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J Biol Chem. 2002 Dec 20;277(51):49212-9. Epub 2002 Oct 4.

Beta-arrestin2 is critically involved in CXCR4-mediated chemotaxis, and this is mediated by its enhancement of p38 MAPK activation.

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Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, People's Republic of China.


Chemotaxis mediated by chemokine receptors such as CXCR4 plays a key role in lymphocyte homing and hematopoiesis as well as in breast cancer metastasis. We have demonstrated previously that beta-arrestin2 functions to attenuate CXCR4-mediated G protein activation and to enhance CXCR4 internalization. Here we show further that the expression of beta-arrestin2 in both HeLa and human embryonic kidney 293 cells significantly enhances the chemotactic efficacy of stromal cell-derived factor 1alpha, the specific agonist of CXCR4, whereas the suppression of beta-arrestin2 endogenous expression by antisense or RNA-mediated interference technology considerably attenuates stromal cell-derived factor 1alpha-induced cell migration. Expression of beta-arrestin2 also augmented chemokine receptor CCR5-mediated but not epidermal growth factor receptor-mediated chemotaxis, indicating the specific effect of beta-arrestin2. Further analysis reveals that expression of beta-arrestin2 strengthened CXCR4-mediated activation of both p38 MAPK and ERK, and the suppression of beta-arrestin2 expression blocked the activation of two kinases. Interestingly, inhibition of p38 MAPK activation (but not ERK activation) by its inhibitors or by expression of a dominant-negative mutant of p38 MAPK effectively blocked the chemotactic effect of beta-arrestin2. Expression of a dominant-negative mutant of ASK1 also exerted the similar blocking effect. The results of our study suggest that beta-arrestin2 can function not only as a regulator of CXCR4 signaling but also as a mediator of stromal cell-derived factor 1alpha-induced chemotaxis and that this activity probably occurs via the ASK1/p38 MAPK pathway.

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