Coumestrol facilitates apoptosis in colorectal cancer cells by interacting with ZIP8 protein via the ferroptosis pathway.

Objective: So far, there have been no reports of coumestrol inhibiting colorectal cancer (CRC) through the ferroptosis pathway. This study is to investigate the mechanism of the traditional Chinese medicine monomer coumestrol in the treatment of CRC. Methods: Data on CRC transcriptome sequencing was obtained from the GEO database and TCGA database. Bioinformatics analyses were conducted to screen for CRC prognostic-related key genes and their potential binding monomers in traditional Chinese medicine. The inhibitory effect of coumestrol on CRC cell lines (COLO 205 & HCT 116) was determined using the CCK-8 assay, and cell apoptosis was assessed by flow cytometry. The content of ferrous ions was measured using the Ferrous Ion Content Assay Kit. The expression of ferroptosis pathway-related genes SLC39A8, NCOA4, VDAC2, and NOX2 before and after small interference RNA (siRNA) was examined through real-time PCR and Western blotting. Results: SLC39A8 was found to be associated with CRC clinical progression staging, and its encoded protein ZIP8 may bind to coumestrol. KEGG enrichment analysis suggested that ZIP8 plays a role in iron transmembrane transport and may affect the expression of ferroptosis pathway-related genes NCOA4, VDAC2, and NOX2. Coumestrol was found to induce apoptosis in CRC cell lines by upregulating the expression of ferroptosis pathway-related genes SLC39A8, NCOA4, VDAC2, and NOX2. However, coumestrol was unable to upregulate the expression of ferroptosis pathway-related genes in CRC cell lines after SLC39A8 interference. Conclusion: Coumestrol facilitates apoptosis in CRC cells by interacting with ZIP8 protein via the ferroptosis pathway.

Variants of SLC39A4 cause acrodermatitis enteropathica in Tibetan, Yi, and Han families in Sichuan region of southwestern China: a case report series.

Acrodermatitis enteropathica (AE, OMIM 201100) is a rare autosomal recessive dermatosis characterized by periorificial dermatitis, diarrhea, alopecia, and hypozincaemia due to pathogenic variants of SLC39A4. Herein, we present a case series describing four unrelated patients with AE from Han, Yi, and Tibetan ethnicities in Sichuan region of southwestern China, speculate the hotspot variants of SLC39A4 causing AE in Sichuan region and highlight physicians should be alerted to unusual presentations of AE, such as the absence of hypozincaemia and the presence of acne-like lesions. Serum alkaline phosphatase and genetic testing should be considered to accurately evaluate the zinc deficiency in human body and help make the correct diagnosis.

UKLF/PCBP2 axis governs the colorectal cancer development by transcriptionally activating SLC39A4.

Colorectal cancer (CRC) is one of the most prevalent malignant tumors with limited treatment options. Therefore, there is an urgent need to investigate new therapeutic targets against CRC. Ubiquitous Kruppel-like factor (UKLF) is involved in various cancer processes, but its effect and detailed molecular mechanism in CRC are not yet fully understood. Here, this study aimed to investigate the function and mechanism of UKLF in the development of CRC. The results showed that UKLF was highly expressed in CRC tissues from clinical patients and its high expression was related to poor prognosis. UKLF promoted cell proliferation, migration and invasion, and inhibited cell apoptosis. The promotion effect of UKLF on tumor growth was further confirmed in vivo. As far as the mechanism was concerned, poly (C) binding protein 2 (PCBP2) was verified to bind to the 3'-UTR of UKLF mRNA and enhance its mRNA stability. Moreover, UKLF modulated the expression of solute carrier family 39 member 4 (SLC39A4) at the transcriptional level. Taken together, these findings elucidated the regulatory mechanism of UKLF and uncovered the importance of the PCBP2/UKLF/SLC39A4 pathway. The targeting of UKLF may be a novel direction for molecular-targeted CRC therapy.

Analysis of similarities and differences between transient symptomatic zinc deficiency and acrodermatitis enteropathica in children: a case report of a Chinese Yi-ethnic infant.

BACKGROUND: Transient symptomatic zinc deficiency (TSZD), an acquired type of zinc deficiency, is a rare, but probably underrecognized disease, extremely in breastfed premature with low birthweight infants. Its clinical manefestations are similar to Acrodermatitis enteropathica (AE), which is a genetic zinc absorption disorder caused by SLC39A4 gene mutations. This gene encodes a member of the zinc/iron-regulated transporter-like protein (ZIP) family. The encoded protein localizes to cell membranes and is required for zinc uptake in the intestine. TSZD is often misdiagnosed as AE because of their extremely similar manefestations, characterized by a typical rash. Therefore, the differention between them is still a clinical challenging. CASE PRESENTATION: Here, we present a case of TSZD in a 4 month and 23 days female Chinese Yi-ethnic premature with AE-like skin lesions, mainly presenting periorificial, perianal and perineal crusted, eroded, erythemato-squamous eruption. Laboratory examination showed the patient's blood zinc level was significantly decreased. Further sequencing of the SLC39A4 gene showed no mutation in the infant and her parents. Skin lesions significantly improved after 6 days of initial zinc supplementation (3 mg/kg/d), and maintenance treatment with 1 mg/kg/day of zinc was discontinued after 8 months without recurrence. CONCLUSIONS: The clinical manifestations of TSZD and AE are extremely similar, leading to a high rate of clinical misdiagnosis. While genetic analysis of the SLC39A4 gene is a reliable method for differentiating TSZD from AE. It is recommended that SLC39A4 gene test should be performed as far as possible in children with AE-like rash.

circAMN1-Mediated Ferroptosis Regulates the Expulsion of Placenta in Trophoblast Cells.

After delivery, the death of trophoblast cells can promote the expulsion of the placenta. Ferroptosis, an iron-dependent programmed cell death, is involved in mammalian development. Circular RNAs are associated with placental development; however, it is unclear whether circular RNAs regulate the expulsion of fetal membranes through ferroptosis. The gene expression profiles in the tail vein blood of Holstein cows with normal and retained placentas were investigated using RNA sequencing and a GSE214588 dataset. circAMN1 and SLC39A8 expression was significantly downregulated in the blood of cows with a retained placenta, whereas miR-205_R-1 expression was significantly upregulated. We validated erastin-induced ferroptosis in trophoblast cells. Transfection with si-circAMN1 and miR-205_R-1 mimic reduced intracellular total iron, Fe2+, and glutathione disulfide levels; increased intracellular glutathione levels and glutathione/glutathione disulfide; and enhanced cell viability in these cells. In contrast, transfection with pcDNA3.1 circAMN1 and an miR-205_R-1 inhibitor promoted ferroptosis. As an miR-205_R-1 sponge, circAMN1 regulated the expression of SLC39A8 to control erastin-induced ferroptosis and regulated the proliferation, invasion, and migration of trophoblast cells. Our findings provide a theoretical basis for studying the mechanism by which programmed cell death regulates fetal membrane expulsion and indicate its potential as a therapeutic target for placenta retention.

Loss of Slc39a12 in hippocampal neurons is responsible for anxiety-like behavior caused by temporomandibular joint osteoarthritis.

Background: An evident association between mood disorders and TMJ dysfunction has been demonstrated in previous studies. This study observed both the behavioral changes and the pathological changes in hippocampal tissue of rats in an animal model of TMJ-OA by injecting MIA into TMJ. Methods: Eighteen SD rats were randomly assigned to the NC group and the MIA groups. A TMJ-OA model was established to assess the HWT in the TMJ region, and the rats were subjected to the OFT and EPM. HE, O-fast green staining, qRT-PCR and immunofluorescence were used to detect condylar damage. Serum and hippocampal oxidative stress levels were detected. Functions of genes obtained by RNA-Seq were investigated using H2O2, ZnCl2 and transfection of siRNA on HT22 cells. Results: Injection of MIA resulted in disorganization of the chondrocyte layer on the condylar surface of rats, with reduced synthesis and increased degradation of the condylar cartilage matrix and reduced HWT. The results of the OFT and EPM showed that the rats in the MIA group developed anxiety-like behavior during the sixth week of MIA injection. Increased Nox4 expression, decreased SOD2 expression, elevated MDA level, and reduced GSH level were detected in serum and hippocampal neurons in the MIA group, with nuclear pyknosis and reduced Nissl bodies observed in neurons. The expression of Slc39a12 in hippocampal neurons of rats in the MIA group decreased. Slc39a12 knockdown in HT22 cells induced increased Nox4 expression, decreased SOD2 expression, increased MDA level, and reduced GSH and intracellular Zn2+. Oxidative stress in HT22 cells after transfection and H2O2 stimulation was reversed when ZnCl2 was added. Conclusion: Loss of Slc39a12 in hippocampal neurons results in cellular oxidative stress, further leading to neuronal damage. This may potentially explain how TMJ-OA triggers anxiety-like behavior in rats.

Zinc Transporters Serve as Prognostic Predictors and their Expression Correlates with Immune Cell Infiltration in Specific Cancer: A Pan-cancer Analysis.

The disruption of zinc (Zn) homeostasis has been implicated in cancer development and progression through various signaling pathways. Maintaining intracellular zinc balance is crucial in the context of cancer. Human cells rely on two families of transmembrane transporters, SLC30A/ZNT and SLC39A/ZIP, to coordinate zinc homeostasis. While some ZNTs and ZIPs have been linked to cancer progression, limited information is available regarding the expression patterns of zinc homeostasis-related genes and their potential roles in predicting prognosis and developing therapeutic strategies for specific cancers. In this study, a systematic analysis was conducted to examine the expression of all genes from the SLC30A and SLC39A families at both mRNA and protein levels across different cancers. As a result, three SLC39A genes (SLC39A1, SLC39A4, and SLC39A8) were found to be significantly dysregulated in specific cancers, including cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), liver hepatocellular carcinoma (LIHC), pancreatic adenocarcinoma (PAAD), and kidney renal papillary cell carcinoma (KIRP). Moreover, the dysregulation of these genes was tightly associated with the prognosis of patients with those cancers. Furthermore, we found that the gene SLC39A8 exhibited the lowest mutation frequency in KIRP, whereas mutations in SLC39A4 were found to significantly impact overall survival (OS), disease-free (DF), and progress-free survival (PFS) in cancer patients, particularly in those with PAAD. Additionally, immune infiltration analysis revealed that SLC39A1, SLC39A4, and SLC39A8 may function as immune regulators in cancers. This provides new insights into understanding the complex relationship between zinc homeostasis and cancer progression.

Gene-Environment Interactions: My Unique Journey.

I am deeply honored to be invited to write this scientific autobiography. As a physician-scientist, pediatrician, molecular biologist, and geneticist, I have authored/coauthored more than 600 publications in the fields of clinical medicine, biochemistry, biophysics, pharmacology, drug metabolism, toxicology, molecular biology, cancer, standardized gene nomenclature, developmental toxicology and teratogenesis, mouse genetics, human genetics, and evolutionary genomics. Looking back, I think my career can be divided into four distinct research areas, which I summarize mostly chronologically in this article: (a) discovery and characterization of the AHR/CYP1 axis, (b) pharmacogenomics and genetic prediction of response to drugs and other environmental toxicants, (c) standardized drug-metabolizing gene nomenclature based on evolutionary divergence, and (d) discovery and characterization of the SLC39A8 gene encoding the ZIP8 metal cation influx transporter. Collectively, all four topics embrace gene-environment interactions, hence the title of my autobiography.

The role of SLC39A4 in the prognosis, immune microenvironment, and contribution to malignant behavior in vivo and in vitro of cervical cancer.

BACKGROUND: Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) are becoming more common in younger women. Solute carrier family 39 member 4 (SLC39A4) produces a zinc ion transporter involved in metastasis and invasion of tumors. METHODS: The Cancer Genome Atlas RNA-seq data was used to investigate the expression of SLC39A4 and its prognostic potential. The assessment of the effect of SLC39A4 on cell growth and migration in CESC was conducted using MTT, colony formation, and Transwell assays. SLC39A4 was studied in vivo using a xenograft mouse model, and its functional involvement in oncogenesis was investigated by identifying the associated differentially expressed genes (DEGs). We evaluated the relationships among SLC39A4 levels, chemosensitivity, radiosensitivity and immune infiltration. RESULTS: SLC39A4 was upregulated in CESC samples, and individuals with greater SLC39A4 mRNA expression had shorter overall survival. SLC39A4 has been identified to be a regulator of tumor cell metastasis and proliferation in vivo and in vitro, with an area under the curve of 0.874 for diagnosing CESC. In total, 948 DEGs were discovered to be enriched in key CESC progression-related signaling pathways. Additionally, intratumoral immune checkpoint and infiltration activity were associated with SLC39A4 expression. High SLC39A4 expression exhibited poor chemosensitivity and radiosensitivity profiles. CONCLUSION: In conclusion, SLC39A4 is a key regulator of CESC development, prognosis, and the composition of the tumor immune microenvironment. SLC39A4 could be used as a prognostic or diagnostic screening tool and as a potential target for CESC treatment.

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.

Knockdown of SLC39A14 inhibits glioma progression by promoting erastin-induced ferroptosis SLC39A14 knockdown inhibits glioma progression.

BACKGROUND: Ferroptosis is a newly classified form of regulated cell death with implications in various tumor progression pathways. However, the roles and mechanisms of ferroptosis-related genes in glioma remain unclear. METHODS: Bioinformatics analysis was employed to identify differentially expressed ferroptosis-related genes in glioma. The expression levels of hub genes were assessed using real-time reverse transcriptase-polymerase chain reaction (RT-qPCR). To explore the role of SLC39A14 in glioma, a series of in vitro assays were conducted, including cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, and Transwell assays. Enzyme-linked immunosorbent assay (ELISA) was utilized to measure the levels of indicators associated with ferroptosis. Hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining were performed to illustrate the clinicopathological features of the mouse transplantation tumor model. Additionally, Western blot analysis was used to assess the expression of the cGMP-PKG pathway-related proteins. RESULTS: Seven ferroptosis-related hub genes, namely SLC39A14, WWTR1, STEAP3, NOTCH2, IREB2, HIF1A, and FANCD2, were identified, all of which were highly expressed in glioma. Knockdown of SLC39A14 inhibited glioma cell proliferation, migration, and invasion, while promoting apoptosis. Moreover, SLC39A14 knockdown also facilitated erastin-induced ferroptosis, leading to the suppression of mouse transplantation tumor growth. Mechanistically, SLC39A14 knockdown inhibited the cGMP-PKG signaling pathway activation. CONCLUSION: Silencing SLC39A14 inhibits ferroptosis and tumor progression, potentially involving the regulation of the cGMP-PKG signaling pathway.

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-1ß: 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/ß-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.

Assessing metal ion transporting activity of ZIPs: Intracellular zinc and iron detection.

Zrt/Irt-like proteins (ZIPs or SLC39A) are a large family of metal ion transporters mainly responsible for zinc uptake. Some ZIPs have been shown to specifically transport zinc, whereas others have broader substrate specificity in divalent metal ion trafficking, notably those of zinc and iron ions. Measuring intracellular zinc and iron levels helps assess their molecular and physiological activities. This chapter presents step-by-step methods for evaluating intracellular metal ion concentrations, including direct measurement using inductively coupled plasma-mass spectrometry (ICP-MS), chemical staining, fluorescent probes, and indirect reporter assays such as activity analysis of enzymes whose activities are dependent on metal ion availability.

In vitro studies of manganese transport and homeostasis.

Manganese (Mn) is an essential micronutrient required for fundamental cell functions and vital physiological processes. More than a dozen putative Mn transporters have been described over the last two decades, but few have been thoroughly evaluated. Recent genetic studies have revealed vital roles for solute carrier family 39, member 8 (SLC39A8) in Mn homeostasis. SLC39A8 can mediate the cellular uptake of the essential metals zinc, iron, and Mn, as well as the non-essential metal cadmium. However, loss-of-function mutations in SLC39A8 have been found in patients with severe Mn deficiency in the blood without affecting other metals. An in vitro study from our laboratory showed that SLC39A8 is a cell-surface transporter that strongly stimulates 54Mn incorporation into cells (Choi, Nguyen, Gupta, Iwase, & Seo, 2018). By contrast, the disease-associated mutations completely abrogated the cellular uptake of 54Mn (Choi et al., 2018), thereby providing a causal link between SLC39A8 deficiency and Mn deficiency. The importance of SLC39A8 is now increasingly recognized in multiple disease processes, and SLC39A8 has emerged as a critical regulator of Mn homeostasis. Thus, exploring the function of SLC39A8 in cellular Mn homeostasis is of significant research interest. This chapter describes the advanced methods used in our laboratory to examine Mn homeostasis and transport. Specifically, genetic and molecular approaches are described in HeLa cells overexpressing SLC39A8 and disease-associated SLC39A8 mutants. These methods are useful for characterizing the roles of Mn in diverse cellular events.

Methods to visualise zinc transporter proteins of the SLC39A family in cells.

Zinc is essential to many important biological processes and the SLC39A family of zinc transporters which help to control zinc levels in cells, are increasingly being implicated in disease states. In order to determine their exact roles in these processes, reliable methods for their successful production are now required. Unfortunately, extensive post-translational modification and temporally specific activation makes visualisation of ZIP family transporters difficult. As such, modifications of common molecular cell biology techniques are necessary to maximise success when studying these proteins. These include zinc stimulation and nocodazole synchronisation to enhance the activation of ZIP7 and ZIP6/ZIP10, respectively. Maximal ZIP6/ZIP10 retention can also be achieved through careful handling of loosely adhered mitotic fractions when harvesting cell cultures for lysis. Transfection can also be used to enhance ZIP visualisation, however consideration of transfection periods and inclusion of sodium butyrate are recommended to enhance transfection efficiency. When probing for ZIP family transporters, we recommend that epitope choice considers post-translational cleavage and phosphorylated protein isoforms. Finally, where expression of a particular ZIP transporter is manipulated, researchers should consider parallel evaluation of related ZIP transporter expression, to account for transporter compensation.

A simple and highly reproducible method for the detection of erythrocyte membrane ZIP metal transporters by immunoblotting.

Manganese is one of the essential trace elements found in erythrocytes. Metal transporters situated on the plasma membrane generally facilitate the movement of manganese into and out of cells. This study aims at determining whether two recently discovered manganese importers, ZIP8 and ZIP14, are located in the erythrocyte membrane. We outline a simple, effective and repeatable method for the isolation of erythrocyte membrane from a minimum of 50 µL mouse blood, followed by the identification of ZIP metal transporters using immunoblotting. Our results revealed that ZIP8 is expressed within the erythrocyte membrane, in contrast to ZIP14 which is not identified using immunoblotting approach. A direct measurement of the ZIP8 protein expression in erythrocyte membranes could provide valuable information for further analyzing its biological function.

Sucrose-induced hyperglycemia dysregulates intestinal zinc metabolism and integrity: risk factors for chronic diseases.

Objective: Zinc is an essential micronutrient that is critical for many physiological processes, including glucose metabolism, regulation of inflammation, and intestinal barrier function. Further, zinc dysregulation is associated with an increased risk of chronic inflammatory diseases such as type II diabetes, obesity, and inflammatory bowel disease. However, whether altered zinc status is a symptom or cause of disease onset remains unclear. Common symptoms of these three chronic diseases include the onset of increased intestinal permeability and zinc dyshomeostasis. The specific focus of this work is to investigate how dietary sources of intestinal permeability, such as high sucrose consumption, impact transporter-mediated zinc homeostasis and subsequent zinc-dependent physiology contributing to disease development. Method: We used in vivo subchronic sucrose treatment, ex vivo intestinal organoid culture, and in vitro cell systems. We analyze the alterations in zinc metabolism and intestinal permeability and metabolic outcomes. Results: We found that subchronic sucrose treatment resulted in systemic changes in steady-state zinc distribution and increased 65Zn transport (blood-to-intestine) along with greater ZIP14 expression at the basolateral membrane of the intestine. Further, sucrose treatment enhanced cell survival of intestinal epithelial cells, activation of the EGFR-AKT-STAT3 pathway, and intestinal permeability. Conclusion: Our work suggests that subchronic high sucrose consumption alters systemic and intestinal zinc homeostasis linking diet-induced changes in zinc homeostasis to the intestinal permeability and onset of precursors for chronic disease.

Hepatobiliary manganese homeostasis is dynamic in the setting of inflammation or infection in mice.

Manganese is a diet-derived micronutrient that is essential for critical cellular processes like redox homeostasis, protein glycosylation, and lipid and carbohydrate metabolism. Control of Mn availability, especially at the local site of infection, is a key component of the innate immune response. Less has been elucidated about Mn homeostasis at the systemic level. In this work, we demonstrate that systemic Mn homeostasis is dynamic in response to inflammation and infection in mice. This phenomenon is evidenced in male and female mice, mice of two genetic backgrounds (C57BL/6 and BALB/c), in multiple models of acute (dextran sodium sulfate-induced) and chronic (enterotoxigenic Bacteroides fragilis) colitis, and systemic infection with Candida albicans. When mice were fed a standard corn-based chow with excess Mn (100 ppm), liver Mn decreased and biliary Mn increased threefold in response to infection or colitis. Liver iron, copper, and zinc were unchanged. When dietary Mn was restricted to minimally adequate amounts (10 ppm), baseline hepatic Mn levels decreased by approximately 60% in the liver, and upon induction of colitis, liver Mn did not decrease further, however, biliary Mn still increased 20-fold. In response to acute colitis, hepatic Slc39a8 mRNA (gene encoding the Mn importer, Zip8) and Slc30a10 mRNA (gene encoding the Mn exporter, Znt10) are decreased. Zip8 protein is decreased. Inflammation/infection-associated dynamic Mn homeostasis may represent a novel host immune/inflammatory response that reorganizes systemic Mn availability through differential expression of key Mn transporters with down-regulation of Zip8.

Metal-ion transporter SLC39A8 is required for brain manganese uptake and accumulation.

Manganese (Mn) is an essential nutrient, but is toxic in excess. Whole-body Mn levels are regulated in part by the metal-ion influx transporter SLC39A8, which plays an essential role in the liver by reclaiming Mn from bile. Physiological roles of SLC39A8 in Mn homeostasis in other tissues, however, remain largely unknown. To screen for extrahepatic requirements for SLC39A8 in tissue Mn homeostasis, we crossed Slc39a8-inducible global-KO (Slc39a8 iKO) mice with Slc39a14 KO mice, which display markedly elevated blood and tissue Mn levels. Tissues were then analyzed by inductively coupled plasma-mass spectrometry to determine levels of Mn. Although Slc39a14 KO; Slc39a8 iKO mice exhibited systemic hypermanganesemia and increased Mn loading in the bone and kidney due to Slc39a14 deficiency, we show Mn loading was markedly decreased in the brains of these animals, suggesting a role for SLC39A8 in brain Mn accumulation. Levels of other divalent metals in the brain were unaffected, indicating a specific effect of SLC39A8 on Mn. In vivo radiotracer studies using 54Mn in Slc39a8 iKO mice revealed that SLC39A8 is required for Mn uptake by the brain, but not most other tissues. Furthermore, decreased 54Mn uptake in the brains of Slc39a8 iKO mice was associated with efficient inactivation of Slc39a8 in isolated brain microvessels but not in isolated choroid plexus, suggesting SLC39A8 mediates brain Mn uptake via the blood-brain barrier. These findings establish SLC39A8 as a candidate therapeutic target for mitigating Mn uptake and accumulation in the brain, the primary organ of Mn toxicity.

Hepatic and intestinal manganese excretion are both required to regulate brain manganese during elevated manganese exposure.

Manganese (Mn) is essential but neurotoxic at elevated levels. Under physiological conditions, Mn is primarily excreted by the liver, with the intestines playing a secondary role. Recent analyses of tissue-specific Slc30a10 or Slc39a14 knockout mice (SLC30A10 and SLC39A14 are Mn transporters) revealed that, under physiological conditions: 1) excretion of Mn by the liver and intestines is a major pathway that regulates brain Mn; and surprisingly, 2) the intestines compensate for loss of hepatic Mn excretion in controlling brain Mn. The unexpected importance of the intestines in controlling physiological brain Mn led us to determine the role of hepatic and intestinal Mn excretion in regulating brain Mn during elevated Mn exposure. We used liver- or intestine-specific Slc30a10 knockout mice as models to inhibit hepatic or intestinal Mn excretion. Compared with littermates, both knockout strains exhibited similar increases in brain Mn after elevated Mn exposure in early or later life. Thus, unlike physiological conditions, both hepatic and intestinal Mn excretion are required to control brain Mn during elevated Mn exposure. However, brain Mn levels of littermates and both knockout strains exposed to elevated Mn only in early life were normalized in later life. Thus, hepatic and intestinal Mn excretion play compensatory roles in clearing brain Mn accumulated by early life Mn exposure. Finally, neuromotor assays provided evidence consistent with a role for hepatic and intestinal Mn excretion in functionally modulating Mn neurotoxicity during Mn exposure. Put together, these findings substantially enhance understanding of the regulation of brain Mn by excretion.NEW & NOTEWORTHY This article shows that, in contrast with expectations from prior studies and physiological conditions, excretion of manganese by the intestines and liver is equally important in controlling brain manganese during human-relevant manganese exposure. The results provide foundational insights about the interorgan mechanisms that control brain manganese homeostasis at the organism level and have important implications for the development of therapeutics to treat manganese-induced neurological disease.