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Liang W, Hu L, Dai F, Shi Y, Yang L, Li C. Calreticulin from Apostichopus japonicus relieves endoplasmic reticulum stress induced by Vibrio splendidus through autophagy. FISH & SHELLFISH IMMUNOLOGY 2024; 153:109798. [PMID: 39084275 DOI: 10.1016/j.fsi.2024.109798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/26/2024] [Accepted: 07/28/2024] [Indexed: 08/02/2024]
Abstract
When organisms are exposed to external stimuli, misfolded proteins accumulate continuously, resulting in endoplasmic reticulum (ER) stress. Autophagy is of great significance for eliminating aggregated proteins and maintaining cellular homeostasis. However, the molecular mechanism of activating autophagy in response to ER stress in sea cucumber is remain unclear. In the current study, we demonstrated that the pathogen Vibrio splendidus can cause ER stress in Apostichopus japonicus coelomocytes and identified a Ca2+ binding partner calreticulin (designated as AjCRT), which increased with the occurrence of ER stress. The nucleotide sequence analysis showed that the open reading frame of AjCRT was 1242 bp and encoded a 413-amino-acid residue polyprotein with calreticulin domains. The spatial expression analysis revealed that AjCRT was ubiquitously expressed in all examined tissues with large magnitude in the coelomocytes and was minimally expressed in muscle. Furthermore, silencing AjCRT in vivo could significantly exacerbate ER stress induced by V. splendidus and resulted in the significant reduction of coelomocyte autophagy. These findings indicate a calreticulin-based mechanism that positively regulates autophagy in response to ER stress induced by pathogen infection. The results will provide a basis for understanding the way of host alleviating ER stress through autophagy, and pharmacological approaches may have potential for managing ER stress induced by pathogen and related cellular disorders.
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Affiliation(s)
- Weikang Liang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China
| | - Lincheng Hu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China
| | - Fa Dai
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China
| | - Yue Shi
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China
| | - Lei Yang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China.
| | - Chenghua Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
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2
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Cifric S, Turi M, Folino P, Clericuzio C, Barello F, Maciel T, Anderson KC, Gulla A. DAMPening Tumor Immune Escape: The Role of Endoplasmic Reticulum Chaperones in Immunogenic Chemotherapy. Antioxid Redox Signal 2024. [PMID: 38366728 DOI: 10.1089/ars.2024.0558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
Significance: Preclinical and clinical research in the past two decades has redefined the mechanism of action of some chemotherapeutics that are able to activate the immune system against cancer when cell death is perceived by the immune cells. This immunogenic cell death (ICD) activates antigen-presenting cells (APCs) and T cells to induce immune-mediated tumor clearance. One of the key requirements to achieve this effect is the externalization of the damage-associated molecular patterns (DAMPs), molecules released or exposed by cancer cells during ICD that increase the visibility of the cancer cells by the immune system. Recent Advances: In this review, we focus on the role of calreticulin (CRT) and other endoplasmic reticulum (ER) chaperones, such as the heat-shock proteins (HSPs) and the protein disulfide isomerases (PDIs), as surface-exposed DAMPs. Once exposed on the cell membrane, these proteins shift their role from that of ER chaperone and regulator of Ca2+ and protein homeostasis to act as an immunogenic signal for APCs, driving dendritic cell (DC)-mediated phagocytosis and T-mediated antitumor response. Critical Issues: However, cancer cells exploit several mechanisms of resistance to immune attack, including subverting the exposure of ER chaperones on their surface to avoid immune recognition. Future Directions: Overcoming these mechanisms of resistance represents a potential therapeutic opportunity to improve cancer treatment effectiveness and patient outcomes.
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Affiliation(s)
- Selma Cifric
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcello Turi
- Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italy
| | - Pietro Folino
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Cole Clericuzio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Tallya Maciel
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Kenneth C Anderson
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
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3
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Michalak M. Calreticulin: Endoplasmic reticulum Ca 2+ gatekeeper. J Cell Mol Med 2024; 28:e17839. [PMID: 37424156 PMCID: PMC10902585 DOI: 10.1111/jcmm.17839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/11/2023] Open
Abstract
Endoplasmic reticulum (ER) luminal Ca2+ is vital for the function of the ER and regulates many cellular processes. Calreticulin is a highly conserved, ER-resident Ca2+ binding protein and lectin-like chaperone. Over four decades of studying calreticulin demonstrate that this protein plays a crucial role in maintaining Ca2+ supply under different physiological conditions, in managing access to Ca2+ and how Ca2+ is used depending on the environmental events and in making sure that Ca2+ is not misused. Calreticulin plays a role of ER luminal Ca2+ sensor to manage Ca2+-dependent ER luminal events including maintaining interaction with its partners, Ca2+ handling molecules, substrates and stress sensors. The protein is strategically positioned in the lumen of the ER from where the protein manages access to and distribution of Ca2+ for many cellular Ca2+-signalling events. The importance of calreticulin Ca2+ pool extends beyond the ER and includes influence of cellular processes involved in many aspects of cellular pathophysiology. Abnormal handling of the ER Ca2+ contributes to many pathologies from heart failure to neurodegeneration and metabolic diseases.
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Affiliation(s)
- Marek Michalak
- Department of BiochemistryUniversity of AlbertaEdmontonAlbertaCanada
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4
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Shan Z, Song X, Yang X, Xue Y, Wu Y, Wang X, Liu J, Liu Q. Calreticulin (CALR) promotes ionophore-induced microneme secretion in Toxoplasma gondii. Parasitol Res 2024; 123:139. [PMID: 38381180 DOI: 10.1007/s00436-024-08162-9] [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: 12/07/2023] [Accepted: 02/11/2024] [Indexed: 02/22/2024]
Abstract
The flow of calcium ions (Ca2+) is involved in numerous vital activities of Toxoplasma gondii. Calreticulin is a type of Ca2+-binding protein in the endoplasmic reticulum (ER) that is involved in Ca2+ signaling pathway regulation, Ca2+ storage, and protein folding. In this work, the calreticulin (CALR), a protein predicted to possess a conserved domain of calreticulin in T. gondii, was characterized. The CALR localized in the ER. Using reverse genetics, we discovered that CALR is not necessary for the lytic cycle, including invasion and replication. However, depletion of CALR affected microneme secretion triggered by A23187, which is a Ca2+ ionophore used to increase cytoplasmic Ca2+ concentration. Furthermore, we discovered that CALR influences Ca2+ release. Transcriptomic comparison between Δcalr and Δku80 parasites showed that 226 genes in the Δcalr parasites were significantly downregulated (p < 0.05). The cellular biological functions of the downregulated genes were mainly involved in calmodulin-dependent protein kinase pathways. Furthermore, in the absence of CALR, tachyzoites were still able to cause acute infection in mice. These results imply that by influencing ER Ca2+ release content, CALR may further impair the ionophore-induced secretion of the parasite. However, this protein is not required for the completion of the parasite's lytic cycle or for the acute virulence of the parasite.
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Affiliation(s)
- Zhili Shan
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Xingju Song
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
- College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Xu Yang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Yangfei Xue
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Yayun Wu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, China
| | - Xianmei Wang
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Jing Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Qun Liu
- National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
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5
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Chen S, Zhang W, Li X, Cao Z, Liu C. DNA polymerase beta connects tumorigenicity with the circadian clock in liver cancer through the epigenetic demethylation of Per1. Cell Death Dis 2024; 15:78. [PMID: 38245510 PMCID: PMC10799862 DOI: 10.1038/s41419-024-06462-7] [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: 09/12/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/22/2024]
Abstract
The circadian-controlled DNA repair exhibits a strong diurnal rhythm. Disruption in circadian clock and DNA repair is closely linked with hepatocellular carcinoma (HCC) progression, but the mechanism remains unknown. Here, we show that polymerase beta (POLB), a critical enzyme in the DNA base excision repair pathway, is rhythmically expressed at the translational level in mouse livers. Hepatic POLB dysfunction dampens clock homeostasis, whereas retards HCC progression, by mediating the methylation of the 4th CpG island on the 5'UTR of clock gene Per1. Clinically, POLB is overexpressed in human HCC samples and positively associated with poor prognosis. Furthermore, the hepatic rhythmicity of POLB protein expression is orchestrated by Calreticulin (CALR). Our findings provide important insights into the molecular mechanism underlying the synergy between clock and food signals on the POLB-driven BER system and reveal new clock-dependent carcinogenetic effects of POLB. Therefore, chronobiological modulation of POLB may help to promote precise interventions for HCC.
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Affiliation(s)
- Siyu Chen
- State Key Laboratory of Natural Medicines and School of Life Science and Technology, China Pharmaceutical University, Nanjing, 211198, Jiangsu, China
| | - Wenxiang Zhang
- State Key Laboratory of Natural Medicines and School of Life Science and Technology, China Pharmaceutical University, Nanjing, 211198, Jiangsu, China
| | - Xiao Li
- Department of Pathology, First Affiliated Hospital with Nanjing Medical University, Nanjing, 210029, Jiangsu, China
| | - Zhengyu Cao
- Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Development, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, 211198, Jiangsu, China
| | - Chang Liu
- State Key Laboratory of Natural Medicines and School of Life Science and Technology, China Pharmaceutical University, Nanjing, 211198, Jiangsu, China.
- Chongqing Innovation Institute of China Pharmaceutical University, Chongqing, 401135, China.
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6
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Esperante D, Flisser A, Mendlovic F. The many faces of parasite calreticulin. Front Immunol 2023; 14:1101390. [PMID: 36993959 PMCID: PMC10040973 DOI: 10.3389/fimmu.2023.1101390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/23/2023] [Indexed: 03/16/2023] Open
Abstract
Calreticulin from parasites and its vertebrate hosts share ~50% identity and many of its functions are equally conserved. However, the existing amino acid differences can affect its biological performance. Calreticulin plays an important role in Ca2+ homeostasis and as a chaperone involved in the correct folding of proteins within the endoplasmic reticulum. Outside the endoplasmic reticulum, calreticulin is involved in several immunological functions such as complement inhibition, enhancement of efferocytosis, and immune upregulation or inhibition. Several parasite calreticulins have been shown to limit immune responses and promote infectivity, while others are strong immunogens and have been used for the development of potential vaccines that limit parasite growth. Furthermore, calreticulin is essential in the dialogue between parasites and hosts, inducing Th1, Th2 or regulatory responses in a species-specific manner. In addition, calreticulin participates as initiator of endoplasmic reticulum stress in tumor cells and promotion of immunogenic cell death and removal by macrophages. Direct anti-tumoral activity has also been reported. The highly immunogenic and pleiotropic nature of parasite calreticulins, either as positive or negative regulators of the immune response, render these proteins as valuable tools to modulate immunopathologies and autoimmune disorders, as well as a potential treatment of neoplasms. Moreover, the disparities in the amino acid composition of parasite calreticulins might provide subtle variations in the mechanisms of action that could provide advantages as therapeutic tools. Here, we review the immunological roles of parasite calreticulins and discuss possible beneficial applications.
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Affiliation(s)
- Diego Esperante
- Plan de Estudios Combinados en Medicina (PECEM), Facultad de Medicine, Universidad Nacional Autonóma de México (UNAM), Mexico City, Mexico
| | - Ana Flisser
- Plan de Estudios Combinados en Medicina (PECEM), Facultad de Medicine, Universidad Nacional Autonóma de México (UNAM), Mexico City, Mexico
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autonóma de México (UNAM), Mexico City, Mexico
| | - Fela Mendlovic
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autonóma de México (UNAM), Mexico City, Mexico
- Facultad de Ciencias de la Salud, Universidad Anahuac Mexico Norte, Huixquilucan, Mexico
- *Correspondence: Fela Mendlovic,
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7
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Store-Operated Calcium Entry: Shaping the Transcriptional and Epigenetic Landscape in Pancreatic Cancer. Cells 2021; 10:cells10050966. [PMID: 33919156 PMCID: PMC8143176 DOI: 10.3390/cells10050966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/13/2021] [Accepted: 04/19/2021] [Indexed: 12/14/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) displays a particularly poor prognosis and low survival rate, mainly due to late diagnosis and high incidence of chemotherapy resistance. Genomic aberrations, together with changes in the epigenomic profile, elicit a shift in cellular signaling response and a transcriptional reprograming in pancreatic tumors. This endows them with malignant attributes that enable them to not only overcome chemotherapeutic challenges, but to also attain diverse oncogenic properties. In fact, certain genetic amplifications elicit a rewiring of calcium signaling, which can confer ER stress resistance to tumors while also aberrantly activating known drivers of oncogenic programs such as NFAT. While calcium is a well-known second messenger, the transcriptional programs driven by aberrant calcium signaling remain largely undescribed in pancreatic cancer. In this review, we focus on calcium-dependent signaling and its role in epigenetic programs and transcriptional regulation. We also briefly discuss genetic aberration events, exemplifying how genetic alterations can rewire cellular signaling cascades, including calcium-dependent ones.
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Roles of Calreticulin in Protein Folding, Immunity, Calcium Signaling and Cell Transformation. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 59:145-162. [PMID: 34050865 DOI: 10.1007/978-3-030-67696-4_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The endoplasmic reticulum (ER) is an organelle that mediates the proper folding and assembly of proteins destined for the cell surface, the extracellular space and subcellular compartments such as the lysosomes. The ER contains a wide range of molecular chaperones to handle the folding requirements of a diverse set of proteins that traffic through this compartment. The lectin-like chaperones calreticulin and calnexin are an important class of structurally-related chaperones relevant for the folding and assembly of many N-linked glycoproteins. Despite the conserved mechanism of action of these two chaperones in nascent protein recognition and folding, calreticulin has unique functions in cellular calcium signaling and in the immune response. The ER-related functions of calreticulin in the assembly of major histocompatibility complex (MHC) class I molecules are well-studied and provide many insights into the modes of substrate and co-chaperone recognition by calreticulin. Calreticulin is also detectable on the cell surface under some conditions, where it induces the phagocytosis of apoptotic cells. Furthermore, mutations of calreticulin induce cell transformation in myeloproliferative neoplasms (MPN). Studies of the functions of the mutant calreticulin in cell transformation and immunity have provided many insights into the normal biology of calreticulin, which are discussed.
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9
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Structural Analysis of Calreticulin, an Endoplasmic Reticulum-Resident Molecular Chaperone. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 59:13-25. [PMID: 34050860 DOI: 10.1007/978-3-030-67696-4_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Calreticulin (Calr) is an endoplasmic reticulum (ER) chaperone involved in protein quality control, Ca2+ regulation and other cellular processes. The structure of Calr is unusual, reflecting different functions of the protein: a proline-rich β-hairpin arm and an acidic C-terminal tail protrude from a globular core, composed of a β-sheet sandwich and an α-helix. The arm and tail interact in the presence of Ca2+ and cover the upper β-sheet, where a carbohydrate-binding site gives the chaperone glycoprotein affinity. At the edge of the carbohydrate-binding site is a conserved, strained disulphide bridge, formed between C106 and C137 of human Calr, which lies in a polypeptide-binding site. The lower β-sheet has several conserved residues, comprised of a characteristic triad, D166-H170-D187, Tyr172 and the free C163. In addition to its role in the ER, Calr translocates to the cell surface upon stress and functions as an immune surveillance marker. In some myeloproliferative neoplasms, the acidic Ca2+-binding C-terminal tail is transformed into a polybasic sequence.
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10
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Kozlov G, Gehring K. Calnexin cycle - structural features of the ER chaperone system. FEBS J 2020; 287:4322-4340. [PMID: 32285592 PMCID: PMC7687155 DOI: 10.1111/febs.15330] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/31/2020] [Accepted: 04/08/2020] [Indexed: 12/21/2022]
Abstract
The endoplasmic reticulum (ER) is the major folding compartment for secreted and membrane proteins and is the site of a specific chaperone system, the calnexin cycle, for folding N-glycosylated proteins. Recent structures of components of the calnexin cycle have deepened our understanding of quality control mechanisms and protein folding pathways in the ER. In the calnexin cycle, proteins carrying monoglucosylated glycans bind to the lectin chaperones calnexin and calreticulin, which recruit a variety of function-specific chaperones to mediate protein disulfide formation, proline isomerization, and general protein folding. Upon trimming by glucosidase II, the glycan without an inner glucose residue is no longer able to bind to the lectin chaperones. For proteins that have not yet folded properly, the enzyme UDP-glucose:glycoprotein glucosyltransferase (UGGT) acts as a checkpoint by adding a glucose back to the N-glycan. This allows the misfolded proteins to re-associate with calnexin and calreticulin for additional rounds of chaperone-mediated refolding and prevents them from exiting the ERs. Here, we review progress in structural studies of the calnexin cycle, which reveal common features of how lectin chaperones recruit function-specific chaperones and how UGGT recognizes misfolded proteins.
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Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
| | - Kalle Gehring
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
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11
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Zhang IX, Raghavan M, Satin LS. The Endoplasmic Reticulum and Calcium Homeostasis in Pancreatic Beta Cells. Endocrinology 2020; 161:bqz028. [PMID: 31796960 PMCID: PMC7028010 DOI: 10.1210/endocr/bqz028] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 12/01/2019] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) mediates the first steps of protein assembly within the secretory pathway and is the site where protein folding and quality control are initiated. The storage and release of Ca2+ are critical physiological functions of the ER. Disrupted ER homeostasis activates the unfolded protein response (UPR), a pathway which attempts to restore cellular equilibrium in the face of ER stress. Unremitting ER stress, and insufficient compensation for it results in beta-cell apoptosis, a process that has been linked to both type 1 diabetes (T1D) and type 2 diabetes (T2D). Both types are characterized by progressive beta-cell failure and a loss of beta-cell mass, although the underlying causes are different. The reduction of mass occurs secondary to apoptosis in the case of T2D, while beta cells undergo autoimmune destruction in T1D. In this review, we examine recent findings that link the UPR pathway and ER Ca2+ to beta cell dysfunction. We also discuss how UPR activation in beta cells favors cell survival versus apoptosis and death, and how ER protein chaperones are involved in regulating ER Ca2+ levels. Abbreviations: BiP, Binding immunoglobulin Protein ER; endoplasmic reticulum; ERAD, ER-associated protein degradation; IFN, interferon; IL, interleukin; JNK, c-Jun N-terminal kinase; KHE, proton-K+ exchanger; MODY, maturity-onset diabetes of young; PERK, PRKR-like ER kinase; SERCA, Sarco/Endoplasmic Reticulum Ca2+-ATPases; T1D, type 1 diabetes; T2D, type 2 diabetes; TNF, tumor necrosis factor; UPR, unfolded protein response; WRS, Wolcott-Rallison syndrome.
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Affiliation(s)
- Irina X Zhang
- Department of Pharmacology and Brehm Diabetes Research Center, University of Michigan, Ann Arbor, MI
| | - Malini Raghavan
- Department of Microbiology and Immunology Michigan Medicine, University of Michigan, Ann Arbor, MI
| | - Leslie S Satin
- Department of Pharmacology and Brehm Diabetes Research Center, University of Michigan, Ann Arbor, MI
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12
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Thermal unfolding of calreticulin. Structural and thermodynamic characterization of the transition. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:175-183. [DOI: 10.1016/j.bbapap.2018.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 12/11/2022]
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13
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A Novel Gold Calreticulin Nanocomposite Based on Chitosan for Wound Healing in a Diabetic Mice Model. NANOMATERIALS 2019; 9:nano9010075. [PMID: 30625974 PMCID: PMC6359502 DOI: 10.3390/nano9010075] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 12/13/2022]
Abstract
The development of new nanomaterials to promote wound healing is rising, because of their topical administration and easy functionalization with molecules that can improve and accelerate the process of healing. A nanocomposite of gold nanoparticles (AuNPs) functionalized with calreticulin was synthetized and evaluated. The ability of the nanocomposite to promote proliferation and migration was determined in vitro, and in vivo wound healing was evaluated using a mice model of diabetes established with streptozotocin (STZ). In vitro, the nanocomposite not affect the cell viability and the expression of proliferating cell nuclear antigen (PCNA). Moreover, the nanocomposite promotes the clonogenicity of keratinocytes, endothelial cells, and fibroblasts, and accelerates fibroblast migration. In vivo, mice treated with the nanocomposite presented significantly faster wound healing. The histological evaluation showed re-epithelization and the formation of granular tissue, as well as an increase of collagen deposition. Therefore, these results confirm the utility of AuNPs–calreticulin nanocomposites as potential treatment for wound healing of diabetic ulcers.
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14
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Trowitzsch S, Tampé R. ABC Transporters in Dynamic Macromolecular Assemblies. J Mol Biol 2018; 430:4481-4495. [DOI: 10.1016/j.jmb.2018.07.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 12/28/2022]
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15
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Varricchio L, Falchi M, Dall'Ora M, De Benedittis C, Ruggeri A, Uversky VN, Migliaccio AR. Calreticulin: Challenges Posed by the Intrinsically Disordered Nature of Calreticulin to the Study of Its Function. Front Cell Dev Biol 2017; 5:96. [PMID: 29218307 PMCID: PMC5703715 DOI: 10.3389/fcell.2017.00096] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/31/2017] [Indexed: 12/16/2022] Open
Abstract
Calreticulin is a Ca2+-binding chaperone protein, which resides mainly in the endoplasmic reticulum but also found in other cellular compartments including the plasma membrane. In addition to Ca2+, calreticulin binds and regulates almost all proteins and most of the mRNAs deciding their intracellular fate. The potential functions of calreticulin are so numerous that identification of all of them is becoming a nightmare. Still the recent discovery that patients affected by the Philadelphia-negative myeloproliferative disorders essential thrombocytemia or primary myelofibrosis not harboring JAK2 mutations carry instead calreticulin mutations disrupting its C-terminal domain has highlighted the clinical need to gain a deeper understanding of the biological activity of this protein. However, by contrast with other proteins, such as enzymes or transcription factors, the biological functions of which are strictly defined by a stable spatial structure imprinted by their amino acid sequence, calreticulin contains intrinsically disordered regions, the structure of which represents a highly dynamic conformational ensemble characterized by constant changes between several metastable conformations in response to a variety of environmental cues. This article will illustrate the Theory of calreticulin as an intrinsically disordered protein and discuss the Hypothesis that the dynamic conformational changes to which calreticulin may be subjected by environmental cues, by promoting or restricting the exposure of its active sites, may affect its function under normal and pathological conditions.
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Affiliation(s)
- Lilian Varricchio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Mario Falchi
- National HIV/AIDS Center, Istituto Superiore Sanità, Rome, Italy
| | - Massimiliano Dall'Ora
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Caterina De Benedittis
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Alessandra Ruggeri
- Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia
| | - Anna Rita Migliaccio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy
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16
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Migliaccio AR, Uversky VN. Dissecting physical structure of calreticulin, an intrinsically disordered Ca 2+-buffering chaperone from endoplasmic reticulum. J Biomol Struct Dyn 2017; 36:1617-1636. [PMID: 28504081 DOI: 10.1080/07391102.2017.1330224] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Calreticulin (CALR) is a Ca2+ binding multifunctional protein that mostly resides in the endoplasmic reticulum (ER) and plays a number of important roles in various physiological and pathological processes. Although the major functions ascribed to CALR are controlling the Ca2+ homeostasis in ER and acting as a lectin-like ER chaperon for many glycoproteins, this moonlighting protein can be found in various cellular compartments where it has many non-ER functions. To shed more light on the mechanisms underlying polyfunctionality of this moonlighting protein that can be found in different cellular compartments and that possesses a wide spectrum of unrelated biological activities, being able to interact with Ca2+ (and potentially other metal ions), RNA, oligosaccharides, and numerous proteins, we used a set of experimental and computational tools to evaluate the intrinsic disorder status of CALR and the role of calcium binding on structural properties and conformational stability of the full-length CALR and its isolated P- and C-domains.
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Affiliation(s)
- Anna Rita Migliaccio
- a Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai (ISMMS) , New York , NY , USA.,b Department of Biomedical and Neuromotorial Sciences , Alma Mater University , Bologna , Italy
| | - Vladimir N Uversky
- c Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute , Morsani College of Medicine, University of South Florida , Tampa , FL , USA.,d Laboratory of New Methods in Biology , Institute for Biological Instrumentation, Russian Academy of Sciences , Pushchino , Moscow Region 142290 , Russia
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17
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Falchi M, Varricchio L, Martelli F, Marra M, Picconi O, Tafuri A, Girelli G, Uversky VN, Migliaccio AR. The Calreticulin control of human stress erythropoiesis is impaired by JAK2V617F in polycythemia vera. Exp Hematol 2017; 50:53-76. [PMID: 28232234 DOI: 10.1016/j.exphem.2017.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 02/03/2017] [Accepted: 02/04/2017] [Indexed: 12/11/2022]
Abstract
Calreticulin (CALR) is a Ca2+-binding protein that shuttles among cellular compartments with proteins bound to its N/P domains. The knowledge that activation of the human erythropoietin receptor induces Ca2+ fluxes prompted us to investigate the role of CALR in human erythropoiesis. As shown by Western blot analysis, erythroblasts generated in vitro from normal sources and JAK2V617F polycythemia vera (PV) patients expressed robust levels of CALR. However, Ca2+ regulated CALR conformation only in normal cells. Normal erythroblasts expressed mostly the N-terminal domain of CALR (N-CALR) on their cell surface (as shown by flow cytometry) and C-terminal domain (C-CALR) in their cytoplasm (as shown by confocal microscopy) and expression of both epitopes decreased with maturation. In the proerythroblast (proEry) cytoplasm, C-CALR was associated with the glucocorticoid receptor (GR), which initiated the stress response. In these cells, Ca2+ deprivation and inhibition of nuclear export increased GR nuclear localization while decreasing cytoplasmic detection of C-CALR and C-CALR/GR association and proliferation in response to the GR agonist dexamethasone (Dex). C-CALR/GR association and Dex responsiveness were instead increased by Ca2+ and erythropoietin. In contrast, JAK2V617F proErys expressed normal cell-surface levels of N-CALR but barely detectable cytoplasmic levels of C-CALR. These cells contained GR mainly in the nucleus and were Dex unresponsive. Ruxolitinib rescued cytoplasmic detection of C-CALR, C-CALR/GR association, and Dex responsiveness in JAK2V617F proErys and its effects were antagonized by nuclear export and Ca2+ flux inhibitors. These results indicates that Ca2+-induced conformational changes of CALR regulate nuclear export of GR in normal erythroblasts and that JAK2V617F deregulates this function in PV.
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Affiliation(s)
- Mario Falchi
- National AIDS Center, Istituto Superiore Sanita, Rome, Italy
| | - Lilian Varricchio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Fabrizio Martelli
- Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Roma, Italy
| | - Manuela Marra
- Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Roma, Italy
| | - Orietta Picconi
- National AIDS Center, Istituto Superiore Sanita, Rome, Italy
| | - Agostino Tafuri
- Sant'Andrea Hospital-Sapienza, Department of Clinic and Molecular Medicine Sapienza University of Rome, Rome, Italy
| | - Gabriella Girelli
- Immunohematology and Transfusion Medicine Unit, Sapienza University of Rome, Rome, Italy
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Anna Rita Migliaccio
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Biomedical and Neuromotorial Sciences, Alma Mater University, Bologna, Italy.
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18
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Huang G, Sun Z, Wu J, Shui S, Han X, Guo D, Li T. Calreticulin Promotes Proliferation and Migration But Inhibits Apoptosis in Schwann Cells. Med Sci Monit 2016; 22:4516-4522. [PMID: 27876711 PMCID: PMC5132423 DOI: 10.12659/msm.900956] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Background Previous studies indicated that calreticulin (CRT) regulated various biological processes. This study was aimed to investigate the function of CRT in Schwann cells (SCs). Material/Methods SCs were separated from sciatic nerves of mice and were transfected with pcDNA3.1-CRT (pc-CRT), small interfering RNA targets CRT (siCRT), or their corresponding negative controls. The expression of CRT was determined by quantitative reverse transcription PCR (qRT-PCR) and Western blot analysis. Then, cell proliferation, migration, and apoptosis were measured by 3-(4, 5-dimethylhiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, modified 2-chamber migration assay, and flow cytometry, respectively. Finally, the phosphorylation levels of key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT and the extracellular signal-regulated kinase/ribosomal S6 kinase 2 (ERK/S6) pathways were detected by Western blot analysis. Results Overexpression of CRT remarkably increased viability (P<0.05, P<0.01 or P<0.001) and migration (P<0.001), but inhibited apoptosis (P<0.05). The CRT-knockdown showed the inverse impacts on viability (P<0.05 or P<0.001), migration (P<0.001), and apoptosis (P<0.001). Additionally, the phosphorylation levels of AKT (Thr308 and Ser473), ERK, and S6 were all up-regulated in CRT-overexpressed cells (P<0.001), and were down-regulated in CRT-knockdown cells (P<0.05, P<0.01 or P<0.001). Conclusions Overexpression of CRT in SCs promoted cell proliferation and migration but suppressed cell apoptosis. The PI3K/AKT and ERK/S6 pathways might be involved in the functional effects of CRT on SCs.
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Affiliation(s)
- Gui Huang
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Zhulei Sun
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Jiang Wu
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Shaofeng Shui
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Xinwei Han
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Dong Guo
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Tengfei Li
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
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19
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Boelt SG, Norn C, Rasmussen MI, André I, Čiplys E, Slibinskas R, Houen G, Højrup P. Mapping the Ca(2+) induced structural change in calreticulin. J Proteomics 2016; 142:138-48. [PMID: 27195812 DOI: 10.1016/j.jprot.2016.05.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 05/09/2016] [Accepted: 05/14/2016] [Indexed: 01/04/2023]
Abstract
UNLABELLED Calreticulin is a highly conserved multifunctional protein implicated in many different biological systems and has therefore been the subject of intensive research. It is primarily present in the endoplasmatic reticulum where its main functions are to regulate Ca(2+) homeostasis, act as a chaperone and stabilize the MHC class I peptide-loading complex. Although several high-resolution structures of calreticulin exist, these only cover three-quarters of the entire protein leaving the extended structures unsolved. Additionally, the structure of calreticulin is influenced by the presence of Ca(2+). The conformational changes induced by Ca(2+) have not been determined yet as they are hard to study with traditional approaches. Here, we investigated the Ca(2+)-induced conformational changes with a combination of chemical cross-linking, mass spectrometry, bioinformatics analysis and modelling in Rosetta. Using a bifunctional linker, we found a large Ca(2+)-induced change to the cross-linking pattern in calreticulin. Our results are consistent with a high flexibility in the P-loop, a stabilization of the acidic C-terminal and a relatively close interaction of the P-loop and the acidic C-terminal. BIOLOGICAL SIGNIFICANCE The function of calreticulin, an endoplasmatic reticulin chaperone, is affected by fluctuations in Ca(2+)concentration, but the structural mechanism is unknown. The present work suggests that Ca(2+)-dependent regulation is caused by different conformations of a long proline-rich loop that changes the accessibility to the peptide/lectin-binding site. Our results indicate that the binding of Ca(2+) to calreticulin may thus not only just be a question of Ca(2+) storage but is likely to have an impact on the chaperone activity.
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Affiliation(s)
- Sanne Grundvad Boelt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, DK 2300 Copenhagen, Denmark
| | - Christoffer Norn
- Department of Biochemistry and Structural Biology, Lund University, Paradisgatan 2, SE 221 00 Lund, Sweden
| | - Morten Ib Rasmussen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark
| | - Ingemar André
- Department of Biochemistry and Structural Biology, Lund University, Paradisgatan 2, SE 221 00 Lund, Sweden
| | - Evaldas Čiplys
- Department of Eukayote Gene Engineering, Institute of Biotechnology, Vilnius University, V. Graičiūno St, LT 02241 Vilnius, Lithuania
| | - Rimantas Slibinskas
- Department of Eukayote Gene Engineering, Institute of Biotechnology, Vilnius University, V. Graičiūno St, LT 02241 Vilnius, Lithuania
| | - Gunnar Houen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, Artillerivej 5, DK 2300 Copenhagen, Denmark
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK 5230 Odense, Denmark.
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20
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Garbati MR, Welgan CA, Landefeld SH, Newell LF, Agarwal A, Dunlap JB, Chourasia TK, Lee H, Elferich J, Traer E, Rattray R, Cascio MJ, Press RD, Bagby GC, Tyner JW, Druker BJ, Dao KHT. Mutant calreticulin-expressing cells induce monocyte hyperreactivity through a paracrine mechanism. Am J Hematol 2016; 91:211-9. [PMID: 26573090 DOI: 10.1002/ajh.24245] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 11/12/2015] [Indexed: 01/05/2023]
Abstract
Mutations in the calreticulin gene (CALR) were recently identified in approximately 70-80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a nonhematopoietic cell line does not directly activate JAK/STAT signaling compared to wildtype CALR and JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.
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Affiliation(s)
- Michael R. Garbati
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Catherine A. Welgan
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Sally H. Landefeld
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Laura F. Newell
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Anupriya Agarwal
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Jennifer B. Dunlap
- Knight Cancer Institute, Oregon Health and Science University; Portland Oregon
- Department of Pathology; Oregon Health and Science University; Portland Oregon
| | - Tapan K. Chourasia
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Hyunjung Lee
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Johannes Elferich
- Department of Biochemistry and Molecular Biology; Oregon Health and Science University; Portland Oregon
| | - Elie Traer
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Rogan Rattray
- Knight Cancer Institute, Oregon Health and Science University; Portland Oregon
- Department of Pathology; Oregon Health and Science University; Portland Oregon
| | - Michael J. Cascio
- Department of Pathology; Oregon Health and Science University; Portland Oregon
| | - Richard D. Press
- Knight Cancer Institute, Oregon Health and Science University; Portland Oregon
- Department of Pathology; Oregon Health and Science University; Portland Oregon
| | - Grover C. Bagby
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
| | - Jeffrey W. Tyner
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
- Department of Cell, Development, and Cancer Biology; Oregon Health and Science University, Knight Cancer Institute; Portland Oregon
| | - Brian J. Druker
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
- Department of Cell, Development, and Cancer Biology; Oregon Health and Science University, Knight Cancer Institute; Portland Oregon
- Howard Hughes Medical Institute, Oregon Health and Science University; Portland Oregon
| | - Kim-Hien T. Dao
- Knight Cancer Institute, Hematology and Medical Oncology, Oregon Health and Science University; Portland Oregon
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21
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Feng R, Ye J, Zhou C, Qi L, Fu Z, Yan B, Liang Z, Li R, Zhai W. Calreticulin down-regulation inhibits the cell growth, invasion and cell cycle progression of human hepatocellular carcinoma cells. Diagn Pathol 2015; 10:149. [PMID: 26307067 PMCID: PMC4549864 DOI: 10.1186/s13000-015-0382-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 08/19/2015] [Indexed: 01/08/2023] Open
Abstract
Background Hepatocellular carcinoma (HCC) is one of the most frequent cancers in the world. Calreticulin(CRT) is aberrantly overexpressed in many human cancer cells. The function of CRT in HCC cells remains unclear. We attempted to investigate the effects and the underlying mechanisms of CRT down-regulation on HCC cell growth, apoptosis, cell cycle progression and invasion. Methods To investigate the function of CRT in HCC cells, small interfering RNA (siRNA) was used to knock down the expression of CRT in SMMC7721 and HepG2 HCC cells. CRT expression was examined by Western blot and immunofluorescence. Cell proliferation was detected by CCK-8 assay. Cell cycle and apoptosis were measured by the flow cytometry. The invasion capability was assessed by transwell assay. The phosphorylation level of Akt was evaluated by Western blot. Results Compared with human hepatic cells L02, CRT was apparently up-regulated in SMMC7721, HepG2 and Huh7 HCC cells. Down-regulation of CRT expression effectively inhibited HCC cell growth and invasion. CRT knockdown induced cell cycle arrest and the apoptosis in SMMC7721 and HepG2 cells. Furthermore, down-regulation of CRT expression significantly decreased the Akt phosphorylation. Conclusions CRT was aberrantly over-expressed in HCC cell lines. CRT over-expression contributes greatly to HCC malignant behavior, likely via PI3K/Akt pathway. CRT could serve as a potential biomarker and therapeutic target for hepatocellular carcinoma.
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Affiliation(s)
- Ruo Feng
- Department of Histology and Embryology, Medical College of Zhengzhou University, Zhengzhou, People's Republic of China.
| | - Jianwen Ye
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China. .,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China.
| | - Chuang Zhou
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China. .,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China.
| | - Lei Qi
- Department of Endocrine, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China
| | - Zhe Fu
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China.,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China
| | - Bing Yan
- Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China.
| | - Zhiwei Liang
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China. .,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China.
| | - Renfeng Li
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China.,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China
| | - Wenlong Zhai
- Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China. .,Key Laboratory of Hepatobiliary and Pancreatic Surgery & Digestive Organ Transplantation of Henan Province, Zhengzhou, People's Republic of China.
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22
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Caramelo JJ, Parodi AJ. A sweet code for glycoprotein folding. FEBS Lett 2015; 589:3379-87. [PMID: 26226420 DOI: 10.1016/j.febslet.2015.07.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 07/15/2015] [Accepted: 07/15/2015] [Indexed: 12/11/2022]
Abstract
Glycoprotein synthesis is initiated in the endoplasmic reticulum (ER) lumen upon transfer of a glycan (Glc3Man9GlcNAc2) from a lipid derivative to Asn residues (N-glycosylation). N-Glycan-dependent quality control of glycoprotein folding in the ER prevents exit to Golgi of folding intermediates, irreparably misfolded glycoproteins and incompletely assembled multimeric complexes. It also enhances folding efficiency by preventing aggregation and facilitating formation of proper disulfide bonds. The control mechanism essentially involves four components, resident lectin-chaperones (calnexin and calreticulin) that recognize monoglucosylated polymannose protein-linked glycans, lectin-associated oxidoreductase acting on monoglucosylated glycoproteins (ERp57), a glucosyltransferase that creates monoglucosylated epitopes in protein-linked glycans (UGGT) and a glucosidase (GII) that removes the glucose units added by UGGT. This last enzyme is the only mechanism component sensing glycoprotein conformations as it creates monoglucosylated glycans exclusively in not properly folded glycoproteins or in not completely assembled multimeric glycoprotein complexes. Glycoproteins that fail to properly fold are eventually driven to proteasomal degradation in the cytosol following the ER-associated degradation pathway, in which the extent of N-glycan demannosylation by ER mannosidases play a relevant role in the identification of irreparably misfolded glycoproteins.
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Affiliation(s)
- Julio J Caramelo
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Avda. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina.
| | - Armando J Parodi
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Avda. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina.
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23
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Boelt SG, Houen G, Højrup P. Agarose gel shift assay reveals that calreticulin favors substrates with a quaternary structure in solution. Anal Biochem 2015; 481:33-42. [PMID: 25908558 DOI: 10.1016/j.ab.2015.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/13/2015] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
Abstract
Here we present an agarose gel shift assay that, in contrast to other electrophoresis approaches, is loaded in the center of the gel. This allows proteins to migrate in either direction according to their isoelectric points. Therefore, the presented assay enables a direct visualization, separation, and prefractionation of protein interactions in solution independent of isoelectric point. We demonstrate that this assay is compatible with immunochemical methods and mass spectrometry. The assay was used to investigate interactions with several potential substrates for calreticulin, a chaperone that is involved in different biological aspects through interaction with other proteins. The current analytical assays used to investigate these interactions are mainly spectroscopic aggregation assays or solid phase assays that do not provide a direct visualization of the stable protein complex but rather provide an indirect measure of interactions. Therefore, no interaction studies between calreticulin and substrates in solution have been investigated previously. The results presented here indicate that calreticulin has a preference for substrates with a quaternary structure and primarily β-sheets in their secondary structure. It is also demonstrated that the agarose gel shift assay is useful in the study of other protein interactions and can be used as an alternative method to native polyacrylamide gel electrophoresis.
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Affiliation(s)
- Sanne Grundvad Boelt
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, DK-2300 Copenhagen, Denmark
| | - Gunnar Houen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; Department of Autoimmunology and Biomarkers, Statens Serum Institut, DK-2300 Copenhagen, Denmark
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark.
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24
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Sun C, Zhang S, Li J. Calreticulin gene mutations in myeloproliferative neoplasms without Janus kinase 2 mutations. Leuk Lymphoma 2014; 56:1593-8. [PMID: 25115511 DOI: 10.3109/10428194.2014.953153] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Calreticulin, an endoplasmic reticulum protein with multiple functions involving chaperone activity and calcium homeostasis, plays an important role in cellular proliferation and differentiation. Calreticulin dysfunction is known to be associated with different cancers. Very recently, calreticulin mutations have been identified in myeloproliferative neoplasms (MPNs), with a particularly high frequency in MPNs without Janus kinase 2 (JAK2) mutations, which exhibit clinical characteristics different from those with mutant JAK2. Here, we focus on the structure, function and carcinogenicity of calreticulin, as well as its relationship with MPNs not involving JAK2 mutations.
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Affiliation(s)
- Chao Sun
- Department of Hematology, Wuxi People's Hospital, Affiliated of Nanjing Medical University , Wuxi, Jiangsu , China
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25
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Bioinformatic analyses of CALR mutations in myeloproliferative neoplasms support a role in signaling. Leukemia 2014; 28:2106-9. [PMID: 24919806 DOI: 10.1038/leu.2014.190] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Ye C, Wang Z, Lu W, Zhong M, Chai Q, Wei Y. Correlation between AcrB trimer association affinity and efflux activity. Biochemistry 2014; 53:3738-46. [PMID: 24854514 PMCID: PMC4067148 DOI: 10.1021/bi5000838] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
The majority of membrane proteins
function as oligomers. However,
it remains largely unclear how the oligomer stability of protein complexes
correlates with their function. Understanding the relationship between
oligomer stability and activity is essential to protein research and
to virtually all cellular processes that depend on the function of
protein complexes. Proteins make lasting or transient interactions
as they perform their functions. Obligate oligomeric proteins exist
and function exclusively at a specific oligomeric state. Although
oligomerization is clearly critical for such proteins to function,
a direct correlation between oligomer affinity and biological activity
has not yet been reported. Here, we used an obligate trimeric membrane
transporter protein, AcrB, as a model to investigate the correlation
between its relative trimer affinity and efflux activity. AcrB is
a component of the major multidrug efflux system in Escherichia coli. We created six AcrB constructs
with mutations at the transmembrane intersubunit interface, and we
determined their activities using both a drug susceptibility assay
and an ethidium bromide accumulation assay. The relative trimer affinities
of these mutants in detergent micelles were obtained using blue native
polyacrylamide gel electrophoresis. A correlation between the relative
trimer affinity and substrate efflux activity was observed, in which
a threshold trimer stability was required to maintain efflux activity.
The trimer affinity of the wild-type protein was approximately 3 kcal/mol
more stable than the threshold value. Once the threshold was reached,
an additional increase of stability in the range observed had no observable
effect on protein activity.
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Affiliation(s)
- Cui Ye
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
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27
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Shivarov V, Ivanova M, Tiu RV. Mutated calreticulin retains structurally disordered C terminus that cannot bind Ca(2+): some mechanistic and therapeutic implications. Blood Cancer J 2014; 4:e185. [PMID: 24562385 PMCID: PMC3944664 DOI: 10.1038/bcj.2014.7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- V Shivarov
- Laboratory of Hematopathology and Immunology, National Hematology Hospital, Sofia, Bulgaria
| | - M Ivanova
- Department of Clinical Immunology, Alexandrovska University Hospital, Medical University, Sofia, Bulgaria
| | - R V Tiu
- Department of Translational Hematology and Oncology Research, Cleveland Clinic Taussig Cancer Institute, Cleveland, Ohio, USA
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Workenhe ST, Mossman KL. Oncolytic virotherapy and immunogenic cancer cell death: sharpening the sword for improved cancer treatment strategies. Mol Ther 2013; 22:251-256. [PMID: 24048442 DOI: 10.1038/mt.2013.220] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/10/2013] [Indexed: 12/22/2022] Open
Abstract
Oncolytic viruses are novel immunotherapeutics with increasingly promising outcomes in cancer patient clinical trials. Preclinical and clinical studies have uncovered the importance of virus-induced activation of antitumor immune responses for optimal therapeutic efficacy. Recently, several classes of chemotherapeutics have been shown to cause immunogenic cancer cell death characterized by the release of immunomodulatory molecules that activate antigen-presenting cells and thus trigger the induction of more potent anticancer adaptive immune responses. In preclinical models, several oncolytic viruses induce immunogenic cell death, which is associated with increased cross-priming of tumor-associated antigens. In this review, we discuss the recent advances in immunogenic cancer cell death as induced by chemotherapeutic treatments, including the roles of relevant danger-associated molecular patterns and signaling pathways, and highlighting the significance of the endoplasmic reticulum (ER) stress response. As virtually all viruses modulate both ER stress and cell death responses, we provide perspectives on future research directions that can be explored to optimize oncolytic viruses, alone or in combination with targeted drug therapies, as potent immunogenic cancer cell death-inducing agents. We propose that such optimized virus-drug synergistic strategies will improve the therapeutic outcomes for many currently intractable cancers.
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Affiliation(s)
- Samuel T Workenhe
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Karen L Mossman
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada.
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29
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Mahmazi S, Parivar K, Rahnema M, Ohadi M. Calreticulin novel mutations in type 2 diabetes mellitus. Int J Diabetes Dev Ctries 2013. [DOI: 10.1007/s13410-013-0152-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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30
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Tóth E, Kulcsár PI, Fodor E, Ayaydin F, Kalmár L, Borsy AÉ, László L, Welker E. The highly conserved, N-terminal (RXXX)8 motif of mouse Shadoo mediates nuclear accumulation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1199-211. [PMID: 23360978 DOI: 10.1016/j.bbamcr.2013.01.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/29/2012] [Accepted: 01/15/2013] [Indexed: 01/09/2023]
Abstract
The prion protein (PrP)-known for its central role in transmissible spongiform encephalopathies-has been reported to possess two nuclear localization signals and localize in the nuclei of certain cells in various forms. Although these data are superficially contradictory, it is apparent that nuclear forms of the prion protein can be found in cells in either the healthy or the diseased state. Here we report that Shadoo (Sho)-a member of the prion protein superfamily-is also found in the nucleus of several neural and non-neural cell lines as visualized by using an YFP-Sho construct. This nuclear localization is mediated by the (25-61) fragment of mouse Sho encompassing an (RXXX)8 motif. Bioinformatic analysis shows that the (RXXX)n motif (n=7-8) is a highly conserved and characteristic part of mammalian Shadoo proteins. Experiments to assess if Sho enters the nucleus by facilitated transport gave no decisive results: the inhibition of active processes that require energy in the cell, abolishes nuclear but not nucleolar accumulation. However, the (RXXX)8 motif is not able to mediate the nuclear transport of large fusion constructs exceeding the size limit of the nuclear pore for passive entry. Tracing the journey of various forms of Sho from translation to the nucleus and discerning the potential nuclear function of PrP and Sho requires further studies.
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Affiliation(s)
- E Tóth
- Institute of Biochemistry, Hungarian Academy of Sciences, Szeged, Hungary.
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31
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Rajapaksha M, Lovell S, Janowiak BE, Andra KK, Battaile KP, Bann JG. pH effects on binding between the anthrax protective antigen and the host cellular receptor CMG2. Protein Sci 2012; 21:1467-80. [PMID: 22855243 DOI: 10.1002/pro.2136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/25/2012] [Accepted: 07/26/2012] [Indexed: 11/11/2022]
Abstract
The anthrax protective antigen (PA) binds to the host cellular receptor capillary morphogenesis protein 2 (CMG2) with high affinity. To gain a better understanding of how pH may affect binding to the receptor, we have investigated the kinetics of binding as a function of pH to the full-length monomeric PA and to two variants: a 2-fluorohistidine-labeled PA (2-FHisPA), which is ∼1 pH unit more stable to variations in pH than WT, and an ∼1 pH unit less stable variant in which Trp346 in the domain 2β(3) -2β(4) loop is substituted with a Phe (W346F). We show using stopped-flow fluorescence that the binding rate increases as the pH is lowered for all proteins, with little influence on the rate of dissociation. In addition, we have crystallized PA and the two variants and examine the influence of pH on structure. In contrast to previous X-ray studies, the domain 2β(3) -2β(4) loop undergoes little change in structure from pH ∼8 to 5.5 for the WT protein, but for the 2-FHis labeled and W346F mutant there are changes in structure consistent with previous X-ray studies. In accord with pH stability studies, we find that the average B-factor values increase by ∼20-30% for all three proteins at low pH. Our results suggest that for the full-length PA, low pH increases the binding affinity, likely through a change in structure that favors a more "bound-like" conformation.
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32
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Csala M, Kereszturi É, Mandl J, Bánhegyi G. The endoplasmic reticulum as the extracellular space inside the cell: role in protein folding and glycosylation. Antioxid Redox Signal 2012; 16:1100-8. [PMID: 22149109 DOI: 10.1089/ars.2011.4227] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
SIGNIFICANCE Proteins destined to secretion and exposure on the cell surface are synthesized and processed in the extracellular-like environment of the endoplasmic reticulum (ER) of higher eukaryotic cells. Compartmentation plays a crucial role in the post-translational modifications, such as oxidative folding and N-glycosylation in the ER lumen. Transport of the required intermediates across the ER membrane and maintenance of the luminal redox conditions and Ca(2+) ion concentration are indispensable for appropriate protein maturation. RECENT ADVANCES Cooperation of enzymes and transporters to maintain a thiol-oxidizing milieu in the ER lumen has been recently elucidated. Ca(2+)-dependence of certain ER chaperones is a subject of intensive research. CRITICAL ISSUES Mounting evidence supports the existence of a real barrier between the ER lumen and the cytosol. The unique set of enzymes, selection of metabolites, and characteristic ion and redox milieu of the luminal compartment strongly argue against the general permeability of the ER membrane. FUTURE DIRECTIONS Alterations in the luminal environment can trigger the unfolded protein response, a common event in a variety of pathological conditions. Therefore, redox and calcium homeostasis and protein glycosylation in the ER provide novel drug-targets for medical treatment in a wide array of diseases.
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Affiliation(s)
- Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary.
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34
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Wu G, Berka V, Tsai AL. Binding kinetics of calmodulin with target peptides of three nitric oxide synthase isozymes. J Inorg Biochem 2011; 105:1226-37. [PMID: 21763233 DOI: 10.1016/j.jinorgbio.2011.06.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/09/2011] [Accepted: 06/15/2011] [Indexed: 11/17/2022]
Abstract
Efficient electron transfer from reductase domain to oxygenase domain in nitric oxide synthase (NOS) is dependent on the binding of calmodulin (CaM). Rate constants for the binding of CaM to NOS target peptides was only determined previously by surface plasmon resonance (SPR) (Biochemistry 35, 8742-8747, 1996) suggesting that the binding of CaM to NOSs is slow and does not support the fast electron transfer in NOSs measured in previous and this studies. To resolve this contradiction, the binding rates of holo Alexa 350 labeled T34C/T110W CaM (Alexa-CaM) to target peptides from three NOS isozymes were determined using fluorescence stopped-flow. All three target peptides exhibited fast k(on) constants at 4.5°C: 6.6×10(8)M(-1)s(-1) for nNOS(726-749), 2.9×10(8)M(-1)s(-1) for eNOS(492-511) and 6.1×10(8)M(-1)s(-1) for iNOS(507-531), 3-4 orders of magnitude faster than those determined previously by SPR. Dissociation rates of NOS target peptides from Alexa-CaM/peptide complexes were measured by Ca(2+) chelation with ETDA: 3.7s(-1) for nNOS(726-749), 4.5s(-1) for eNOS(492-511), and 0.063s(-1) for iNOS(507-531). Our data suggest that the binding of CaM to NOS is fast and kinetically competent for efficient electron transfer and is unlikely rate-limiting in NOS catalysis. Only iNOS(507-531) was able to bind apo Alexa-CaM, but in a very different conformation from its binding to holo Alexa-CaM.
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Affiliation(s)
- Gang Wu
- Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
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35
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Wijeyesakere SJ, Gafni AA, Raghavan M. Calreticulin is a thermostable protein with distinct structural responses to different divalent cation environments. J Biol Chem 2011; 286:8771-85. [PMID: 21177861 PMCID: PMC3058961 DOI: 10.1074/jbc.m110.169193] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/24/2010] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is a soluble calcium-binding chaperone of the endoplasmic reticulum (ER) that is also detected on the cell surface and in the cytosol. Calreticulin contains a single high affinity calcium-binding site within a globular domain and multiple low affinity sites within a C-terminal acidic region. We show that the secondary structure of calreticulin is remarkably thermostable at a given calcium concentration. Rather than corresponding to complete unfolding events, heat-induced structural transitions observed for calreticulin relate to tertiary structural changes that expose hydrophobic residues and reduce protein rigidity. The thermostability and the overall secondary structure content of calreticulin are impacted by the divalent cation environment, with the ER range of calcium concentrations enhancing stability, and calcium-depleting or high calcium environments reducing stability. Furthermore, magnesium competes with calcium for binding to calreticulin and reduces thermostability. The acidic domain of calreticulin is an important mediator of calcium-dependent changes in secondary structure content and thermostability. Together, these studies indicate interactions between the globular and acidic domains of calreticulin that are impacted by divalent cations. These interactions influence the structure and stability of calreticulin, and are likely to determine the multiple functional activities of calreticulin in different subcellular environments.
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Affiliation(s)
| | - Ari A. Gafni
- Biophysics, University of Michigan, Ann Arbor, Michigan 48109
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Abstract
Ca(2+) is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca(2+) storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca(2+) is buffered by specific proteins known as Ca(2+) buffers. Ca(2+) buffers are a diverse group of proteins, varying in their affinities and capacities for Ca(2+), but they typically also carry out other functions within the cell. The wide range of organelles containing Ca(2+) and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca(2+) signaling, mediated by a variety of organellar Ca(2+) buffers.
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Affiliation(s)
- Daniel Prins
- Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Canada
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37
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Kozlov G, Pocanschi CL, Rosenauer A, Bastos-Aristizabal S, Gorelik A, Williams DB, Gehring K. Structural basis of carbohydrate recognition by calreticulin. J Biol Chem 2010; 285:38612-20. [PMID: 20880849 PMCID: PMC2992293 DOI: 10.1074/jbc.m110.168294] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/06/2010] [Indexed: 11/06/2022] Open
Abstract
The calnexin cycle is a process by which glycosylated proteins are subjected to folding cycles in the endoplasmic reticulum lumen via binding to the membrane protein calnexin (CNX) or to its soluble homolog calreticulin (CRT). CNX and CRT specifically recognize monoglucosylated Glc(1)Man(9)GlcNAc(2) glycans, but the structural determinants underlying this specificity are unknown. Here, we report a 1.95-Å crystal structure of the CRT lectin domain in complex with the tetrasaccharide α-Glc-(1→3)-α-Man-(1→2)-α-Man-(1→2)-Man. The tetrasaccharide binds to a long channel on CRT formed by a concave β-sheet. All four sugar moieties are engaged in the protein binding via an extensive network of hydrogen bonds and hydrophobic contacts. The structure explains the requirement for glucose at the nonreducing end of the carbohydrate; the oxygen O(2) of glucose perfectly fits to a pocket formed by CRT side chains while forming direct hydrogen bonds with the carbonyl of Gly(124) and the side chain of Lys(111). The structure also explains a requirement for the Cys(105)-Cys(137) disulfide bond in CRT/CNX for efficient carbohydrate binding. The Cys(105)-Cys(137) disulfide bond is involved in intimate contacts with the third and fourth sugar moieties of the Glc(1)Man(3) tetrasaccharide. Finally, the structure rationalizes previous mutagenesis of CRT and lays a structural groundwork for future studies of the role of CNX/CRT in diverse biological pathways.
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Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Cosmin L. Pocanschi
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Angelika Rosenauer
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Sara Bastos-Aristizabal
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Alexei Gorelik
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - David B. Williams
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Kalle Gehring
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
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Srivastava AK, Sharma Y, Chary KVR. A Natively Unfolded βγ-Crystallin Domain from Hahella chejuensis. Biochemistry 2010; 49:9746-55. [DOI: 10.1021/bi101000m] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Atul K. Srivastava
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Yogendra Sharma
- Center for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Kandala V. R. Chary
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
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Endoplasmic reticulum calcium regulates the retrotranslocation of Trypanosoma cruzi calreticulin to the cytosol. PLoS One 2010; 5. [PMID: 20957192 PMCID: PMC2950133 DOI: 10.1371/journal.pone.0013141] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/08/2010] [Indexed: 11/19/2022] Open
Abstract
For most secretory pathway proteins, crossing the endoplasmic reticulum (ER) membrane is an irreversible process. However, in some cases this flow can be reversed. For instance, misfolded proteins retained in the ER are retrotranslocated to the cytosol to be degraded by the proteasome. This mechanism, known as ER associated degradation (ERAD), is exploited by several bacterial toxins to gain access to the cytosol. Interestingly, some ER resident proteins can also be detected in the cytosol or nucleus, calreticulin (CRT) being the most studied. Here we show that in Trypanosoma cruzi a minor fraction of CRT localized to the cytosol. ER calcium depletion, but not increasing cytosolic calcium, triggered the retrotranslocation of CRT in a relatively short period of time. Cytosolic CRT was subsequently degraded by the proteasome. Interestingly, the single disulfide bridge of CRT is reduced when the protein is located in the cytosol. The effect exerted by ER calcium was strictly dependent on the C-terminal domain (CRT-C), since a CRT lacking it was totally retained in the ER, whereas the localization of an unrelated protein fused to CRT-C mirrored that of endogenous CRT. This finding expands the regulatory mechanisms of protein sorting and may represent a new crossroad between diverse physiological processes.
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40
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Kozlov G, Määttänen P, Thomas DY, Gehring K. A structural overview of the PDI family of proteins. FEBS J 2010; 277:3924-36. [DOI: 10.1111/j.1742-4658.2010.07793.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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41
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Zitvogel L, Kepp O, Senovilla L, Menger L, Chaput N, Kroemer G. Immunogenic tumor cell death for optimal anticancer therapy: the calreticulin exposure pathway. Clin Cancer Res 2010; 16:3100-4. [PMID: 20421432 DOI: 10.1158/1078-0432.ccr-09-2891] [Citation(s) in RCA: 285] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In response to some chemotherapeutic agents such as anthracyclines and oxaliplatin, cancer cells undergo immunogenic apoptosis, meaning that their corpses are engulfed by dendritic cells and that tumor cell antigens are presented to tumor-specific CD8(+) T cells, which then control residual tumor cells. One of the peculiarities of immunogenic apoptosis is the early cell surface exposure of calreticulin (CRT), a protein that usually resides in the lumen of the endoplasmic reticulum (ER). When elicited by anthracyclines or oxaliplatin, the CRT exposure pathway is activated by pre-apoptotic ER stress and the phosphorylation of the eukaryotic translation initiation factor eIF2alpha by the kinase PERK, followed by caspase-8-mediated proteolysis of the ER-sessile protein BAP31, activation of the pro-apoptotic proteins Bax and Bak, anterograde transport of CRT from the ER to the Golgi apparatus and exocytosis of CRT-containing vesicles, finally resulting in CRT translocation onto the plasma membrane surface. Interruption of this complex pathway abolishes CRT exposure, annihilates the immunogenicity of apoptosis, and reduces the immune response elicited by anticancer chemotherapies. We speculate that human cancers that are incapable of activating the CRT exposure pathway are refractory to the immune-mediated component of anticancer therapies.
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