Trihydrophobin 1 Interacts with PAK1 and Regulates ERK/MAPK Activation and Cell Migration.

Authors:
Dr. Chunming Cheng, PhD
Dr. Chunming Cheng, PhD
The Ohio State University
Senior Research Associate
biochemistry
Columbus, OH | United States

J Biol Chem 2009 Mar 9;284(13):8786-96. Epub 2009 Jan 9.

Gene Research Center, Shanghai Medical College, and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China.

The Rac1/Cdc42 effector, p21-activated kinase (PAK), is activated by various signaling cascades, including receptor-tyrosine kinases and integrins, and regulates a number of processes such as cell proliferation and motility. PAK activity has been shown to be required for maximal activation of the canonical RAF-MEK-MAPK signaling cascade, possibly because of PAK co-activation of RAF and MEK. Here we have shown that trihydrophobin 1 (TH1), originally identified as a negative regulator of A-RAF kinase, also interacted with PAK1 in cultured cells. Confocal microscopy assay indicated that TH1 colocalized with PAK1 in both the cytoplasm and nucleus, which is consistent with our previous results. GST pulldown and coimmunoprecipitation experiments demonstrated that TH1 interacted directly with PAK1 and bound selectively to the carboxyl-terminal kinase domain of PAK1, and the ability of the binding was enhanced along with activation of PAK1. The binding pattern of PAK1 implies that this interaction was mediated in part by PAK1 kinase activity. As indicated by in vitro kinase activity assays and Western blot detections, TH1 inhibited PAK1 kinase activity and negatively regulated MAPK signal transduction. Interestingly, TH1 bound with MEK1/ERK in cells and in vitro without directly suppressing their kinase activity. Furthermore, we observed that TH1 localized to focal adhesions and filopodia in the leading edge of cells, where TH1 reduced cell migration through affecting actin and adhesion dynamics. Based on these observations, we propose a model in which TH1 interacts with PAK1 and specifically restricts the activation of MAPK modules through the upstream region of the MAPK pathway, thereby influencing cell migration.

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M806144200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2659237PMC
March 2009
83 Reads
6.140 Impact Factor

Publication Analysis

Top Keywords

kinase activity
16
cell migration
12
pak1
10
th1
8
pak1 kinase
8
interacts pak1
8
kinase
7
activity
5
th1 bound
4
cytoplasm nucleus
4
pak1 cytoplasm
4
bound mek1/erk
4
mek1/erk cells
4
th1 colocalized
4
colocalized pak1
4
interestingly th1
4
nucleus consistent
4
mapk signal
4
gst pulldown
4
previous gst
4

References

(Supplied by CrossRef)

Similar Publications