IL-4 induces serine phosphorylation of the STAT6 transactivation domain in B lymphocytes

ABSTRACT The Epstein-Barr virus (EBV) EBNA-LP and EBNA2 proteins are the first to be synthesized during establishment of latent infection in B lymphocytes. EBNA2 is a key transcriptional regulator of both viral and cellular gene expression and is essential for EBV-induced immortalization of B lymphocytes. EBNA-LP is also important for EBV-induced immortalization of B lymphocytes, but far less is known about the functional domains and cellular cofactors that mediate EBNA-LP function. While recent studies suggest that serine phosphorylation of EBNA-LP and coactivation of EBNA2-mediated transactivation are important, more detailed mutational and genetic studies are complicated by the repeat regions that comprise the majority of the EBNA-LP sequence. Therefore, we have used a comparative approach by studying the EBNA-LP homologues from baboon and rhesus macaque lymphocryptoviruses (LCVs) (baboon LCV and rhesus LCV). The predicted baboon and rhesus LCV EBNA-LP amino acid sequences are 61 and 64% identical to the EBV EBNA-LP W1 and W2 exons and 51% identical to the EBV EBNA-LP Y1 and Y2 exons. Five evolutionarily conserved regions can be defined, and four of eight potential serine residues are conserved among all three EBNA-LPs. The major internal repeat sequence also revealed a highly conserved Wp EBNA promoter with strong conservation of upstream activating sequences important for Wp transcriptional regulation. To test whether transcriptional coactivating properties were common to the rhesus LCV EBNA-LP, a rhesus LCV EBNA2 homologue was cloned and expressed. The rhesus LCV EBNA2 transcriptionally transactivates EBNA2-responsive promoters through a CBF1-dependent mechanism. The rhesus LCV EBNA-LP was able to further enhance rhesus LCV or EBV EBNA2 transactivation 5- to 12-fold. Thus, there is strong structural and functional conservation among the simian EBNA-LP homologues. Identification of evolutionarily conserved serine residues and regions in EBNA-LP homologues provides important clues for identifying the cellular cofactors and molecular mechanisms mediating these conserved viral functions.

Download Full-text

Recruitment of Stat1 to chromatin is required for interferon-induced serine phosphorylation of Stat1 transactivation domain

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0801794105 ◽

2008 ◽

Vol 105 (26) ◽

pp. 8944-8949 ◽

Cited By ~ 81

Author(s):

Iwona Sadzak ◽

Melanie Schiff ◽

Irene Gattermeier ◽

Reingard Glinitzer ◽

Ines Sauer ◽

...

Keyword(s):

Serine Phosphorylation ◽

Transactivation Domain

Download Full-text

Protein Kinase C δ Associates with the Interleukin-6 Receptor Subunit Glycoprotein (gp) 130 via Stat3 and Enhances Stat3-gp130 Interaction

Journal of Biological Chemistry ◽

10.1074/jbc.m206727200 ◽

2002 ◽

Vol 277 (51) ◽

pp. 49134-49142 ◽

Cited By ~ 46

Author(s):

Veronica Novotny-Diermayr ◽

Tong Zhang ◽

Lei Gu ◽

Xinmin Cao

Keyword(s):

Protein Kinase ◽

Catalytic Domain ◽

Nuclear Translocation ◽

Phosphorylation Site ◽

Initial Step ◽

Dominant Negative ◽

Serine Phosphorylation ◽

Dependent Manner ◽

Transactivation Domain ◽

Receptor Subunit

The transcriptional regulation of Stat proteins is controlled through their C-terminal domains, which harbor both a tyrosine phosphorylation site, required for dimerization and subsequent nuclear translocation, and a serine phosphorylation site, required for maximum transcriptional activity. Previously, we reported that protein kinase Cδ (PKCδ) phosphorylates and interacts with Stat3 in an interleukin (IL)-6-dependent manner. In this study, we further characterized this interaction, and investigated the potential role of such an interaction. We show here that the catalytic domain of PKCδ interacts with the Src homology 2 domain and part of the adjacent C-terminal transactivation domain of Stat3. This interaction, which does not seem to involve a classical phosphotyrosine SH2-mediated binding, however, significantly enhances the interaction of Stat3 and the IL-6 receptor subunit glycoprotein (gp) 130, which is the initial step for Stat3 activation by IL-6. Expression of a dominant negative PKCδ or depletion of the endogenous PKCδ by phorbol 12-myristate 3-acetate treatment abrogates the association of Stat3 with gp130. At the same time, PKCδ is recruited to gp130 via association with Stat3, which may facilitate its phosphorylation on the gp130 receptor. Finally, we identified Thr-890, a putative PKC phosphorylation site on gp130, to be critical for the effect of PKCδ. Our data indicate that PKCδ plays important regulatory roles in IL-6 signaling.

Download Full-text

Normal Myeloid Development Requires Both the Glutamine-Rich Transactivation Domain and the PEST Region of Transcription Factor PU.1 but Not the Potent Acidic Transactivation Domain

Molecular and Cellular Biology ◽

10.1128/mcb.18.7.4347 ◽

1998 ◽

Vol 18 (7) ◽

pp. 4347-4357 ◽

Cited By ~ 36

Author(s):

Robert C. Fisher ◽

Marilyn C. Olson ◽

Jagan M. R. Pongubala ◽

Jeffrey M. Perkel ◽

Michael L. Atchison ◽

...

Keyword(s):

Transcription Factor ◽

Dna Binding ◽

Es Cells ◽

Serine Phosphorylation ◽

Functional Domains ◽

Dna Binding Domain ◽

Transactivation Domain ◽

Es Cell ◽

Rescue System

ABSTRACT Gene targeting of transcription factor PU.1 results in an early block to fetal hematopoiesis, with no detectable lymphoid or myeloid cells produced in mouse embryos. Furthermore,PU.1 −/− embryonic stem (ES) cells fail to differentiate into Mac-1+ and F4/80+macrophages in vitro. We have previously shown that a PU.1 transgene under the control of its own promoter restores the ability ofPU.1 −/− ES cells to differentiate into macrophages. In this study, we take advantage of ourPU.1 −/− ES cell rescue system to genetically test which previously identified PU.1 functional domains are necessary for the development of mature macrophages. PU.1 functional domains include multiple N-terminal acidic and glutamine-rich transactivation domains, a PEST domain, several serine phosphorylation sites, and a C-terminal Ets DNA binding domain, all delineated and characterized by using standard biochemical and transactivational assays. By using the production of mature macrophages as a functional readout in our assay system, we have established that the glutamine-rich transactivation domain, a portion of the PEST domain, and the DNA binding domain are required for myelopoiesis. Deletion of three acidic domains, which exhibit potent transactivation potential in vitro, had no effect on the ability of PU.1 to promote macrophage development. Furthermore, mutagenesis of four independent sites of serine phosphorylation also had no effect on myelopoiesis. Collectively, our results indicate that PU.1 interacts with important regulatory proteins during macrophage development via the glutamine-rich and PEST domains. ThePU.1 −/− ES cell rescue system represents a powerful, in vitro strategy to functionally map domains of PU.1 essential for normal hematopoiesis and the generation of mature macrophages.

Download Full-text

Serine Phosphorylation of the STAT1 Transactivation Domain Promotes Autoreactive B Cell and Systemic Autoimmunity Development

The Journal of Immunology ◽

10.4049/jimmunol.2000170 ◽

2020 ◽

Vol 204 (10) ◽

pp. 2641-2650 ◽

Cited By ~ 1

Author(s):

Sathi Babu Chodisetti ◽

Adam J. Fike ◽

Phillip P. Domeier ◽

Stephanie L. Schell ◽

Taryn E. Mockus ◽

...

Keyword(s):

B Cell ◽

Serine Phosphorylation ◽

Transactivation Domain ◽

Systemic Autoimmunity

Download Full-text

180 Recruitment of Stat1 to chromatin is required for interferon-induced serine phosphorylation of Stat1 transactivation domain

Cytokine ◽

10.1016/j.cyto.2008.07.242 ◽

2008 ◽

Vol 43 (3) ◽

pp. 282

Author(s):

Iwona Sadzak ◽

Melanie Schiff ◽

Edward Yang ◽

Barbara Schaljo ◽

Pavel Kovarik

Keyword(s):

Serine Phosphorylation ◽

Transactivation Domain

Download Full-text

Altered Fine Structure of B Lymphocytes Correlated with Defective Terminal Differentiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007237x ◽

1973 ◽

Vol 31 ◽

pp. 386-387

Author(s):

Dale E. Bockman ◽

L. Y. Frank Wu ◽

Alexander R. Lawton ◽

Max D. Cooper

Keyword(s):

Immune Deficiency ◽

B Lymphocytes ◽

Plasma Cells ◽

Present Report ◽

Specific Antigen ◽

Terminal Differentiation ◽

Second Stage ◽

Two Stages ◽

Deficiency Diseases ◽

Cell Line Generation

B-lymphocytes normally synthesize small amounts of immunoglobulin, some of which is incorporated into the cell membrane where it serves as receptor of antigen. These cells, on contact with specific antigen, proliferate and differentiate to plasma cells which synthesize and secrete large quantities of immunoglobulin. The two stages of differentiation of this cell line (generation of B-lymphocytes and antigen-driven maturation to plasma cells) are clearly separable during ontogeny and in some immune deficiency diseases. The present report describes morphologic aberrations of B-lymphocytes in two diseases in which second stage differentiation is defective.

Download Full-text