A pair of transporters controls mitochondrial Zn2+ levels to maintain mitochondrial homeostasis

ZIF-8-based Nanoparticles for Inflammation Treatment and Oxidative Stress Reduction in Periodontitis

Periodontitis, an inflammatory bone resorption disease associated with dental plaque, poses significant challenges for effective treatment. In this study, we developed Mino@ZIF-8 nanoparticles inspired by the periodontal microenvironment and the unique properties of zeolitic imidazolate framework 8, aiming to address the complex pathogenesis of periodontitis. Transcriptome analysis revealed the active engagement of Mino@ZIF-8 nanoparticles in innate and adaptive inflammatory host defense and cellular metabolic remodeling. Through sustained release of the anti-inflammatory and antibacterial agent minocycline hydrochloride (Mino) and the generation of Zn2+ with pro-antioxidant effects during degradation, Mino@ZIF-8 nanoparticles synergistically alleviate inflammation and oxidative damage. Notably, our study focuses on the pivotal role of zinc ions in mitochondrial oxidation protection. Under lipopolysaccharide (LPS) stimulation, periodontal ligament cells undergo a metabolic shift from oxidative phosphorylation (OXPHOS) to glycolysis, leading to reduced ATP production and increased reactive oxygen species levels. However, Zn2+ effectively rebalances the glycolysis-OXPHOS imbalance, restoring cellular bioenergetics, mitigating oxidative damage, rescuing impaired mitochondria, and suppressing inflammatory cytokine production through modulation of the AKT/GSK3β/NRF2 pathway. This research not only presents a promising approach for periodontitis treatment but also offers novel therapeutic opportunities for zinc-containing materials, providing valuable insights into the design of biomaterials targeting cellular energy metabolism regulation.

2,4,6-trinitrotoluene causes mitochondrial toxicity in Caenorhabditis elegans by affecting electron transport

As a typical energetic compound widely used in military activities, 2,4,6-trinitrotoluene (TNT) has attracted great attention in recent years due to its heavy pollution and wide distribution in and around the training facilities, firing ranges, and demolition sites. However, the subcellular targets and the underlying toxic mechanism of TNT remain largely unknown. In this study, we explored the toxic effects of TNT biological reduction on the mitochondrial function and homeostasis in Caenorhabditis elegans (C. elegans). With short-term exposure of L4 larvae, 10-1000 ng/mL TNT reduced mitochondrial membrane potential and adenosine triphosphate (ATP) content, which was associated with decreased expression of specific mitochondrial complex involving gas-1 and mev-1 genes. Using fluorescence-labeled transgenic nematodes, we found that fluorescence expression of sod-3 (muls84) and gst-4 (dvls19) was increased, suggesting that TNT disrupted the mitochondrial antioxidant defense system. Furthermore, 10 ng/mL TNT exposure increased the expression of the autophagy-related gene pink-1 and activated mitochondrial unfolded protein response (mt UPR), which was indicated by the increased expression of mitochondrial stress activated transcription factor atfs-1, ubiquitin-like protein ubl-5, and homeobox protein dve-1. Our findings demonstrated that TNT biological reduction caused mitochondrial dysfunction and the development of mt UPR protective stress responses, and provided a basis for determining the potential risks of energetic compounds to living organisms.

Zinc-Based ROS Amplifiers Trigger Cancer Chemodynamic/Ion Interference Therapy Through Self-Cascade Catalysis

Nanozyme-mediated chemodynamic therapy has emerged as a promising strategy due to its tumor specificity and controlled catalytic activity. However, the poor efficacy caused by low hydrogen peroxide (H2O2) levels in the tumor microenvironment (TME) poses challenges. Herein, an H2O2 self-supplying nanozyme is constructed through loading peroxide-like active platinum nanoparticles (Pt NPs) on zinc peroxide (ZnO2) (denoted as ZnO2@Pt). ZnO2 releases H2O2 in response to the acidic TME. Pt NPs catalyze the hydroxyl radical generation from H2O2 while reducing the mitigation of oxidative stress by glutathione, serving as a reactive oxygen (ROS) amplifier through self-cascade catalysis. In addition, Zn2+ released from ZnO2 interferes with tumor cell energy supply and metabolism, enabling ion interference therapy to synergize with chemodynamic therapy. In vitro studies demonstrate that ZnO2@Pt induces cellular oxidative stress injury through enhanced ROS generation and Zn2+ release, downregulating ATP and NAD+ levels. In vivo assessment of anticancer effects showed that ZnO2@Pt could generate ROS at tumor sites to induce apoptosis and downregulate energy supply pathways associated with glycolysis, resulting in an 89.7% reduction in tumor cell growth. This study presents a TME-responsive nanozyme capable of H2O2 self-supply and ion interference therapy, providing a paradigm for tumor-specific nanozyme design.

Organellophagy regulates cell death:A potential therapeutic target for inflammatory diseases

BACKGROUND

Dysregulated alterations in organelle structure and function have a significant connection with cell death, as well as the occurrence and development of inflammatory diseases. Maintaining cell viability and inhibiting the release of inflammatory cytokines are essential measures to treat inflammatory diseases. Recently, many studies have showed that autophagy selectively targets dysfunctional organelles, thereby sustaining the functional stability of organelles, alleviating the release of multiple cytokines, and maintaining organismal homeostasis. Organellophagy dysfunction is critically engaged in different kinds of cell death and inflammatory diseases.

AIM OF REVIEW

We summarized the current knowledge of organellophagy (e.g., mitophagy, reticulophagy, golgiphagy, lysophagy, pexophagy, nucleophagy, and ribophagy) and the underlying mechanisms by which organellophagy regulates cell death.

KEY SCIENTIFIC CONCEPTS OF REVIEW

We outlined the potential role of organellophagy in the modulation of cell fate during the inflammatory response to develop an intervention strategy for the organelle quality control in inflammatory diseases.

ZnT 9 Involvement in Estradiol-Modulated Zinc Homeostasis of the Human Follicular Microenvironment

Female subfertility has been a growing concern for reproductive health. Assisted reproductive technologies make pregnancy possible, but the outcome rate is still suboptimal. Zinc is an essential factor for fertility and development. Zinc levels in follicular fluids were measured by electrochemical method, and we found that zinc in the follicular fluids was related to high-quality embryo rate (R = 0.39, p = 0.01). Basal estradiol levels and estradiol levels on the day of HCG injection were negatively correlated with zinc concentrations in the follicular fluid (R =  - 0.53, p < 0.001; R =  - 0.32, p < 0.05), and estradiol promoted ZnT 9 protein expression in cumulus granulosa cells in vitro and in vivo. When the zinc level was at 3.63-3.85 μg/mL, follicular fluid samples had the highest SOD activity. Therefore, zinc played an important role in improving oocyte development by increasing antioxidant capacity. Our results suggested that estradiol affected zinc homeostasis in follicles by controlling the expression of ZnT 9, which in turn influenced the potential of oocytes to develop into good-quality embryos. This study to provide tangible improvements to patient outcomes will make it a focus of both scientific and translational efforts in the future.

Mechanism of metal ion-induced cell death in gastrointestinal cancer

Gastrointestinal (GI) cancer is one of the most severe types of cancer, with a significant impact on human health worldwide. Due to the urgent demand for more effective therapeutic strategies against GI cancers, novel research on metal ions for treating GI cancers has attracted increasing attention. Currently, with accumulating research on the relationship between metal ions and cancer therapy, several metal ions have been discovered to induce cell death. In particular, the three novel modes of cell death, including ferroptosis, cuproptosis, and calcicoptosis, have become focal points of research in the field of cancer. Meanwhile, other metal ions have also been found to trigger cell death through various mechanisms. Accordingly, this review focuses on the mechanisms of metal ion-induced cell death in GI cancers, hoping to provide theoretical support for further GI cancer therapies.

Charge-Reversal NaCl/G-Quartets for Aggregation-Induced Mitochondrial MicroRNA Imaging and Ion-Interference Therapy

Mitochondrial therapy is a promising new strategy that offers the potential to achieve precise disease diagnosis or maximum therapeutic response. However, versatile mitochondrial theranostic platforms that integrate biomarker detection and therapy have rarely been exploited. Here, we report a charge-reversal nanomedicine activated by an acidic microenvironment for mitochondrial microRNA (mitomiR) detection and ion-interference therapy. The transporter liposome (DD-DC) was constructed from a pH-responsive polymer and a positively charged phospholipid, encapsulating NaCl nanoparticles with coloading of the aggregation-induced emission (AIE) fluorogens AIEgen-DNA/G-quadruplexes precursor and brequinar (NAB@DD-DC). The negatively charged nanomedicine ensured good blood stability and high tumor accumulation, while the charge-reversal to positive in response to the acidic pH in the tumor microenvironment (TME) and lysosomes enhanced the uptake by tumor cells and lysosome escape, achieving accumulation in mitochondria. The subsequently released Na+ in mitochondria not only contributed to the formation of mitomiR-494 induced G-quadruplexes for AIE imaging diagnosis but also led to an osmolarity surge that was enhanced by brequinar to achieve effective ion-interference therapy.

The NLRX1-SLC39A7 complex orchestrates mitochondrial dynamics and mitophagy to rejuvenate intervertebral disc by modulating mitochondrial Zn2+ trafficking

Intervertebral disc degeneration (IDD) is the most critical pathological factor in the development of low back pain. The maintenance of nucleus pulposus (NP) cell and intervertebral disc integrity benefits largely from well-controlled mitochondrial quality, surveilled by mitochondrial dynamics (fission and fusion) and mitophagy, but the outcome is cellular context-dependent that remain to be clarified. Our studies revealed that the loss of NLRX1 is correlated with NP cell senescence and IDD progression, which involve disordered mitochondrial quality. Further using animal and in vitro tissue and cell models, we demonstrated that NLRX1 could facilitate mitochondrial quality by coupling mitochondrial dynamic factors (p-DNM1L, L-OPA1:S-OPA1, OMA1) and mitophagy activity. Conversely, mitochondrial collapse occurred in NLRX1-defective NP cells and switched on the compensatory PINK1-PRKN pathway that led to excessive mitophagy and aggressive NP cell senescence. Mechanistically, NLRX1 was originally shown to interact with zinc transporter SLC39A7 and modulate mitochondrial Zn2+ trafficking via the formation of an NLRX1-SLC39A7 complex on the mitochondrial membrane of NP cells, subsequently orchestrating mitochondrial dynamics and mitophagy. The restoration of NLRX1 function by gene overexpression or pharmacological agonist (NX-13) treatment showed great potential for regulating mitochondrial fission with synchronous fusion and mitophagy, thus sustaining mitochondrial homeostasis, ameliorating NP cell senescence and rejuvenating intervertebral discs. Collectively, our findings highlight a working model whereby the NLRX1-SLC39A7 complex coupled mitochondrial dynamics and mitophagy activity to surveil and target damaged mitochondria for degradation, which determines the beneficial function of the mitochondrial surveillance system and ultimately rejuvenates intervertebral discs.Abbreviations: 3-MA: 3-methyladenine; Baf-A1: bafilomycin A1; CDKN1A/p21: cyclin dependent kinase inhibitor 1A; CDKN2A/p16: cyclin dependent kinase inhibitor 2A; DNM1L/DRP1: dynamin 1 like; EdU: 5-Ethynyl-2'-deoxyuridine; HE: hematoxylin-eosin; IDD: intervertebral disc degeneration; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MKI67/Ki67: marker of proliferation Ki-67; LBP: low back pain; MMP: mitochondrial membrane potential; MFN1: mitofusin 1; MFN2: mitofusin 2; MFF: mitochondrial fission factor; NP: nucleus pulposus; NLRX1: NLR family member X1; OMA1: OMA1 zinc metallopeptidase; OPA1: OPA1 mitochondrial dynamin like GTPase; PINK1: PTEN induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; ROS: reactive oxidative species; SASP: senescence-associated secretory phenotype; SA-GLB1/β-gal: senescence-associated galactosidase beta 1; SO: safranin o; TBHP: tert-butyl hydroperoxide; TP53/p53: tumor protein p53; SLC39A7/ZIP7: solute carrier family 39 member 7; TOMM20: translocase of outer mitochondrial membrane 20; TIMM23: translocase of inner mitochondrial membrane 23.

SYNJ2BP ameliorates intervertebral disc degeneration by facilitating mitochondria-associated endoplasmic reticulum membrane formation and mitochondrial Zn2+ homeostasis

Nucleus pulposus (NP) cell function-loss is one main contributor during intervertebral disc degeneration (IDD) progression. Both mitochondria and endoplasmic reticulum (ER) play vital roles in sustaining NP cell homeostasis, while the precise function of ER-mitochondria tethering and cross talk in IDD remain to be clarified. Here, we demonstrated that a notable disruption of mitochondria-associated ER membrane (MAM) was identified in degenerated discs and TBHP-induced NP cells, accompanied by mitochondrial Zn2+ overload and NP cell senescence. Importantly, experimental coupling of MAM contacts by MFN2, a critical regulator of MAM formation, could enhance NLRX1-SLC39A7 complex formation and mitochondrial Zn2+ homeostasis. Further using the sequencing data from TBHP-induced degenerative model of NP cells, combining the reported MAM proteomes, we demonstrated that SYNJ2BP loss was one critical pathological characteristic of NP cell senescence and IDD progression, which showed close relationship with MAM disruption. Overexpression of SYNJ2BP could facilitate MAM contact organization and NLRX1-SLC39A7 complex formation, thus promoted mitochondrial Zn2+ homeostasis, NP cell proliferation and intervertebral disc rejuvenation. Collectively, our present study revealed a critical role of SYNJ2BP in maintaining mitochondrial Zn2+ homeostasis in NP cells during IDD progression, partially via sustaining MAM contact and NLRX1-SLC39A7 complex formation.

Reduced corrosion of Zn alloy by HA nanorods for enhancing early bone regeneration

Zinc alloys have emerged as promising materials for bone regeneration due to their moderate biodegradation rates. However, the blast release of Zn2+ from Zn alloy substrates affects cell behaviors and the subsequent osseointegration quality, retarding their early service performance. To address this issue, extracellular matrix-like hydroxyapatite (HA) nanorods were prepared on Zn-1Ca (ZN) by a combined hydrothermal treatment (HT). HA nanoclusters nucleate on the presetting ZnO layer and grow into nanorods with prolonged HT. HA nanorods protect the ZN substrate from serious corrosion and the corrosion rate is reduced by dozens of times compared with the bare ZN, resulting in a significantly decreased release of Zn2+ ions. The synergistic effect of HA nanorods and appropriate Zn2+ endow ZN implants with obviously improved behaviors of osteoblasts and endothelial cells (e.g. adhesion, proliferation and differentiation) in vitro and new bone formation in vivo. Our work opens up a promising avenue for Zn-based alloys to improve bone regeneration in clinics.

In vitro and in vivo studies on biodegradable Zn porous scaffolds with a drug-loaded coating for the treatment of infected bone defect

Additively manufactured biodegradable zinc (Zn) scaffolds have great potential to repair infected bone defects due to their osteogenic and antibacterial properties. However, the enhancement of antibacterial properties depends on a high concentration of dissolved Zn2+, which in return deteriorates osteogenic activity. In this study, a vancomycin (Van)-loaded polydopamine (PDA) coating was prepared on pure Zn porous scaffolds to solve the above dilemma. Compared with pure Zn scaffolds according to comprehensive in vitro tests, the PDA coating resulted in a slow degradation and inhibited the excessive release of Zn2+ at the early stage, thus improving cytocompatibility and osteogenic activity. Meanwhile, the addition of Van drug substantially suppressed the attachment and proliferation of S. aureus and E. coli bacterial. Furthermore, in vivo implantation confirmed the simultaneously improved osteogenic and antibacterial functions by using the pure Zn scaffolds with Van-loaded PDA coating. Therefore, it is promising to employ biodegradable Zn porous scaffolds with the proposed drug-loaded coating for the treatment of infected bone defects.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

A tumor microenvironment-activatable nanoplatform with phycocyanin-assisted in-situ nanoagent generation for synergistic treatment of colorectal cancer

The in-situ generation of therapeutic agents in targeted lesions is promising for revolutionizing oncotherapy but is limited by the low production efficiency. Given the specific tumor microenvironment (TME) of colorectal cancer (CRC), i.e., mild acidity, overexpressed H2O2, glutathione (GSH) and H2S, we develop phycocyanin (PC) encapsulated PZTC/SS/HA nanocapsules (NCs) for TME-responsive, protein-assisted "turn-on'' therapy of CRC. The NCs are prepared by sequentially assembling Cu2+-tannic acid (TA) coordination shell, disulfide bond-bearing cross-linker, and hyaluronic acid (HA) on the sacrificial template ZIF-8, thus achieving pH-, GSH-responsiveness, and tumor targeting capability, respectively. Once reaching the CRC sites, the NCs can quickly disintegrate and release Cu2+ and PC, accompanied by subsequent endogenous H2S-triggered generation of copper sulfide (CuS). Significantly, the intracellular sulfidation process can be accelerated by PC, thereby enabling efficient photothermal therapy (PTT) under NIR-Ⅱ laser. Besides, Cu2+-associated chemodynamic therapy (CDT) can be simultaneously activated and enhanced by PTT-induced local hyperthermia and disulfide bond-induced GSH consumption. This CRC-targeted and TME-activated synergistic PTT/CDT strategy displays high therapeutic efficacy both in vitro and in vivo, which can open up a new avenue for biomolecule-assisted in-situ nanoagent generation and effective TME-responsive synergistic treatment of CRC.

Human genetic adaptation related to cellular zinc homeostasis

SLC30A9 encodes a ubiquitously zinc transporter (ZnT9) and has been consistently suggested as a candidate for positive selection in humans. However, no direct adaptive molecular phenotype has been demonstrated. Our results provide evidence for directional selection operating in two major complementary haplotypes in Africa and East Asia. These haplotypes are associated with differential gene expression but also differ in the Met50Val substitution (rs1047626) in ZnT9, which we show is found in homozygosis in the Denisovan genome and displays accompanying signatures suggestive of archaic introgression. Although we found no significant differences in systemic zinc content between individuals with different rs1047626 genotypes, we demonstrate that the expression of the derived isoform (ZnT9 50Val) in HEK293 cells shows a gain of function when compared with the ancestral (ZnT9 50Met) variant. Notably, the ZnT9 50Val variant was found associated with differences in zinc handling by the mitochondria and endoplasmic reticulum, with an impact on mitochondrial metabolism. Given the essential role of the mitochondria in skeletal muscle and since the derived allele at rs1047626 is known to be associated with greater susceptibility to several neuropsychiatric traits, we propose that adaptation to cold may have driven this selection event, while also impacting predisposition to neuropsychiatric disorders in modern humans.

Zinc Ions Modulate YY1 Activity: Relevance in Carcinogenesis

YY1 is widely recognized as an intrinsically disordered transcription factor that plays a role in development of many cancers. In most cases, its overexpression is correlated with tumor progression and unfavorable patient outcomes. Our latest research focusing on the role of zinc ions in modulating YY1's interaction with DNA demonstrated that zinc enhances the protein's multimeric state and affinity to its operator. In light of these findings, changes in protein concentration appear to be just one element relevant to modulating YY1-dependent processes. Thus, alterations in zinc ion concentration can directly and specifically impact the regulation of gene expression by YY1, in line with reports indicating a correlation between zinc ion levels and advancement of certain tumors. This review concentrates on other potential consequences of YY1 interaction with zinc ions that may act by altering charge distribution, conformational state distribution, or oligomerization to influence its interactions with molecular partners that can disrupt gene expression patterns.

Case report: Birk-Landau-Perez syndrome linked to the gene-identification of additional cases and expansion of the phenotypic spectrum

Birk-Landau-Perez syndrome (BILAPES) is an autosomal recessive cerebro-renal syndrome associated with genetic defects in the SLC30A9 gene, initially reported in 2017 in six individuals belonging to a large Bedouin kindred. The SLC30A9 gene encodes a putative mitochondrial zinc transporter with ubiquitous expression, the highest found in the brain, kidney, and skeletal muscle. Since the first report, only one additional affected patient has been described, but there were some inconsistencies, such as hearing loss, failure to thrive, and neuroimaging findings between the clinical presentation of the disease in the Bedouin family and the second patient. Here, we present two more patients from a consanguineous Middle Eastern family with features of chronic kidney disease, neurodevelopmental regression, ataxia, hearing loss, and eye abnormalities, which were largely consistent with BILAPES. Whole-exome sequencing detected a homozygous in-frame deletion c.1049_1051delCAG (p.Ala350del) in the SLC30A9 gene, which was the same variant detected in the patients from the primary literature report and the variant segregated with disease in the family. However, in the patients described here, brain MRI showed cerebellar atrophy, which was not a cardinal feature of the syndrome from the primary report. Our findings provide further evidence for SLC30A9-associated BILAPES and contribute to defining the clinical spectrum.

How fish cells responded to zinc challenges: Insights from bioimaging

Zinc ion (Zn) is an essential nutrition element and it is important to understand its regulation and distribution among different cellular organelles. Here, subcellular trafficking of Zn in rabbitfish fin cells was investigated through bioimaging, and the results showed that the toxicity and bioaccumulation of Zn were both dose- and time-dependent. Cytotoxicity of Zn only occurred when the Zn concentration reached 200-250 μM after 3 h of exposure when the cellular quota of Zn:P reached a threshold level around 0.7. Remarkably, the cells were able to maintain homeostasis at a low Zn exposure concentration or within the first 4-h exposure. Zn homeostasis was mainly regulated by the lysosomes which stored Zn within the short exposure period, during which the number and size of lysosomes as well as the lysozyme activity increased in response to incoming Zn. However, with increasing Zn concentration beyond a threshold concentration (> 200 μM) and an exposure time > 3 h, homeostasis was disrupted, leading to an Zn spillover to cytoplasm and other cellular organelles. At the same time, cell viability decreased due to the Zn damage on mitochondria which caused morphological changes (smaller and rounder dots) and over production of reactive oxygen species, indicating the dysfunction of mitochondria. By further purifying the cellular organelles, cell viability was found to be consistent with the mitochondrial Zn amount. This study suggested that the amount of mitochondrial Zn was an excellent predictor of Zn toxicity on fish cells.

Thermogenic adipocyte-derived zinc promotes sympathetic innervation in male mice

Sympathetic neurons activate thermogenic adipocytes through release of catecholamine; however, the regulation of sympathetic innervation by thermogenic adipocytes is unclear. Here, we identify primary zinc ion (Zn) as a thermogenic adipocyte-secreted factor that promotes sympathetic innervation and thermogenesis in brown adipose tissue and subcutaneous white adipose tissue in male mice. Depleting thermogenic adipocytes or antagonizing β₃-adrenergic receptor on adipocytes impairs sympathetic innervation. In obesity, inflammation-induced upregulation of Zn chaperone protein metallothionein-2 decreases Zn secretion from thermogenic adipocytes and leads to decreased energy expenditure. Furthermore, Zn supplementation ameliorates obesity by promoting sympathetic neuron-induced thermogenesis, while sympathetic denervation abrogates this antiobesity effect. Thus, we have identified a positive feedback mechanism for the reciprocal regulation of thermogenic adipocytes and sympathetic neurons. This mechanism is important for adaptive thermogenesis and could serve as a potential target for the treatment of obesity.

Development and Characterization of a Red Fluorescent Protein-Based Sensor RZnP1 for the Detection of Cytosolic Zn2

Fluorescent sensors have been developed to record Zn²⁺ dynamics and measure Zn²⁺ concentrations within the cell. Most previous efforts on developing single-wavelength sensors are focused on green sensors. Here, we engineer a genetically encoded, single red fluorescent protein-based Zn²⁺ sensor, Red Zinc Probe (RZnP1), which can detect intracellular concentrations of Zn²⁺. RZnP1 demonstrates a sensitive response to cytosolic Zn²⁺ (K_d = 438 pM), decent brightness (quantum yield (QY) = 0.15), good in situ dynamic range (F_max/F_min = 4.0), and specificity for Zn²⁺ over other biologically relevant metal cations. RZnP1 offers a way to image Zn²⁺ with multiple intracellular ions in tandem. We demonstrate the simultaneous recording of Zn²⁺ and Ca²⁺ using RZnP1 alongside the Ca²⁺ sensor GCaMP5G in HeLa cells. We also use RZnP1 with mito-GZnP2, a green fluorescent protein (GFP)-based mitochondrial Zn²⁺ sensor, to track Zn²⁺ dynamics in the cytosol and mitochondria concurrently in rat primary neuron culture. Our work not only expands the toolbox of Zn²⁺ sensors but also demonstrates techniques for imaging Zn²⁺ dynamics along with other cations and between multiple subcellular compartments simultaneously.

ZnT8 loss-of-function accelerates functional maturation of hESC-derived β cells and resists metabolic stress in diabetes

Human embryonic stem cell-derived β cells (SC-β cells) hold great promise for treatment of diabetes, yet how to achieve functional maturation and protect them against metabolic stresses such as glucotoxicity and lipotoxicity remains elusive. Our single-cell RNA-seq analysis reveals that ZnT8 loss of function (LOF) accelerates the functional maturation of SC-β cells. As a result, ZnT8 LOF improves glucose-stimulated insulin secretion (GSIS) by releasing the negative feedback of zinc inhibition on insulin secretion. Furthermore, we demonstrate that ZnT8 LOF mutations endow SC-β cells with resistance to lipotoxicity/glucotoxicity-triggered cell death by alleviating endoplasmic reticulum (ER) stress through modulation of zinc levels. Importantly, transplantation of SC-β cells with ZnT8 LOF into mice with preexisting diabetes significantly improves glycemia restoration and glucose tolerance. These findings highlight the beneficial effect of ZnT8 LOF on the functional maturation and survival of SC-β cells that are useful as a potential source for cell replacement therapies.

Immature function and fragility hinder application of hESC-derived β cells (SC-β cell) for diabetes cell therapy. Here, the authors identify ZnT8 as a gene editing target to enhance the insulin secretion and cell survival under metabolic stress by abolishing zinc transport in SC-β cells.

Interplay between Zn2+ Homeostasis and Mitochondrial Functions in Cardiovascular Diseases and Heart Ageing

Zinc plays an important role in cardiomyocytes, where it exists in bound and histochemically reactive labile Zn²⁺ forms. Although Zn²⁺ concentration is under tight control through several Zn²⁺-transporters, its concentration and intracellular distribution may vary during normal cardiac function and pathological conditions, when the protein levels and efficacy of Zn²⁺ transporters can lead to zinc re-distribution among organelles in cardiomyocytes. Such dysregulation of cellular Zn²⁺ homeostasis leads to mitochondrial and ER stresses, and interrupts normal ER/mitochondria cross-talk and mitophagy, which subsequently, result in increased ROS production and dysregulated metabolic function. Besides cardiac structural and functional defects, insufficient Zn²⁺ supply was associated with heart development abnormalities, induction and progression of cardiovascular diseases, resulting in accelerated cardiac ageing. In the present review, we summarize the recently identified connections between cellular and mitochondrial Zn²⁺ homeostasis, ER stress and mitophagy in heart development, excitation–contraction coupling, heart failure and ischemia/reperfusion injury. Additionally, we discuss the role of Zn²⁺ in accelerated heart ageing and ageing-associated rise of mitochondrial ROS and cardiomyocyte dysfunction.

Prime Real Estate: Metals, Cofactors and MICOS

Metals are key elements for the survival and normal development of humans but can also be toxic to cells when mishandled. In fact, even mild disruption of metal homeostasis causes a wide array of disorders. Many of the metals essential to normal physiology are required in mitochondria for enzymatic activities and for the formation of essential cofactors. Copper is required as a cofactor in the terminal electron transport chain complex cytochrome c oxidase, iron is required for the for the formation of iron-sulfur (Fe-S) clusters and heme, manganese is required for the prevention of oxidative stress production, and these are only a few examples of the critical roles that mitochondrial metals play. Even though the targets of these metals are known, we are still identifying transporters, investigating the roles of known transporters, and defining regulators of the transport process. Mitochondria are dynamic organelles whose content, structure and localization within the cell vary in different tissues and organisms. Our knowledge of the impact that alterations in mitochondrial physiology have on metal content and utilization in these organelles is very limited. The rates of fission and fusion, the ultrastructure of the organelle, and rates of mitophagy can all affect metal homeostasis and cofactor assembly. This review will focus of the emerging areas of overlap between metal homeostasis, cofactor assembly and the mitochondrial contact site and cristae organizing system (MICOS) that mediates multiple aspects of mitochondrial physiology. Importantly the MICOS complexes may allow for localization and organization of complexes not only involved in cristae formation and contact between the inner and outer mitochondrial membranes but also acts as hub for metal-related proteins to work in concert in cofactor assembly and homeostasis.

The Role of the Metabolism of Zinc and Manganese Ions in Human Cancerogenesis

Metal ion homeostasis is fundamental for life. Specifically, transition metals iron, manganese and zinc play a pivotal role in mitochondrial metabolism and energy generation, anti-oxidation defense, transcriptional regulation and the immune response. The misregulation of expression or mutations in ion carriers and the corresponding changes in Mn²⁺ and Zn²⁺ levels suggest that these ions play a pivotal role in cancer progression. Moreover, coordinated changes in Mn²⁺ and Zn²⁺ ion carriers have been detected, suggesting that particular mechanisms influenced by both ions might be required for the growth of cancer cells, metastasis and immune evasion. Here, we present a review of zinc and manganese pathophysiology suggesting that these ions might cooperatively regulate cancerogenesis. Zn and Mn effects converge on mitochondria-induced apoptosis, transcriptional regulation and the cGAS-STING signaling pathway, mediating the immune response. Both Zn and Mn influence cancer progression and impact treatment efficacy in animal models and clinical trials. We predict that novel strategies targeting the regulation of both Zn and Mn in cancer will complement current therapeutic strategies.

The Insecticidal Efficacy and Physiological Action Mechanism of a Novel Agent GC16 against Tetranychus pueraricola (Acari: Tetranychidae)

Simple Summary

Spider mite is major pest in agriculture and have developed resistance to commonly used pesticides. Therefore, it is urgent to discover new pesticides to control the pest. In order to provide alternatives for its management, we evaluated the effectiveness of a new agent GC16 against the spider mite Tetranychus pueraricola. Then, we preliminarily revealed the its acaricidal mechanism of action based on the damage of cuticle and organelles of mites. We confirmed that GC16 has a good controlling effect on T. pueraricola and it is not harmful to Picromerus lewisi and Harmonia axyridis. Our research provides not only an alternative pesticide for the management of spider mites, but also guidance for the application of GC16 in sustainable agriculture.

Abstract

Chemical control plays a crucial role in pest management but has to face challenges due to insect resistance. It is important to discover alternatives to traditional pesticides. The spider mite Tetranychus pueraricola (Ehara & Gotoh) (Acari: Tetranychidae) is a major agricultural pest that causes severe damage to many crops. GC16 is a new agent that consists of a mixture of Calcium chloride (CaCl₂) and lecithin. To explore the acaricidal effects and mode of action of GC16 against T. pueraricola, bioassays, cryogenic scanning electron microscopy (cryo-SEM) and transmission electron microscopy (TEM) were performed. GC16 had lethal effects on the eggs, larvae, nymphs, and adults of T. pueraricola, caused the mites to dehydrate and inactivate, and inhibited the development of eggs. GC16 displayed contact toxicity rather than stomach toxicity through the synergistic effects of CaCl₂ with lecithin. Cryo-SEM analysis revealed that GC16 damaged T. pueraricola by disordering the array of the cuticle layer crest. Mitochondrial abnormalities were detected by TEM in mites treated by GC16. Overall, GC16 had the controlling efficacy on T. pueraricola by cuticle penetration and mitochondria dysfunction and had no effects on Picromerus lewisi and Harmonia axyridis, indicating that GC16 is likely a new eco-friendly acaricide.

A feedback loop engaging propionate catabolism intermediates controls mitochondrial morphology

D-2-Hydroxyglutarate (D-2HG) is an α-ketoglutarate-derived mitochondrial metabolite that causes D-2-hydroxyglutaric aciduria, a devastating developmental disorder. How D-2HG adversely affects mitochondria is largely unknown. Here, we report that in Caenorhabditis elegans, loss of the D-2HG dehydrogenase DHGD-1 causes D-2HG accumulation and mitochondrial damage. The excess D-2HG leads to a build-up of 3-hydroxypropionate (3-HP), a toxic metabolite in mitochondrial propionate oxidation, by inhibiting the 3-HP dehydrogenase HPHD-1. We demonstrate that 3-HP binds the MICOS subunit MIC60 (encoded by immt-1) and inhibits its membrane-binding and membrane-shaping activities. We further reveal that dietary and gut bacteria affect mitochondrial health by modulating the host production of 3-HP. These findings identify a feedback loop that links the toxic effects of D-2HG and 3-HP on mitochondria, thus providing important mechanistic insights into human diseases related to D-2HG and 3-HP.