TY - JOUR
T1 - Caspase-mediated Cleavage of Hematopoietic Progenitor Kinase 1 (HPK1) Converts an Activator of NFκB into an Inhibitor of NFκB
AU - Arnold, Ruediger
AU - Liou, Jen
AU - Drexler, Hannes C A
AU - Weiss, Arthur
AU - Kiefer, Friedemann
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2001/5/4
Y1 - 2001/5/4
N2 - Hematopoietic progenitor kinase 1 (HPK1), a mammalian Ste20-related protein kinase, is a potent stimulator of the stress-activated protein kinases (SAPKs/JNKs). Here we report activation of NFκB transcription factors by HPK1 that was independent of SAPK/JNK activation. Overexpression of a dominant-negative SEK1 significantly inhibited SAPK/JNK activation, whereas NFκB stimulation by HPK1 remained unaffected. Furthermore, activation of NFκB required the presence of full-length, kinase-active HPK1, whereas the isolated kinase domain of HPK1 was sufficient for activation of SAPK/JNK. We also demonstrate that overexpression of a dominant-negative IKKβ blocks HPK1-mediated NFκB activation suggesting that HPK1 acts upstream of the IκB kinase complex. In apoptotic myeloid progenitor cells HPK1 was cleaved at a DDVD motif resulting in the release of the kinase domain and a C-terminal part. Although expression of the isolated HPK1 kinase domain led to SAPK/JNK activation, the C-terminal part inhibited NFκB activation. This dominant-negative effect was not only restricted to HPK1-mediated but also to NIK-and tumor necrosis factor α-mediated NFκB activation, suggesting an impairment of the IκB kinase complex. Thus HPK1 activates both the SAPK/JNK and NFκB pathway in hematopoietic cells but is converted into an inhibitor of NFκB activation in apoptotic cells.
AB - Hematopoietic progenitor kinase 1 (HPK1), a mammalian Ste20-related protein kinase, is a potent stimulator of the stress-activated protein kinases (SAPKs/JNKs). Here we report activation of NFκB transcription factors by HPK1 that was independent of SAPK/JNK activation. Overexpression of a dominant-negative SEK1 significantly inhibited SAPK/JNK activation, whereas NFκB stimulation by HPK1 remained unaffected. Furthermore, activation of NFκB required the presence of full-length, kinase-active HPK1, whereas the isolated kinase domain of HPK1 was sufficient for activation of SAPK/JNK. We also demonstrate that overexpression of a dominant-negative IKKβ blocks HPK1-mediated NFκB activation suggesting that HPK1 acts upstream of the IκB kinase complex. In apoptotic myeloid progenitor cells HPK1 was cleaved at a DDVD motif resulting in the release of the kinase domain and a C-terminal part. Although expression of the isolated HPK1 kinase domain led to SAPK/JNK activation, the C-terminal part inhibited NFκB activation. This dominant-negative effect was not only restricted to HPK1-mediated but also to NIK-and tumor necrosis factor α-mediated NFκB activation, suggesting an impairment of the IκB kinase complex. Thus HPK1 activates both the SAPK/JNK and NFκB pathway in hematopoietic cells but is converted into an inhibitor of NFκB activation in apoptotic cells.
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U2 - 10.1074/jbc.M008343200
DO - 10.1074/jbc.M008343200
M3 - Article
C2 - 11278403
AN - SCOPUS:0035805496
SN - 0021-9258
VL - 276
SP - 14675
EP - 14684
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 18
ER -