Identification and functional characterization of novel phosphorylation sites in TAK1-binding protein (TAB) 1.
TAB1 was defined as a regulatory subunit of the protein kinase TAK1, which functions upstream in the pathways activated by interleukin (IL)-1, tumor necrosis factor (TNF), toll-like receptors (TLRs) and stressors. However, TAB1 also functions in the p38 MAPK pathway downstream of TAK1. We identified amino acids (aa) 452/453 and 456/457 of TAB1 as novel sites phosphorylated by TAK1 as well as by p38 MAPK in intact cells as well as in vitro. Serines 452/453 and 456/457 were phosphorylated upon phosphatase blockade by calyculin A, or in response to IL-1 or translational stressors such as anisomycin and sorbitol. Deletion or phospho-mimetic mutations of aa 452-457 of TAB1 retain TAB1 and p38 MAPK in the cytoplasm. The TAB1 mutant lacking aa 452-457 decreases TAB1-dependent phosphorylation of p38 MAPK. It also enhances TAB1-dependent CCL5 secretion in response to IL-1 and increases activity of a post-transcriptional reporter gene, which contains the CCL5 3' untranslated region. These data suggest a complex role of aa 452-457 of TAB1 in controlling p38 MAPK activity and subcellular localization and implicate these residues in TAK1- or p38 MAPK-dependent post-transcriptional control of gene expression.
Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, Giessen, Germany.
Alexander
A
Wolf
Knut
K
Beuerlein
Christoph
C
Eckart
Hendrik
H
Weiser
Beate
B
Dickkopf
Helmut
H
Müller
Hiroaki
H
Sakurai
Michael
M
Kracht
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D012323:RNA Processing, Post-Transcriptional; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological; D054875:Ubiquitination; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; C099510:TAB1 protein, MAPKKK activator, vertebrate; D048051:p38 Mitogen-Activated Protein Kinases