Lacruz, R. | bioRxiv Science

bioRxiv2025

Age-Related Decline in NCKX4-Mediated Calcium Clearance Accelerates Aortic Remodeling and Drives Early Vascular Aging

Aging is the primary nonmodifiable 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 (Ca2+) handling are recognized as central contributors to arterial stiffening and calcification. However, the molecular and functional determinants of Ca2+ clearance in vascular aging remains a topic of ongoing research. We identify the (Na+)-sodium/Ca2+-calcium (K+)-potassium-dependent exchanger 4 (NCKX4) as a critical functional regulator of VSMCs Ca{superscript 2} clearance and vascular integrity. We demonstrate that NCKX4 (coded by Slc24A4) expression is markedly reduced in aorta of aged (72-78 weeks) mice, with a pronounced decline in females. Functional assays revealed impaired Ca2+ clearance in both aged and Nckx4-/- VSMCs, which was accompanied by increased calcification. Histomorphometric analyses of young Nckx4-/- mice revealed fragmentation of elastic fibers, collagen accumulation, wall thickening, and extracellular matrix (ECM) remodeling, all hallmarks of vascular aging that closely resembled those of aged wild-type mice. Transcriptomic profiling of VSMCs showed that loss of NCKX4 alters pathways linked to Ca2+-integrin signaling, ECM turnover, and mineralization, including dysregulation of protective anchorage integrins, microfibril-stabilizing, osteogenic drivers and pro-fibrotic integrins. These findings support a model in which impaired Ca2+ clearance promotes maladaptive inside-out integrin signaling, disrupting VSMCs anchorage, ECM homeostasis, and mineralization processes. Collectively, our results establish NCKX4 as a previously unrecognized determinant of vascular aging, whose decline accelerates premature arterial remodeling and calcification. This study positions NCKX4 as a potential mechanistic link between age, sex-dependent vulnerability, and vascular stiffening, with implications for novel therapeutic strategies targeting Ca2+ handling in CVDs prevention.

cell biology↗

bioRxiv2024

Machine Learning Approach to Single Cell Transcriptomic Analysis of Sjogren's Disease Reveals Altered Activation States of B and T Lymphocytes

Sjogrens Disease (SjD) is an autoimmune disorder characterized by salivary and lacrimal gland dysfunction and immune cell infiltration leading to gland inflammation and destruction. Although SjD is a common disease, its pathogenesis is not fully understood. In this study, we conducted a single-cell transcriptome analysis of peripheral blood mononuclear cells (PBMC) from patients with SjD and symptomatic non-SjD controls to identify cell types and functional changes involved in SjD pathogenesis. All PBMC populations showed marked differences in gene expression between SjD patients and controls, particularly an increase in interferon (IFN) signaling gene signatures. T and B cells of SjD patients displayed a depletion of ribosomal gene expression and pathways linked to protein translation. SjD patients had increased frequencies of naive B cells, which featured a unique gene expression profile (GEP) distinct from controls and had hallmarks of B cell hyperactivation. Non-negative matrix factorization (NMF) also identified several non-overlapping GEPs in CD4+ and CD8+ T cells with differential usage in SjD patients and controls. Of these, only the Th1 activation GEP was enriched in T cells of SjD patients whereas the other two GEPs were depleted in T cells, emphasizing the important role of Th1 cells in SjD. Our study provides evidence for aberrant and unique gene expression patterns in both B and T lymphocytes of SjD patients that point to their altered activation states and may provide new insights into the pathogenesis of SjD.

immunology↗