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Ramos-Fernández E, Arrázola MS, Oliva CA, Arredondo SB, Varela-Nallar L, Inestrosa NC. Wnt5a promotes hippocampal postsynaptic development and GluN2B-induced expression via the eIF2α HRI kinase. Sci Rep 2021; 11:7395. [PMID: 33795747 PMCID: PMC8016897 DOI: 10.1038/s41598-021-86708-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/18/2021] [Indexed: 12/30/2022] Open
Abstract
Wnt signaling plays a key role in neurodevelopment and neuronal maturation. Specifically, Wnt5a stimulates postsynaptic assemblies, increases glutamatergic neurotransmission and, through calcium signaling, generates nitric oxide (NO). Trying to unveil the molecular pathway triggering these postsynaptic effects, we found that Wnt5a treatment induces a time-dependent increases in the length of the postsynaptic density (PSD), elicits novel synaptic contacts and facilitates F-actin flow both in in vitro and ex vivo models. These effects were partially abolished by the inhibition of the Heme-regulated eukaryotic initiation factor 2α (HRI) kinase, a kinase which phosphorylates the initiation translational factor eIF2α. When phosphorylated, eIF2α normally avoids the translation of proteins not needed during stress conditions, in order to avoid unnecessary energetic expenses. However, phosphorylated eIF2α promotes the translation of some proteins with more than one open reading frame in its 5′ untranslated region. One of these proteins targeted by Wnt-HRI-eIF2α mediated translation is the GluN2B subunit of the NMDA receptor. The identified increase in GluN2B expression correlated with increased NMDA receptor function. Considering that NMDA receptors are crucial for excitatory synaptic transmission, the molecular pathway described here contributes to the understanding of the fast and plastic translational mechanisms activated during learning and memory processes.
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Affiliation(s)
- Eva Ramos-Fernández
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile. .,École polytechnique fédérale de Lausanne, Lausanne, Switzerland.
| | - Macarena S Arrázola
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile.,Centro de Biología Integrativa, Universidad Mayor, Santiago, Chile
| | - Carolina A Oliva
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile
| | - Sebastián B Arredondo
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile
| | - Lorena Varela-Nallar
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile. .,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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Yamada KE, Eckhert CD. Boric Acid Activation of eIF2α and Nrf2 Is PERK Dependent: a Mechanism that Explains How Boron Prevents DNA Damage and Enhances Antioxidant Status. Biol Trace Elem Res 2019; 188:2-10. [PMID: 30196486 DOI: 10.1007/s12011-018-1498-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 08/28/2018] [Indexed: 02/06/2023]
Abstract
Boron is abundant in vegetables, nuts, legumes, and fruit and intake is associated with reduced risk of cancer and DNA damage and increased antioxidant status. Blood boric acid (BA) levels are approximately 10 μM BA in men at the mean US boron intake. Treatment of DU-145 human prostate cancer cells with 10 μM BA stimulates phosphorylation of elongation initiation factor 2α (eIF2α) at Ser51 leading to activation of the eIF2α/ATF4 pathway which activates the DNA damage-inducible protein GADD34. In the present study, we used MEF WT and MEF PERK (±) cells to test the hypothesis that BA-activated eIF2α phosphorylation requires protein kinase RNA-like endoplasmic reticulum kinase (PERK) and activates Nrf2 and the antioxidant response element (ARE). BA (10 μM) increased phosphorylation of eIF2α Ser51 in MEF WT cells at 1 h, but not in MEF Perk -/- cells exposed for as long as 6 h. GCN2 kinase-dependent phosphorylation of eIF2α Ser51 was activated in MEF PERK -/- cells by amino acid starvation. Nrf2 phosphorylation is PERK dependent and when activated is translocated from the cytoplasm to the nucleus where it acts as a transcription factor for ARE. DU-145 cells were treated with 10 μM BA and Nrf2 measured by immunofluorescence. Cytoplasmic Nrf2 was translocated to the nucleus at 1.5-2 h in DU-145 and MEF WT cells, but not MEF PERK -/- cells. Real-time PCR was used to measure mRNA levels of three ARE genes (HMOX-1, NQO1, and GCLC). Treatment with 10 μM BA increased the mRNA levels of all three genes at 1-4 h in DU-145 cells and HMOX1 and GCLC in MEF WT cells. These results extend the known boric acid signaling pathway to ARE-regulated genes. The BA signaling pathway can be expressed using the schematic [BA + cADPR → cADPR-BA → [[ER]i Ca2+↓] → 3 pathways: PERK/eIF2αP → pathways ATF4 and Nrf2; and [[ER]i Ca2+↓] → ER stress → ATF6 pathway. This signaling pathway provides a framework that links many of the molecular changes that underpin the biological effects of boron intake.
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Affiliation(s)
- Kristin E Yamada
- Interdepartmental Program in Molecular Toxicology, University of California, Los Angeles, 90095, CA, USA
| | - Curtis D Eckhert
- Interdepartmental Program in Molecular Toxicology, University of California, Los Angeles, 90095, CA, USA.
- Department of Environmental Health Sciences, Fielding School of Public Health, University of California, 650 Charles E. Young Dr., Los Angeles, CA, 90095, USA.
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Comer JM, Zhang L. Experimental Methods for Studying Cellular Heme Signaling. Cells 2018; 7:cells7060047. [PMID: 29795036 PMCID: PMC6025097 DOI: 10.3390/cells7060047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/15/2018] [Accepted: 05/18/2018] [Indexed: 01/10/2023] Open
Abstract
The study of heme is important to our understanding of cellular bioenergetics, especially in cancer cells. The function of heme as a prosthetic group in proteins such as cytochromes is now well-documented. Less is known, however, about its role as a regulator of metabolic and energetic pathways. This is due in part to some inherent difficulties in studying heme. Due to its slightly amphiphilic nature, heme is a "sticky" molecule which can easily bind non-specifically to proteins. In addition, heme tends to dimerize, oxidize, and aggregate in purely aqueous solutions; therefore, there are constraints on buffer composition and concentrations. Despite these difficulties, our knowledge of heme's regulatory role continues to grow. This review sums up the latest methods used to study reversible heme binding. Heme-regulated proteins will also be reviewed, as well as a system for imaging the cellular localization of heme.
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Affiliation(s)
- Jonathan M Comer
- Department of Biological Sciences, School of Natural Sciences and Mathematics, The University of Texas at Dallas, Richardson, TX 75080, USA.
| | - Li Zhang
- Department of Biological Sciences, School of Natural Sciences and Mathematics, The University of Texas at Dallas, Richardson, TX 75080, USA.
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Ramos-Fernández E, Tajes M, ILL-Raga G, Vargas L, Busquets-García A, Bosch-Morató M, Guivernau B, Valls-Comamala V, Gomis M, Grau C, Fandos C, Rosen MD, Rabinowitz MH, Inestrosa N, Maldonado R, Altafaj X, Ozaita A, Alvarez A, Vicente R, Valverde MA, Muñoz FJ. Glutamatergic stimulation induces GluN2B translation by the nitric oxide-Heme-Regulated eIF2α kinase in cortical neurons. Oncotarget 2016; 7:58876-58892. [PMID: 27557499 PMCID: PMC5312282 DOI: 10.18632/oncotarget.11417] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/13/2016] [Indexed: 02/06/2023] Open
Abstract
The activation of N-Methyl D-Aspartate Receptor (NMDAR) by glutamate is crucial in the nervous system function, particularly in memory and learning. NMDAR is composed by two GluN1 and two GluN2 subunits. GluN2B has been reported to participate in the prevalent NMDAR subtype at synapses, the GluN1/2A/2B. Here we studied the regulation of GluN2B expression in cortical neurons finding that glutamate up-regulates GluN2B translation through the action of nitric oxide (NO), which induces the phosphorylation of the eukaryotic translation initiation factor 2 α (eIF2α). It is a process mediated by the NO-heme-regulated eIF2α kinase (HRI), as the effect was avoided when a specific HRI inhibitor or a HRI small interfering RNA (siHRI) were used. We found that the expressed GluN2B co-localizes with PSD-95 at the postsynaptic ending, which strengthen the physiological relevance of the proposed mechanism. Moreover the receptors bearing GluN2B subunits upon NO stimulation are functional as high Ca2+ entry was measured and increases the co-localization between GluN2B and GluN1 subunits. In addition, the injection of the specific HRI inhibitor in mice produces a decrease in memory retrieval as tested by the Novel Object Recognition performance. Summarizing our data suggests that glutamatergic stimulation induces HRI activation by NO to trigger GluN2B expression and this process would be relevant to maintain postsynaptic activity in cortical neurons.
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Affiliation(s)
- Eva Ramos-Fernández
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Marta Tajes
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Gerard ILL-Raga
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Lina Vargas
- Cell Signaling Laboratory, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Arnau Busquets-García
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Mònica Bosch-Morató
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Biuse Guivernau
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Victòria Valls-Comamala
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Maria Gomis
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Cristina Grau
- Bellvitge Biomedical Research Institute, Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona, Spain
| | - César Fandos
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Mark D. Rosen
- Janssen Research and Development, L.L.C., San Diego, CA, United States of America
| | | | - Nibaldo Inestrosa
- CARE, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Rafael Maldonado
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Xavier Altafaj
- Bellvitge Biomedical Research Institute, Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona, Spain
| | - Andrés Ozaita
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Alejandra Alvarez
- Cell Signaling Laboratory, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Rubén Vicente
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Miguel A. Valverde
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Francisco J. Muñoz
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
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Smith AT, Pazicni S, Marvin KA, Stevens DJ, Paulsen KM, Burstyn JN. Functional divergence of heme-thiolate proteins: a classification based on spectroscopic attributes. Chem Rev 2015; 115:2532-58. [PMID: 25763468 DOI: 10.1021/cr500056m] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron T Smith
- †Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208, United States
| | - Samuel Pazicni
- ‡Department of Chemistry, University of New Hampshire, 23 Academic Way, Durham, New Hampshire 03824, United States
| | - Katherine A Marvin
- §Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Daniel J Stevens
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Katherine M Paulsen
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Judith N Burstyn
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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Abstract
AI (anaemia of inflammation) often manifests in patients with chronic immune activation due to cancer, chronic infections, autoimmune disorders, rheumatoid arthritis and other diseases. The pathogenesis of AI is complex and involves cytokine-mediated inhibition of erythropoiesis, insufficient erythropoietin production and diminished sensitivity of erythroid progenitors to this hormone, and retention of iron in haemoglobin-processing macrophages. NO (nitric oxide) is a gaseous molecule produced by activated macrophages that has been identified as having numerous effects on iron metabolism. In the present study, we explore the possibility that NO affects iron metabolism in reticulocytes and our results suggest that NO may also contribute to AI. We treated reticulocytes with the NO donor SNP (sodium nitroprusside). The results indicate that NO inhibits haem synthesis dramatically and rapidly at the level of erythroid-specific 5-aminolaevulinic acid synthase 2, which catalyses the first step of haem synthesis in erythroid cells. We also show that NO leads to the inhibition of iron uptake via the Tf (transferrin)-Tf receptor pathway. In addition, NO also causes an increase in eIF2α (eukaryotic initiation factor 2α) phosphorylation levels and decreases globin translation. The profound impairment of haem synthesis, iron uptake and globin translation in reticulocytes by NO raises the possibility that this gas may also contribute to AI.
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Dalton LE, Healey E, Irving J, Marciniak SJ. Phosphoproteins in stress-induced disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:189-221. [PMID: 22340719 DOI: 10.1016/b978-0-12-396456-4.00003-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The integrated stress response (ISR) is an evolutionarily conserved homeostatic program activated by specific pathological states. These include amino acid deprivation, viral infection, iron deficiency, and the misfolding of proteins within the endoplasmic reticulum (ER), the so-called ER stress. Although apparently disparate, each of these stresses induces phosphorylation of a translation initiation factor, eIF2α, to attenuate new protein translation while simultaneously triggering a transcriptional program. This is achieved by four homologous stress-sensing kinases: GCN2, PKR, HRI, and PERK. In addition to these kinases, mammals possess two specific eIF2α phosphatases, GADD34 and CReP, which play crucial roles in the recovery of protein synthesis following the initial insult. They are not only important in embryonic development but also appear to play important roles in disease, particularly cancer. In this chapter, we discuss each of the eIF2α kinases, in turn, with particular emphasis on their regulation and the new insights provided by recent structural studies. We also discuss the potential for developing novel drug therapies that target the ISR.
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Affiliation(s)
- Lucy E Dalton
- Division of Respiratory Medicine, Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
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Tong L, Heim RA, Wu S. Nitric oxide: a regulator of eukaryotic initiation factor 2 kinases. Free Radic Biol Med 2011; 50:1717-25. [PMID: 21463677 PMCID: PMC3096732 DOI: 10.1016/j.freeradbiomed.2011.03.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 03/24/2011] [Accepted: 03/26/2011] [Indexed: 12/18/2022]
Abstract
Generation of nitric oxide (NO(•)) can upstream induce and downstream mediate the kinases that phosphorylate the α subunit of eukaryotic initiation factor 2 (eIF2α), which plays a critical role in regulating gene expression. There are four known eIF2α kinases (EIF2AKs), and NO(•) affects each one uniquely. Whereas NO(•) directly activates EIF2AK1 (HRI), it indirectly activates EIF2AK3 (PERK). EIF2AK4 (GCN2) is activated by depletion of l-arginine, which is used by nitric oxide synthase (NOS) during the production of NO(•). Finally EIF2AK2 (PKR), which can mediate inducible NOS expression and therefore NO(•) production, can also be activated by NO(•). The production of NO(•) and activation of EIF2AKs coordinately regulate physiological and pathological events such as innate immune response and cell apoptosis.
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Affiliation(s)
| | | | - Shiyong Wu
- Address correspondence to: Dr. Shiyong Wu, Edison Biotechnology Institute, 101 Konneker Laboratories, The Ridges, Building 25, Athens, OH 45701, Tel. (740) 597-1318, Fax (740) 593-4795;
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Yao X, Balamurugan P, Arvey A, Leslie C, Zhang L. Heme controls the regulation of protein tyrosine kinases Jak2 and Src. Biochem Biophys Res Commun 2010; 403:30-5. [PMID: 21036157 DOI: 10.1016/j.bbrc.2010.10.101] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 10/22/2010] [Indexed: 10/18/2022]
Abstract
Protein tyrosine kinases play key roles in many molecular and cellular processes in diverse living organisms. Their proper functioning is crucial for the normal growth, development, and health in humans, whereas their dysfunction can cause serious diseases, including various cancers. As such, intense studies have been performed to understand the molecular mechanisms by which the activities of protein tyrosine kinases are regulated in mammalian cells. Particularly, small molecules that can modulate the activity of tyrosine kinases are of great importance for discovering therapeutic drug candidates for numerous diseases. Notably, heme cannot only serve as a prosthetic group for hemoglobins and enzymes, but it also is a small signaling molecule that can control the activity of diverse signaling and regulatory proteins. Using a computational search, we found that a group of non-membrane spanning tyrosine kinases contains one or more CP motifs that can potentially bind to heme and mediate heme regulation. We then used experimental approaches to determine whether heme can affect the activity of any of these tyrosine kinases. We found that heme indeed affects the phosphorylation of key tyrosine residues in Jak2 and Src, and is therefore able to modulate Jak2 and Src activity. Further experiments showed that Jak2 and Src bind to heme and that the presence of heme alters the sensitivity of Jak2 and Src to trypsin digestion. These results suggest that heme actively interacts with Jak2 and Src and alters their conformation.
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Affiliation(s)
- Xiao Yao
- Department of Molecular and Cell Biology, University of Texas at Dallas, Mail Stop FO31, 800 W. Campbell Road, Richardson, TX 75080, USA
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Pervin S, Tran AH, Zekavati S, Fukuto JM, Singh R, Chaudhuri G. Increased susceptibility of breast cancer cells to stress mediated inhibition of protein synthesis. Cancer Res 2008; 68:4862-74. [PMID: 18559534 DOI: 10.1158/0008-5472.can-08-0074] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Protein synthesis is a tightly controlled process, and its deregulation plays an important role in tumorigenesis. Protein synthesis remains poorly understood with very few well-identified validated targets for therapeutic purposes. In this study, we use nitric oxide (NO), which suppresses protein synthesis by inactivating eukaryotic initiation factor 2-alpha (eIF2-alpha), to examine the mechanism by which low and high oxidative stress inhibits protein synthesis. In breast cancer cells, low NO stress induced heme-regulated inhibitor (HRI) activation, which facilitated gradual decline in short half-life proteins. High NO stress induced HRI and protein kinase R (PKR) activation, leading to a sharp decline in protein synthesis as accessed by a decline in short and long half-life proteins and dramatic morphologic changes. In contrast, human mammary epithelial (HME) and Ras transfected untransformed HME (MCF-10A1 neo N) cells were less susceptible to NO-induced inhibition of protein synthesis and cytostasis. Our results suggest that NO-induced cytostasis in breast cancer cells was due to PKR activation and increased phosphorylation of eIF2-alpha, whereas the reduced susceptibility of normal mammary epithelial cells to NO could be due to the inaccessibility of PKR, which is bound to inhibitor p58.
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Affiliation(s)
- Shehla Pervin
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at University of California, Los Angeles, USA.
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Kim HP, Morse D, Choi AMK. Heat-shock proteins: new keys to the development of cytoprotective therapies. Expert Opin Ther Targets 2006; 10:759-69. [PMID: 16981832 DOI: 10.1517/14728222.10.5.759] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
As molecular chaperones, heat-shock proteins (HSPs) function to limit protein aggregation, facilitate protein refolding and chaperone other proteins. Under conditions of cellular stress, intracellular HSP levels increase in order to provide cellular protection and maintain homeostasis. Evidence exists that the HSP family may be secreted into the circulation via lipid raft-mediated, granule-mediated or exosome-mediated exocytosis in haematopoietic and tumour cells. Extracellular HSPs exert immunomodulatory activities and play an important role in innate immune activation against pathogen infection. Membrane-bound Hsp70 in tumour cells or released chaperone-tumour associated antigen complex represent a target structure for the cytolytic attack by natural killer cells or T lymphocytes. Cellular stresses induce stress granule formation to evade detrimental cellular effects, mediating preconditioning phenotype. Therefore, induction of cellular stress tolerance by preconditioning (e.g., heat shock) might be potential therapeutic targets.
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Affiliation(s)
- Hong Pyo Kim
- University of Pittsburgh, Division of Pulmonary Allergy and Critical Care Medicine, Department of Medicine, MUH 628NW, 3459 Fifth Avenue, Pittsburgh, PA 15213, USA
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Mense SM, Zhang L. Heme: a versatile signaling molecule controlling the activities of diverse regulators ranging from transcription factors to MAP kinases. Cell Res 2006; 16:681-92. [PMID: 16894358 DOI: 10.1038/sj.cr.7310086] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Heme (iron protoporphyrin IX) is an essential molecule for numerous living organisms. Not only does it serve as a prosthetic group in enzymes, it also acts as a signaling molecule that controls diverse molecular and cellular processes ranging from signal transduction to protein complex assembly. Deficient heme synthesis or function impacts the hematopoietic, hepatic and nervous systems in humans. Recent studies have revealed a series of heme-regulated transcription factors and signal transducers including Hap1, a heme-activated transcription factor that mediates the effects of oxygen on gene transcription in the yeast Saccharomyces cerevisiae; Bach1, a transcriptional repressor that is negatively regulated by heme in mammalian cells; IRR, an iron regulatory protein that mediates the iron-dependant regulation of heme synthesis in the bacterium Bradyrhizobium japonicum; and heme-regulated inhibitor, an eucaryotic initiation factor 2alpha kinase that coordinates protein synthesis with heme availability in reticulocytes. In this review, we summarize the current knowledge about how heme controls the activity of these transcriptional regulators and signal transducers, and discuss diseases associated with defective heme synthesis, degradation and function.
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Affiliation(s)
- Sarah M Mense
- Department of Environmental Health Sciences, Columbia University, Mailman School of Public Health, New York, NY 10032, USA
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