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Xu X, Xie T, Zhou M, Sun Y, Wang F, Tian Y, Chen Z, Xie Y, Wu R, Cen X, Zhou J, Hou T, Zhang L, Huang C, Zhao Q, Wang D, Xia H. Hsc70 promotes anti-tumor immunity by targeting PD-L1 for lysosomal degradation. Nat Commun 2024; 15:4237. [PMID: 38762492 PMCID: PMC11102475 DOI: 10.1038/s41467-024-48597-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 05/07/2024] [Indexed: 05/20/2024] Open
Abstract
Immune checkpoint inhibition targeting the PD-1/PD-L1 pathway has become a powerful clinical strategy for treating cancer, but its efficacy is complicated by various resistance mechanisms. One of the reasons for the resistance is the internalization and recycling of PD-L1 itself upon antibody binding. The inhibition of lysosome-mediated degradation of PD-L1 is critical for preserving the amount of PD-L1 recycling back to the cell membrane. In this study, we find that Hsc70 promotes PD-L1 degradation through the endosome-lysosome pathway and reduces PD-L1 recycling to the cell membrane. This effect is dependent on Hsc70-PD-L1 binding which inhibits the CMTM6-PD-L1 interaction. We further identify an Hsp90α/β inhibitor, AUY-922, which induces Hsc70 expression and PD-L1 lysosomal degradation. Either Hsc70 overexpression or AUY-922 treatment can reduce PD-L1 expression, inhibit tumor growth and promote anti-tumor immunity in female mice; AUY-922 can further enhance the anti-tumor efficacy of anti-PD-L1 and anti-CTLA4 treatment. Our study elucidates a molecular mechanism of Hsc70-mediated PD-L1 lysosomal degradation and provides a target and therapeutic strategies for tumor immunotherapy.
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Affiliation(s)
- Xiaoyan Xu
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Tingxue Xie
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China
| | - Mengxin Zhou
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China
| | - Yaqin Sun
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China
| | - Fengqi Wang
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China
| | - Yanan Tian
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China
| | - Ziyan Chen
- Department of Urology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yanqi Xie
- Department of Urology, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ronghai Wu
- Hangzhou PhecdaMed Co.Ltd, 2626 Yuhangtang Road, Hangzhou, China
| | - Xufeng Cen
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Jichun Zhou
- Department of Surgical Oncology, Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Tingjun Hou
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Lei Zhang
- Department of Cardiology/Health Management Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chaoyang Huang
- Department of Cardiology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Qingwei Zhao
- Department of Clinical Pharmacy, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Dongrui Wang
- Bone Marrow Transplantation Center, the First Affiliated Hospital, and Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China.
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China.
| | - Hongguang Xia
- Research Center of Clinical Pharmacy of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China.
- Department of Biochemistry, Zhejiang University School of Medicine, Hangzhou, China.
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Renman E, Ekici R, Sundström M, Lejon K. HSC70 is a novel binding partner involved in the capture of immunoglobulins on B cells in the NOD mouse. Autoimmunity 2022; 55:520-528. [PMID: 36120986 DOI: 10.1080/08916934.2022.2117307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
B cells have been shown to be essential for Type 1 diabetes development in the non-obese diabetic mouse, where their contribution as antigen presenting cells has been emphasised. Other important functions for B cells include surface capture of immunoglobulins and transportation of immune complexes, with subsequent endocytosis, antigen processing and antigen presentation. We have previously demonstrated that NOD B cells capture IgM and IgG immune complexes through an unknown surface molecule. In this study, we revealed the presumptive immunoglobulin-binding molecule to be HSC70. Moreover, we detected increased levels of HSC70 on NOD B cells. HSC70 has been shown to play a role in antigen processing and presentation as well as being important in several autoimmune diseases, including rheumatoid arthritis and systemic lupus erythematosus. Due to its protein stabilising properties, increased HSC70 could contribute to enhanced self-antigen collection and presentation and thereby contribute to the development of Type 1 diabetes.
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Affiliation(s)
- Emma Renman
- Department of Clinical Microbiology Umeå, Umeå University, Umeå, Sweden
| | - Rifat Ekici
- Department of Clinical Microbiology Umeå, Umeå University, Umeå, Sweden
| | - Mia Sundström
- Department of Clinical Microbiology Umeå, Umeå University, Umeå, Sweden
| | - Kristina Lejon
- Department of Clinical Microbiology Umeå, Umeå University, Umeå, Sweden
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De Maio A, Hightower L. The interaction of heat shock proteins with cellular membranes: a historical perspective. Cell Stress Chaperones 2021; 26:769-783. [PMID: 34478113 PMCID: PMC8413713 DOI: 10.1007/s12192-021-01228-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 01/09/2023] Open
Abstract
The interaction of heat shock proteins (HSP) with cellular membranes has been an enigmatic process, initially observed by morphological studies, inferred during the purification of HSP70s, and confirmed after the detection of these proteins on the surface of cancer cells and their insertion into artificial lipid bilayers. Today, the association of several HSP with lipid membranes is well established. However, the mechanisms for membrane insertion have been elusive. There is conclusive evidence indicating that HSP70s have a great selectivity for negatively charged phospholipids, whereas other HSP have a broader spectrum of lipid specificity. HSP70 also oligomerizes upon membrane insertion, forming ion conductance channels. The functional role of HSP70 lipid interactions appears related to membrane stabilization that may play a role during cell membrane biogenesis. They could also play a role as membrane chaperones as well as during endocytosis, microautophagy, and signal transduction. Moreover, HSP membrane association is a key component in the extracellular export of these proteins. The presence of HSP70 on the surface of cancer cells and its interaction with lysosome membranes have been envisioned as potential therapeutic targets. Thus, the biology and function of HSP membrane association are reaching a new level of excitement. This review is an attempt to preserve the recollection of the pioneering contributions of many investigators that have participated in this endeavor.
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Affiliation(s)
- Antonio De Maio
- Department of Surgery, Division of Trauma, Critical Care, Burns, and Acute Care Surgery, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
- Center for Investigations of Health and Education Disparities, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Lawrence Hightower
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
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Dores-Silva PR, Cauvi DM, Coto ALS, Silva NSM, Borges JC, De Maio A. Human heat shock cognate protein (HSC70/HSPA8) interacts with negatively charged phospholipids by a different mechanism than other HSP70s and brings HSP90 into membranes. Cell Stress Chaperones 2021; 26:671-684. [PMID: 34003451 PMCID: PMC8129608 DOI: 10.1007/s12192-021-01210-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/28/2021] [Accepted: 05/01/2021] [Indexed: 12/15/2022] Open
Abstract
Heat shock proteins (HSP) are critical elements for the preservation of cellular homeostasis by participating in an array of biological processes. In addition, HSP play an important role in cellular protection from various environmental stresses. HSP are part of a large family of different molecular mass polypeptides, displaying various expression patterns, subcellular localizations, and diversity functions. An unexpected observation was the detection of HSP on the cell surface. Subsequent studies have demonstrated that HSP have the ability to interact and penetrate lipid bilayers by a process initiated by the recognition of phospholipid heads, followed by conformational changes, membrane insertion, and oligomerization. In the present study, we described the interaction of HSPA8 (HSC70), the constitutive cytosolic member of the HSP70 family, with lipid membranes. HSPA8 showed high selectivity for negatively charged phospholipids, such as phosphatidylserine and cardiolipin, and low affinity for phosphatidylcholine. Membrane insertion was mediated by a spontaneous process driven by increases in entropy and diminished by the presence of ADP or ATP. Finally, HSPA8 was capable of driving into the lipid bilayer HSP90 that does not display any lipid biding capacity by itself. This observation suggests that HSPA8 may act as a membrane chaperone.
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Affiliation(s)
- Paulo R Dores-Silva
- Department of Surgery, School of Medicine, Division of Trauma, Critical Care, Burns and Acute Care Surgery, University of California, San Diego, La Jolla, CA, 92093, USA
- São Carlos Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - David M Cauvi
- Department of Surgery, School of Medicine, Division of Trauma, Critical Care, Burns and Acute Care Surgery, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Amanda L S Coto
- São Carlos Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Noeli S M Silva
- São Carlos Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Júlio C Borges
- São Carlos Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Antonio De Maio
- Department of Surgery, School of Medicine, Division of Trauma, Critical Care, Burns and Acute Care Surgery, University of California, San Diego, La Jolla, CA, 92093, USA.
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
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Fitter S, Gronthos S, Ooi SS, Zannettino AC. The Mesenchymal Precursor Cell Marker Antibody STRO-1 Binds to Cell Surface Heat Shock Cognate 70. Stem Cells 2017; 35:940-951. [DOI: 10.1002/stem.2560] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/25/2016] [Accepted: 12/02/2016] [Indexed: 01/07/2023]
Affiliation(s)
- Stephen Fitter
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Stan Gronthos
- Mesenchymal Stem Cell Laboratory, Faculty of Health and Medical Sciences, Adelaide Medical School, University of Adelaide; Adelaide South Australia Australia
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Soo Siang Ooi
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
| | - Andrew C.W. Zannettino
- Myeloma Research Laboratory, Faculty of Health and Medical Science, Adelaide Medical School
- Cancer Theme, South Australian Health and Medical Research Institute; Adelaide South Australia Australia
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Lopez V, Cauvi DM, Arispe N, De Maio A. Bacterial Hsp70 (DnaK) and mammalian Hsp70 interact differently with lipid membranes. Cell Stress Chaperones 2016; 21:609-16. [PMID: 27075190 PMCID: PMC4907991 DOI: 10.1007/s12192-016-0685-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 10/22/2022] Open
Abstract
The cellular response to stress is orchestrated by the expression of a family of proteins termed heat shock proteins (hsp) that are involved in the stabilization of basic cellular processes to preserve cell viability and homeostasis. The bulk of hsp function occurs within the cytosol and subcellular compartments. However, some hsp have also been found outside cells released by an active mechanism independent of cell death. Extracellular hsp act as signaling molecules directed at activating a systemic response to stress. The export of hsp requires the translocation from the cytosol into the extracellular milieu across the plasma membrane. We have proposed that membrane insertion is the initial step in this export process. We investigated the interaction of the major inducible hsp from mammalian (Hsp70) and bacterial (DnaK) species with liposomes. We found that mammalian Hsp70 displayed a high specificity for negatively charged phospholipids, such as phosphatidyl serine, whereas DnaK interacted with all lipids tested regardless of the charge. Both proteins were inserted into the lipid bilayer as demonstrated by resistance to acid or basic washes that was confirmed by partial protection from proteolytic cleavage. Several regions of mammalian Hsp70 were inserted into the membrane with a small portion of the N-terminus end exposed to the outer phase of the liposome. In contrast, the N-terminus end of DnaK was inserted into the membrane, exposing the C-terminus end outside the liposome. Mammalian Hsp70 was found to make high oligomeric complexes upon insertion into the membranes whereas DnaK only formed dimers within the lipid bilayer. These observations suggest that both Hsp70s interact with lipids, but mammalian Hsp70 displays a high degree of specificity and structure as compared with the bacterial form.
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Affiliation(s)
- Victor Lopez
- Initiative for Maximizing Student Development (IMSD) Program, La Jolla, CA, USA
| | - David M Cauvi
- Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | | | - Antonio De Maio
- Department of Surgery, School of Medicine, University of California San Diego, La Jolla, CA, USA.
- Center for Investigations of Health and Education Disparities, La Jolla, CA, USA.
- Department of Neuroscience, School of Medicine, University of California San Diego, La Jolla, CA, USA.
- University of California San Diego, 9500 Gilman Drive, #0739, La Jolla, CA, 92093-0739, USA.
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Abstract
The expression of heat shock proteins (HSPs) is a basic and well-conserved cellular response to an array of stresses. These proteins are involved in the repair of cellular damage induced by the stress, which is necessary for the salutary resolution from the insult. Moreover, they confer protection from subsequent insults, which has been coined stress tolerance. Because these proteins are expressed in subcellular compartments, it was thought that their function during stress conditions was circumscribed to the intracellular environment. However, it is now well established that HSPs can also be present outside cells where they appear to display a function different than the well-understood chaperone role. Extracellular HSPs act as alert stress signals priming other cells, particularly of the immune system, to avoid the propagation of the insult and favor resolution. Because the majority of HSPs do not possess a secretory peptide signal, they are likely to be exported by a nonclassic secretory pathway. Different mechanisms have been proposed to explain the export of HSPs, including translocation across the plasma membrane and release associated with lipid vesicles, as well as the passive release after cell death by necrosis. Extracellular HSPs appear in various flavors, including membrane-bound and membrane-free forms. All of these variants of extracellular HSPs suggest that their interactions with cells may be quite diverse, both in target cell types and the activation signaling pathways. This review addresses some of our current knowledge about the release and relevance of extracellular HSPs.
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Qi L, Zhang XD, Wu JC, Lin F, Wang J, DiFiglia M, Qin ZH. The role of chaperone-mediated autophagy in huntingtin degradation. PLoS One 2012; 7:e46834. [PMID: 23071649 PMCID: PMC3469570 DOI: 10.1371/journal.pone.0046834] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/06/2012] [Indexed: 12/31/2022] Open
Abstract
Huntington Disease (HD) is caused by an abnormal expansion of polyQ tract in the protein named huntingtin (Htt). HD pathology is featured by accumulation and aggregation of mutant Htt in striatal and cortical neurons. Aberrant Htt degradation is implicated in HD pathogenesis. The aim of this study was to investigate the regulatory role of chaperone-mediated autophagy (CMA) components, heat shock protein cognate 70 (Hsc70) and lysosome-associated protein 2A (LAMP-2A) in degradation of Htt fragment 1-552aa (Htt-552). A cell model of HD was produced by overexpression of Htt-552 with adenovirus. The involvement of CMA components in degradation of Htt-552 was determined with over-expression or silencing of Hsc70 and LAMP-2A. The results confirmed previous reports that both macroautophagy and CMA were involved in degradation of Htt-552. Changing the levels of CMA-related proteins affected the accumulation of Htt-552. The lysosomal binding and luminal transport of Htt-552 was demonstrated by incubation of Htt-552 with isolated lysosomes. Expansion of the polyQ tract in Htt-552 impaired its uptake and degradation by lysosomes. Mutation of putative KFERQ motif in wild-type Htt-552 interfered with interactions between Htt-552 and Hsc70. Endogenous Hsc70 and LAMP-2A interacted with exogenously expressed Htt-552. Modulating the levels of CMA related proteins degraded endogenous full-length Htt. These studies suggest that Hsc70 and LAMP-2A through CMA play a role in the clearance of Htt and suggest a novel strategy to target the degradation of mutant Htt.
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Affiliation(s)
- Lin Qi
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
| | - Xing-Ding Zhang
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
| | - Jun-Chao Wu
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
| | - Fang Lin
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
| | - Jin Wang
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
| | - Marian DiFiglia
- Laboratory of Cellular Neurobiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - Zheng-Hong Qin
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Pharmaceutical Science, Suzhou, China
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De Maio A. Extracellular heat shock proteins, cellular export vesicles, and the Stress Observation System: a form of communication during injury, infection, and cell damage. It is never known how far a controversial finding will go! Dedicated to Ferruccio Ritossa. Cell Stress Chaperones 2011; 16:235-49. [PMID: 20963644 PMCID: PMC3077223 DOI: 10.1007/s12192-010-0236-4] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 10/06/2010] [Indexed: 12/27/2022] Open
Abstract
Heat shock proteins (hsp) have been found to play a fundamental role in the recovery from multiple stress conditions and to offer protection from subsequent insults. The function of hsp during stress goes beyond their intracellular localization and chaperone role as they have been detected outside cells activating signaling pathways. Extracellular hsp are likely to act as indicators of the stress conditions, priming other cells, particularly of the immune system, to avoid the propagation of the insult. Some extracellular hsp, for instance Hsp70, are associated with export vesicles, displaying a robust activation of macrophages. We have coined the term Stress Observation System (SOS) for the mechanism for sensing extracellular hsp, which we propose is a form of cellular communication during stress conditions. An enigmatic and still poorly understood process is the mechanism for the release of hsp, which do not contain any consensus secretory signal. The export of hsp appears to be a very complex phenomenon encompassing different alternative pathways. Moreover, extracellular hsp may not come in a single flavor, but rather in a variety of physical conditions. This review addresses some of our current knowledge about the release and function of extracellular hsp, in particular those associated with vesicles.
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Affiliation(s)
- Antonio De Maio
- School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0739, USA.
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Clifton J, Huang F, Rucevic M, Cao L, Hixson D, Josic D. Protease inhibitors as possible pitfalls in proteomic analyses of complex biological samples. J Proteomics 2011; 74:935-41. [PMID: 21333769 DOI: 10.1016/j.jprot.2011.02.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 01/27/2011] [Accepted: 02/09/2011] [Indexed: 11/16/2022]
Abstract
Sample preparation, especially protein and peptide fractionation prior to identification by mass spectrometry (MS), is typically applied to reduce sample complexity. The second key element in this process is proteolytic digestion, which is performed most often with trypsin. Optimization of this step is an important factor in order to achieve both speed and better performance of proteomic analysis, and tryptic digestion prior to the MS analysis has been a topic of many studies. To date, only a few studies have paid attention to the negative interaction between the proteolytic enzyme and sample components, and sample losses caused by these interactions. In this study, we demonstrated impaired activity after "in solution" tryptic digestion of plasma proteins caused by a potent trypsin inhibitor family, inter-alpha inhibitor proteins. Sample boiling followed by gel electrophoretic separation and "in-gel" digestion drastically improved both the number of identified proteins and the sequence coverage in subsequent LC-ESI-MS/MS. The present investigations show that a thorough validation is necessary when "in solution" digestion followed by LC-MS analysis of complex biological samples is performed. The parallel use of two or more different mass spectrometers can also yield additional information and contribute to further method validation.
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Affiliation(s)
- James Clifton
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, USA
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