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Alon Margalit Avinoam A. Livne Jørgen Funder Yosef Granot 《The Journal of membrane biology》1993,136(3):303-311
Platelets revert hypotonic-induced swelling by the process of regulatory volume decrease (RVD). We have recently shown that this process is under the control of endogenous hepoxilin A3. In this work, we investigated the mechanical-biochemical transduction that leads to hepoxilin A3 formation. We demonstrate that this process is mediated by pertussis-toxin-sensitive G protein, which activates Ca2+-insensitive phospholipase A2, and the sequential release of arachidonic acid. This conclusion is supported by the following observations: (i) RVD response is blocked selectively by the phospholipase A2 inhibitors manoalide and bromophenacyl-bromide (0.2 and 5
m, respectively) but not by phospholipase C inhibitors. The addition of arachidonic acid overcame this inhibition; (ii) extracellular Ca2+ depletion by EGTA (up to 10 mm) does not affect RVD; (iii) intracellular Ca2+ depletion by BAPTAAM (100
m) inhibits RVD but not hepoxilin A3 formation, as tested by the RVD reconstitution assay; (iv) RVD is inhibited by the G-protein inhibitors, GDP
S (1
m) and pertussis toxin (1 ng/ml). This inhibition is overcome by addition of arachidonic acid or hypotonic cell-free eluate that contains hepoxilin A3; (v) NaF, 1 mm, induces hepoxilin A3 formation, tested by the RVD reconstitution assay; and (vii) GDP
S inhibits hepoxilin A3 formation associated with flow. Therefore, it seems that G proteins are involved in the initial step of the mechanical-biochemical transduction leading to hepoxilin A3 formation in human platelets.DeceasedThis work is dedicated to the memory of Prof. A.A. Livne. It was carried out at the Amelia (Mimi) Rose Laboratory for Cellular Signal Transduction at the Department of Life Sciences, Ben-Gurion University of the Negev. We thank A. Dannon for helpful discussion. 相似文献
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Misael Neri Dionisio-Vicuña Tania Yareli Gutiérrez-López Sendi Rafael Adame-García José Vázquez-Prado Guadalupe Reyes-Cruz 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2018,1865(7):1012-1022
The mitotic spindle is a dynamic macromolecular complex essential for chromosome segregation. ESCRT (endosomal sorting complexes required for transport) proteins are emerging as relevant mitotic players putatively recruiting spindle organizers. Here, we describe that VPS28, an ESCRT-I component, directly interacts with Gβγ, a signaling heterodimer with documented impact on microtubule dynamics, composing a novel organizer of the mitotic spindle aster. We found that VPS28 localizes to mitotic microtubules where it recruits Gβγ. Reducing VPS28 expression impairs kinesin Eg5 and TPX2 localization to the mitotic spindle. The interaction between VPS28 and Gβγ involves the carboxyl-terminal region of VPS28, which usually interacts with VPS36, its regular partner at multivesicular bodies. The VPS28-Gβγ complex is better constituted in the presence of Gα independently of G protein coupled receptor-stimulation, suggesting an intrinsic mechanism of regulation by which this novel complex contributes to mitotic spindle organization in mammalian cells. 相似文献
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