Dual Phosphorylation of Btk by Akt/Protein Kinase B Provides Docking for 14-3-3ζ, Regulates Shuttling, and Attenuates both Tonic and Induced Signaling in B Cells

Splice-correcting oligonucleotides restore BTK function in X-linked agammaglobulinemia model

“…Cells were then pelleted and resuspended in 5 × 10 6 cells per ml in 1x dPBS. Then anti-IgM was added to a concentration of 20 μg/ml, and cells were incubated for exactly 1 minute, as previously described (78). Cells were then harvested for immunoprecipitation and immunoblotting as described above.…”

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“…Instead, it seems as if serine/threonine kinases (S/T kinases) are involved in the down-regulation of BCR signaling, often with 14-3-3 proteins being crucial contributors to this process. Examples of the BCR downstream proteins involved in this process are BTK, Spleen tyrosine kinase (SYK) and B cell linker/adapter protein (BLNK) [5]. Thus, we have previously shown that the S/T kinase, protein kinase B (AKT/PKB), phosphorylates two sites in BTK, one located in the Pleckstrin homology (PH) domain and the other in the kinase domain [5].…”

“…Examples of the BCR downstream proteins involved in this process are BTK, Spleen tyrosine kinase (SYK) and B cell linker/adapter protein (BLNK) [5]. Thus, we have previously shown that the S/T kinase, protein kinase B (AKT/PKB), phosphorylates two sites in BTK, one located in the Pleckstrin homology (PH) domain and the other in the kinase domain [5]. 14-3-3 proteins are small and acidic, lack enzymatic activity and naturally occur as dimers.…”

“…B. Thereafter, BCR signaling is turned off: PI3-kinase mediates activation of AKT/PKB leading to serine/threonine phosphorylation of BTK (S51/T495) [5] and SYK (S295/S297) [7], while AKT and HPK1 jointly phosphorylate BLNK (S285 and T152, respectively) [7,8]. Subsequently, 14-3-3 proteins tether to the dual serine/threonine phosphorylated sites of target proteins.…”

ANKRD54 preferentially selects Bruton’s Tyrosine Kinase (BTK) from a Human Src-Homology 3 (SH3) domain library

“…Since the discovery of BTK mutations as the cause of X-linked agammaglobulinemia (XLA) [18,19], the role of BTK in B-cell signaling has been extensively studied [1–3,12,20–22]. Although, a huge number of protein partners have been reported to interact with various domains of BTK, only some of them were validated both in vitro and in vivo , while others have not been explored further [13,23].…”