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Inhibition of connexin43 gap junctional intercellular communication by TPA requires ERK activation

✍ Scribed by Randall J. Ruch; James E. Trosko; Burra V. Madhukar


Publisher
John Wiley and Sons
Year
2001
Tongue
English
Weight
243 KB
Volume
83
Category
Article
ISSN
0730-2312

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✦ Synopsis


Abstract

The phorbol ester, 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), is a potent inhibitor of gap junctional intercellular communication (GJIC). This inhibition requires activation of protein kinase C (PKC), but the events downstream of this kinase are not known. Since PKC can activate extracellular signal regulated kinases (ERKs) and these also downregulate GJIC, we hypothesized that the inhibition of GJIC by TPA involved ERKs. TPA treatment (10 ng/ml for 30 min) of WB‐F344 rat liver epithelial cells strongly activated p42 and p44 ERK‐1 and ‐2, blocked gap junction‐mediated fluorescent dye‐coupling, and induced connexin43 hyperphosphorylation and gap junction internalization. These effects were completely prevented by inhibitors of PKC (bis‐indolylmaleimide I; 2 μM) and ERK activation (U‐0126; 10 μM). These data suggest that ERKs are activated by PKC in response to TPA treatment and are downstream mediators of the gap junction effects of the phorbol ester. J. Cell. Biochem. 83: 163–169, 2001. © 2001 Wiley‐Liss, Inc.


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