Marija Ljubojević

Zinc is an essential micronutrient involved in structural, catalytic, and regulatory functions across all levels of biological organization. Despite substantial advances over the past two decades, the zinc literature remains highly fragmented, with mechanistic, nutritional, and clinical findings often reported in isolation. Additionally, the synergistic interactions between zinc and other micronutrients—particularly minerals and vitamins—are dispersed across multiple research domains, complicating efforts to understand their integrated roles in maintaining homeostasis. Recent developments in artificial intelligence (AI) present new opportunities to consolidate these data, enabling multi-scale analyses of zinc-dependent processes and the broader zinc interactome. Although a complete map of the zinc interactome is not yet feasible, an integrative perspective is needed to contextualize zinc’s contributions within the framework of the hallmarks of health. This narrative review highlights zinc’s involvement in cellular maintenance, metabolic regulation, stress response, and systemic physiological function. It further examines how disruptions in zinc status, alone or in combination with other nutrient imbalances, contribute to clinically relevant disorders. By combining current knowledge across molecular, cellular, and systems biology levels, this review illustrates zinc’s pleiotropic effects on physiological resilience and healthspan, with particular emphasis on its role in nutritional status, homeostatic regulation, and overall human health.

The anti-aging gene/protein Klotho (Kl), most present in kidneys, has been well studied in mice (mKl), but not in rats (rKl). This study investigated the renal rKl expression in male and female rats. Sex-related measurement of rKl-controlled electrolytes was performed in plasma/urine samples, as were tests on species differences in renal Kl expression (rats vs. mice). rKl mRNA/protein expression was studied by qRT-PCR/Western-blotting in renal total RNA/cell membranes and its localization by immunofluorescence microscopy. Urine/plasma ions (phosphate/total calcium) and macroelements (phosphorus/calcium) were measured biochemically and by ICP-MS, respectively. In rat kidneys, the rKl mRNA/protein was detected in the cortex, outer and inner stripe but not in the papilla, and was immunolocalized in the basolateral membrane of proximal tubules in the cortex and outer stripe, but not in the intercalating cells of the cortical distal tubules, whereas mKl was observed in the mouse kidney cortex but not the outer stripe. Female-dominant expression of renal rKl, affected by androgen’s inhibitory effect, may have contributed to the sex-related level of urine electrolytes, particularly phosphates. Renal mKl expression was male-dominant. Sex- and species-related differences in renal Kl expression may be relevant for the selection of the sex and/or the model organism in studies addressing aging/mineral homeostasis.

Background: Given the growing challenges posed by an ageing population, particularly in Western countries, we aimed to investigate the potential geroprotective effects of resveratrol and melatonin in ageing rats. Methods: The animals were treated with these two compounds starting at 3 months of age and continuing until 1 year or 2 years of age. Using a multibiomarker approach, we assessed DNA damage, telomere length, and the oxidative status in their urine, liver, and kidneys. Results: Despite employing this experimental approach, our results did not provide conclusive evidence of geroprotective effects across the evaluated organs. However, we observed sex-dependent differences in response to treatment. Conclusions: Given the high potency of these two compounds, further research is warranted to explore their incorporation into daily routines as a strategy to mitigate ageing-related effects.

Ferritin is the main intracellular storage of iron. Animal studies show that female liver and kidney express more ferritin and accumulate more iron than male. However, no study so far has investigated sex and age differences in light (FtL) and heavy (FtH) ferritin chain expression. To address this, we relied on specific antibodies and immunochemical methods to analyse the expression of both ferritin chains in the liver and kidney of 3-month and 2-year-old male and female Wistar rats. To see how sex hormones may affect expression we also studied adult animals gonadectomised at the age of 10 weeks. FtL and FtH were more expressed in both organs of female rats, while gonadectomy increased the expression in males and decreased it in females, which suggests that it is stimulated by female and inhibited by male steroid hormones. Normal kidney ferritin distribution and change with aging warrant more attention in studies of (patho) physiological and toxicological processes.

Metallothioneins are peculiar cysteine rich, heat resistant, small cellular plasma proteins expressed through almost all life forms. The currently established biological functions of metallothioneins are the homeostasis of essential metals and protection against toxic transitional metals (TM) alongside defence from oxidative stress by direct scavenging of reactive oxygen and nitrogen species (ROS and RNS). In mammals, among the four main evolutionary conserved forms, only the ubiquitously expressed metallothionein 1 and 2 (here abbreviated as MT) are inducible by TM, oxidative stress, glucocorticoids and starvation among various other stimuli. However, more than sixty years after being discovered, metallothioneins still bear unresolved issues about their possible physiological function and regulation. The biological function of MTs has still not been associated with the in vitro -demonstrated capacity of MT interaction with cellular molecules glutathione (GSH) or adenosine triphosphate (ATP), or with the possibility of direct iron-MT binding in the reducing intracellular environment of some organelles, e.g. lysosomes. Iron as the most abundant cellular TM is also one of the main physiological sources of ROS. Moreover, iron exhibits strain, sex and age differences that reflected ROS generation and MT induction in (patho)physiology and toxicology studies. A recent study showed that iron sex differences follows expression of both ferritin and MT leading to wide implications from essential TM interconnectivity to aging. This review places emphasis on biochemically proven but physiologically ignored interactions of MT with iron to stimulate advanced research for establishing a wide frame of the biological roles of MTs important for health and longevity.