TY - JOUR
T1 - BLNK mediates Syk-dependent Btk activation
AU - Baba, Yoshihiro
AU - Hashimoto, Shoji
AU - Matsushita, Masato
AU - Watanabe, Dai
AU - Kishimoto, Tadamitsu
AU - Kurosaki, Tomohiro
AU - Tsukada, Satoshi
PY - 2001/2/27
Y1 - 2001/2/27
N2 - Btk is a critical molecule in B cell antigen receptor (BCR)-coupled signaling, and its activity is regulated by Lyn and Syk. Although the molecular mechanism of Lyn-dependent Btk activation has been investigated, that of Syk-dependent Btk activation has remained unidentified. We have demonstrated that BLNK mediates Syk-dependent Btk activation. In a reconstitution cell system, coexpression of BLNK allows Syk to phosphorylate Btk on its tyrosine 551, leading to the enhancement of Btk activity. This phosphorylation depends on the interaction of Btk and BLNK by means of the Btk-Src homology 2 domain. The existence of such an activation mechanism is supported by the observation that the BCR-induced Btk phosphorylation and activation are significantly reduced in BLNK-deficient B cells as well as in Syk-deficient B cells. Although previous observations have identified the function of BLNK as the linker that integrates the action of Btk and Syk into downstream effectors such as phospholipase Cγ2, our present study indicates another function of BLNK that connects the activity of Syk to that of Btk.
AB - Btk is a critical molecule in B cell antigen receptor (BCR)-coupled signaling, and its activity is regulated by Lyn and Syk. Although the molecular mechanism of Lyn-dependent Btk activation has been investigated, that of Syk-dependent Btk activation has remained unidentified. We have demonstrated that BLNK mediates Syk-dependent Btk activation. In a reconstitution cell system, coexpression of BLNK allows Syk to phosphorylate Btk on its tyrosine 551, leading to the enhancement of Btk activity. This phosphorylation depends on the interaction of Btk and BLNK by means of the Btk-Src homology 2 domain. The existence of such an activation mechanism is supported by the observation that the BCR-induced Btk phosphorylation and activation are significantly reduced in BLNK-deficient B cells as well as in Syk-deficient B cells. Although previous observations have identified the function of BLNK as the linker that integrates the action of Btk and Syk into downstream effectors such as phospholipase Cγ2, our present study indicates another function of BLNK that connects the activity of Syk to that of Btk.
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U2 - 10.1073/pnas.051626198
DO - 10.1073/pnas.051626198
M3 - Article
C2 - 11226282
AN - SCOPUS:0035956958
SN - 0027-8424
VL - 98
SP - 2582
EP - 2586
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 5
ER -