TY - JOUR
T1 - Targeted deletion of MKK4 gene potentiates TNF-induced apoptosis through the down-regulation of NF-κB activation and NF-κB-regulated antiapoptotic gene products
AU - Sethi, Gautam
AU - Kwang, Seok Ahn
AU - Xia, Dianren
AU - Kurie, Jonathan M.
AU - Aggarwal, Bharat B.
PY - 2007/8/1
Y1 - 2007/8/1
N2 - MAPK kinase 4 (MKK4) is a dual-specificity kinase that activates both JNK and p38 MAPK. However, the mechanism by which MKK4 regulates TNF-induced apoptosis is not fully understood. Therefore, we used fibroblasts derived from MKK4 gene-deleted (MKK4-KO) mice to determine the role of this kinase in TNF signaling. We found that when compared with the wild-type cells, deletion of MKK4 gene enhanced TNF-induced apoptosis, and this correlated with down-regulation of TNF-induced cell-proliferative (COX-2 and cyclin D1) and antiapoptotic (survivin, IAP1, XIAP, Bcl-2, Bcl-xL, and cFLIP) gene products, all regulated by NF-κB. Indeed we found that TNF-induced NF-κB activation was abrogated in MKK4 gene-deleted cells, as determined by DNA binding. Further investigation revealed that TNF-induced IκBα kinase activation, IκBα phosphorylation, IκBα degradation, and p65 nuclear translocation were all suppressed in MKK4-KO cells. NF-κB reporter assay revealed that NF-κB activation induced by TNF, TNFR1, TRADD, TRAF2, NIK, and IκBα kinase was modulated in gene-deleted cells. Overall, our results indicate that MKK4 plays a central role in TNF-induced apoptosis through the regulation of NF-κB-regulated gene products.
AB - MAPK kinase 4 (MKK4) is a dual-specificity kinase that activates both JNK and p38 MAPK. However, the mechanism by which MKK4 regulates TNF-induced apoptosis is not fully understood. Therefore, we used fibroblasts derived from MKK4 gene-deleted (MKK4-KO) mice to determine the role of this kinase in TNF signaling. We found that when compared with the wild-type cells, deletion of MKK4 gene enhanced TNF-induced apoptosis, and this correlated with down-regulation of TNF-induced cell-proliferative (COX-2 and cyclin D1) and antiapoptotic (survivin, IAP1, XIAP, Bcl-2, Bcl-xL, and cFLIP) gene products, all regulated by NF-κB. Indeed we found that TNF-induced NF-κB activation was abrogated in MKK4 gene-deleted cells, as determined by DNA binding. Further investigation revealed that TNF-induced IκBα kinase activation, IκBα phosphorylation, IκBα degradation, and p65 nuclear translocation were all suppressed in MKK4-KO cells. NF-κB reporter assay revealed that NF-κB activation induced by TNF, TNFR1, TRADD, TRAF2, NIK, and IκBα kinase was modulated in gene-deleted cells. Overall, our results indicate that MKK4 plays a central role in TNF-induced apoptosis through the regulation of NF-κB-regulated gene products.
UR - http://www.scopus.com/inward/record.url?scp=34548643396&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34548643396&partnerID=8YFLogxK
U2 - 10.4049/jimmunol.179.3.1926
DO - 10.4049/jimmunol.179.3.1926
M3 - Article
C2 - 17641059
AN - SCOPUS:34548643396
SN - 0022-1767
VL - 179
SP - 1926
EP - 1933
JO - Journal of Immunology
JF - Journal of Immunology
IS - 3
ER -