Age‐related decline in NCKX4‐mediated calcium clearance accelerates aortic remodelling and drives early vascular ageing

Abstract Ageing is the primary non‐modifiable risk factor for cardiovascular diseases (CVDs), with older women facing a greater risk of CVDs than age‐matched men. Vascular smooth muscle cells (VSMCs) dysfunction and impaired calcium (Ca 2+ ) handling are recognized as central contributors to arterial stiffening and vascular calcification. However, the molecular and functional determinants of Ca 2+ clearance that drive vascular ageing remain poorly understood. We identify the ( N a + )‐sodium/ C a 2+ ‐calcium ( K + )‐potassium‐dependent e x changer 4 ( NCKX4 ) as a critical functional regulator of VSMC Ca 2+ clearance and vascular integrity. Expression of NCKX4 (encoded by Slc24A4 ) was significantly reduced in aortae from aged (72–78 weeks) mice. Aged‐related loss of NCKX4 impaired Ca 2+ clearance function and increased Ca 2+ ‐phosphate mineralization. Notably, young (12–15 weeks) Nckx4 −/− mice exhibited elastic fibre fragmentation, collagen accumulation, arterial wall thickening and extracellular matrix (ECM) remodelling, which are hallmarks of vascular ageing that closely resembled those observed in aged wild‐type mice. Transcriptomic profiling revealed that loss of NCKX4 alters pathways associated with Ca 2+ ‐integrin signalling, ECM turnover and mineralization, including dysregulation of anchorage integrins, microfibril‐stabilizing components, osteogenic drivers and profibrotic integrins. Collectively, these findings demonstrate that impaired Ca 2+ clearance promotes maladaptive inside‐out integrin signalling, disrupting VSMC anchorage, ECM homeostasis and mineralization. Our results establish NCKX4 as a previously unrecognized determinant of vascular ageing, and its decline accelerates premature arterial remodelling and calcification. This study positions NCKX4 as a mechanistic link between age‐dependent vascular vulnerability and arterial stiffening, with implications for novel therapeutic strategies targeting Ca 2+ handling to prevent CVDs. image Key points Dysfunctional calcium (Ca 2+ ) handling in vascular smooth muscle cells (VSMCs) increases susceptibility to cardiovascular diseases (CVDs), vascular calcification, stiffness and aortic remodelling. The K + ‐dependent Na + /Ca 2+ exchanger NCKX4 mediates high‐capacity Ca 2+ clearance extrusion, thereby maintaining VSMC Ca 2 + homeostasis. NCKX4 (encoded by Slc24a4 ) expression markedly declines in the aorta and VSMCs of aged (72–78 weeks) mice. Genetic deletion or age‐related loss of NCKX4 impairs Ca 2+ clearance, leading to enhanced VSMCs calcification, premature arterial remodelling through disruption of Ca 2+ ‐mediated integrin‐ECM signalling. NCKX4 is a newly identified mechanistic driver of vascular ageing and a potential therapeutic target for early detection, preservation of vascular integrity and mitigation of age‐related CVDs risk.