Aberrant Expression of ZIP and ZnT Zinc Transporters in UROtsa Cells Transformed to Malignant Cells by Cadmium

Maintenance of zinc homeostasis is pivotal to the regulation of cell growth, differentiation, apoptosis, and defense mechanisms. In mammalian cells, control of cellular zinc homeostasis is through zinc uptake, zinc secretion, and zinc compartmentalization, mediated by metal transporters of the Zrt-/Irt-like protein (ZIP) family and the Cation Diffusion Facilitators (CDF) or ZnT family. We quantified transcript levels of ZIP and ZnT zinc transporters expressed by non-tumorigenic UROtsa cells and compared with those expressed by UROtsa clones that were experimentally transformed to cancer cells by prolonged exposure to cadmium (Cd). Although expression of the ZIP8 gene in parent UROtsa cells was lower than ZIP14 (0.1 vs. 83 transcripts per 1000 β-actin transcripts), an increased expression of ZIP8 concurrent with a reduction in expression of one or two zinc influx transporters, namely ZIP1, ZIP2, and ZIP3, were seen in six out of seven transformed UROtsa clones. Aberrant expression of the Golgi zinc transporters ZIP7, ZnT5, ZnT6, and ZnT7 were also observed. One transformed clone showed distinctively increased expression of ZIP6, ZIP10, ZIP14, and ZnT1, with a diminished ZIP8 expression. These data suggest intracellular zinc dysregulation and aberrant zinc homeostasis both in the cytosol and in the Golgi in the transformed UROtsa clones. These results provide evidence for zinc dysregulation in transformed UROtsa cells that may contribute in part to their malignancy and/or muscle invasiveness.

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Expression Analysis of Zinc Transporters in Nervous Tissue Cells Reveals Neuronal and Synaptic Localization of ZIP4

International Journal of Molecular Sciences ◽

10.3390/ijms22094511 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4511

Author(s):

Chiara A. De Benedictis ◽

Claudia Haffke ◽

Simone Hagmeyer ◽

Ann Katrin Sauer ◽

Andreas M. Grabrucker

Keyword(s):

Brain Function ◽

Zinc Homeostasis ◽

Zinc Transporters ◽

Excitatory Synapses ◽

Short Term ◽

Synaptic Localization ◽

Zinc Levels ◽

Rat Astrocyte ◽

Cellular Zinc ◽

The Brain

In the last years, research has shown that zinc ions play an essential role in the physiology of brain function. Zinc acts as a potent neuromodulatory agent and signaling ions, regulating healthy brain development and the function of both neurons and glial cells. Therefore, the concentration of zinc within the brain and its cells is tightly controlled. Zinc transporters are key regulators of (extra-) cellular zinc levels, and deregulation of zinc homeostasis and zinc transporters has been associated with neurodegenerative and neuropsychiatric disorders. However, to date, the presence of specific family members and their subcellular localization within brain cells have not been investigated in detail. Here, we analyzed the expression of all zinc transporters (ZnTs) and Irt-like proteins (ZIPs) in the rat brain. We further used primary rat neurons and rat astrocyte cell lines to differentiate between the expression found in neurons or astrocytes or both. We identified ZIP4 expressed in astrocytes but significantly more so in neurons, a finding that has not been reported previously. In neurons, ZIP4 is localized to synapses and found in a complex with major postsynaptic scaffold proteins of excitatory synapses. Synaptic ZIP4 reacts to short-term fluctuations in local zinc levels. We conclude that ZIP4 may have a so-far undescribed functional role at excitatory postsynapses.

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Function, Structure, and Transport Aspects of ZIP and ZnT Zinc Transporters in Immune Cells

Journal of Immunology Research ◽

10.1155/2018/9365747 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 13

Author(s):

Bum-Ho Bin ◽

Juyeon Seo ◽

Sung Tae Kim

Keyword(s):

Immune Cells ◽

Drug Targets ◽

Therapeutic Potential ◽

Family Members ◽

Zinc Transporter ◽

Zinc Homeostasis ◽

Zinc Transporters ◽

Function Structure ◽

Rich Domain ◽

Zip Family

Zinc is an important trace metal in immune systems, and zinc transporters are involved in many immune responses. Recent advances have revealed the structural and biochemical bases for zinc transport across the cell membrane, with clinical implications for the regulation of zinc homeostasis in immune cells like dendritic cells, T cells, B cells, and mast cells. In this review, we discuss the function, structure, and transport aspects of two major mammalian zinc transporter types, importers and exporters. First, Zrt-/Irt-like proteins (ZIPs) mediate the zinc influx from the extracellular or luminal side into the cytoplasm. There are 14 ZIP family members in humans. They form a homo- or heterodimer with 8 transmembrane domains and extra-/intracellular domains of various lengths. Several ZIP members show specific extracellular domains composed of two subdomains, a helix-rich domain and proline-alanine-leucine (PAL) motif-containing domain. Second, ZnT (zinc transporter) was initially identified in early studies of zinc biology; it mediates zinc efflux as a counterpart of ZIPs in zinc homeostasis. Ten family members have been identified. They show a unique architecture characterized by a Y-shaped conformation and a large cytoplasmic domain. A precise, comprehensive understanding of the structures and transport mechanisms of ZIP and ZnT in combination with mice experiments would provide promising drug targets as well as a basis for identifying other transporters with therapeutic potential.

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The histidine-rich loop in the extracellular domain of ZIP4 binds zinc and plays a role in zinc transport

Biochemical Journal ◽

10.1042/bcj20190108 ◽

2019 ◽

Vol 476 (12) ◽

pp. 1791-1803 ◽

Cited By ~ 4

Author(s):

Tuo Zhang ◽

Eziz Kuliyev ◽

Dexin Sui ◽

Jian Hu

Keyword(s):

Extracellular Domain ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Zinc Binding ◽

Functional Study ◽

Acrodermatitis Enteropathica ◽

Zinc Transport ◽

Metal Transporters ◽

Histidine Residues ◽

Zip Family

Abstract The Zrt-/Irt-like protein (ZIP) family mediates zinc influx from extracellular space or intracellular vesicles/organelles, playing a central role in systemic and cellular zinc homeostasis. Out of the 14 family members encoded in human genome, ZIP4 is exclusively responsible for zinc uptake from dietary food and dysfunctional mutations of ZIP4 cause a life-threatening genetic disorder, Acrodermatitis Enteropathica (AE). About half of the missense AE-causing mutations occur within the large N-terminal extracellular domain (ECD), and our previous study has shown that ZIP4–ECD is crucial for optimal zinc uptake but the underlying mechanism has not been clarified. In this work, we examined zinc binding to the isolated ZIP4–ECD from Pteropus Alecto (black fruit bat) and located zinc-binding sites with a low micromolar affinity within a histidine-rich loop ubiquitously present in ZIP4 proteins. Zinc binding to this protease-susceptible loop induces a small and highly localized structural perturbation. Mutagenesis and functional study on human ZIP4 by using an improved cell-based zinc uptake assay indicated that the histidine residues within this loop are not involved in preselection of metal substrate but play a role in promoting zinc transport. The possible function of the histidine-rich loop as a metal chaperone facilitating zinc binding to the transport site and/or a zinc sensor allosterically regulating the transport machinery was discussed. This work helps to establish the structure/function relationship of ZIP4 and also sheds light on other metal transporters and metalloproteins with clustered histidine residues.

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Zinc Homeostasis in Bone: Zinc Transporters and Bone Diseases

International Journal of Molecular Sciences ◽

10.3390/ijms21041236 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1236 ◽

Cited By ~ 4

Author(s):

Tongling Huang ◽

Guoyong Yan ◽

Min Guan

Keyword(s):

Cell Types ◽

Bone Diseases ◽

Zinc Transporter ◽

Zinc Homeostasis ◽

Zinc Transporters ◽

Bone Homeostasis ◽

Microstructural Stability ◽

Physiological Processes ◽

Zip Family ◽

Intracellular Compartments

Zinc is an essential micronutrient that plays critical roles in numerous physiological processes, including bone homeostasis. The majority of zinc in the human body is stored in bone. Zinc is not only a component of bone but also an essential cofactor of many proteins involved in microstructural stability and bone remodeling. There are two types of membrane zinc transporter proteins identified in mammals: the Zrt- and Irt-like protein (ZIP) family and the zinc transporter (ZnT) family. They regulate the influx and efflux of zinc, accounting for the transport of zinc through cellular and intracellular membranes to maintain zinc homeostasis in the cytoplasm and in intracellular compartments, respectively. Abnormal function of certain zinc transporters is associated with an imbalance of bone homeostasis, which may contribute to human bone diseases. Here, we summarize the regulatory roles of zinc transporters in different cell types and the mechanisms underlying related pathological changes involved in bone diseases. We also present perspectives for further studies on bone homeostasis-regulating zinc transporters.

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Zinc, metallothioneins and immunosenescence

Proceedings of The Nutrition Society ◽

10.1017/s0029665110001862 ◽

2010 ◽

Vol 69 (3) ◽

pp. 290-299 ◽

Cited By ~ 22

Author(s):

E. Mocchegiani ◽

M. Malavolta ◽

L. Costarelli ◽

R. Giacconi ◽

C. Cipriano ◽

...

Keyword(s):

Innate Immunity ◽

Zinc Supplementation ◽

Killer Cell ◽

Zinc Content ◽

Zinc Homeostasis ◽

Zinc Transporters ◽

Intracellular Zinc ◽

Natural Killer Cell Cytotoxicity ◽

Zip Family

Ageing is an inevitable biological process with gradual and spontaneous biochemical and physiological changes and increased susceptibility to diseases. The nutritional factor, zinc, may remodel these changes with subsequent healthy ageing, because zinc improves the inflammatory/immune response as shown by in vitro and in vivo studies. The intracellular zinc homeostasis is regulated by buffering metallothioneins (MT) and zinc transporters (ZnT and ZIP families) that mediate the intracellular zinc signalling assigning to zinc a role of ‘second messenger’. In ageing, the intracellular zinc homeostasis is altered, because high MT are unable to release zinc and some zinc transporters deputed to zinc influx (ZIP family) are defective leading to low intracellular zinc content for the immune efficiency. Physiological zinc supplementation in the elderly improves these functions. However, the choice of old subjects for zinc supplementation has to be performed in relation to the specific genetic background of MT and IL-6, because the latter is involved both in MTmRNA and in intracellular zinc homeostasis. Old subjects carrying GG genotypes (C–carriers) in the IL-6–174G/C locus display high IL-6, low intracellular zinc content, impaired innate immunity and enhanced MT. Old subjects carrying GC and CC genotypes (C+carriers) display satisfactory intracellular zinc content, adequate innate immunity and are more prone to reach longevity. Zinc supplementation in old C–carriers restores natural killer cell cytotoxicity and zinc status. The genetic variations of the IL-6−174G/C locus when associated with those of the MT1A+647A/C locus are useful tools for the choice of old people for zinc supplementation.

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The role of zinc transporter proteins as predictive and prognostic biomarkers of hepatocellular cancer

PeerJ ◽

10.7717/peerj.12314 ◽

2021 ◽

Vol 9 ◽

pp. e12314

Author(s):

Ceylan V. Bitirim

Keyword(s):

Tumor Progression ◽

Zinc Deficiency ◽

Zinc Level ◽

Zinc Transporter ◽

Tumor Formation ◽

Zinc Homeostasis ◽

Zinc Transporters ◽

Transporter Proteins ◽

Grade Ii ◽

Cellular Zinc

Identification of the key processes involved in the tumor progression, malignancy and the molecular factors which are responsible for the transition of the cirrhotic cells to the tumor cells, contribute to the detection of biomarkers for diagnosis of hepatocellular carcinoma (HCC) at an early stage. According to clinical data, HCC is mostly characterized by a significant decrease in zinc levels. It is strongly implied that zinc deficiency is the major event required in the early stages of tumor formation and development of malignancy. Due to this reason, the definition of the molecular players which have a role in zinc homeostasis and cellular zinc level could give us a clue about the transition state of the cirrhosis to hepatic tumor formation. Despite the well-known implications of zinc in the development of HCCthe correlation of the expression of zinc transporter proteins with tumor progression and malignancy remain largely unknown. In the present study, we evaluated in detail the relationship of zinc deficiency on the prognosis of early HCC patients. In this study, we aimed to test the potential zinc transporters which contribute tothe transformation of cirrhosis to HCCand the progression of HCC. Among the 24 zinc transporter proteins, the proteins to be examined were chosen by using Gene Expression Profiling Interactive Analysis (GEPIA) webpage and RNA-seq analysis using TCGA database. ZIP14 and ZIP5 transporters were found as common differentially expressed genes from both bioinformatic analyses. ZnT1, ZnT7 and ZIP7 transporters have been associated with tumor progression. Relative abundance of ZnT1, ZIP5 and ZIP14 protein level was determined by immunohistochemistry (IHC) in surgically resected liver specimens from 16 HCC patients at different stages. IHC staining intensity was analyzed by using ImageJ software and scored with the histological scoring (H-score) method. The staining of ZnT1 was significantly higher in Grade III comparing to Grade II and Grade I. On the contrary, ZIP14 staining decreased almost 10-foldcomparing to Grade Iand Grade II. ZIP5 staining was detected almost 2-fold higher in cirrhosis than HCC. But ZnT1 staining was observed almost 3-fold lower in cirrhosis comparing to HCC. Intracellular free zinc level was measured by flow cytometry in Hep40 and Snu398 cells using FluoZin-3 dye. The intracellular free zinc level was almost 9-fold decreased in poor differentiated Snu398 HCC cells comparing to well differentiated Hep40 HCC cells.This report establishes for the first time the correlation between the expression pattern of ZIP14, ZnT1 and ZIP5 and significant zinc deficiency which occurs concurrently with the advancing of malignancy. Our results provide new molecular insight into ZnT1, ZIP14 and ZIP5 mediated regulation of cellular zinc homeostasis and indicate that zinc transporters might be important factors and events in HCC malignancy, which can lead to the development of early biomarkers.

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Cooperation of metallothionein and zinc transporters for regulating zinc homeostasis in human intestinal Caco-2 cells

Nutrition Research ◽

10.1016/j.nutres.2008.02.011 ◽

2008 ◽

Vol 28 (6) ◽

pp. 406-413 ◽

Cited By ~ 25

Author(s):

Hui Shen ◽

Haihong Qin ◽

Junsheng Guo

Keyword(s):

Zinc Homeostasis ◽

Zinc Transporters

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A distinct role in breast cancer for two LIV-1 family zinc transporters

Biochemical Society Transactions ◽

10.1042/bst0361247 ◽

2008 ◽

Vol 36 (6) ◽

pp. 1247-1251 ◽

Cited By ~ 26

Author(s):

Kathryn M. Taylor

Keyword(s):

Breast Cancer ◽

Cancer Metastasis ◽

Prognostic Indicator ◽

Breast Cancer Metastasis ◽

Zinc Transporters ◽

Aberrant Expression ◽

Disease States ◽

Cancer Spread ◽

Protein Transporters

Zinc, essential for normal cell growth, is tightly controlled in cells by two families of zinc transporters. The aberrant expression of zinc transporters from the LIV-1 family of ZIP (Zrt/Irt-like protein) transporters is increasingly being implicated in a variety of disease states. In the present paper, I describe a mechanism for the role of ZIP7 in the progression of breast cancer, identifying it as a new target in breast cancer. Furthermore, I document a link between another zinc transporter, LIV-1, and breast cancer metastasis, identifying it as a potential new prognostic indicator of breast cancer spread.

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