scholarly journals Modulation of gap junction mediated intercellular communication in TM3 Leydig cells

2003 ◽  
Vol 177 (2) ◽  
pp. 327-335 ◽  
Author(s):  
RC Goldenberg ◽  
FS Fortes ◽  
JM Cristancho ◽  
MM Morales ◽  
CR Franci ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Gap Junction ◽  
Intercellular Communication ◽  
Leydig Cells ◽  
Connexin 43 ◽  
Lucifer Yellow ◽  
Surface Membrane ◽  
Hormone Secretion ◽  
Functional Coupling ◽  
Western Blots

Long-term modulation of intercellular communication via gap junctions was investigated in TM3 Leydig cells, under low and high confluence states, and upon treatment of the cells for different times with activators of protein kinase A (PKA) and protein kinase C (PKC). Cells in low confluence were readily coupled, as determined by transfer of the dye Lucifer Yellow; on reaching confluence, the cells uncoupled. Western blots and RT-PCR revealed that connexin 43 (Cx43) was abundantly expressed in TM3 Leydig cells and its expression was decreased after the cells achieved confluence. Stimulation of PKA or PKC induced a decrease in cell-cell communication. Staurosporin, an inhibitor of protein kinases, increased coupling and was able to prevent and reverse the uncoupling actions of dibutyryl cAMP and 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Under modulation by confluence, Cx43 was localized to the appositional membranes when cells were coupled and was mainly in the cytoplasm when they were uncoupled. In addition, cAMP and TPA reduced the surface membrane labeling for Cx43, whereas staurosporin increased it. These data show a strong correlation between functional coupling and the membrane distribution of Cx43, implying that this connexin has an important role in intercellular communication between TM3 cells. Furthermore, increased testosterone secretion in response to luteinizing hormone was accompanied by a decrease in intercellular communication, suggesting that gap junction mediated coupling may be a modulator of hormone secretion in TM3 cells.

scholarly journals Primary Cultures of Chick Osteocytes Retain Functional Gap Junctions between Osteocytes and between Osteocytes and Osteoblasts

2007 ◽  
Vol 13 (2) ◽  
pp. 108-117 ◽  
Author(s):  
Hiroshi Kamioka ◽  
Yoshihito Ishihara ◽  
Hans Ris ◽  
Sakhr A. Murshid ◽  
Yasuyo Sugawara ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Intercellular Communication ◽  
Connexin 43 ◽  
Lucifer Yellow ◽  
Primary Cultures ◽  
Bone Matrix ◽  
Dye Coupling ◽  
Direct Demonstration

The inaccessibility of osteocytes due to their embedment in the calcified bone matrix in vivo has precluded direct demonstration that osteocytes use gap junctions as a means of intercellular communication. In this article, we report successfully isolating primary cultures of osteocytes from chick calvaria, and, using anti-connexin 43 immunocytochemistry, demonstrate gap junction distribution to be comparable to that found in vivo. Next, we demonstrate the functionality of the gap junctions by (1) dye coupling studies that showed the spread of microinjected Lucifer Yellow from osteoblast to osteocyte and between adjacent osteocytes and (2) analysis of fluorescence replacement after photobleaching (FRAP), in which photobleaching of cells loaded with a membrane-permeable dye resulted in rapid recovery of fluorescence into the photobleached osteocyte, within 5 min postbleaching. This FRAP effect did not occur when cells were treated with a gap junction blocker (18α-glycyrrhetinic acid), but replacement of fluorescence into the photobleached cell resumed when it was removed. These studies demonstrate that gap junctions are responsible for intercellular communication between adjacent osteocytes and between osteoblasts and osteocytes. This role is consistent with the ability of osteocytes to respond to and transmit signals over long distances while embedded in a calcified matrix.

Roles of Cx43-associated protein kinases in suppression of gap junction-mediated chemical coupling by ischemic preconditioning

2009 ◽  
Vol 296 (2) ◽  
pp. H396-H403 ◽  
Author(s):  
Kazuyuki Naitoh ◽  
Toshiyuki Yano ◽  
Tetsuji Miura ◽  
Takahito Itoh ◽  
Takayuki Miki ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Ischemic Preconditioning ◽  
Connexin 43 ◽  
Lucifer Yellow ◽  
Inhibitory Peptide ◽  
Before And After ◽  
Chemical Coupling ◽  
The Difference ◽  
Sb 203580

Ischemic preconditioning (PC) suppresses chemical coupling of cardiomyocytes via gap junctions (GJs) during ischemia, which is an adjunct mechanism of protection. The aim of this study was to characterize roles of protein kinases in PC-induced GJ modulation. In isolated rat hearts, ventricular tissues were sampled before and after ischemia with or without PC, and intercalated disc-rich fractions were separated for immunoprecipitation and immunoblotting. Levels of protein kinase C (PKC)-ε, p38mitogen-activated protein kinase (MAPK)-α, and Src coimmunoprecipitated with connexin-43 (Cx43) were increased after ischemia, whereas p38MAPKβ was not detected in the Cx43 immunoprecipitates. PC did not modify the level of Cx43-Src complex after ischemia. However, PC enhanced Cx43-PKCε complex formation, which was abolished by PKCε translocation inhibitory peptide (TIP). In contrast, PC reduced Cx43-p38MAPKα complex level and p38MAPK activity in the Cx43 immunoprecipitates after ischemia. The effect of PC on Cx43-p38MAPKα interaction was mimicked by SB-203580, a p38MAPK inhibitor. PC reduced permeability of GJs to Lucifer yellow in the myocardium at 25 min after ischemia, and this effect was abolished by PKCε-TIP. SB-203580 increased the GJ permeability at 15 min after ischemia compared with that in untreated controls, but the difference became insignificant 25 min after ischemia. In conclusion, PC has distinct effects on interaction of GJ Cx43 with PKCε, p38MAPKα, and Src during ischemia. Suppression of GJ permeability during ischemia by PC is primarily achieved by enhanced interaction of Cx43 with PKCε, which overwhelms the counterbalancing effect of reduced Cx43-p38MAPKα interaction.

scholarly journals Fibroblast Growth Factor 4 Directs Gap Junction Expression in the Mesenchyme of the Vertebrate Limb Bud

1997 ◽  
Vol 138 (5) ◽  
pp. 1125-1137 ◽  
Author(s):  
H. Makarenkova ◽  
D.L. Becker ◽  
C. Tickle ◽  
A.E. Warner
Keyword(s):  
Growth Factor ◽  
Gap Junctions ◽  
Gap Junction ◽  
Fibroblast Growth Factor ◽  
Connexin 43 ◽  
Limb Bud ◽  
Functional Coupling ◽  
Fibroblast Growth ◽  
Mesenchyme Cells

Pattern in the developing limb depends on signaling by polarizing region mesenchyme cells, which are located at the posterior margin of the bud tip. Here we address the underlying cellular mechanisms. We show in the intact bud that connexin 43 (Cx43) and Cx32 gap junctions are at higher density between distal posterior mesenchyme cells at the tip of the bud than between either distal anterior or proximal mesenchyme cells. These gradients disappear when the apical ectodermal ridge (AER) is removed. Fibroblast growth factor 4 (FGF4) produced by posterior AER cells controls signaling by polarizing cells. We find that FGF4 doubles gap junction density and substantially improves functional coupling between cultured posterior mesenchyme cells. FGF4 has no effect on cultured anterior mesenchyme, suggesting that any effects of FGF4 on responding anterior mesenchyme cells are not mediated by a change in gap junction density or functional communication through gap junctions. In condensing mesenchyme cells, connexin expression is not affected by FGF4. We show that posterior mesenchyme cells maintained in FGF4 under conditions that increase functional coupling maintain polarizing activity at in vivo levels. Without FGF4, polarizing activity is reduced and the signaling mechanism changes. We conclude that FGF4 regulation of cell–cell communication and polarizing signaling are intimately connected.

scholarly journals Modulation of mouse neural crest cell motility by N-cadherin and connexin 43 gap junctions

2001 ◽  
Vol 154 (1) ◽  
pp. 217-230 ◽  
Author(s):  
X. Xu ◽  
W.E.I. Li ◽  
G.Y. Huang ◽  
R. Meyer ◽  
T. Chen ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Neural Crest ◽  
Cell Motility ◽  
Gap Junction ◽  
Connexin 43 ◽  
Neural Crest Cell ◽  
Neural Crest Cells ◽  
Functional Coupling ◽  
Dye Coupling ◽  
Crest Cell

Connexin 43 (Cx43α1) gap junction has been shown to have an essential role in mediating functional coupling of neural crest cells and in modulating neural crest cell migration. Here, we showed that N-cadherin and wnt1 are required for efficient dye coupling but not for the expression of Cx43α1 gap junctions in neural crest cells. Cell motility was found to be altered in the N-cadherin–deficient neural crest cells, but the alterations were different from that elicited by Cx43α1 deficiency. In contrast, wnt1-deficient neural crest cells showed no discernible change in cell motility. These observations suggest that dye coupling may not be a good measure of gap junction communication relevant to motility. Alternatively, Cx43α1 may serve a novel function in motility. We observed that p120 catenin (p120ctn), an Armadillo protein known to modulate cell motility, is colocalized not only with N-cadherin but also with Cx43α1. Moreover, the subcellular distribution of p120ctn was altered with N-cadherin or Cx43α1 deficiency. Based on these findings, we propose a model in which Cx43α1 and N-cadherin may modulate neural crest cell motility by engaging in a dynamic cross-talk with the cell's locomotory apparatus through p120ctn signaling.

Differentiation of human fetal osteoblastic cells and gap junctional intercellular communication

2000 ◽  
Vol 278 (2) ◽  
pp. C315-C322 ◽  
Author(s):  
Henry J. Donahue ◽  
Zhongyong Li ◽  
Zhiyi Zhou ◽  
Clare E. Yellowley
Keyword(s):  
Alkaline Phosphatase ◽  
Gap Junction ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Intercellular Communication ◽  
Connexin 43 ◽  
Osteoblastic Cells ◽  
Gap Junctional Intercellular Communication ◽  
Osteoblastic Cell Line ◽  
Gap Junctional

Gap junctional channels facilitate intercellular communication and in doing so may contribute to cellular differentiation. To test this hypothesis, we examined gap junction expression and function in a temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19) that when cultured at 37°C proliferates rapidly but when cultured at 39.5°C proliferates slowly and displays increased alkaline phosphatase activity and osteocalcin synthesis. We found that hFOB 1.19 cells express abundant connexin 43 (Cx43) protein and mRNA. In contrast, Cx45 mRNA was expressed to a lesser degree, and Cx26 and Cx32 mRNA were not detected. Culturing hFOB 1.19 cells at 39.5°C, relative to 37°C, inhibited proliferation, increased Cx43 mRNA and protein expression, and increased gap junctional intercellular communication (GJIC). Blocking GJIC with 18α-glycyrrhetinic acid prevented the increase in alkaline phosphatase activity resulting from culture at 39.5°C but did not affect osteocalcin levels. These results suggest that gap junction function and expression parallel osteoblastic differentiation and contribute to the expression of alkaline phosphatase activity, a marker for fully differentiated osteoblastic cells.

Expression of a dominant negative inhibitor of intercellular communication in the early Xenopus embryo causes delamination and extrusion of cells

Development ◽  
1995 ◽  
Vol 121 (2) ◽  
pp. 371-381
Author(s):  
D.L. Paul ◽  
K. Yu ◽  
R. Bruzzone ◽  
R.L. Gimlich ◽  
D.A. Goodenough
Keyword(s):  
Gap Junction ◽  
Intercellular Communication ◽  
Lucifer Yellow ◽  
Single Cells ◽  
Positional Information ◽  
Embryonic Cell ◽  
Dominant Negative ◽  
Dye Transfer ◽  
Cell Stage ◽  
The Right

A chimeric construct, termed 3243H7, composed of fused portions of the rat gap junction proteins connexin32 (Cx32) and connexin43 (Cx43) has been shown to have selective dominant inhibitory activity when tested in the Xenopus oocyte pair system. Co-injection of mRNA coding for 3243H7 together with mRNAs coding for Cx32 or Cx43 completely blocked the development of channel conductances, while the construct was ineffective at blocking intercellular channel assembly when coinjected with rat connexin37 (Cx37). Injection of 3243H7 into the right anterodorsal blastomere of 8-cell-stage Xenopus embryos resulted in disadhesion and delamination of the resultant clone of cells evident by embryonic stage 8; a substantial number, although not all, of the progeny of the injected cell were eliminated from the embryo by stage 12. A second construct, 3243H8, differing from 3243H7 in the relative position of the middle splice, had no dominant negative activity in the oocyte pair assay, nor any detectable effects on Xenopus development, even when injected at four-fold higher concentrations. The 3243H7-induced embryonic defects could be rescued by coinjection of Cx37 with 3243H7. A blastomere reaggregation assay was used to demonstrate that a depression of dye-transfer could be detected in 3243H7-injected cells as early as stage 7; Lucifer yellow injections into single cells also demonstrated that injection of 3243H7 resulted in a block of intercellular communication. These experiments indicate that maintenance of embryonic cell adhesion with concomitant positional information requires gap junction-mediated intercellular communication.

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