| Autor: |
Lampe, Paul D., Qiu Qiu, Meyer, Rita A., TenBroek, Erica M., Walseth, Timothy F., Starich, Todd A., Grunenwald, Haiying L., Johnson, Ross G. |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Cell Physiology; Oct2001, Vol. 281 Issue 4, pC1211, 12p, 7 Black and White Photographs, 1 Chart, 3 Graphs |
| Abstrakt: |
T Gap junction assembly: PTX-sensitive G proteins regulate the distribution of connexin43 within cells. Am J Physiol Cell Physiol 281: C1211-C1222, 2001.—Cells expressing connexin43 are able to upregulate gap junction (GJ) communication by enhancing the assembly of new GJs, apparently through increased connexin trafficking. Because G proteins are known to regulate different aspects of protein trafficking, we examined the effects of pertussis toxin (PTX; a specific inhibitor of certain G proteins) on GJ assembly. Dissociated Novikoff hepatoma cells were reaggregated for 60 min to form nascent junctions. PTX inhibited GJ assembly, as indicated by a reduction in dye transfer. Electron microscopy also revealed a 60% decrease in the number of GJ channels per cell interface. Importantly, PTX blocked the twofold enhancement in GJ assembly found in the presence of low-density lipoprotein. Two G[sub iα] proteins (G[sub iα2] and G[sub iα3]), which have been implicated in the control of membrane trafficking, reacted with PTX in ADP-ribosylation studies. PTX and/or the trafficking inhibitors, brefeldin A and monensin, inhibited GJ assembly to comparable degrees. In addition, assays for GJ hemichannels demonstrated reduced plasma membrane levels of connexin43 following PTX treatment. These results suggest that PTX-sensitive G proteins regulate connexin43 trafficking, and, as a result of inhibition with PTX, the number of plasma membrane hemichannels available for GJ assembly is reduced. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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