scholarly journals Phosphatidylinositol 3-Kinase-Dependent Mitogen-Activated Protein/Extracellular Signal-Regulated Kinase Kinase 1/2 and NF-κB Signaling Pathways Are Required for B Cell Antigen Receptor-Mediated Cyclin D2 Induction in Mature B Cells

2004 ◽  
Vol 172 (5) ◽  
pp. 2753-2762 ◽  
Author(s):  
Michael J. Piatelli ◽  
Carrie Wardle ◽  
Joseph Blois ◽  
Cheryl Doughty ◽  
Brian R. Schram ◽  
...  
1998 ◽  
Vol 188 (7) ◽  
pp. 1297-1306 ◽  
Author(s):  
Aimin Jiang ◽  
Andrew Craxton ◽  
Tomohiro Kurosaki ◽  
Edward A. Clark

B cell antigen receptor (BCR) cross-linking activates three distinct families of nonreceptor protein tyrosine kinases (PTKs): src-family kinases, Syk, and Btk; these PTKs are responsible for initiating downstream events. BCR cross-linking in the chicken DT40 B cell line also activates three distinct mitogen-activated protein kinases (MAPKs): extracellular signal–regulated kinase (ERK)2, c-jun NH2-terminal kinase (JNK)1, and p38 MAPK. To dissect the functional roles of these PTKs in MAPK signaling, activation of MAPKs was examined in various PTK-deficient DT40 cells. BCR-mediated activation of ERK2, although maintained in Lyn-deficient cells, was abolished in Syk-deficient cells and partially inhibited in Btk-deficient cells, indicating that BCR-mediated ERK2 activation requires Syk and that sustained ERK2 activation requires Btk. BCR-mediated JNK1 activation was maintained in Lyn-deficient cells but abolished in both Syk- and Btk-deficient cells, suggesting that JNK1 is activated via a Syk- and Btk-dependent pathway. Consistent with this, BCR-mediated JNK1 activation was dependent on intracellular calcium and phorbol myristate acetate–sensitive protein kinase Cs. In contrast, BCR-mediated p38 MAPK activation was detected in all three PTK-deficient cells, suggesting that no single PTK is essential. However, BCR-mediated p38 MAPK activation was abolished in Lyn/Syk double deficient cells, demonstrating that either Lyn or Syk alone may be sufficient to activate p38 MAPK. Our data show that BCR-mediated MAPK activation is regulated at the level of the PTKs.


Blood ◽  
1999 ◽  
Vol 94 (7) ◽  
pp. 2357-2364 ◽  
Author(s):  
Shoji Hashimoto ◽  
Akihiro Iwamatsu ◽  
Masamichi Ishiai ◽  
Katsuya Okawa ◽  
Tomoki Yamadori ◽  
...  

Bruton’s tyrosine kinase (Btk) is a critical component in the B-cell antigen receptor (BCR)-coupled signaling pathway. Its deficiency in B cells leads to loss or marked reduction in the BCR-induced calcium signaling. It is known that this BCR-induced calcium signaling depends on the activation of phospholipase Cγ (PLCγ), which is mediated by Btk and another tyrosine kinase Syk and that the SH2 and pleckstrin homology (PH) domains of Btk play important roles in this activation process. Although the importance of the PH domain of Btk has been explained by its role in the membrane targeting of Btk, the functional significance of the SH2 domain in the calcium signaling has remained merely a matter of speculation. In this report, we identify that one of the major Btk-SH2 domain-binding proteins in B cells is BLNK (B-cell linker protein) and present evidences that the interaction of BLNK and the SH2 domain of Btk contributes to the complete tyrosine phosphorylation of PLCγ.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Kanika Vanshylla ◽  
Caren Bartsch ◽  
Christoffer Hitzing ◽  
Laura Krümpelmann ◽  
Jürgen Wienands ◽  
...  

2002 ◽  
Vol 22 (15) ◽  
pp. 5479-5491 ◽  
Author(s):  
Aaron J. Marshall ◽  
Allyson K. Krahn ◽  
Kewei Ma ◽  
Vincent Duronio ◽  
Sen Hou

ABSTRACT We report the characterization of two signal transduction proteins related to Bam32, known as TAPP1 and TAPP2. Bam32, TAPP1, and TAPP2 share several characteristics, including small size (32 to 47 kDa), lack of enzymatic domains, high conservation between humans and mice, and the presence of pleckstrin homology (PH) domains near their C termini which contain the 3-phosphoinositide-binding motif. Unlike Bam32, the N-terminal regions of TAPP1 and TAPP2 contain a second PH domain. TAPP1 and TAPP2 transcripts are expressed in a variety of tissues including lymphoid tissues. Using live-cell imaging, we demonstrate that TAPP1 and TAPP2 are recruited to the plasma membrane of BJAB human B-lymphoma cells upon activation through the B-cell antigen receptor (BCR). The C-terminal PH domain is necessary and sufficient for BCR-induced membrane recruitment of both TAPP1 and TAPP2. Blockade of phosphatidylinositol 3-kinase (PI3K) activity completely abolished BCR-induced recruitment of TAPP1 and TAPP2, while expression of active PI3K is sufficient to drive constitutive membrane localization of TAPP1 and TAPP2. TAPP1 and TAPP2 preferentially accumulate within ruffled, F-actin-rich areas of plasma membrane, suggesting a potential role in PI3K-driven cytoskeletal reorganization. Like Bam32, BCR-driven TAPP1 and TAPP2 recruitment is a relatively slow and sustained response, in contrast to Btk recruitment and Ca2+ mobilization responses, which are rapid and transient. Consistent with recent studies indicating that Bam32, TAPP1, and TAPP2 can bind to PI(3,4)P2, we find that membrane recruitment correlates well with production of PI(3,4)P2 but not with that of PI(3,4,5)P3. Our results indicate that TAPP1 and TAPP2 are direct targets of PI3K signaling that are recruited into plasma membranes with distinctive delayed kinetics and accumulate within F-actin-rich membrane ruffles. We postulate that the TAPPs function to orchestrate cellular responses during the sustained phase of signaling.


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