INTRODUCTIONADP-stimulated elevation of cytosolic Ca²⁺ is an important effector mechanism for platelet activation. The rapidly elevating cytosolic Ca²⁺ is also transported to mitochondrial matrix via Mitochondrial Ca²⁺ Uniporter (MCU) and extruded via Na⁺/Ca²⁺/Li⁺ Exchanger (NCLX). However, the exact contribution of MCU and NCLX in ADP-mediated platelet responses remains incompletely understood.METHODS AND RESULTSThe present study aimed to elucidate the role of mitochondrial Ca²⁺ transport in ADP-stimulated platelet responses by inhibition of MCU and NCLX with mitoxantrone (MTX) and CGP37157 (CGP), respectively. As these inhibitory strategies are reported to cause distinct effects on matrix Ca²⁺ concentration, we hypothesized to observe opposite impact of MTX and CGP on ADP-induced platelet responses. Platelet aggregation profiling was performed by microplate-based spectrophotometery while p-selectin externalization and integrin αIIbβ3 activation were analyzed by fluorescent immunolabeling using flow cytometery. Our results confirmed the expression of both MCU and NCLX mRNAs with relatively low abundance of NCLX in human platelets. In line with our hypothesis, MTX caused a dose-dependent inhibition of ADP-induced platelet aggregation without displaying any cytotoxicity. Likewise, ADP-induced p-selectin externalization and integrin αIIbβ3 activation was also significantly attenuated in MTX-treated platelets. Concordantly, inhibition of NCLX with CGP yielded an accelerated ADP-stimulated platelet aggregation which was associated with an elevation of p-selectin surface expression and αIIbβ3 activation.CONCLUSIONTogether, these findings uncover a vital and hitherto poorly characterized role of mitochondrial Ca²⁺ transporters in ADP-induced platelet activation.

2024-11-01·Hypertension

Dysregulated Mitochondrial Calcium Causes Spiral Artery Remodeling Failure in Preeclampsia

Article

作者: Zhang, Ning ; Feng, Xueqing ; Lu, Xiyuan ; Xu, Zhice ; Wang, Yuehong ; Geng, Na ; Wang, Yifan ; Pu, Jun ; Zou, Zhiguo

BACKGROUND: Calcium deficiency in women is strongly linked to an increased risk of developing preeclampsia. Mitochondrial calcium ([Ca 2+ ] m ) homeostasis is essential to regulate vascular smooth muscle cell (VSMC) function. However, the role of [Ca 2+ ] m in preeclampsia development remains largely unknown. METHODS: To investigate this, human spiral arteries obtained from normotensive and preeclamptic women were collected for vascular function, RNA sequencing, and VSMC studies. N(ω)-nitro-L-arginine methyl ester–induced preeclampsia animal experiments were established to investigate the effects of intervening in [Ca 2+ ] m to improve the outcome for preeclamptic mothers or their infants. RESULTS: Our initial findings revealed compromised vessel function in spiral arteries derived from patients with preeclampsia, as evidenced by diminished vasoconstriction and vasodilation responses to angiotensin II and sodium nitroprusside, respectively. Moreover, the spiral artery VSMCs from patients with preeclampsia exhibited phenotypic transformation and proliferation associated with the disrupted regulatory mechanisms of [Ca 2+ ] m uptake. Subsequent in vitro experiments employing gain- and loss-of-function approaches demonstrated that the mitochondrial Na + /Ca 2+ exchanger played a role in promoting phenotypic switching and impaired mitochondrial functions in VSMCs. Furthermore, mtNCLX (mitochondrial Na + /Ca 2+ exchanger) inhibitor CGP37157 significantly improved VSMC phenotypic changes and restored mitochondrial function in both patients with preeclampsia–derived VSMCs and the preeclampsia rat model. CONCLUSIONS: This study provides comprehensive evidence supporting the disrupted regulatory mechanisms of [Ca 2+ ] m uptake in VSMCs of spiral arteries of patients with preeclampsia and further elucidates its correlation with VSMC phenotypic switching and defective spiral artery remodeling. The findings suggest that targeting mtNCLX holds promise as a novel therapeutic approach for managing preeclampsia.

2024-02-15·The FASEB Journal

Mitochondrial sodium/calcium exchanger (NCLX) regulates basal and starvation‐induced autophagy through calcium signaling

Article

作者: Ramos, Vitor M ; Kowaltowski, Alicia J ; Cunha, Fernanda M ; Korolchuk, Viktor I ; Kataura, Tetsushi ; Vilas-Boas, Eloisa A ; Serna, Julian D C ; Cabral-Costa, João Victor

AbstractMitochondria shape intracellular Ca2+ signaling through the concerted activity of Ca2+ uptake via mitochondrial calcium uniporters and efflux by Na+/Ca2+ exchangers (NCLX). Here, we describe a novel relationship among NCLX, intracellular Ca2+, and autophagic activity. Conditions that stimulate autophagy in vivo and in vitro, such as caloric restriction and nutrient deprivation, upregulate NCLX expression in hepatic tissue and cells. Conversely, knockdown of NCLX impairs basal and starvation‐induced autophagy. Similarly, acute inhibition of NCLX activity by CGP 37157 affects bulk and endoplasmic reticulum autophagy (ER‐phagy) without significant impacts on mitophagy. Mechanistically, CGP 37157 inhibited the formation of FIP200 puncta and downstream autophagosome biogenesis. Inhibition of NCLX caused decreased cytosolic Ca2+ levels, and intracellular Ca2+ chelation similarly suppressed autophagy. Furthermore, chelation did not exhibit an additive effect on NCLX inhibition of autophagy, demonstrating that mitochondrial Ca2+ efflux regulates autophagy through the modulation of Ca2+ signaling. Collectively, our results show that the mitochondrial Ca2+ extrusion pathway through NCLX is an important regulatory node linking nutrient restriction and autophagy regulation.

100 项与 CGP-37157 相关的药物交易

登录后查看更多信息