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Török Z, Crul T, Maresca B, Schütz GJ, Viana F, Dindia L, Piotto S, Brameshuber M, Balogh G, Péter M, Porta A, Trapani A, Gombos I, Glatz A, Gungor B, Peksel B, Vigh L, Csoboz B, Horváth I, Vijayan MM, Hooper PL, Harwood JL, Vigh L. Plasma membranes as heat stress sensors: from lipid-controlled molecular switches to therapeutic applications. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1594-618. [PMID: 24374314 DOI: 10.1016/j.bbamem.2013.12.015] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 12/09/2013] [Accepted: 12/18/2013] [Indexed: 12/31/2022]
Abstract
The classic heat shock (stress) response (HSR) was originally attributed to protein denaturation. However, heat shock protein (Hsp) induction occurs in many circumstances where no protein denaturation is observed. Recently considerable evidence has been accumulated to the favor of the "Membrane Sensor Hypothesis" which predicts that the level of Hsps can be changed as a result of alterations to the plasma membrane. This is especially pertinent to mild heat shock, such as occurs in fever. In this condition the sensitivity of many transient receptor potential (TRP) channels is particularly notable. Small temperature stresses can modulate TRP gating significantly and this is influenced by lipids. In addition, stress hormones often modify plasma membrane structure and function and thus initiate a cascade of events, which may affect HSR. The major transactivator heat shock factor-1 integrates the signals originating from the plasma membrane and orchestrates the expression of individual heat shock genes. We describe how these observations can be tested at the molecular level, for example, with the use of membrane perturbers and through computational calculations. An important fact which now starts to be addressed is that membranes are not homogeneous nor do all cells react identically. Lipidomics and cell profiling are beginning to address the above two points. Finally, we observe that a deregulated HSR is found in a large number of important diseases where more detailed knowledge of the molecular mechanisms involved may offer timely opportunities for clinical interventions and new, innovative drug treatments. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.
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Affiliation(s)
- Zsolt Török
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary.
| | - Tim Crul
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Bruno Maresca
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Felix Viana
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, 03550 San Juan de Alicante, Spain
| | - Laura Dindia
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Stefano Piotto
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Mario Brameshuber
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Gábor Balogh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Amalia Porta
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Alfonso Trapani
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Salerno, Italy
| | - Imre Gombos
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Attila Glatz
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Burcin Gungor
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Begüm Peksel
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Bálint Csoboz
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary
| | - Mathilakath M Vijayan
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada; Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Phillip L Hooper
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Medical School, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | - László Vigh
- Institute of Biochemistry, Biological Research Centre of the Hung. Acad. Sci., Szeged H-6726, Hungary.
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Juhász K, Thuenauer R, Spachinger A, Duda E, Horváth I, Vígh L, Sonnleitner A, Balogi Z. Lysosomal rerouting of Hsp70 trafficking as a potential immune activating tool for targeting melanoma. Curr Pharm Des 2013; 19:430-40. [PMID: 22920897 PMCID: PMC3531874 DOI: 10.2174/138161213804143644] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/15/2012] [Indexed: 12/17/2022]
Abstract
Tumor specific cell surface localization and release of the stress inducible heat shock protein 70 (Hsp70) stimulate the immune
system against cancer cells. A key immune stimulatory function of tumor-derived Hsp70 has been exemplified with the murine melanoma
cell model, B16 overexpressing exogenous Hsp70. Despite the therapeutic potential mechanism of Hsp70 transport to the surface
and release remained poorly understood. We investigated principles of Hsp70 trafficking in B16 melanoma cells with low and high level
of Hsp70. In cells with low level of Hsp70 apparent trafficking of Hsp70 was mediated by endosomes. Excess Hsp70 triggered a series of
changes such as a switch of Hsp70 trafficking from endosomes to lysosomes and a concomitant accumulation of Hsp70 in lysosomes.
Moreover, lysosomal rerouting resulted in an elevated concentration of surface Hsp70 and enabled active release of Hsp70. In fact, hyperthermia,
a clinically applicable approach triggered immediate active lysosomal release of soluble Hsp70 from cells with excess Hsp70.
Furthermore, excess Hsp70 enabled targeting of internalized surface Hsp70 to lysosomes, allowing in turn heat-induced secretion of surface
Hsp70. Altogether, we show that excess Hsp70 expressed in B16 melanoma cells diverts Hsp70 trafficking from endosomes to
lysosomes, thereby supporting its surface localization and lysosomal release. Controlled excess-induced lysosomal rerouting and secretion
of Hsp70 is proposed as a promising tool to stimulate anti-tumor immunity targeting melanoma.
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Affiliation(s)
- Kata Juhász
- Center for Advanced Bioanalysis GmbH, Gruberstr. 40-42, A-4020 Linz, Austria
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53
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Csoboz B, Balogh GE, Kusz E, Gombos I, Peter M, Crul T, Gungor B, Haracska L, Bogdanovics G, Torok Z, Horvath I, Vigh L. Membrane fluidity matters: Hyperthermia from the aspects of lipids and membranes. Int J Hyperthermia 2013; 29:491-9. [DOI: 10.3109/02656736.2013.808765] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Csermely P, Korcsmáros T, Kiss HJM, London G, Nussinov R. Structure and dynamics of molecular networks: a novel paradigm of drug discovery: a comprehensive review. Pharmacol Ther 2013; 138:333-408. [PMID: 23384594 PMCID: PMC3647006 DOI: 10.1016/j.pharmthera.2013.01.016] [Citation(s) in RCA: 511] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 01/22/2013] [Indexed: 02/02/2023]
Abstract
Despite considerable progress in genome- and proteome-based high-throughput screening methods and in rational drug design, the increase in approved drugs in the past decade did not match the increase of drug development costs. Network description and analysis not only give a systems-level understanding of drug action and disease complexity, but can also help to improve the efficiency of drug design. We give a comprehensive assessment of the analytical tools of network topology and dynamics. The state-of-the-art use of chemical similarity, protein structure, protein-protein interaction, signaling, genetic interaction and metabolic networks in the discovery of drug targets is summarized. We propose that network targeting follows two basic strategies. The "central hit strategy" selectively targets central nodes/edges of the flexible networks of infectious agents or cancer cells to kill them. The "network influence strategy" works against other diseases, where an efficient reconfiguration of rigid networks needs to be achieved by targeting the neighbors of central nodes/edges. It is shown how network techniques can help in the identification of single-target, edgetic, multi-target and allo-network drug target candidates. We review the recent boom in network methods helping hit identification, lead selection optimizing drug efficacy, as well as minimizing side-effects and drug toxicity. Successful network-based drug development strategies are shown through the examples of infections, cancer, metabolic diseases, neurodegenerative diseases and aging. Summarizing >1200 references we suggest an optimized protocol of network-aided drug development, and provide a list of systems-level hallmarks of drug quality. Finally, we highlight network-related drug development trends helping to achieve these hallmarks by a cohesive, global approach.
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Affiliation(s)
- Peter Csermely
- Department of Medical Chemistry, Semmelweis University, P.O. Box 260, H-1444 Budapest 8, Hungary.
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55
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Balogh G, Péter M, Glatz A, Gombos I, Török Z, Horváth I, Harwood JL, Vígh L. Key role of lipids in heat stress management. FEBS Lett 2013; 587:1970-80. [PMID: 23684645 DOI: 10.1016/j.febslet.2013.05.016] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 05/06/2013] [Indexed: 12/15/2022]
Abstract
Heat stress is a common and, therefore, an important environmental impact on cells and organisms. While much attention has been paid to severe heat stress, moderate temperature elevations are also important. Here we discuss temperature sensing and how responses to heat stress are not necessarily dependent on denatured proteins. Indeed, it is clear that membrane lipids have a pivotal function. Details of membrane lipid changes and the associated production of signalling metabolites are described and suggestions made as to how the interconnected signalling network could be modified for helpful intervention in disease.
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Affiliation(s)
- Gábor Balogh
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, H-6701 Szeged, Hungary
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Literati-Nagy Z, Tory K, Literáti-Nagy B, Bajza A, Vígh L, Vígh L, Mandl J, Szilvássy Z. Synergic insulin sensitizing effect of rimonabant and BGP-15 in Zucker-obese rats. Pathol Oncol Res 2013; 19:571-5. [PMID: 23640247 DOI: 10.1007/s12253-013-9620-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 02/22/2013] [Indexed: 10/26/2022]
Abstract
Abdominal obesity is referred for as a common pathogenic root of multiple risk factors, which include insulin resistance, dyslipidemia, hypertension, and a pro-atherogenic and pro-inflammatory state. Irrespective of its psychiatric side effects, rimonabant through blocking cannabinoid-1 receptor (CB1R) induces an increase in whole body insulin sensitivity. The aim of this work was to study the effect of selected doses of another insulin sensitizer compound BGP-15, and rimonabant on insulin resistance in Zucker obese rats with a promise of inducing insulin sensitization together at lower doses than would have been expected by rimonabant alone. We found that BGP-15 potentiates the insulin sensitizing effect of rimonabant. The combination at doses, which do not induce insulin sensitization by themselves, improved insulin signaling. Furthermore our results suggest that capsaicin-induced signal may play a role in insulin sensitizing effect of both molecules. Our data might indicate that a lower dose of rimonabant in the treatment of insulin resistance and type 2 diabetes is sufficient to administer, thus a lower incidence of the unfavorable psychiatric side effects of rimonabant are to be expected.
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Affiliation(s)
- Zsuzsanna Literati-Nagy
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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57
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Bromberg Z, Goloubinoff P, Saidi Y, Weiss YG. The membrane-associated transient receptor potential vanilloid channel is the central heat shock receptor controlling the cellular heat shock response in epithelial cells. PLoS One 2013; 8:e57149. [PMID: 23468922 PMCID: PMC3584136 DOI: 10.1371/journal.pone.0057149] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/22/2013] [Indexed: 12/31/2022] Open
Abstract
The heat shock response (HSR) is a highly conserved molecular response to various types of stresses, including heat shock, during which heat-shock proteins (Hsps) are produced to prevent and repair damages in labile proteins and membranes. In cells, protein unfolding in the cytoplasm is thought to directly enable the activation of the heat shock factor 1 (HSF-1), however, recent work supports the activation of the HSR via an increase in the fluidity of specific membrane domains, leading to activation of heat-shock genes. Our findings support the existence of a plasma membrane-dependent mechanism of HSF-1 activation in animal cells, which is initiated by a membrane-associated transient receptor potential vanilloid receptor (TRPV). We found in various non-cancerous and cancerous mammalian epithelial cells that the TRPV1 agonists, capsaicin and resiniferatoxin (RTX), upregulated the accumulation of Hsp70, Hsp90 and Hsp27 and Hsp70 and Hsp90 respectively, while the TRPV1 antagonists, capsazepine and AMG-9810, attenuated the accumulation of Hsp70, Hsp90 and Hsp27 and Hsp70, Hsp90, respectively. Capsaicin was also shown to activate HSF-1. These findings suggest that heat-sensing and signaling in mammalian cells is dependent on TRPV channels in the plasma membrane. Thus, TRPV channels may be important drug targets to inhibit or restore the cellular stress response in diseases with defective cellular proteins, such as cancer, inflammation and aging.
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Affiliation(s)
- Zohar Bromberg
- Dept. of Anesthesiology and Critical Care Medicine and the Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University School of Medicine, Jerusalem, Israel
| | - Pierre Goloubinoff
- Dept. of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | - Younousse Saidi
- Dept. of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | - Yoram George Weiss
- Dept. of Anesthesiology and Critical Care Medicine and the Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University School of Medicine, Jerusalem, Israel
- Dept. of Anesthesiology and Critical Care Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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58
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Literáti-Nagy Z, Tory K, Literáti-Nagy B, Kolonics A, Török Z, Gombos I, Balogh G, Vígh L, Horváth I, Mandl J, Sümegi B, Hooper PL, Vígh L. The HSP co-inducer BGP-15 can prevent the metabolic side effects of the atypical antipsychotics. Cell Stress Chaperones 2012; 17:517-21. [PMID: 22322357 PMCID: PMC3368033 DOI: 10.1007/s12192-012-0327-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/09/2012] [Accepted: 01/16/2012] [Indexed: 01/16/2023] Open
Abstract
Weight gain and dysfunction of glucose and lipid metabolism are well-known side effects of atypical antipsychotic drugs (AAPD). Here, we address the question whether a heat-shock protein (HSP) co-inducer, insulin sensitizer drug candidate, BGP-15, can prevent AAPD-induced glucose, lipid, and weight changes. We also examined how an AAPD alters HSP expression and whether BGP-15 alters that expression. Four different experiments are reported on the AAPD BGP-15 interventions in a human trial of healthy men, a rodent animal model, and an in vitro adipocyte cell culture system. Olanzapine caused rapid insulin resistance in healthy volunteers and was associated with decreased level of HSP72 in peripheral mononuclear blood cells. Both changes were restored by the administration of BGP-15. In Wistar rats, weight gain and insulin resistance induced by clozapine were abolished by BGP-15. In 3T3L1 adipocytes, clozapine increased intracellular fat accumulation, and BGP-15 inhibited this process. Taken together, our results indicate that BGP-15 inhibits multiple metabolic side effects of atypical antipsychotics, and this effect is likely to be related to its HSP co-inducing ability.
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Affiliation(s)
- Zsuzsanna Literáti-Nagy
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Kálmán Tory
- N-Gene Research and Development Ltd., Budapest, Hungary
| | | | | | - Zsolt Török
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
| | - Imre Gombos
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
| | - Gábor Balogh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
| | - László Vígh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
- Mecsek Pharma Research Ltd., Pécs, Hungary
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
| | - József Mandl
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Balázs Sümegi
- Department of Biochemistry and Medical Chemistry, University of Pécs, Pécs, Hungary
| | - Philip L. Hooper
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, Aurora, CO 80045 USA
| | - László Vígh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary
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A novel insulin sensitizer drug candidate-BGP-15-can prevent metabolic side effects of atypical antipsychotics. Pathol Oncol Res 2012; 18:1071-6. [PMID: 22743983 DOI: 10.1007/s12253-012-9546-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 05/30/2012] [Indexed: 10/28/2022]
Abstract
Atypical antipsychotic drugs (AAPD) are widely used to treat severe psychiatric disorders, have well documented metabolic side effects such as disturbances in glucose metabolism, insulin resistance and weight gain. It has been shown that BGP-15, a hydroxylamine derivative with insulin sensitizing activity can prevent AAPD provoked fat accumulation in adipocyte cultures, and insulin resistance in animal experiments and in healthy volunteers. The aim of this study was to compare the preventive effect of BGP-15 with conventional oral antidiabetics on metabolic side effects of AAPDs. We found that BGP-15 that does not belong to either conventional insulin sensitizers or oral antidiabetics, is able to counteract insulin resistance and weight gain provoked by antipsychotic agents in rats while rosiglitazone and metformin were not effective in the applied doses. Our results confirm that BGP-15 is a promising new drug candidate to control the metabolic side effects of atypical antipsychotics. Data indicate that this rat model is suitable to analyze the metabolic side effects of AAPDs and the protective mechanism of BGP-15.
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60
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Kampinga HH, Garrido C. HSPBs: small proteins with big implications in human disease. Int J Biochem Cell Biol 2012; 44:1706-10. [PMID: 22721753 DOI: 10.1016/j.biocel.2012.06.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/07/2012] [Accepted: 06/07/2012] [Indexed: 11/19/2022]
Abstract
Although initially somewhat ignored, recent studies have now clearly established that the diverse members of the human family of small HSPs (HSPB1-HSPB10) play crucial roles in a wide range of cell types to maintain the integrity and function of tissues, in particular that of nervous and muscular tissue. The 10 human HSPBs clearly have overlapping and non-overlapping functional characteristics. Their ability to self- and hetero-oligomerise provides the cells with a large array of potentially different, specific functions. Single HSPB members can have a multitude of functions (moonlighting) and act on different "clients", thus affecting a wide range of different processes or structures that can ultimately affect the rate of aging of tissues and entire organisms. This is underscored by the findings that some inherited diseases involve mutations in several HSPB members that cause premature (mostly muscle and neuronal) tissue degeneration. Inversely, cancer cell resistance to different anticancer therapies is associated with elevated expression of several HSPBs. Still, many unanswered questions exist about the precise functioning of HSPBs, their collaboration with other HSPB members as well as their functions within the entire cellular chaperone network. Also, better insight in the regulation of expression of the various members and how their function is modulated post-translationally is needed. Such may be crucially important to develop means to intervene with their function for therapeutic purposes, which would require functional down-regulation in cancer but up-regulation in, for instance, cardiac or degenerative neuro/neuromuscular diseases. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.
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Affiliation(s)
- Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
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61
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Péter M, Balogh G, Gombos I, Liebisch G, Horváth I, Török Z, Nagy E, Maslyanko A, Benkő S, Schmitz G, Harwood JL, Vígh L. Nutritional lipid supply can control the heat shock response of B16 melanoma cells in culture. Mol Membr Biol 2012; 29:274-89. [PMID: 22583025 DOI: 10.3109/09687688.2012.680203] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The in vitro culture of cells offers an extremely valuable method for probing biochemical questions and many commonly-used protocols are available. For mammalian cells a source of lipid is usually provided in the serum component. In this study we examined the question as to whether the nature of the lipid could become limiting at high cell densities and, therefore, prospectively influence the metabolism and physiology of the cells themselves. When B16 mouse melanoma cells were cultured, we noted a marked decrease in the proportions of n-3 and n-6 polyunsaturated fatty acids (PUFAs) with increasing cell density. This was despite considerable quantities of these PUFAs still remaining in the culture medium and seemed to reflect the preferential uptake of unesterified PUFA rather than other lipid classes from the media. The reduction in B16 total PUFA was reflected in changes in about 70% of the molecular species of membrane phosphoglycerides which were analysed by mass spectrometry. The importance of this finding lies in the need for n-3 and n-6 PUFA in mammalian cells (which cannot synthesize their own). Although the cholesterol content of cells was unchanged the amount of cholesterol enrichment in membrane rafts (as assessed by fluorescence) was severely decreased, simultaneous with a reduced heat shock response following exposure to 42°C. These data emphasize the pivotal role of nutrient supply (in this case for PUFAs) in modifying responses to stress and highlight the need for the careful control of culture conditions when assessing cellular responses in vitro.
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Affiliation(s)
- Mária Péter
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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