The effect of zinc supplementation on fatigue among elderly community dwellers: A parallel clinical trial

Calcium's Role and Signaling in Aging Muscle, Cellular Senescence, and Mineral Interactions

Calcium research, since its pivotal discovery in the early 1800s through the heating of limestone, has led to the identification of its multi-functional roles. These include its functions as a reducing agent in chemical processes, structural properties in shells and bones, and significant role in cells relating to this review: cellular signaling. Calcium signaling involves the movement of calcium ions within or between cells, which can affect the electrochemical gradients between intra- and extracellular membranes, ligand binding, enzyme activity, and other mechanisms that determine cell fate. Calcium signaling in muscle, as elucidated by the sliding filament model, plays a significant role in muscle contraction. However, as organisms age, alterations occur within muscle tissue. These changes include sarcopenia, loss of neuromuscular junctions, and changes in mineral concentration, all of which have implications for calcium's role. Additionally, a field of study that has gained recent attention, cellular senescence, is associated with aging and disturbed calcium homeostasis, and is thought to affect sarcopenia progression. Changes seen in calcium upon aging may also be influenced by its crosstalk with other minerals such as iron and zinc. This review investigates the role of calcium signaling in aging muscle and cellular senescence. We also aim to elucidate the interactions among calcium, iron, and zinc across various cells and conditions, ultimately deepening our understanding of calcium signaling in muscle aging.

Zinc supplementation prevents mitotic accumulation in human keratinocyte cell lines upon environmentally relevant arsenic exposure

Disrupted cell cycle progression underlies the molecular pathogenesis of multiple diseases. Chronic exposure to inorganic arsenic (iAs) is a global health issue leading to multi-organ cancerous and non-cancerous diseases. Exposure to supratherapeutic concentrations of iAs causes cellular accumulation in G2 or M phase of the cell cycle in multiple cell lines by inducing cyclin B1 expression. It is not clear if iAs exposure at doses corresponding to serum levels of chronically exposed populations (∼100 nM) has any effect on cell cycle distribution. In the present study we investigated if environmentally relevant iAs exposure induced cell cycle disruption and mechanisms thereof employing two human keratinocyte cell lines (HaCaT and Ker-CT), flow cytometry, immunoblots and quantitative real-time PCR (qRT-PCR). iAs exposure (100 nM; 24 h) led to mitotic accumulation of cells in both cell lines, along with the stabilization of ANAPC11 ubiquitination targets cyclin B1 and securin, without affecting their steady state mRNA levels. This result suggested that induction of cyclin B1 and securin is modulated at the level of protein degradation. Moreover, zinc supplementation successfully prevented iAs-induced mitotic accumulation and stabilization of cyclin B1 and securin without affecting their mRNA levels. Together, these data suggest that environmentally relevant iAs exposure leads to mitotic accumulation possibly by displacing zinc from the RING finger subunit of anaphase promoting complex/cyclosome (ANAPC11), the cell cycle regulating E3 ubiquitin ligase. This early cell cycle disruptive effect of environmentally relevant iAs concentration could underpin the molecular pathogenesis of multiple diseases associated with chronic iAs exposure.