Slc39a2-Mediated Zinc Homeostasis Modulates Innate Immune Signaling in Phenylephrine-Induced Cardiomyocyte Hypertrophy

Zinc dyshomeostasis has been involved in the pathogenesis of cardiac hypertrophy; however, the dynamic regulation of intracellular zinc and its downstream signaling in cardiac hypertrophy remain largely unknown. Using Zincpyr1 staining, we found a significant decrease of intracellular Zinc concentration in phenylephrine (PE)-induced hypertrophy of neonatal rat ventricular myocytes (NRVMs). We then screened SLC39 family members responsible for zinc uptake and identified Slc39a2 as the only one altered by PE treatment. Slc39a2 knockdown in NRVMs reduced the intracellular Zinc level, and exacerbated the hypertrophic responses to PE treatment. In contrast, adenovirus-mediated Slc39a2 overexpression enhanced zinc uptake and suppressed PE-induced Nppb expression. RNA sequencing analysis showed a pro-hypertrophic transcriptome reprogramming after Slc39a2 knockdown. Interestingly, the innate immune signaling pathways, including NOD signaling, TOLL-like receptor, NFκB, and IRFs, were remarkably enriched in the Slc39a2-regulated genes. Slc39a2 deficiency enhanced the phosphorylation of P65 NFκB and STAT3, and reduced the expression of IκBα. Finally, the expression of IRF7 was significantly increased by Slc39a2 knockdown, which was in turn suppressed by IRF7 knockdown. Our data demonstrate that zinc homeostasis mediated by a Slc39a2/IRF7 regulatory circuit contributes to the alteration of innate immune signaling in cardiomyocyte hypertrophy.

476 Effect of Holding Period on Viability, Acrosome Status and Intracellular Zinc of Boar Sperm During Liquid Storage

Sperm capacitation results in acrosomal remodeling, increased membrane fluidity, plasma membrane fusability and hyperactivated sperm. Distinct sperm zinc signatures reflect intracellular zinc content, capacitation status, and viability. Therefore, flow cytometric assessment could be a useful tool to evaluate sperm quality and longevity during liquid storage of boar semen. Cooled semen (17°C) from commercial boars (n = 12) were assessed at Day-1, -4 and -7 after collection for motility (IVOS II, Hamilton Thorne, Beverly, MA), intracellular zinc and viability. Samples were stained with 8 µg/mL Hoecsht-33342 (Hoe), 1 µM FluoZinTM-3-AM (Zinc), 10 µM propidium iodide (PI) and 5.6 µg/mL PNA-Alexa647TM (Molecular Probes, Eugene, OR), incubated for 30 min, washed with PBS, and aditionally incubated for 30 min. Acquisition and analysis of 20000 events were performed using Bio-Rad ZE5 Cell Analyzer (Hercules, CA) and FLowJoTM (Ashland, OR). Hoe+ events were gated into Zinc/PI plot to determine viable sperm with high Zinc (Zinc+/PI-). Likewise, Hoe+ events were gated into PI/PNA plot and then into Zinc histogram to detect viable-intact-acrosome with high Zinc (Zn+/PI-/PNA-). Data were analyzed by mixed model for repeated measures, Tukey-adjusted pairwise comparisons and Pearson’s correlation. Viable sperm at Day-1 (86.0±3.1; emmean±SM) and Day-4 (84.7±2.8) showed similar percentage of Zinc+ sperm, and both significantly higher compared to Day-7 (52.2±2.8). Also, viable-intact-acrosome sperm displayed similar percentage of Zinc+ sperm at Day-1 (93.8±3.4) and Day-4 (91.6±3.4) and both higher than sperm at Day-7 (64.5±3.1; P < 0.0001). Percentages of Zinc+ sperm were higher (P < 0.001) when viable sperm had intact acrosome within Day. Percentages of Zinc+ sperm strongly correlated to viable-intact-acrosome sperm (r=0.76, P < 0.0001) and total motility (r=0.65, P < 0.0001). We conclude that sperm having intact plasmatic membrane and acrosome display higher intracellular zinc content which is related to capacitated status, remaining non-capacitated until at least to Day-4 after collection in the tested extender.

Theoretical Three-Dimensional Zinc Complexes with Glutathione, Amino Acids and Flavonoids

Zinc plays an important role in the regulation of many cellular functions; it is a signaling molecule involved in the transduction of several cascades in response to intra and extracellular stimuli. Labile zinc is a small fraction of total intracellular zinc, that is loosely bound to proteins and is easily interchangeable. At the cellular level, several molecules can bind labile zinc and promote its passage across lipophilic membranes. Such molecules are known as ionophores. Several of these compounds are known in the scientific literature, but most of them can be harmful to human health and are therefore not allowed for medical use. We here performed a theoretical three-dimensional study of known zinc ionophores, together with a computational energetic study and propose that some dietary flavonoids, glutathione and amino acids could form zinc complexes and facilitate the transport of zinc, with the possible biological implications and potential health benefits of these natural compounds. The study is based on obtaining a molecular conformational structure of the zinc complexes with the lowest possible energy content. The discovery of novel substances that act as zinc ionophores is an attractive research topic that offers exciting opportunities in medicinal chemistry. We propose that these novel complexes could be promising candidates for drug design to provide new solutions for conditions and diseases related to zinc deficiency or impairment derived from the dysregulation of this important metal.

Pharmacological Properties of Zinc Drugs

The review represents data about biochemical and physiological zinc properties, its pharmacological influence. Among the trace elements, zinc is one of the most used elements in biology and medicine. Zinc preserves molecular integration, influences the growth and division of cells, is included in some enzymes. Metallothioneins bind zinc with high affinity and serve as intracellular zinc reservoir. They may release free intracellular zinc when needed and mediate physiological zinc role, maintain zinc homeostasis in brain synaptic activity. Metallothioneins are strong radical scavengers that is why zinc plays the main role in oxidative stress. It is intracellular regulator, which influences apoptosis, osteogenesis, keratogenesis, provides intracellular support to proteins during molecular integration. It is a structural component in nucleonic acids and gene regulator proteins. Zinc deficiency has been detected in neurological and psychic diseases. Zinc supplement was effective in patients with stroke and brain injury. Zinc has a positive impact on memory and reduces hyperactivity in children. Zinc is involved in signals neurotransmission. Its deficiency in brain is connected with Alzheimer`s disease, depression, schizophrenia that is why it is used for the treatment of these diseases. Vitamin C is the zinc synergist in the treatment of neurological and psychic diseases as it has antioxidant properties, takes place in detoxication. Zinc plays the important role in autistic disorders in children and is included in the pharmacotherapy of this status. Zinc deficiency leads to liver diseases, hepatitis, liver cirrhosis and gastrointestinal disturbances such as appetite loss, diarrhea, and anorexia. In chronic liver diseases, zinc corrects amino acids disbalance, capacity to synthesize albumin, metabolize ammonium. It was shown that zinc as a heavy metal has antimicrobial action in diarrheas, cholera and other gastrointestinal diseases. It was detected that zinc has antiviral effects in herpes diseases and diseases of upper respiratory ways. Conclusion. Zinc deficiency is connected with some autoimmune diseases such as asthma, eczema and other dermatological diseases. The supply of human organism with zinc and vitamins A, C, D and E is a promising approach because it is a cofactor of 118 proteins aimed at antiviral protection of the human body including interferon-1-dependent proteins against coronavirus. It was shown that zinc helps to inhibit «cytokine storm» characteristic of COVID-19, reduces chronic systemic inflammation and compensates for comorbid pathologies of cardiovascular system in patients with COVID-19. Zinc may influence other systems such as reproductive function, pregnancy, fetus, testosterone synthesis

ZIP7 Maintains Colon Cancer Radioresistance by Regulating Zinc-dependent Epithelial-mesenchymal Transition

Background: Irradiation-induced radioresistance often leads to the therapeutic failure of colon cancer. By regulating the redistribution of intracellular zinc, ZIP7 plays a dominating role in the activation of many critical signaling pathways in the progression of tumors. However, the relationship between ZIP7 and radioresistance is still unclear. Methods: ZIP7 expression of colon cancer was evaluated by analyzing public data from the GEPIA and CPTAC databases and validated based on immunohistochemistry (IHC) staining. Clonogenic survival assay was employed to examine the influence of intracellular zinc interference and ZIP7 knockdown on radioresistance of colon cancer, based on radioresistant colon cancer cells. At last, Western blot was performed to preliminarily explore the potential mechanisms. Results: ZIP7 was significantly upregulated in human colon cancers compared with adjacent normal tissues. ZIP7 knockdown could significantly reduce the radioresistance of colon cancer cells, while transmembrane ionophore of zinc could partially reverse this effect. In terms of mechanisms, ZIP7 knockdown significantly reversed the radiation-induced expression of elevated ZEB1 and down-regulated E-cadherin through regulating zinc. Conclusion: ZIP7 is crucial to maintain radioresistance of colon cancer cells through regulation of zinc distribution, and at least partially by maintenance of epithelial-mesenchymal transition (EMT).

Synaptic Zinc: An Emerging Player in Parkinson’s Disease

Alterations of zinc homeostasis have long been implicated in Parkinson’s disease (PD). Zinc plays a complex role as both deficiency and excess of intracellular zinc levels have been incriminated in the pathophysiology of the disease. Besides its role in multiple cellular functions, Zn2+ also acts as a synaptic transmitter in the brain. In the forebrain, subset of glutamatergic neurons, namely cortical neurons projecting to the striatum, use Zn2+ as a messenger alongside glutamate. Overactivation of the cortico-striatal glutamatergic system is a key feature contributing to the development of PD symptoms and dopaminergic neurotoxicity. Here, we will cover recent evidence implicating synaptic Zn2+ in the pathophysiology of PD and discuss its potential mechanisms of actions. Emphasis will be placed on the functional interaction between Zn2+ and glutamatergic NMDA receptors, the most extensively studied synaptic target of Zn2+.

Kupyaphores are counter regulatory zinc homeostatic metallophores required for Mycobacterium tuberculosis colonization

Tuberculosis (TB) patients suffer from progressive and debilitating loss of muscle mass and function, referred to as cachexia. Though a multifactorial condition, cachexia in cancer is promoted by systemic zinc redistribution and accumulation in muscles. Clinical studies with TB patients indeed show zinc dyshomeostasis. We therefore set out to understand mechanisms by which Mycobacterium tuberculosis (Mtb) govern zinc metallostasis at the host-pathogen interface. Here, we report a novel zinc metallophore from Mtb that restores zinc metabolic imbalance. These diisonitrile lipopeptides, named kupyaphores are transiently induced early-on during macrophage infection and also in infected mice lungs. Kupyaphores protects bacteria from host-mediated nutritional deprivation and intoxication. Kupyaphore Mtb mutant strain cannot mobilize zinc and shows reduced fitness in mice. Further, we characterize Mtb encoded isonitrile hydratase that could mediate intracellular zinc release through covalent modification of kupyaphores. Our studies could provide a molecular link between TB-induced altered zinc homeostasis and associated cachexia.