THROMBOSIS AND HEMOSTASIS Integrin-linked kinase associated with integrin activation
نویسندگان
چکیده
Platelet integrin IIb 3 activation is tightly controlled by intracellular signaling pathways, and several molecules, including talin, have been identified as critical for IIb 3 activation. However, the whole pathway associated with IIb 3 activation remains to be determined. To address this issue, we established a Chinese hamster ovary cell line (parental cells) that expresses constitutively activated chimeric integrin IIb 6B 3, and then obtained mutant cells expressing inactivated IIb 6B 3 by genome-wide mutagenesis. We have performed expression cloning to isolate signaling molecules responsible for integrin activation in the mutant cells. We show that integrinlinked kinase (ILK) complements defective integrin activation in the mutant cells. ILK mRNAs in the mutant cells contained 2 nonsense mutations, R317X and W383X, in a compound heterozygous state, resulting in a complete loss of ILK expression. Moreover, the mutant cells showed partially impaired activation of endogenous 1 integrins. Knockdown of ILK in parental cells significantly suppressed the activated state of IIb 6B 3. However, ILK overexpression did not rescue the impaired integrin activation in talin knockeddown parental cells, whereas overexpression of talin-F3, a subdomain of the talin head domain, restored the function. Our present data suggest that ILK contributes to inside-out integrin activation. (Blood. 2009;113:5304-5313)
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