Connexin mimetic peptides: specific inhibitors of gap-junctional intercellular communication

2001 ◽  
Vol 29 (4) ◽  
pp. 606-612 ◽  
Author(s):  
W. H. Evans ◽  
S. Boitano
Keyword(s):  
Gap Junctions ◽  
Intercellular Communication ◽  
Gap Junctional Intercellular Communication ◽  
Reversible Inhibitors ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Wide Range ◽  
Mimetic Peptides ◽  
Gap Junctional ◽  
Specific Sequences

Intercellular co-operation is a fundamental and widespread feature in tissues and organs. An important mechanism ensuring multicellular homoeostasis involves signalling between cells via gap junctions that directly connect the cytosolic contents of adjacent cells. Cell proliferation and intercellular communication across gap junctions are closely linked, and a number of pathologies in which communication is disrupted are known where connexins, the gap-junctional proteins, are modified. The proteins of gap junctions thus emerge as therapeutic targets inviting the development and exploitation of chemical tools and drugs that specifically influence intercellular communication. Connexin mimetic peptides that correspond to short specific sequences in the two extracellular loops of connexins are a class of benign, specific and reversible inhibitors of gap-junctional communication that have been studied recently in a broad range of cells, tissues and organs. This review summarizes the properties and uses of these short synthetic peptides, and compares their probable mechanism of action with those of a wide range of other less specific traditional gap-junction inhibitors.

Gap junctions and fluid flow response in MC3T3-E1 cells

2001 ◽  
Vol 281 (6) ◽  
pp. C1917-C1925 ◽  
Author(s):  
M. M. Saunders ◽  
J. You ◽  
J. E. Trosko ◽  
H. Yamasaki ◽  
Z. Li ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Gap Junctions ◽  
Bone Cell ◽  
Dominant Negative ◽  
Prostaglandin E ◽  
Gap Junctional Intercellular Communication ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Text Response ◽  
Gap Junctional

In the current study, we examined the role of gap junctions in oscillatory fluid flow-induced changes in intracellular Ca2+concentration and prostaglandin release in osteoblastic cells. This work was completed in MC3T3-E1 cells with intact gap junctional communication as well as in MC3T3-E1 cells rendered communication deficient through expression of a dominant-negative connexin. Our results demonstrate that MC3T3-E1 cells with intact gap junctions respond to oscillatory fluid flow with significant increases in prostaglandin E2 (PGE2) release, whereas cells with diminished gap junctional communication do not. Furthermore, we found that cytosolic Ca2+ (Ca[Formula: see text]) response was unaltered by the disruption in gap junctional communication and was not significantly different among the cell lines. Thus our results suggest that gap junctions contribute to the PGE2 but not to the Ca[Formula: see text] response to oscillatory fluid flow. These findings implicate gap junctional intercellular communication (GJIC) in bone cell ensemble responsiveness to oscillatory fluid flow and suggest that gap junctions and GJIC play a pivotal role in mechanotransduction mechanisms in bone.

scholarly journals Low pH enhances connexin32 degradation in the pancreatic acinar cell

2014 ◽  
Vol 307 (1) ◽  
pp. G24-G32 ◽  
Author(s):  
Anamika M. Reed ◽  
Thomas Kolodecik ◽  
Sohail Z. Husain ◽  
Fred S. Gorelick
Keyword(s):  
Gap Junctions ◽  
Acinar Cell ◽  
Intercellular Communication ◽  
Pancreatic Acinar Cell ◽  
Low Ph ◽  
Extracellular Ph ◽  
Gap Junctional Intercellular Communication ◽  
Junction Protein ◽  
Clinical Conditions ◽  
Gap Junctional

Decreased extracellular pH is observed in a number of clinical conditions and can sensitize to the development and worsen the severity of acute pancreatitis. Because intercellular communication through gap junctions is pH-sensitive and modulates pancreatitis responses, we evaluated the effects of low pH on gap junctions in the rat pancreatic acinar cell. Decreasing extracellular pH from 7.4 to 7.0 significantly inhibited gap junctional intracellular communication. Acidic pH also significantly reduced levels of connexin32, the predominant gap junction protein in acinar cells, and altered its localization. Increased degradation through the proteasomal, lysosomal, and autophagic pathways mediated the decrease in connexin32 under low-pH conditions. These findings provide the first evidence that low extracellular pH can regulate gap junctional intercellular communication by enhancing connexin degradation.

scholarly journals PI3k and Stat3: Oncogenes that are Required for Gap Junctional, Intercellular Communication

Cancers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 167 ◽  
Author(s):  
Mulu Geletu ◽  
Zaid Taha ◽  
Patrick T. Gunning ◽  
Leda Raptis
Keyword(s):  
Intercellular Communication ◽  
Single Cells ◽  
Survival Function ◽  
Phosphatidyl Inositol ◽  
Transformed Cells ◽  
Gap Junctional Intercellular Communication ◽  
Junctional Communication ◽  
Human Lung Carcinoma ◽  
Mutational Activation ◽  
Gap Junctional

Gap junctional, intercellular communication (GJIC) is interrupted in cells transformed by oncogenes such as activated Src. The Src effector, Ras, is required for this effect, so that Ras inhibition restores GJIC in Src-transformed cells. Interestingly, the inhibition of the Src effector phosphatidyl-inositol-3 kinase (PI3k) or Signal Transducer and Activator of Transcription-3 (Stat3) pathways does not restore GJIC. In the contrary, inhibition of PI3k or Stat3 in non-transformed rodent fibroblasts or epithelial cells or certain human lung carcinoma lines with extensive GJIC inhibits communication, while mutational activation of PI3k or Stat3 increases GJIC. Therefore, it appears that oncogenes such as activated Src have a dual role upon GJIC; acting as inhibitors of communication through the Ras pathway, and as activators through activation of PI3k or Stat3. In the presence of high Src activity the inhibitory functions prevail so that the net effect is gap junction closure. PI3k and Stat3 constitute potent survival signals, so that their inhibition in non-transformed cells triggers apoptosis which, in turn, has been independently demonstrated to suppress GJIC. The interruption of gap junctional communication would confine the apoptotic event to single cells and this might be essential for the maintenance of tissue integrity. We hypothesize that the GJIC activation by PI3k or Stat3 may be linked to their survival function.

Phosphorylation of connexin43 gap junction protein in uninfected and Rous sarcoma virus-transformed mammalian fibroblasts

1990 ◽  
Vol 10 (4) ◽  
pp. 1754-1763
Author(s):  
D S Crow ◽  
E C Beyer ◽  
D L Paul ◽  
S S Kobe ◽  
A F Lau
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Rous Sarcoma Virus ◽  
Gap Junctional Communication ◽  
Rous Sarcoma ◽  
Junctional Communication ◽  
Junction Protein ◽  
Sarcoma Virus ◽  
Gap Junction Protein ◽  
Gap Junctional

Gap junctions are membrane channels that permit the interchange of ions and other low-molecular-weight molecules between adjacent cells. Rous sarcoma virus (RSV)-induced transformation is marked by an early and profound disruption of gap-junctional communication, suggesting that these membrane structures may serve as sites of pp60v-src action. We have begun an investigation of this possibility by identifying and characterizing putative proteins involved in junctional communication in fibroblasts, the major cell type currently used to study RSV-induced transformation. We found that uninfected mammalian fibroblasts do not appear to contain RNA or protein related to connexin32, the major rat liver gap junction protein. In contrast, vole and mouse fibroblasts contained a homologous 3.0-kilobase RNA similar in size to the heart tissue RNA encoding the gap junction protein, connexin43. Anti-connexin43 peptide antisera specifically reacted with three proteins of approximately 43, 45 and 47 kilodaltons (kDa) from communicating fibroblasts. Gap junctions of heart cells contained predominantly 45- and 47-kDa species similar to those found in fibroblasts. Uninfected fibroblast 45- and 47-kDa proteins were phosphorylated on serine residues. Phosphatase digestions of 45- and 47-kDa proteins and pulse-chase labeling studies indicated that these proteins represented phosphorylated forms of the 43-kDa protein. Phosphorylation of connexin protein appeared to occur shortly after synthesis, followed by an equally rapid dephosphorylation. In comparison with these results, connexin43 protein in RSV-transformed fibroblasts contained both phosphotyrosine and phosphoserine. Thus, the presence of phosphotyrosine in connexin43 correlates with the loss of gap-junctional communication observed in RSV-transformed fibroblasts.

scholarly journals Morphofunctional integration between skeletal myoblasts and adult cardiomyocytes in coculture is favored by direct cell-cell contacts and relaxin treatment

2005 ◽  
Vol 288 (4) ◽  
pp. C795-C804 ◽  
Author(s):  
Lucia Formigli ◽  
Fabio Francini ◽  
Alessia Tani ◽  
Roberta Squecco ◽  
Daniele Nosi ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Lucifer Yellow ◽  
Myoblast Differentiation ◽  
Cell Contact ◽  
Cx43 Expression ◽  
Gap Junctional Communication ◽  
Skeletal Myoblasts ◽  
Junctional Communication ◽  
Direct Cell ◽  
Gap Junctional

The success of cellular cardiomyoplasty, a novel therapy for the repair of postischemic myocardium, depends on the anatomical integration of the engrafted cells with the resident cardiomyocytes. Our aim was to investigate the interaction between undifferentiated mouse skeletal myoblasts (C2C12 cells) and adult rat ventricular cardiomyocytes in an in vitro coculture model. Connexin43 (Cx43) expression, Lucifer yellow microinjection, Ca2+ transient propagation, and electrophysiological analysis demonstrated that myoblasts and cardiomyocytes were coupled by functional gap junctions. We also showed that cardiomyocytes upregulated gap junctional communication and expression of Cx43 in myoblasts. This effect required direct cell-to-cell contact between the two cell types and was potentiated by treatment with relaxin, a cardiotropic hormone with potential effects on cardiac development. Analysis of the gating properties of gap junctions by dual cell patch clamping showed that the copresence of cardiomyocytes in the cultures significantly increased the transjunctional current and conductance between myoblasts. Relaxin enhanced this effect in both the myoblast-myoblast and myoblast-cardiomyocyte cell pairs, likely acting not only on gap junction formation but also on the electrical properties of the preexisting channels. Our findings suggest that myoblasts and cardiomyocytes interact actively through gap junctions and that relaxin potentiates the intercellular coupling. A potential role for gap junctional communication in favoring the intercellular exchange of regulatory molecules, including Ca2+, in the modulation of myoblast differentiation is discussed.

scholarly journals Differential phosphorylation of the gap junction protein connexin43 in junctional communication-competent and -deficient cell lines.

1990 ◽  
Vol 111 (5) ◽  
pp. 2077-2088 ◽  
Author(s):  
L S Musil ◽  
B A Cunningham ◽  
G M Edelman ◽  
D A Goodenough
Keyword(s):  
Cell Adhesion ◽  
Gap Junctions ◽  
Gap Junction ◽  
Cell Lines ◽  
Gap Junctional Communication ◽  
Competent Cells ◽  
Deficient Cell ◽  
Junctional Communication ◽  
Gap Junctional ◽  
Cell Cell

Connexin43 is a member of the highly homologous connexin family of gap junction proteins. We have studied how connexin monomers are assembled into functional gap junction plaques by examining the biosynthesis of connexin43 in cell types that differ greatly in their ability to form functional gap junctions. Using a combination of metabolic radiolabeling and immunoprecipitation, we have shown that connexin43 is synthesized in gap junctional communication-competent cells as a 42-kD protein that is efficiently converted to a approximately 46-kD species (connexin43-P2) by the posttranslational addition of phosphate. Surprisingly, certain cell lines severely deficient in gap junctional communication and known cell-cell adhesion molecules (S180 and L929 cells) also expressed 42-kD connexin43. Connexin43 in these communication-deficient cell lines was not, however, phosphorylated to the P2 form. Conversion of S180 cells to a communication-competent phenotype by transfection with a cDNA encoding the cell-cell adhesion molecule L-CAM induced phosphorylation of connexin43 to the P2 form; conversely, blocking junctional communication in ordinarily communication-competent cells inhibited connexin43-P2 formation. Immunohistochemical localization studies indicated that only communication-competent cells accumulated connexin43 in visible gap junction plaques. Together, these results establish a strong correlation between the ability of cells to process connexin43 to the P2 form and to produce functional gap junctions. Connexin43 phosphorylation may therefore play a functional role in gap junction assembly and/or activity.

scholarly journals High-throughput measurement of gap junctional intercellular communication

2014 ◽  
Vol 306 (12) ◽  
pp. H1708-H1713 ◽  
Author(s):  
Jun Liu ◽  
Vinayakumar Siragam ◽  
Jun Chen ◽  
Michael D. Fridman ◽  
Robert M. Hamilton ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Cell Lines ◽  
High Throughput ◽  
Intercellular Communication ◽  
Dye Transfer ◽  
Gap Junctional Intercellular Communication ◽  
Cell Injection ◽  
Operation Speed ◽  
Gap Junctional

Gap junctional intercellular communication (GJIC) is a critical part of cellular activities and is necessary for electrical propagation among contacting cells. Disorders of gap junctions are a major cause for cardiac arrhythmias. Dye transfer through microinjection is a conventional technique for measuring GJIC. To overcome the limitations of manual microinjection and perform high-throughput GJIC measurement, here we present a new robotic microinjection system that is capable of injecting a large number of cells at a high speed. The highly automated system enables large-scale cell injection (thousands of cells vs. a few cells) without major operator training. GJIC of three cell lines of differing gap junction density, i.e., HeLa, HEK293, and HL-1, was evaluated. The effect of a GJIC inhibitor (18-α-glycyrrhetinic acid) was also quantified in the three cell lines. System operation speed, success rate, and cell viability rate were quantitatively evaluated based on robotic microinjection of over 4,000 cells. Injection speed was 22.7 cells per min, with 95% success for cell injection and >90% survival. Dye transfer cell counts and dye transfer distance correlated with the expected connexin expression of each cell type, and inhibition of dye transfer correlated with the concentration of GJIC inhibitor. Additionally, real-time monitoring of dye transfer enables the calculation of coefficients of molecular diffusion through gap junctions. This robotic microinjection dye transfer technique permits rapid assessment of gap junction function in confluent cell cultures.

scholarly journals Myocardial gap junctions: targets for novel approaches in the prevention of life-threatening cardiac arrhythmias

2008 ◽  
pp. S1-S13
Author(s):  
N Tribulová ◽  
V Knezl ◽  
Ľ Okruhlicová ◽  
J Slezák
Keyword(s):  
Gap Junctions ◽  
Heart Function ◽  
Cell Communication ◽  
Persistent Atrial Fibrillation ◽  
Gap Junctional Communication ◽  
Novel Treatments ◽  
Junctional Communication ◽  
Life Threatening ◽  
Direct Cell ◽  
Gap Junctional

Direct cell-to-cell communication in the heart is maintained via gap junction channels composed of proteins termed connexins. Connexin channels ensure molecular and electrical signals propagation and hence are crucial in myocardial synchronization and heart function. Disease-induced gap junctions remodeling and/or an impairment or even block of intercellular communication due to acute pathological conditions results in derangements of myocardial conduction and synchronization. This is critical in the development of both ventricular fibrillation, which is a major cause of sudden cardiac death and persistent atrial fibrillation, most common arrhythmia in clinical practice often resulting in stroke. Many studies suggest that alterations in topology (remodeling), expression, phosphorylation and particularly function of connexin channels due to age or disease are implicated in the development of these life-threatening arrhythmias. It seems therefore challenging to examine whether compounds that could prevent or attenuate gap junctions remodeling and connexin channels dysfunction can protect the heart against arrhythmias that cause sudden death in humans. This assumption is supported by very recent findings showing that an increase of gap junctional conductance by specific peptides can prevents atrial conduction slowing or re-entrant ventricular tachycardia in ischemic heart. Suppression of ischemia-induced dephosphorylation of connexin seems to be one of the mechanisms involved. Another approach for identifying novel treatments is based on the hypothesis that even non-antiarrhythmic drugs with antiarrhythmic ability can modulate gap junctional communication and hence attenuate arrhythmogenic substrates.

scholarly journals Involvement of connexin 43 phosphorylation and gap junctional communication between smooth muscle cells in vasopressin-induced ROCK-dependent vasoconstriction after hemorrhagic shock

2017 ◽  
Vol 313 (4) ◽  
pp. C362-C370 ◽  
Author(s):  
Guangming Yang ◽  
Xiaoyong Peng ◽  
Yue Wu ◽  
Tao Li ◽  
Liangming Liu
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Gap Junctions ◽  
Hemorrhagic Shock ◽  
Connexin 43 ◽  
Muscle Cells ◽  
Gap Junctional Communication ◽  
Contractile Effect ◽  
Junctional Communication ◽  
Gap Junctional

We examined the roles played by gap junctions (GJs) and the GJ channel protein connexin 43 (Cx43) in arginine vasopressin (AVP)-induced vasoconstriction after hemorrhagic shock and their relationship to Rho kinase (ROCK) and protein kinase C (PKC). The results showed that AVP induced an endothelium-independent contraction in rat superior mesenteric arteries (SMAs). Blocking the GJs significantly decreased the contractile response of SMAs and vascular smooth muscle cells (VSMCs) to AVP after shock and hypoxia. The selective Cx43-mimetic peptide inhibited the vascular contractile effect of AVP after shock and hypoxia. AVP restored hypoxia-induced decrease of Cx43 phosphorylation at Ser262 and gap junctional communication in VSMCs. Activation of RhoA with U-46619 increased the contractile effect of AVP. This effect was antagonized by the ROCK inhibitor Y27632 and the Cx43-mimetic peptide. In contrast, neither an agonist nor an inhibitor of PKC had significant effects on AVP-induced contraction after hemorrhagic shock. In addition, silencing of Cx43 with siRNA blocked the AVP-induced increase of ROCK activity in hypoxic VSMCs. In conclusion, AVP-mediated vascular contractile effects are endothelium and myoendothelial gap junction independent. Gap junctions between VSMCs, gap junctional communication, and Cx43 phosphorylation at Ser262 play important roles in the vascular effects of AVP. RhoA/ROCK, but not PKC, is involved in this process.

Sign in / Sign up

Export Citation Format

Share Document