Agonist stimulation, talin-1, and kindlin-3 are crucial for α(IIb)β(3) activation in a human megakaryoblastic cell line, CMK
In: Experimental hematology, Jg. 41 (2012-08-20), Heft 1
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Zugriff:
Platelet integrin α IIb β 3 activation is regulated by inside-out signaling via agonist stimulation. However, when α IIb β 3 was exogenously expressed in cell lines such as Chinese hamster ovarian cells, physiological agonists hardly induced α IIb β 3 activation. To overcome this disadvantage, we characterized the functional regulation of endogenously expressed α IIb β 3 in a megakaryoblastic cell line, CMK, employing an initial velocity assay for PAC-1 binding. We firstly demonstrated that protease-activated receptor 1-activating peptide induced robust, but transient α IIb β 3 activation in CMK cells with high glycoprotein-Ib expression. Stable talin-1 or kindlin-3 knockdown cells confirmed that the protease-activated receptor 1-activating peptide–induced α IIb β 3 activation was dependent on talin-1 and kindlin-3 expression. In sharp contrast to exogenously expressed α IIb β 3 in Chinese hamster ovarian cells, transient overexpression of full-length talin (FL-talin) or talin-head domain (THD) alone did not activate α IIb β 3 in CMK cells, but required agonist stimulation. Similarly, kindlin-3 overexpression alone did not induce α IIb β 3 activation, but it significantly augmented agonist-induced α IIb β 3 activation. Several mutants of FL-talin and THD suggested that the head–rod interaction was critical for autoinhibition of talin-1, and the interaction between the THD and the membrane-proximal region of the β 3 cytoplasmic tail was essential for talin-mediated α IIb β 3 activation. In addition, THD and kindlin-3 cooperatively augmented protease-activated receptor 1–induced α IIb β 3 activation. We proposed that the CMK cell line is an attractive platform for investigating agonist-, talin-1-, and kindlin-3- dependent α IIb β 3 activation.
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Agonist stimulation, talin-1, and kindlin-3 are crucial for α(IIb)β(3) activation in a human megakaryoblastic cell line, CMK
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Autor/in / Beteiligte Person: | Kanakura, Yuzuru ; Nakazawa, Tsuyoshi ; Kamae, Tsuyoshi ; Kashiwagi, Hirokazu ; Tadokoro, Seiji ; Tomiyama, Yoshiaki ; Honda, Shigenori ; Kiyomizu, Kazunobu |
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Zeitschrift: | Experimental hematology, Jg. 41 (2012-08-20), Heft 1 |
Veröffentlichung: | 2012 |
Medientyp: | unknown |
ISSN: | 1873-2399 (print) |
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