The expression of Wiskott-Aldrich syndrome protein (WASP) is dependent on WASP-interacting protein (WIP).
The Wiskott-Aldrich syndrome protein (WASP) is a key molecule for transduction of extracellular signals that induce a variety of critical biological events involving actin cytoskeleton rearrangement. Among the cellular partners of WASP, the Wiskott-Aldrich syndrome protein-interacting protein (WIP) has been speculated to play a critical role in the pathophysiology of Wiskott-Aldrich syndrome since WASP mutation hot spots map to the WIP-binding region. The notion that WIP promotes WASP function, however, conflicts with evidence that WIP inhibits WASP-mediated actin polymerization and IL-2 production and suggests a complex regulation of WASP function by WIP. Here we show that WASP gene transfer results in high WASP expression only when WIP is concomitantly expressed in K562 cells. Furthermore, WIP-knockdown experiments demonstrated that T cells with reduced WIP expression show a concordant reduction of WASP levels. Mapping studies using WIP mutants showed that the minimal WIP region able to rescue WASP expression in WIP-knockdown cells was the WASP-binding domain. However, expression of such a minimal domain of WIP failed to rescue WASP-dependent, nuclear factor of activated T-cells-mediated IL-2 transcriptional activity. These results demonstrate that expression of WIP is necessary for functional WASP expression in human cells and provide a new paradigm for understanding the function of these two molecules.
Konno
Akihiro
A
Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, 49 Convent Drive, Bethesday, MD 20892, USA.
Kirby
Martha
M
Anderson
Stacie A
SA
Schwartzberg
Pamela L
PL
Candotti
Fabio
F
D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003598:Cytoskeletal Proteins; D005434:Flow Cytometry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D051316:Wiskott-Aldrich Syndrome Protein / Q000096:biosynthesis*
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C109903:WIPF1 protein, human; D051316:Wiskott-Aldrich Syndrome Protein