arteries is dependent on Cx43 and gap junctions.

scholarly journals Evidence for a Role of Connexin 43 in Trigeminal Pain Using RNA Interference In Vivo

2008 ◽  
Vol 100 (6) ◽  
pp. 3064-3073 ◽  
Author(s):  
Peter T. Ohara ◽  
Jean-Philippe Vit ◽  
Aditi Bhargava ◽  
Luc Jasmin
Keyword(s):  
Rna Interference ◽  
Gap Junctions ◽  
Gap Junction ◽  
Glial Cells ◽  
Trigeminal Ganglion ◽  
Connexin 43 ◽  
Infraorbital Nerve ◽  
Nociceptive Behavior ◽  
Cx43 Expression

The importance of glial cells in the generation and maintenance of neuropathic pain is becoming widely accepted. We examined the role of glial-specific gap junctions in nociception in the rat trigeminal ganglion in nerve-injured and -uninjured states. The connexin 43 (Cx43) gap-junction subunit was found to be confined to the satellite glial cells (SGCs) that tightly envelop primary sensory neurons in the trigeminal ganglion and we therefore used Cx43 RNA interference (RNAi) to alter gap-junction function in SGCs. Using behavioral evaluation, together with immunocytochemical and Western blot monitoring, we show that Cx43 increased in the trigeminal ganglion in rats with a chronic constriction injury (CCI) of the infraorbital nerve. Reducing Cx43 expression using RNAi in CCI rats reduced painlike behavior, whereas in non-CCI rats, reducing Cx43 expression increased painlike behavior. The degree of painlike behavior in CCI rats and intact, Cx43-silenced rats was similar. Our results support previous suggestions that increases in glial gap junctions after nerve injury increases nociceptive behavior but paradoxically the reduction of gap junctions in normal ganglia also increases nociceptive behavior, possibly a reflection of the multiple functions performed by glia.

Expression of connexin 43 (Cx43) is critical for normal hematopoiesis

Blood ◽  
2000 ◽  
Vol 96 (3) ◽  
pp. 917-924
Author(s):  
Encarnacion Montecino-Rodriguez ◽  
Hyosuk Leathers ◽  
Kenneth Dorshkind
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Blood Cell ◽  
Gap Junctions ◽  
Connexin 43 ◽  
Cell Formation ◽  
Cx43 Expression ◽  
Hematopoietic System ◽  
Blood Cell Formation

Gap junctions are intercellular channels, formed by individual structural units known as connexins (Cx), that allow the intercellular exchange of various messenger molecules. The finding that numbers of Cx43-type gap junctions in bone marrow are elevated during establishment and regeneration of the hematopoietic system has led to the hypothesis that expression of Cx43 is critical during the initiation of blood cell formation. To test this hypothesis, lymphoid and myeloid development were examined in mice with a targeted disruption of the gene encoding Cx43. Because Cx43−/− mice die perinatally, initial analyses were performed on Cx43−/−, Cx43+/−, and Cx43+/+ embryos and newborns. The data indicate that lack of Cx43 expression during embryogenesis compromises the terminal stages of primary T and B lymphopoiesis. Cx43−/− embryos and neonates had a reduced frequency of CD4+ and T-cell receptor-expressing thymocytes and surface IgM+cells compared to their Cx43+/+ littermates. Surprisingly, Cx43+/− embryos/neonates also showed defects in B- and T-cell development similar to those observed in Cx43−/− littermates, but their hematopoietic system was normal at 4 weeks of age. However, the regeneration of lymphoid and myeloid cells was severely impaired in the Cx43+/− mice after cytoablative treatment. Taken together, these data indicate that loss of a single Cx43 allele can affect blood cell formation. Finally, the results of reciprocal bone marrow transplants between Cx43+/+ and Cx43+/− mice and examination of hematopoietic progenitors and stromal cells in vitro indicates that the primary effects of Cx43 are mediated through its expression in the hematopoietic microenvironment.

scholarly journals Prostaglandin Promotion of Osteocyte Gap Junction Function through Transcriptional Regulation of Connexin 43 by Glycogen Synthase Kinase 3/β-Catenin Signaling

2009 ◽  
Vol 30 (1) ◽  
pp. 206-219 ◽  
Author(s):  
Xuechun Xia ◽  
Nidhi Batra ◽  
Qian Shi ◽  
Lynda F. Bonewald ◽  
Eugene Sprague ◽  
...  
Keyword(s):  
Shear Stress ◽  
Gap Junctions ◽  
Gap Junction ◽  
Connexin 43 ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Nuclear Accumulation ◽  
Glycogen Synthase Kinase 3 ◽  
Prostaglandin E ◽  
Cx43 Expression

ABSTRACT Gap junction intercellular communication in osteocytes plays an important role in bone remodeling in response to mechanical loading; however, the responsible molecular mechanisms remain largely unknown. Here, we show that phosphoinositide-3 kinase (PI3K)/Akt signaling activated by fluid flow shear stress and prostaglandin E2 (PGE2) had a stimulatory effect on both connexin 43 (Cx43) mRNA and protein expression. PGE2 inactivated glycogen synthase kinase 3 (GSK-3) and promoted nuclear localization and accumulation of β-catenin. Knockdown of β-catenin expression resulted in a reduction in Cx43 protein. Furthermore, the chromatin immunoprecipitation (ChIP) assay demonstrated an association of β-catenin with the Cx43 promoter, suggesting that β-catenin could regulate Cx43 expression at the level of gene transcription. We have previously reported that PGE2 activates cyclic AMP (cAMP)-protein kinase A (PKA) signaling and increases Cx43 and gap junctions. Interestingly, the activation of PI3K/Akt appeared to be independent of the activation of PKA, whereas both PI3K/Akt and PKA signaling inactivated GSK-3 and increased β-catenin translocation. Together, these results suggest that shear stress, through PGE2 release, activates both PI3K/Akt and cAMP-PKA signaling, which converge through the inactivation of GSK-3, leading to the increase in nuclear accumulation of β-catenin. β-Catenin binds to the Cx43 promoter, stimulating Cx43 expression and functional gap junctions between osteocytes.

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