Constitutive Phosphorylation of STAT3 by the CK2-BLNK-CD5 Complex.

ABSTRACT: In chronic lymphocytic leukemia (CLL), STAT3 is constitutively phosphorylated on serine 727 and plays a role in the pathobiology of CLL. However, what induces constitutive phosphorylation of STAT3 is currently unknown. Mass spectrometry was used to identify casein kinase 2 (CK2), a serine/threonine kinase that coimmunoprecipitated with serine phosphorylated STAT3 (pSTAT3). Furthermore, activated CK2 incubated with recombinant STAT3 induced phosphorylation of STAT3 on serine 727. Although STAT3 and CK2 are present in normal B- and T cells, STAT3 is not constitutively phosphorylated in these cells. Further study found that CD5 and BLNK coexpressed in CLL, but not in normal B- or T cells, are required for STAT3 phosphorylation. To elucidate the relationship of CD5 and BLNK to CK2 and STAT3, S

SUBMITTER: Rozovski U 

PROVIDER: S-EPMC5415425 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature