Ischaemia-induced autophagy leads to degradation of gap junction protein connexin43 in cardiomyocytes

2015 ◽  
Vol 467 (2) ◽  
pp. 231-245 ◽  
Author(s):  
Tania Martins-Marques ◽  
Steve Catarino ◽  
Monica Zuzarte ◽  
Carla Marques ◽  
Paulo Matafome ◽  
...  
Keyword(s):  
Gap Junction ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Perfused Heart ◽  
Gap Junction Intercellular Communication ◽  
Junction Protein ◽  
Autophagic Degradation ◽  
Epidermal Growth ◽  
Heart Cultures ◽  
Amp Activated Protein Kinase

GJIC (gap junction intercellular communication) between cardiomyocytes is essential for synchronous heart contraction and relies on Cx (connexin)-containing channels. Increased breakdown of Cx43 has been often associated with various cardiac diseases. However, the mechanisms whereby Cx43 is degraded in ischaemic heart remain unknown. The results obtained in the present study, using both HL-1 cells and organotypic heart cultures, show that simulated ischaemia induces degradation of Cx43 that can be prevented by chemical or genetic inhibitors of autophagy. Additionally, ischaemia-induced degradation of Cx43 results in GJIC impairment in HL-1 cells, which can be restored by autophagy inhibition. In cardiomyocytes, ubiquitin signals Cx43 for autophagic degradation, through the recruitment of the ubiquitin-binding proteins Eps15 (epidermal growth factor receptor substrate 15) and p62, that assist in Cx43 internalization and targeting to autophagic vesicles, via LC3 (light chain 3). Moreover, we establish that degradation of Cx43 in ischaemia or I/R (ischaemia/reperfusion) relies upon different molecular players. Indeed, degradation of Cx43 during early periods of ischaemia depends on AMPK (AMP-activated protein kinase), whereas in late periods of ischaemia and I/R Beclin 1 is required. In the Langendorff-perfused heart, Cx43 is dephosphorylated in ischaemia and degraded during I/R, where Cx43 degradation correlates with autophagy activation. In summary, the results of the present study provide new evidence regarding the molecular mechanisms whereby Cx43 is degraded in ischaemia, which may contribute to the development of new strategies that aim to preserve GJIC and cardiac function in ischaemic heart.

scholarly journals EHD1 Modulates Cx43 Gap Junction Remodeling Associated With Cardiac Diseases

2020 ◽  
Vol 126 (10) ◽  
Author(s):  
Tania Martins-Marques ◽  
Steve Catarino ◽  
Alexandre Gonçalves ◽  
Daniela Miranda-Silva ◽  
Lino Gonçalves ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Connexin 43 ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Heart Cells ◽  
Proteomic Study ◽  
Epidermal Growth ◽  
Electrical Impulses ◽  
And Function

Rationale: Efficient communication between heart cells is vital to ensure the anisotropic propagation of electrical impulses, a function mainly accomplished by gap junctions (GJ) composed of Cx43 (connexin 43). Although the molecular mechanisms remain unclear, altered distribution and function of gap junctions have been associated with acute myocardial infarction and heart failure. Objective: A recent proteomic study from our laboratory identified EHD1 (Eps15 [endocytic adaptor epidermal growth factor receptor substrate 15] homology domain-containing protein 1) as a novel interactor of Cx43 in the heart. Methods and Results: In the present work, we demonstrate that knockdown of EHD1 impaired the internalization of Cx43, preserving gap junction-intercellular coupling in cardiomyocytes. Interaction of Cx43 with EHD1 was mediated by Eps15 and promoted by phosphorylation and ubiquitination of Cx43. Overexpression of wild-type EHD1 accelerated internalization of Cx43 and exacerbated ischemia-induced lateralization of Cx43 in isolated adult cardiomyocytes. In addition, we show that EHDs associate with Cx43 in human and murine failing hearts. Conclusions: Overall, we identified EHDs as novel regulators of endocytic trafficking of Cx43, participating in the pathological remodeling of gap junctions, paving the way to innovative therapeutic strategies aiming at preserving intercellular communication in the heart.

scholarly journals Molecular mechanisms of epidermal growth factor receptor overexpression in patients with cervical cancer

2011 ◽  
Vol 24 (5) ◽  
pp. 720-728 ◽  
Author(s):  
Marlies Schrevel ◽  
Arko Gorter ◽  
Sandra M Kolkman-Uljee ◽  
J Baptist M Z Trimbos ◽  
Gert Jan Fleuren ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Epidermal Growth

Drug-induced alterations in Mg2+ homoeostasis

2012 ◽  
Vol 123 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Anke L. Lameris ◽  
Leo A. Monnens ◽  
René J. Bindels ◽  
Joost G. J. Hoenderop
Keyword(s):  
Adverse Effects ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Calcineurin Inhibitors ◽  
Drug Induced ◽  
Neuromuscular Abnormalities ◽  
Broad Variety ◽  
Epidermal Growth ◽  
High Doses ◽  
Insight Into

Magnesium (Mg2+) balance is tightly regulated by the concerted actions of the intestine, bone and kidneys. This balance can be disturbed by a broad variety of drugs. Diuretics, modulators of the EGFR (epidermal growth factor receptor), proton pump inhibitors, antimicrobials, calcineurin inhibitors and cytostatics may all cause hypomagnesaemia, potentially leading to tetany, seizures and cardiac arrhythmias. Conversely, high doses of Mg2+ salts, frequently administered as an antacid or a laxative, may lead to hypermagnesaemia causing various cardiovascular and neuromuscular abnormalities. A better understanding of the molecular mechanisms underlying the adverse effects of these medications on Mg2+ balance will indicate ways of prevention and treatment of these adverse effects and could potentially provide more insight into Mg2+ homoeostasis.

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 Structural insights into the activation mechanism of dynamin-like EHD ATPases

2017 ◽  
Vol 114 (22) ◽  
pp. 5629-5634 ◽  
Author(s):  
Arthur Alves Melo ◽  
Balachandra G. Hegde ◽  
Claudio Shah ◽  
Elin Larsson ◽  
J. Mario Isas ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Cellular Membrane ◽  
Activation Mechanism ◽  
Gtpase Domain ◽  
Membrane Recruitment ◽  
Spin Resonance ◽  
Epidermal Growth ◽  
Electron Paramagnetic

Eps15 (epidermal growth factor receptor pathway substrate 15)-homology domain containing proteins (EHDs) comprise a family of dynamin-related mechano-chemical ATPases involved in cellular membrane trafficking. Previous studies have revealed the structure of the EHD2 dimer, but the molecular mechanisms of membrane recruitment and assembly have remained obscure. Here, we determined the crystal structure of an amino-terminally truncated EHD4 dimer. Compared with the EHD2 structure, the helical domains are 50° rotated relative to the GTPase domain. Using electron paramagnetic spin resonance (EPR), we show that this rotation aligns the two membrane-binding regions in the helical domain toward the lipid bilayer, allowing membrane interaction. A loop rearrangement in GTPase domain creates a new interface for oligomer formation. Our results suggest that the EHD4 structure represents the active EHD conformation, whereas the EHD2 structure is autoinhibited, and reveal a complex series of domain rearrangements accompanying activation. A comparison with other peripheral membrane proteins elucidates common and specific features of this activation mechanism.

Molecular mechanisms of asymmetric RAF dimer activation

2014 ◽  
Vol 42 (4) ◽  
pp. 784-790 ◽  
Author(s):  
Pablo G. Jambrina ◽  
Olga Bohuszewicz ◽  
Nicolae-Viorel Buchete ◽  
Walter Kolch ◽  
Edina Rosta
Keyword(s):  
Molecular Mechanisms ◽  
Kinase Activity ◽  
Growth Factor Receptor ◽  
Structural Data ◽  
Md Simulations ◽  
Cyclin Dependent Kinase ◽  
Post Translational Modifications ◽  
Raf Kinase ◽  
Epidermal Growth ◽  
Determination Methods

Protein phosphorylation is one of the most common post-translational modifications in cell regulatory mechanisms. Dimerization plays also a crucial role in the kinase activity of many kinases, including RAF, CDK2 (cyclin-dependent kinase 2) and EGFR (epidermal growth factor receptor), with heterodimers often being the most active forms. However, the structural and mechanistic details of how phosphorylation affects the activity of homo- and hetero-dimers are largely unknown. Experimentally, synthesizing protein samples with fully specified and homogeneous phosphorylation states remains a challenge for structural biology and biochemical studies. Typically, multiple changes in phosphorylation lead to activation of the same protein, which makes structural determination methods particularly difficult. It is also not well understood how the occurrence of phosphorylation and dimerization processes synergize to affect kinase activities. In the present article, we review available structural data and discuss how MD simulations can be used to model conformational transitions of RAF kinase dimers, in both their phosphorylated and unphosphorylated forms.

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