Biology subjects

Asam, K.

Publications and source records attributed to Asam, K..

3 recordsLinked to original sources

bioRxiv2026

A single-nucleus multiome analysis of transcriptome and chromatin accessibility reveals cell-type-specific immune modulation for chronic cannabis use among people with HIV infection

As cannabis use continues to rise among people with HIV (PWH), understanding its impact on immune function in this population is becoming increasingly important. To provide new insights on how cannabis modulates immune function, we analyzed single-nucleus multi-omic profiles of peripheral blood mononuclear cells (PBMCs) from PWH to characterize the changes in gene expression and chromatin accessibility associated with chronic cannabis exposure. We identified numerous differentially expressed genes (DEGs) between cannabis users and non-users in each cell type, approximately half of which were unique to individual cell types. Changes in pro- and anti-inflammatory gene expression associated with cannabis use are dependent on cell lineage and type. We identified hundreds of differential chromatin accessibility regions in each cell type, including cis-regulatory elements correlated with cell-type-dependent DEGs (e.g. NFKBIA in CD4+ T cells and CCL3L1 in classical monocytes). Multiple cannabis-associated transcription factors (e.g., NFKB1, FOS, and TCF7) emerge as regulators of the differentially expressed inflammatory genes. Furthermore, cannabis altered the communication between classical monocytes and lymphocytes. These findings indicate that cannabis-induced immunomodulatory effects are profound, dynamic and complex among cell types and that transcriptional changes are regulated at least in part by epigenetic mechanisms.

genomics↗

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↗

bioRxiv2025

PP2A METHYLESTERASE, PME-1, AND PP2A METHYLTRANSFERASE, LCMT-1, CONTROL SENSITIVITY TO IMPAIRMENTS CAUSED BY INJURY-RELATED OLIGOMERIC TAU

Oligomeric species of tau are a hallmark of multiple neurodegenerative diseases such as Alzheimers disease (AD) and chronic traumatic encephalopathy (CTE). Given the evidence implicating protein phosphatase 2A (PP2A) in the molecular pathogenesis of tau-related neurodegenerative disorders, we sought to determine whether manipulating the expression of enzymes that regulate PP2A activity, such as leucine carboxyl methyltransferase 1 (LCMT-1) and protein methyl esterase 1 (PME-1), might impact pathological responses to oligomeric tau. Here, we tested the effect of transgenic overexpression of LCMT-1 or PME-1 on cognitive and electrophysiological impairments caused by exposure to either recombinant oligomeric human tau or oligomeric tau prepared from mice subjected to blast-induced traumatic brain injury. We found that overexpression of LCMT-1 reduced sensitivity to tau-induced impairments, while overexpression of PME-1 increased sensitivity to these impairments. Moreover, we found that shockwave exposure increased the propensity of endogenous tau to form toxic oligomers. These results suggest that manipulating LCMT-1 or PME-1 activity may represent novel therapeutic approaches for disorders involving exposure to pathogenic forms of oligomeric tau.

neuroscience↗