scholarly journals Five-hour half-life of mouse liver gap-junction protein.

1981 ◽  
Vol 90 (2) ◽  
pp. 521-526 ◽  
Author(s):  
R F Fallon ◽  
D A Goodenough
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Half Life ◽  
Mouse Liver ◽  
Polyacrylamide Gels ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Polypeptide Band

The half-life of a gap-junction polypeptide band migrating at 21,000 Mr on SDS polyacrylamide gels isolated from mouse liver is measured to be 5 h. Two low-molecular wight bands, probably related to the 21,000 Mr material by proteolysis, have measured half-lives of 4.6 and 5.2 h. Gap junctions are labeled in vivo using the 14C-bicarbonate labeling procedure, followed by quantitative fluorography.

scholarly journals Differential effect of subcellular localization of communication impairing gap junction protein connexin43 on tumor cell growth in vivo

Oncogene ◽  
2000 ◽  
Vol 19 (4) ◽  
pp. 505-513 ◽  
Author(s):  
V A Krutovskikh ◽  
S M Troyanovsky ◽  
C Piccoli ◽  
H Tsuda ◽  
M Asamoto ◽  
...  
Keyword(s):  
Cell Growth ◽  
Subcellular Localization ◽  
Tumor Cell ◽  
Gap Junction ◽  
Differential Effect ◽  
Tumor Cell Growth ◽  
Junction Protein ◽  
Gap Junction Protein

Analysis of distribution patterns of gap junctions during development of embryonic chick facial primordia and brain

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 509-522
Author(s):  
R. Minkoff ◽  
S.B. Parker ◽  
E.L. Hertzberg
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Uniform Distribution ◽  
Rat Liver ◽  
Connexin 43 ◽  
Cell Communication ◽  
Exterior Surface ◽  
Junction Protein ◽  
Primary Palate ◽  
Gap Junction Protein

Gap junction distribution in the facial primordia of chick embryos at the time of primary palate formation was studied employing indirect immunofluorescence localization with antibodies to gap junction proteins initially identified in rat liver (27 × 10(3) Mr, connexin 32) and heart (43 × 10(3) Mr, connexin 43). Immunolocalization with antibodies to the rat liver gap junction protein (27 × 10(3) Mr) demonstrated a ubiquitous and uniform distribution in all regions of the epithelium and mesenchyme except the nasal placode. In the placodal epithelium, a unique non-random distribution was found characterized by two zones: a very heavy concentration of signal in the superficial layer of cells adjacent to the exterior surface and a region devoid of detectable signal in the interior cell layer adjacent to the mesenchyme. This pattern was seen during all stages of placode invagination that were examined. The separation of gap junctions in distinct cell layers was unique to the nasal placode, and was not found in any other region of the developing primary palate. One other tissue was found that exhibited this pattern-the developing neural epithelium of the brain and retina. These observations suggest the presence of region-specific signaling mechanisms and, possibly, an impedance of cell communication among subpopulations of cells in these structures at critical stages of development. Immunolocalization with antibodies to the ‘heart’ 43 × 10(3) Mr gap junction protein also revealed the presence of gap junction protein in facial primordia and neural epithelium. A non-uniform distribution of immunoreactivity was also observed for connexin 43.

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.

Sharp Wave-Like Activity in the Hippocampus In Vitro in Mice Lacking the Gap Junction Protein Connexin 36

2003 ◽  
Vol 89 (4) ◽  
pp. 2046-2054 ◽  
Author(s):  
Isabel Pais ◽  
Sheriar G. Hormuzdi ◽  
Hannah Monyer ◽  
Roger D. Traub ◽  
Ian C. Wood ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Frequency Oscillation ◽  
Connexin 36 ◽  
Sharp Wave ◽  
Bath Application ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Electrical Signaling

Bath application of kainate (100–300 nM) induced a persistent gamma-frequency (30–80 Hz) oscillation that could be recorded in stratum radiatum of the CA3 region in vitro. We have previously described that in knockout mice lacking the gap junction protein connexin 36 (Cx36KO), γ-frequency oscillations are reduced but still present. We now demonstrate that in the Cx36KO mice, but not in wild-type (WT), large population field excitatory postsynaptic potentials, or sharp wave-burst discharges, also occurred during the on-going γ-frequency oscillation. These spontaneous burst discharges were not seen in WT mice. Burst discharges in the Cx36KO mice occurred with a mean frequency of 0.23 ± 0.11 Hz and were accompanied by a series of fast (approximately 60–115 Hz) population spikes or “ripple” oscillations in many recordings. Intracellular recordings from CA3 pyramidal cells showed that the burst discharges consisted of a depolarizing response and presumed coupling potentials (spikelets) could occasionally be seen either before or during the burst discharge. The burst discharges occurring in Cx36KO mice were sensitive to gap junctions blockers as they were fully abolished by carbenoxolone (200 μM). In control mice we made several attempts to replicate this pattern of sharp wave activity/ripples occurring with the on-going kainate-evoked γ-frequency oscillation by manipulating synaptic and electrical signaling. Partial disruption of inhibition, in control slices, by bath application of the γ-aminobutyric acid-A (GABAA) receptor antagonist bicuculline (1–4 μM) completely abolished all γ-frequency activity before any burst discharges occurred. Increasing the number of open gap junctions in control slices by using trimethylamine (TMA; 2–10 mM), in conjunction with kainate, failed to elicit any sharp wave bursts or fast ripples. However, bath application of the potassium channel blocker 4-aminopyridine (4-AP; 20–80 μM) produced a pattern of activity in control mice (13/16 slices), consisting of burst discharges occurring in conjunction with kainate-evoked γ-frequency oscillations, that was similar to that seen in Cx36KO mice. In a few cases ( n = 9) the burst discharges were accompanied by fast ripple oscillations. Carbenoxolone also fully blocked the 4-AP-evoked burst discharges ( n = 5). Our results show that disruption of electrical signaling in the interneuronal network can, in the presence of kainate, lead to the spontaneous generation of sharp wave/ripple activity similar to that observed in vivo. This suggests a complex role for electrically coupled interneurons in the generation of hippocampal network activity.

Molecular cloning of a rat uterine gap junction protein and analysis of gene expression during gestation

1991 ◽  
Vol 260 (5) ◽  
pp. E787-E793 ◽  
Author(s):  
L. M. Lang ◽  
E. C. Beyer ◽  
A. L. Schwartz ◽  
J. D. Gitlin
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Cdna Clone ◽  
Blot Analysis ◽  
Nucleotide Sequence Analysis ◽  
Uterine Tissue ◽  
Coding Region ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Rna Blot Analysis

To study the molecular mechanisms controlling the rapid increase in myometrial gap junctions observed in the parturient uterus, we have isolated a full-length cDNA clone corresponding to a rat uterine gap junction protein. Nucleotide sequence analysis of the cDNA clone reveals complete identity of the coding region with that of a previously reported heart gap junction protein (connexin43). Southern blot analysis suggests that the gene encoding this gap junction protein exists as a single copy in the rat haploid genome and contains no introns within the coding region. RNA blot analysis with this gap junction cDNA reveals a single 3.0-kb mRNA in uterine tissue without changes in transcript size throughout gestation. When normalized to the amount of 28S rRNA, the relative abundance of the connexin43 transcript in uterine tissue is quite constant between the nonpregnant state, during gestation, intrapartum, and postpartum. Similar size transcripts are shown by RNA blot analysis to be present in heart, lung, liver, brain, and skeletal muscle, and these transcripts are identified by the same 3'-nontranslated sequence probe. The results of these studies suggest that rat connexin43 is encoded by a single gene that is transcribed to identical transcripts in heart, uterus, and other tissues. They further suggest that changes in the abundance of connexin43 transcript are unlikely to be responsible for the abrupt increase in connexin43-containing myometrial gap junctions at term.

Differences between liver gap junction protein and lens MIP 26 from rat: Implications for tissue specificity of gap junctions

Cell ◽  
1983 ◽  
Vol 32 (3) ◽  
pp. 967-978 ◽  
Author(s):  
Bruce J. Nicholson ◽  
Larry J. Takemoto ◽  
Michael W. Hunkapiller ◽  
Leroy E. Hood ◽  
Jean-Paul Revel
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Tissue Specificity ◽  
Junction Protein ◽  
Gap Junction Protein

scholarly journals Simultaneous light and electron microscopic observation of immunolabeled liver 27 KD gap junction protein on ultra-thin cryosections.

1987 ◽  
Vol 35 (3) ◽  
pp. 387-392 ◽  
Author(s):  
R Dermietzel ◽  
B Yancey ◽  
U Janssen-Timmen ◽  
O Traub ◽  
K Willecke ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Polyclonal Antibodies ◽  
Electron Microscopic Observation ◽  
Major Constituent ◽  
Frozen Sections ◽  
Electron Microscopic ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Antigenic Targets

We report on immunolabeling of gap junction protein in rat liver. Simultaneous light and electron microscopic immunolabeling of ultra-thin frozen sections was performed to confirm that the antigenic targets of polyclonal antibodies and a monoclonal 27 KD antibody (12/1 C5) are the gap junctions. Our results clearly demonstrate that the immunoreactive sites determined by indirect immunofluorescence correspond to immunogold-labeled gap junctions identified in the same section according to electron microscopic criteria. Our results also support the concept that the 27 KD protein is a major constituent of gap junctions.

scholarly journals Proteoglycans and glycosaminoglycans induce gap junction synthesis and function in primary liver cultures.

1987 ◽  
Vol 105 (1) ◽  
pp. 541-551 ◽  
Author(s):  
D C Spray ◽  
M Fujita ◽  
J C Saez ◽  
H Choi ◽  
T Watanabe ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Intercellular Communication ◽  
Electrical Coupling ◽  
Sulfated Polysaccharides ◽  
Sulfate Proteoglycan ◽  
Dye Coupling ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
In Cells

Intercellular communication via gap junctions, as measured by dye and electrical coupling, disappears within 12 h in primary rat hepatocytes cultured in serum-supplemented media or within 24 h in cells in a serum-free, hormonally defined medium (HDM) designed for hepatocytes. Glucagon and linoleic acid/BSA were the primary factors in the HDM responsible for the extended life span of the electrical coupling. After 24 h of culture, no hormone or growth factor tested could restore the expression of gap junctions. After 4-5 d of culture, the incidence of coupling was undetectable in a serum-supplemented medium and was only 4-5% in HDM alone. However, treatment with glycosaminoglycans or proteoglycans of 24-h cultures, having no detectable gap junction protein, resulted in synthesis of gap junction protein and of reexpression of electrical and dye coupling within 48 h. Most glycosaminoglycans were inactive (heparan sulfates, chondroitin-6 sulfates) or only weakly active (dermatan sulfates, chondroitin 4-sulfates, hyaluronates), the weakly active group increasing the incidence of coupling to 10-30% with the addition of 50-100 micrograms/ml of the factor. Treatment of the cells with 50-100 micrograms/ml of heparins derived from lung or intestine resulted in cells with intermediate levels of coupling (30-50%). By contrast, 10-20 micrograms/ml of chondroitin sulfate proteoglycan, dermatan sulfate proteoglycan, or liver-derived heparin resulted in dye coupling in 80-100% of the cells, with numerous cells showing dye spread from a single injected cell. Sulfated polysaccharides of glucose (dextran sulfates) or of galactose (carrageenans) were inactive or only weakly active except for lambda-carrageenan, which induced up to 70% coupling (albeit no multiple coupling in the cultures). The abundance of mRNA (Northern blots) encoding gap junction protein and the amounts of the 27-kD gap junction polypeptide (Western blots) correlated with the degree of electrical and dye coupling indicating that the active glycosaminoglycans and proteoglycans are inducing synthesis and expression of gap junctions. Thus, proteoglycans and glycosaminoglycans, especially those found in abundance in the extracellular matrix of liver cells, are important in the regulation of expression of gap junctions and, thereby, in the regulation of intercellular communication in the liver. The relative potencies of heparins from different tissue sources at inducing gap junction expression are suggestive of functional tissue specificity for these glycosaminoglycans.

scholarly journals Calmodulin dependent protein kinase increases conductance at gap junctions formed by the neuronal gap junction protein connexin36

2012 ◽  
Vol 1487 ◽  
pp. 69-77 ◽  
Author(s):  
Cristiane del Corsso ◽  
Rodolfo Iglesias ◽  
Georg Zoidl ◽  
Rolf Dermietzel ◽  
David C. Spray
Keyword(s):  
Protein Kinase ◽  
Gap Junctions ◽  
Gap Junction ◽  
Dependent Protein Kinase ◽  
Junction Protein ◽  
Dependent Protein ◽  
Gap Junction Protein
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