CGP-37157

ADP-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.

The 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.

Together, these findings uncover a vital and hitherto poorly characterized role of mitochondrial Ca²⁺ transporters in ADP-induced platelet activation.

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.

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.

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.

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.