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 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.

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 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

Mechanism of regulation of the gap junction protein connexin 43 by protein kinase C-mediated phosphorylation

2004 ◽  
Vol 286 (3) ◽  
pp. C647-C654 ◽  
Author(s):  
Xiaoyong Bao ◽  
Guillermo A. Altenberg ◽  
Luis Reuss
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Gap Junction ◽  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Xenopus Laevis Oocytes ◽  
Solute Permeability ◽  
Kinase C ◽  
Junction Protein ◽  
Gap Junction Protein

Phosphorylation of the gap junction protein connexin 43 (Cx43) by protein kinase C (PKC) decreases dye coupling in many cell types. We report an investigation of the regulation by PKC of Cx43 gap junctional hemichannels (GJH) expressed in Xenopus laevis oocytes. The activity of GJH was assessed from the uptake of hydrophilic fluorescent probes. PKC inhibitors increased probe uptake in isolated oocytes expressing recombinant Cx43, indicating that the regulatory effect occurs at the hemichannel level. We identified by mutational analysis the carboxy-terminal (CT) domain sequences involved in this response. We found that 1) Ser368 is responsible for the regulation of Cx43 GJH solute permeability by PKC-mediated phosphorylation, 2) CT domain residues 253-270 and 288-359 are not necessary for the effect of PKC, and 3) the prolinerich CT region is not involved in the effect of phosphorylation by PKC. Our results demonstrate that Ser368 (but not Ser372) is involved in the regulation of Cx43 solute permeability by PKC-mediated phosphorylation, and we conclude that different molecular mechanisms underlie the regulation of Cx43 by intracellular pH and PKC-mediated phosphorylation.

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.

Regulation of Gap Junction Protein (Connexin) Genes and Function in Differentiating ES Cells

2003 ◽  
pp. 63-69
Author(s):  
Masahito Oyamada ◽  
Yumiko Oyamada ◽  
Tomoyuki Kaneko ◽  
Tetsuro Takamatsu
Keyword(s):  
Gap Junction ◽  
Es Cells ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Connexin Genes ◽  
And Function

Abstract 3860: Arrhythmia Vulnerability of Aged Haploinsufficient Cx43 Mice is Determined by Heterogeneous Downregulation of Cx43 Combined with Increased Fibrosis

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
John A Jansen ◽  
Toon A van Veen ◽  
Astrid A Bosch ◽  
Roel van der Nagel ◽  
Marc A Vos ◽  
...  
Keyword(s):  
Gap Junction ◽  
Ventricular Arrhythmias ◽  
Interstitial Fibrosis ◽  
Cx43 Expression ◽  
Slow Conduction ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Heterogeneous Reduction ◽  
Perfused Hearts ◽  
Activation Mapping

Background: Reduced gap junction expression and increased collagen deposition are commonly found in ventricles of electrically remodeled diseased hearts. Their interactive contribution to slow conduction and increased arrhythmogeneity is, however, unclear. In this study, we investigated the effect of increased fibrosis with normal or reduced levels of the ventricular gap junction protein Cx43 on impulse propagation and arrhythmogeneity. Methods: 11 Cx43fl/fl (Control) and 13 Cx43CreER(T)/fl mice (expressing only 50% of Cx43 protein compared to control; Cx43HZ) were aged to 20 months. Epicardial activation mapping (208 electrode terminals) of right (RV) and left (LV) ventricle was performed on Langendorff perfused hearts. Effective refractory period (ERP) was determined by premature stimulation and arrhythmia inducibility was tested by 1–3 premature stimuli and burst pacing. Epicardial conduction velocity longitudinal (CVL) and transverse (CVT) to fiber orientation and inhomogeneity of conduction was determined during S1S1 pacing (150 ms). Cx43, N-cadherin expression, and tissue collagen content was determined by (immuno)histology and Western blotting. Results: Sustained ventricular arrhythmias were induced in 0/11 control and 8/13 Cx43HZ mice (p<0.01). CVL and CVT were unchanged, except for CVT in RV, which was decreased from 48.2±2 to 39.3±1.8 cm/s (Control vs Cx43HZ, p<0.05). In RV, ERP was decreased from 78.2±6.0 to 53.1±3.3 ms (Control vs Cx43HZ, p<0.05). In both RV and LV, inhomogeneity of conduction was significantly higher in Cx43HZ mice with arrhythmias (VT+), compared to both Control and Cx43HZ mice without arrhythmias (VT−). Cx43 expression levels were comparable between VT+ and VT- Cx43HZ mice, though strongly reduced compared to Control. However, Cx43 distribution was very heterogeneous in VT+ mice with large areas devoid of Cx43 while N-cadherin was unaffected, indicating the presence of intact intercalated disks. Compared to Control interstitial fibrosis was increased in Cx43HZ mice, but more pronounced in VT+ Cx43HZ mice when compared to Cx43HZ VT- mice. Conclusions: Combined heterogeneous reduction of Cx43 and increased fibrosis strongly enhance arrhythmogenic vulnerability in aged haploinsufficient Cx43 mice.

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