TY - JOUR
T1 - Rapid mitogen-activated protein kinase activation by transforming growth factor α in wounded rat intestinal epithelial cells
AU - Goke, M.
AU - Kanai, M.
AU - Lynch-Devaney, K.
AU - Podolsky, D. K.
PY - 1998
Y1 - 1998
N2 - Background and Aims: To define signaling events initiating healing after intestinal epithelial injury, activation of mitogen-activated protein kinase (MAPK) pathways was assessed after wounding using an in vitro model. Methods: Proteins isolated from wounded monolayers of nontransformed intestinal epithelial cells (IEC-6) were analyzed for tyrosine phosphorylation and MAPK expression by Western blot. Extracellular signal-regulated kinase (ERK) 1, ERK2, and Raf-1 activities were assessed by immune complex kinase assays. Results: Tyrosine phosphorylation of several proteins including ERK1 was substantially increased 5 minutes after injury. Another MAPK, c-Jun-N- terminal protein kinase (JNK), was also activated after wounding. Conditioned medium from wounded but not intact IEC-6 monolayers resulted in increased activity of ERK1, ERK2, and Raf-1 kinase. Wound-conditioned medium stimulated proliferation of subconfluent IEC-6 cells compared with conditioned medium from intact IEC-6 cultures and contained higher amounts of transforming growth factor (TGF)-α than supernatants of confluent IEC-6 cultures. Activation of ERK1 and ERK2 was partially inhibited by neutralizing anti- TGF-α. Conclusions: Wounding of intestinal epithelial cells results in activation of Raf-1, ERK1, ERK2, and JNK1 MAPKs and subsequent cell proliferation in vitro. Activation of ERK1 and ERK2 is mediated in part by TGF-α.
AB - Background and Aims: To define signaling events initiating healing after intestinal epithelial injury, activation of mitogen-activated protein kinase (MAPK) pathways was assessed after wounding using an in vitro model. Methods: Proteins isolated from wounded monolayers of nontransformed intestinal epithelial cells (IEC-6) were analyzed for tyrosine phosphorylation and MAPK expression by Western blot. Extracellular signal-regulated kinase (ERK) 1, ERK2, and Raf-1 activities were assessed by immune complex kinase assays. Results: Tyrosine phosphorylation of several proteins including ERK1 was substantially increased 5 minutes after injury. Another MAPK, c-Jun-N- terminal protein kinase (JNK), was also activated after wounding. Conditioned medium from wounded but not intact IEC-6 monolayers resulted in increased activity of ERK1, ERK2, and Raf-1 kinase. Wound-conditioned medium stimulated proliferation of subconfluent IEC-6 cells compared with conditioned medium from intact IEC-6 cultures and contained higher amounts of transforming growth factor (TGF)-α than supernatants of confluent IEC-6 cultures. Activation of ERK1 and ERK2 was partially inhibited by neutralizing anti- TGF-α. Conclusions: Wounding of intestinal epithelial cells results in activation of Raf-1, ERK1, ERK2, and JNK1 MAPKs and subsequent cell proliferation in vitro. Activation of ERK1 and ERK2 is mediated in part by TGF-α.
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U2 - 10.1016/S0016-5085(98)70583-9
DO - 10.1016/S0016-5085(98)70583-9
M3 - Article
C2 - 9516390
AN - SCOPUS:0031921299
SN - 0016-5085
VL - 114
SP - 697
EP - 705
JO - Gastroenterology
JF - Gastroenterology
IS - 4 I
ER -