Ca2+-independent activation of Bruton's tyrosine kinase is required for store-mediated Ca2+ entry in human platelets

Redondo, Pedro C.; Amor, Nidhal Ben; Salido, Ginés M.; Bartegi, Aghleb; Pariente, José A.; Rosado, Juan A.

doi:10.1016/j.cellsig.2004.11.019

Cited by 51 publications

(47 citation statements)

References 33 publications

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“…AA-evoked Ca 2ϩ influx was measured as the integral of ⌬F 340 /F 380 above basal for 3 min after the addition of the agonist in the presence of external Ca 2ϩ . Immunoprecipitation and Western Blotting-The immunoprecipitation and Western blotting were performed as described previously (12). Briefly, 500-l aliquots of cell suspension (4 ϫ 10 6 cell/ml) were lysed with an equal volume of 2ϫ Nonidet P-40 buffer, pH 8, containing 274 mM NaCl, 40 mM Tris, 4 mM EDTA, 20% glycerol, 2% Nonidet P-40, 2 mM Na 3 VO 4 , and complete EDTA-free protease inhibitor tablets.…”

Section: Methodsmentioning

confidence: 99%

Store-operated Ca2+ Entry-associated Regulatory factor (SARAF) Plays an Important Role in the Regulation of Arachidonate-regulated Ca2+ (ARC) Channels

Albarrán

López

Woodard

et al. 2016

Journal of Biological Chemistry

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The store-operated Ca 2؉ entry-associated regulatory factor (SARAF) has recently been identified as a STIM1 regulatory protein that facilitates slow Ca 2؉ -dependent inactivation of store-operated Ca 2؉ entry (SOCE). Both the store-operated channels and the store-independent arachidonate-regulated Ca 2؉ (ARC) channels are regulated by STIM1. In the present study, we show that, in addition to its location in the endoplasmic reticulum, SARAF is constitutively expressed in the plasma membrane, where it can interact with plasma membrane (PM)-resident ARC forming subunits in the neuroblastoma cell line SH-SY5Y. Using siRNA-based and overexpression approaches we report that SARAF negatively regulates store-independent Ca 2؉ entry via the ARC channels. Arachidonic acid (AA) increases the association of PM-resident SARAF with Orai1. Finally, our results indicate that SARAF modulates the ability of AA to promote cell survival in neuroblastoma cells. In addition to revealing new insight into the biology of ARC channels in neuroblastoma cells, these findings provide evidence for an unprecedented location of SARAF in the plasma membrane.

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Section: Methodsmentioning

confidence: 99%

Store-operated Ca2+ Entry-associated Regulatory factor (SARAF) Plays an Important Role in the Regulation of Arachidonate-regulated Ca2+ (ARC) Channels

Albarrán

López

Woodard

et al. 2016

Journal of Biological Chemistry

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“…We previously have shown that Btk inhibition reduced Ca 2ϩ entry evoked following thrombin-evoked Ca 2ϩ store depletion. 45 Here we found that Btk inhibition increased the latency of thrombinevoked Ca 2ϩ entry as assessed by Mn 2ϩ quench of fura-2 fluorescence. These alterations in the activation of Ca 2ϩ entry following Btk inhibition might be explained by a failure of SOCE activation by de novo conformational coupling when actin depolymerization is inhibited.…”

Section: Discussionmentioning

confidence: 83%

“…Pretreatment of platelets for 10 minutes with 10 M LFM-A13, which we have previously shown abolishes Btk activation, 45 inhibited the early cofilin dephosphorylation and the actin depolymerization evoked by thrombin. Our results demonstrate that thrombin induced rapid Btk phosphorylation and activation, which is consistent with a role for Btk in the activation of cofilin and actin filament reorganization stimulated by thrombin.…”

Section: Discussionmentioning

confidence: 99%

“…Pretreatment of platelets for 10 minutes with 10 M LFM-A13, which abolishes Btk activation, 45 inhibited the thrombin-evoked dephosphorylation of cofilin detected in the first 1.5 seconds after stimulation with the agonist and enhanced thrombin-evoked cofilin phosphorylation as detected by Western blotting with an anti-phosphoSer 3 -cofilin antibody ( Figure 4; n ϭ 6). Consistent with this, treatment of the cells for 10 minutes with 10 M LFM-A13 abolished thrombin-evoked net actin depolymerization ( Figure 5).…”

Section: Time Course Of Actin Filament Reorganization and Cofilin Phomentioning

confidence: 99%

“…We recently have demonstrated the involvement of Bruton tyrosine kinase (Btk) in actin remodeling and SOCE in thapsigargin-treated human platelets. 45 Hence, we have investigated whether the role of Btk in SOCE might be mediated by cofilin and the regulation of actin reorganization. The activation of Btk was analyzed by Western blotting using a rabbit monoclonal phosphospecific anti-Btk antibody that only detects Btk autophosphorylated at the tyrosine residue 223, which has been shown to be the full activated form of Btk.…”

Section: Time Course Of Cofilin Phosphorylation Evoked By Thrombinmentioning

confidence: 99%

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A role for cofilin in the activation of store-operated calcium entry by de novo conformational coupling in human platelets

Redondo

Harper

Rosado

et al. 2006

Blood

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Store-operated Ca 2؉ entry (SOCE) is a major mechanism for Ca 2؉ influx in platelets and other cells. De novo conformational coupling between elements in the plasma membrane and Ca 2؉ stores, where the actin cytoskeleton plays an important regulatory role, has been proposed as the most likely mechanism to activate SOCE in platelets. Here we have examined for the first time changes in platelet F-actin levels on a subsecond time scale. Using stopped-flow fluorimetry and a quenchedflow approach, we provide evidence for the involvement of cofilin in actin filament reorganization and SOCE in platelets. Thrombin (0.1 U/mL) evoked an initial decrease in F-actin that commenced within 0.1 second and reached a minimum 0.9 second after stimulation, prior to the activation of SOCE. F-actin then increased, exceeding basal levels approximately 2.5 seconds after stimulation. Thrombin also induced cofilin dephosphorylation and activation, which paralleled the changes observed in F-actin, and rapid Btk activation. Inhibition of cofilin dephosphorylation by LFM-A13 resulted in the loss of net actin depolymerization and an increased delay in SOCE initiation. These results suggest that cofilin is important for the rapid actin remodeling necessary for the activation of SOCE in platelets through de novo conformational coupling. IntroductionIn nonexcitable cells such as platelets, store-operated calcium entry (SOCE), regulated by the filling state of the intracellular Ca 2ϩ stores, is a major mechanism for calcium influx. [1][2][3][4][5] Different models that have been presented to account for the activation of SOCE in distinct cell types can be grouped into 2 main categories that propose either indirect or direct coupling between the Ca 2ϩ stores and the plasma membrane (PM). Indirect coupling models assume the generation of a small diffusible molecule that operates as a Ca 2ϩ influx factor (CIF), so gating Ca 2ϩ channels in the PM. [6][7][8] On the other hand, direct or constitutive conformational coupling models propose a physical interaction between Ca 2ϩ channels in the PM and IP 3 receptors in the membrane of the intracellular Ca 2ϩ stores. 5,9 It also has been suggested that SOCE might be activated by the insertion of preformed channels into the PM by vesicle fusion in a secretion-like coupling model. 10,11 A modification of the constitutive conformational coupling model proposes a dynamic and reversible conformational coupling based on the transport of portions of the endoplasmic reticulum (ER) containing IP 3 receptors to the PM to facilitate de novo protein coupling. 9,[12][13][14] De novo conformational coupling requires a mechanical support provided by the actin cytoskeleton. 14 In addition, the cortical actin cytoskeleton plays a regulatory role by acting as a negative clamp that prevents constitutive coupling and activation of SOCE. 4,5,14,15 The de novo conformational coupling model requires that the cortical actin barrier be rapidly disrupted following cell stimulation to allow the coupling to occur. 9,12,16 Earlier d...

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Early caspase‐3 activation independent of apoptosis is required for cellular function

Rosado

López

Gómez-Arteta

et al. 2006

Journal Cellular Physiology

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A number of pro-apoptotic stimuli induce the activation of caspase-9, an initiator protease that activates executioner caspases, such as caspase-3, leading to the development of programmed cell death. Here we demonstrate that cell (platelets and pancreatic acinar cells) stimulation with agonists induces a bimodal activation of caspase-3. The early caspase-3 activation occurs within 1 min of stimulation and is independent on caspase-9 or mitochondrial cytochrome c release suggesting that is a non-apoptotic event. The ability of agonists to induce early activation of caspase-3 is similar to that observed for other physiological processes. Activation of caspase-3 by physiological concentrations of cellular agonists, including thrombin or CCK-8, is independent of rises in cytosolic calcium concentration but requires PKC activation, and is necessary for agonist-induced activation of the tyrosine kinases Btk and pp60src and for several cellular functions, including store-operated calcium entry, platelet aggregation, or pancreatic secretion. Thus, early activation of caspase-3 seems to be a non-apoptotic event required for cellular function.

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Ca2+-independent activation of Bruton's tyrosine kinase is required for store-mediated Ca2+ entry in human platelets

Cited by 51 publications

References 33 publications

Store-operated Ca2+ Entry-associated Regulatory factor (SARAF) Plays an Important Role in the Regulation of Arachidonate-regulated Ca2+ (ARC) Channels

Store-operated Ca2+ Entry-associated Regulatory factor (SARAF) Plays an Important Role in the Regulation of Arachidonate-regulated Ca2+ (ARC) Channels

A role for cofilin in the activation of store-operated calcium entry by de novo conformational coupling in human platelets

Early caspase‐3 activation independent of apoptosis is required for cellular function

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