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Crapart CC, Scott ZC, Konno T, Sharma A, Parutto P, Bailey DMD, Westrate LM, Avezov E, Koslover EF. Luminal transport through intact endoplasmic reticulum limits the magnitude of localized Ca 2+ signals. Proc Natl Acad Sci U S A 2024; 121:e2312172121. [PMID: 38502705 PMCID: PMC10990089 DOI: 10.1073/pnas.2312172121] [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: 07/17/2023] [Accepted: 02/09/2024] [Indexed: 03/21/2024] Open
Abstract
The endoplasmic reticulum (ER) forms an interconnected network of tubules stretching throughout the cell. Understanding how ER functionality relies on its structural organization is crucial for elucidating cellular vulnerability to ER perturbations, which have been implicated in several neuronal pathologies. One of the key functions of the ER is enabling Ca[Formula: see text] signaling by storing large quantities of this ion and releasing it into the cytoplasm in a spatiotemporally controlled manner. Through a combination of physical modeling and live-cell imaging, we demonstrate that alterations in ER shape significantly impact its ability to support efficient local Ca[Formula: see text] releases, due to hindered transport of luminal content within the ER. Our model reveals that rapid Ca[Formula: see text] release necessitates mobile luminal buffer proteins with moderate binding strength, moving through a well-connected network of ER tubules. These findings provide insight into the functional advantages of normal ER architecture, emphasizing its importance as a kinetically efficient intracellular Ca[Formula: see text] delivery system.
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Affiliation(s)
- Cécile C. Crapart
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | | | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Aman Sharma
- Department of Physics, University of California, San Diego, La Jolla, CA92130
| | - Pierre Parutto
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - David M. D. Bailey
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Laura M. Westrate
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI49546
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Elena F. Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA92130
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2
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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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3
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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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4
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Guay KP, Ke H, Canniff NP, George GT, Eyles SJ, Mariappan M, Contessa JN, Gershenson A, Gierasch LM, Hebert DN. ER chaperones use a protein folding and quality control glyco-code. Mol Cell 2023; 83:4524-4537.e5. [PMID: 38052210 PMCID: PMC10790639 DOI: 10.1016/j.molcel.2023.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/18/2023] [Accepted: 11/07/2023] [Indexed: 12/07/2023]
Abstract
N-glycans act as quality control tags by recruiting lectin chaperones to assist protein maturation in the endoplasmic reticulum. The location and composition of N-glycans (glyco-code) are key to the chaperone-selection process. Serpins, a class of serine protease inhibitors, fold non-sequentially to achieve metastable active states. Here, the role of the glyco-code in assuring successful maturation and quality control of two human serpins, alpha-1 antitrypsin (AAT) and antithrombin III (ATIII), is described. We find that AAT, which has glycans near its N terminus, is assisted by early lectin chaperone binding. In contrast, ATIII, which has more C-terminal glycans, is initially helped by BiP and then later by lectin chaperones mediated by UGGT reglucosylation. UGGT action is increased for misfolding-prone disease variants, and these clients are preferentially glucosylated on their most C-terminal glycan. Our study illustrates how serpins utilize N-glycan presence, position, and composition to direct their proper folding, quality control, and trafficking.
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Affiliation(s)
- Kevin P Guay
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Haiping Ke
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Nathan P Canniff
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Gracie T George
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Stephen J Eyles
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Institute for Applied Life Sciences, Mass Spectrometry Center, University of Massachusetts Amherst, Amherst, MA, USA
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT, USA
| | - Joseph N Contessa
- Departments of Therapeutic Radiology and Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Lila M Gierasch
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, USA
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, USA; Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA, USA.
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5
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Rahimi N, White MR, Amraei R, Lotfollahzadeh S, Xia C, Michalak M, Costello CE, Mühlberger E. Calreticulin Regulates SARS-CoV-2 Spike Protein Turnover and Modulates SARS-CoV-2 Infectivity. Cells 2023; 12:2694. [PMID: 38067122 PMCID: PMC10705507 DOI: 10.3390/cells12232694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/14/2023] [Accepted: 11/18/2023] [Indexed: 12/18/2023] Open
Abstract
Cardiovascular complications are major clinical hallmarks of acute and post-acute coronavirus disease 2019 (COVID-19). However, the mechanistic details of SARS-CoV-2 infectivity of endothelial cells remain largely unknown. Here, we demonstrate that the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein shares a similarity with the proline-rich binding ena/VASP homology (EVH1) domain and identified the endoplasmic reticulum (ER) resident calreticulin (CALR) as an S-RBD interacting protein. Our biochemical analysis showed that CALR, via its proline-rich (P) domain, interacts with S-RBD and modulates proteostasis of the S protein. Treatment of cells with the proteasomal inhibitor bortezomib increased the expression of the S protein independent of CALR, whereas the lysosomal/autophagy inhibitor bafilomycin 1A, which interferes with the acidification of lysosome, selectively augmented the S protein levels in a CALR-dependent manner. More importantly, the shRNA-mediated knockdown of CALR increased SARS-CoV-2 infection and impaired calcium homeostasis of human endothelial cells. This study provides new insight into the infectivity of SARS-CoV-2, calcium hemostasis, and the role of CALR in the ER-lysosome-dependent proteolysis of the spike protein, which could be associated with cardiovascular complications in COVID-19 patients.
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Affiliation(s)
- Nader Rahimi
- Department of Pathology, School of Medicine, Boston University, Boston, MA 02118, USA;
| | - Mitchell R. White
- Department of Microbiology, School of Medicine, Boston University, Boston, MA 02118, USA; (M.R.W.); (E.M.)
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, MA 02118, USA
| | - Razie Amraei
- Department of Pathology, School of Medicine, Boston University, Boston, MA 02118, USA;
| | - Saran Lotfollahzadeh
- Renal Section, Department of Medicine, Medical Center, Boston University, Boston, MA 02118, USA;
| | - Chaoshuang Xia
- Center for Biomedical Mass Spectrometry, School of Medicine, Boston University, Boston, MA 02118, USA; (C.X.); (C.E.C.)
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada;
| | - Catherine E. Costello
- Center for Biomedical Mass Spectrometry, School of Medicine, Boston University, Boston, MA 02118, USA; (C.X.); (C.E.C.)
| | - Elke Mühlberger
- Department of Microbiology, School of Medicine, Boston University, Boston, MA 02118, USA; (M.R.W.); (E.M.)
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, MA 02118, USA
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6
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Eisner D, Neher E, Taschenberger H, Smith G. Physiology of intracellular calcium buffering. Physiol Rev 2023; 103:2767-2845. [PMID: 37326298 DOI: 10.1152/physrev.00042.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/08/2023] [Accepted: 06/11/2023] [Indexed: 06/17/2023] Open
Abstract
Calcium signaling underlies much of physiology. Almost all the Ca2+ in the cytoplasm is bound to buffers, with typically only ∼1% being freely ionized at resting levels in most cells. Physiological Ca2+ buffers include small molecules and proteins, and experimentally Ca2+ indicators will also buffer calcium. The chemistry of interactions between Ca2+ and buffers determines the extent and speed of Ca2+ binding. The physiological effects of Ca2+ buffers are determined by the kinetics with which they bind Ca2+ and their mobility within the cell. The degree of buffering depends on factors such as the affinity for Ca2+, the Ca2+ concentration, and whether Ca2+ ions bind cooperatively. Buffering affects both the amplitude and time course of cytoplasmic Ca2+ signals as well as changes of Ca2+ concentration in organelles. It can also facilitate Ca2+ diffusion inside the cell. Ca2+ buffering affects synaptic transmission, muscle contraction, Ca2+ transport across epithelia, and the killing of bacteria. Saturation of buffers leads to synaptic facilitation and tetanic contraction in skeletal muscle and may play a role in inotropy in the heart. This review focuses on the link between buffer chemistry and function and how Ca2+ buffering affects normal physiology and the consequences of changes in disease. As well as summarizing what is known, we point out the many areas where further work is required.
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Affiliation(s)
- David Eisner
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Erwin Neher
- Membrane Biophysics Laboratory, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Godfrey Smith
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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7
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Zhang M, Xiao J, Liu J, Bai X, Zeng X, Zhang Z, Liu F. Calreticulin as a marker and therapeutic target for cancer. Clin Exp Med 2023; 23:1393-1404. [PMID: 36335525 DOI: 10.1007/s10238-022-00937-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022]
Abstract
Calreticulin (CRT) is a multifunctional protein found within the endoplasmic reticulum (ER). In addition, CRT participates in the formation and development of tumors and promotes the proliferation and migration of tumor cells. When a malignant tumor occurs in the human body, cancer cells that die from immunogenic cell death (ICD) expose CRT on their surface, and CRT that is transferred to the cell surface represents an "eat me" signal, which promotes dendritic cells to phagocytose the tumor cells, thereby increasing the sensitivity of tumors to anticancer immunotherapy. Expression of CRT in tumor tissues is higher than in normal tissues and is associated with disease progression in many malignant tumors. Thus, the dysfunctional production of CRT can promote tumorigenesis because it disturbs not only the balance of healthy cells but also the body's immune surveillance. CRT may be a diagnostic marker and a therapeutic target for cancer, which is discussed extensively in this review.
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Affiliation(s)
- Meilan Zhang
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Juan Xiao
- Department of Otolaryngology, Hengyang Medical School, The Second Affiliated Hospital, University of South China, Hengyang, 421001, Hunan, China
| | - Jiangrong Liu
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Xue Bai
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Xuemei Zeng
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Zhiwei Zhang
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China.
| | - Feng Liu
- Department of Cancer Research Institute, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China.
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8
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Zhao S, Feng H, Jiang D, Yang K, Wang ST, Zhang YX, Wang Y, Liu H, Guo C, Tang TS. ER Ca 2+ overload activates the IRE1α signaling and promotes cell survival. Cell Biosci 2023; 13:123. [PMID: 37400935 DOI: 10.1186/s13578-023-01062-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/26/2023] [Indexed: 07/05/2023] Open
Abstract
BACKGROUND Maintaining homeostasis of Ca2+ stores in the endoplasmic reticulum (ER) is crucial for proper Ca2+ signaling and key cellular functions. Although Ca2+ depletion has been known to cause ER stress which in turn activates the unfolded protein response (UPR), how UPR sensors/transducers respond to excess Ca2+ when ER stores are overloaded remain largely unclear. RESULTS Here, we report for the first time that overloading of ER Ca2+ can directly sensitize the IRE1α-XBP1 axis. The overloaded ER Ca2+ in TMCO1-deficient cells can cause BiP dissociation from IRE1α, promote the dimerization and stability of the IRE1α protein, and boost IRE1α activation. Intriguingly, attenuation of the over-activated IRE1α-XBP1s signaling by a IRE1α inhibitor can cause a significant cell death in TMCO1-deficient cells. CONCLUSIONS Our data establish a causal link between excess Ca2+ in ER stores and the selective activation of IRE1α-XBP1 axis, underscoring an unexpected role of overload of ER Ca2+ in IRE1α activation and in preventing cell death.
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Affiliation(s)
- Song Zhao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haiping Feng
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dongfang Jiang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Keyan Yang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Si-Tong Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu-Xin Zhang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yun Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Hongmei Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
| | - Caixia Guo
- Beijing Institute of Genomics, Chinese Academy of Sciences/China National Center for Bioinformation, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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9
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Desikan H, Kaur A, Pogozheva ID, Raghavan M. Effects of calreticulin mutations on cell transformation and immunity. J Cell Mol Med 2023; 27:1032-1044. [PMID: 36916035 PMCID: PMC10098294 DOI: 10.1111/jcmm.17713] [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: 11/04/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/16/2023] Open
Abstract
Myeloproliferative neoplasms (MPNs) are cancers involving dysregulated production and function of myeloid lineage hematopoietic cells. Among MPNs, Essential thrombocythemia (ET), Polycythemia Vera (PV) and Myelofibrosis (MF), are driven by mutations that activate the JAK-STAT signalling pathway. Somatic mutations of calreticulin (CRT), an endoplasmic reticulum (ER)-localized lectin chaperone, are driver mutations in approximately 25% of ET and 35% of MF patients. The MPN-linked mutant CRT proteins have novel frameshifted carboxy-domain sequences and lack an ER retention motif, resulting in their secretion. Wild type CRT is a regulator of ER calcium homeostasis and plays a key role in the assembly of major histocompatibility complex (MHC) class I molecules, which are the ligands for antigen receptors of CD8+ T cells. Mutant CRT-linked oncogenesis results from the dysregulation of calcium signalling in cells and the formation of stable complexes of mutant CRT with myeloproliferative leukemia (MPL) protein, followed by downstream activation of the JAK-STAT signalling pathway. The intricate participation of CRT in ER protein folding, calcium homeostasis and immunity suggests the involvement of multiple mechanisms of mutant CRT-linked oncogenesis. In this review, we highlight recent findings related to the role of MPN-linked CRT mutations in the dysregulation of calcium homeostasis, MPL activation and immunity.
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Affiliation(s)
- Harini Desikan
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
| | - Amanpreet Kaur
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
| | - Irina D. Pogozheva
- Department of Medicinal ChemistryCollege of Pharmacy, University of MichiganAnn ArborMichiganUSA
| | - Malini Raghavan
- Department of Microbiology and ImmunologyUniversity of Michigan Medical SchoolAnn ArborMichiganUSA
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10
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Structural and Dynamic Differences between Calreticulin Mutants Associated with Essential Thrombocythemia. Biomolecules 2023; 13:biom13030509. [PMID: 36979444 PMCID: PMC10046389 DOI: 10.3390/biom13030509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/28/2023] [Accepted: 03/03/2023] [Indexed: 03/12/2023] Open
Abstract
Essential thrombocythemia (ET) is a blood cancer. ET is characterized by an overproduction of platelets that can lead to thrombosis formation. Platelet overproduction occurs in megakaryocytes through a signaling pathway that could involve JAK2, MPL, or CALR proteins. CALR mutations are associated with 25–30% of ET patients; CALR variants must be dimerized to induce ET. We classified these variants into five classes named A to E; classes A and B are the most frequent classes in patients with ET. The dynamic properties of these five classes using structural models of CALR’s C-domain were analyzed using molecular dynamics simulations. Classes A, B, and C are associated with frameshifts in the C-domain. Their dimers can be stable only if a disulfide bond is formed; otherwise, the two monomers repulse each other. Classes D and E cannot be stable as dimers due to the absence of disulfide bonds. Class E and wild-type CALR have similar dynamic properties. These results suggest that the disulfide bond newly formed in classes A, B, and C may be essential for the pathogenicity of these variants. They also underline that class E cannot be directly related to ET but corresponds to human polymorphisms.
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11
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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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12
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Calnexin, More Than Just a Molecular Chaperone. Cells 2023; 12:cells12030403. [PMID: 36766745 PMCID: PMC9913998 DOI: 10.3390/cells12030403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/26/2023] Open
Abstract
Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein with an N-terminal domain that resides in the lumen of the ER and a C-terminal domain that extends into the cytosol. Calnexin is commonly referred to as a molecular chaperone involved in the folding and quality control of membrane-associated and secreted proteins, a function that is attributed to its ER- localized domain with a structure that bears a strong resemblance to another luminal ER chaperone and Ca2+-binding protein known as calreticulin. Studies have discovered that the cytosolic C-terminal domain of calnexin undergoes distinct post-translational modifications and interacts with a variety of proteins. Here, we discuss recent findings and hypothesize that the post-translational modifications of the calnexin C-terminal domain and its interaction with specific cytosolic proteins play a role in coordinating ER functions with events taking place in the cytosol and other cellular compartments.
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13
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Ibarra J, Elbanna YA, Kurylowicz K, Ciboddo M, Greenbaum HS, Arellano NS, Rodriguez D, Evers M, Bock-Hughes A, Liu C, Smith Q, Lutze J, Baumeister J, Kalmer M, Olschok K, Nicholson B, Silva D, Maxwell L, Dowgielewicz J, Rumi E, Pietra D, Casetti IC, Catricala S, Koschmieder S, Gurbuxani S, Schneider RK, Oakes SA, Elf SE. Type I but Not Type II Calreticulin Mutations Activate the IRE1α/XBP1 Pathway of the Unfolded Protein Response to Drive Myeloproliferative Neoplasms. Blood Cancer Discov 2022; 3:298-315. [PMID: 35405004 PMCID: PMC9338758 DOI: 10.1158/2643-3230.bcd-21-0144] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 01/21/2022] [Accepted: 04/08/2022] [Indexed: 01/09/2023] Open
Abstract
Approximately 20% of patients with myeloproliferative neoplasms (MPN) harbor mutations in the gene calreticulin (CALR), with 80% of those mutations classified as either type I or type II. While type II CALR-mutant proteins retain many of the Ca2+ binding sites present in the wild-type protein, type I CALR-mutant proteins lose these residues. The functional consequences of this differential loss of Ca2+ binding sites remain unexplored. Here, we show that the loss of Ca2+ binding residues in the type I mutant CALR protein directly impairs its Ca2+ binding ability, which in turn leads to depleted endoplasmic reticulum (ER) Ca2+ and subsequent activation of the IRE1α/XBP1 pathway of the unfolded protein response. Genetic or pharmacologic inhibition of IRE1α/XBP1 signaling induces cell death in type I mutant but not type II mutant or wild-type CALR-expressing cells, and abrogates type I mutant CALR-driven MPN disease progression in vivo. SIGNIFICANCE Current targeted therapies for CALR-mutated MPNs are not curative and fail to differentiate between type I- versus type II-driven disease. To improve treatment strategies, it is critical to identify CALR mutation type-specific vulnerabilities. Here we show that IRE1α/XBP1 represents a unique, targetable dependency specific to type I CALR-mutated MPNs. This article is highlighted in the In This Issue feature, p. 265.
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Affiliation(s)
- Juan Ibarra
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
| | - Yassmin A. Elbanna
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Katarzyna Kurylowicz
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Michele Ciboddo
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Harrison S. Greenbaum
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Nicole S. Arellano
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Deborah Rodriguez
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Maria Evers
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
| | - Althea Bock-Hughes
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
- Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, Illinois
| | - Chenyu Liu
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Quinn Smith
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Julian Lutze
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois
| | - Julian Baumeister
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University and Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Milena Kalmer
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University and Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Kathrin Olschok
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University and Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | - Benjamin Nicholson
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
| | - Diane Silva
- Department of Pathology, University of Chicago, Chicago, Illinois
| | - Luke Maxwell
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
| | - Jonathan Dowgielewicz
- Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, Illinois
| | - Elisa Rumi
- Department of Hematology Oncology, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Policlinico San Matteo, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Daniela Pietra
- Department of Hematology Oncology, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Policlinico San Matteo, Pavia, Italy
| | | | - Silvia Catricala
- Department of Hematology Oncology, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Policlinico San Matteo, Pavia, Italy
| | - Steffen Koschmieder
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Faculty of Medicine, RWTH Aachen University and Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), Aachen, Germany
| | | | - Rebekka K. Schneider
- Department of Cell Biology, Institute for Biomedical Technologies, RWTH Aachen University, Aachen, Germany
- Department of Hematology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - Scott A. Oakes
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
- Department of Pathology, University of Chicago, Chicago, Illinois
| | - Shannon E. Elf
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois
- Committee on Cancer Biology, University of Chicago, Chicago, Illinois
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14
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Xu Y, Wang Z, Zhang Y, Liang J, He G, Liu X, Zheng Z, Deng Y, Zhao L. Transcriptome analysis reveals acclimation responses of pearl oysters to marine heatwaves. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 810:151189. [PMID: 34757105 DOI: 10.1016/j.scitotenv.2021.151189] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/11/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Marine heatwaves (MHWs) are weather-timescale extreme events in the oceans and can have devastating effects on marine bivalves and ecosystems they support, with considerable socio-economic consequences. Yet, the extent to which marine bivalves have the capacity to acclimate and adapt to MHWs remains unknown. Understanding molecular responses to MHWs is imperative to develop strategies for conservation of ecologically and economically important marine organisms. Here, using RNA-Seq, we investigate how various MHWs scenarios elicit molecular changes in threatened and vulnerable pearl oysters, Pinctada maxima (Jameson). Acute exposure of MHWs - mimicked by rapid increases of seawater temperature from 24 °C to 28 °C and 32 °C, respectively - significantly affected the expression levels of metabolic and immune-related genes, with thermal stress-responsive genes especially like HSP20, HSP70 and HSP90 being remarkably up-regulated. Following repeat exposure to MHWs, encouragingly, pearl oysters exhibited evident acclimation responses, as best exemplified by significantly lowered expression levels of key stress-responsive genes involved in metabolism and immunity in comparison to those observed during acute exposure. Findings of the present study provide a better understanding of molecular processes underpinning the acclimation and adaptation of marine bivalves to MHWs in the context of climate change.
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Affiliation(s)
- Yang Xu
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Ziman Wang
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Yuehuan Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, China.
| | - Jian Liang
- Fisheries College, Guangdong Ocean University, Zhanjiang, China; Department of Fisheries, Tianjin Agricultural University, Tianjin, China
| | - Guixiang He
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Xiaolong Liu
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Zhe Zheng
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Yuewen Deng
- Fisheries College, Guangdong Ocean University, Zhanjiang, China
| | - Liqiang Zhao
- Fisheries College, Guangdong Ocean University, Zhanjiang, China.
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15
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Intertwined and Finely Balanced: Endoplasmic Reticulum Morphology, Dynamics, Function, and Diseases. Cells 2021; 10:cells10092341. [PMID: 34571990 PMCID: PMC8472773 DOI: 10.3390/cells10092341] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/02/2021] [Accepted: 09/04/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker sheet-like regions in the perinuclear region are linked to the nuclear envelope. It is becoming apparent that the complex morphology and dynamics of the ER are linked to its function. Mutations in the proteins involved in regulating ER structure and movement are implicated in many diseases including neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis (ALS). The ER is also hijacked by pathogens to promote their replication. Bacteria such as Legionella pneumophila and Chlamydia trachomatis, as well as the Zika virus, bind to ER morphology and dynamics-regulating proteins to exploit the functions of the ER to their advantage. This review covers our understanding of ER morphology, including the functional subdomains and membrane contact sites that the organelle forms. We also focus on ER dynamics and the current efforts to quantify ER motion and discuss the diseases related to ER morphology and dynamics.
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16
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Mapping human calreticulin regions important for structural stability. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140710. [PMID: 34358706 DOI: 10.1016/j.bbapap.2021.140710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/24/2021] [Accepted: 08/02/2021] [Indexed: 12/28/2022]
Abstract
Calreticulin (CALR) is a highly conserved multifunctional chaperone protein primarily present in the endoplasmic reticulum, where it regulates Ca2+ homeostasis. Recently, CALR has gained special interest for its diverse functions outside the endoplasmic reticulum, including the cell surface and extracellular space. Although high-resolution structures of CALR exist, it has not yet been established how different regions and individual amino acid residues contribute to structural stability of the protein. In the present study, we have identified key residues determining the structural stability of CALR. We used a Saccharomyces cerevisiae expression system to express and purify 50 human CALR mutants, which were analysed for several parameters including secretion titer, melting temperature (Tm), stability and oligomeric state. Our results revealed the importance of a previously identified small patch of conserved surface residues, amino acids 166-187 ("cluster 2") for structural stability of the human CALR protein. Two residues, Tyr172 and Asp187, were critical for maintaining the native structure of the protein. Mutant D187A revealed a severe drop in secretion titer, it was thermally unstable, prone to degradation, and oligomer formation. Tyr172 was critical for thermal stability of CALR and interacted with the third free Cys163 residue. This illustrates an unusual thermal stability of CALR dominated by Asp187, Tyr172 and Cys163, which may interact as part of a conserved structural unit. Besides structural clusters, we found a correlation of some measured parameter values in groups of CALR mutants that cause myeloproliferative neoplasms (MPN) and in mutants that may be associated with sudden unexpected death (SUD).
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17
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Kielbik M, Szulc-Kielbik I, Klink M. Calreticulin-Multifunctional Chaperone in Immunogenic Cell Death: Potential Significance as a Prognostic Biomarker in Ovarian Cancer Patients. Cells 2021; 10:130. [PMID: 33440842 PMCID: PMC7827772 DOI: 10.3390/cells10010130] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 12/11/2022] Open
Abstract
Immunogenic cell death (ICD) is a type of death, which has the hallmarks of necroptosis and apoptosis, and is best characterized in malignant diseases. Chemotherapeutics, radiotherapy and photodynamic therapy induce intracellular stress response pathways in tumor cells, leading to a secretion of various factors belonging to a family of damage-associated molecular patterns molecules, capable of inducing the adaptive immune response. One of them is calreticulin (CRT), an endoplasmic reticulum-associated chaperone. Its presence on the surface of dying tumor cells serves as an "eat me" signal for antigen presenting cells (APC). Engulfment of tumor cells by APCs results in the presentation of tumor's antigens to cytotoxic T-cells and production of cytokines/chemokines, which activate immune cells responsible for tumor cells killing. Thus, the development of ICD and the expression of CRT can help standard therapy to eradicate tumor cells. Here, we review the physiological functions of CRT and its involvement in the ICD appearance in malignant disease. Moreover, we also focus on the ability of various anti-cancer drugs to induce expression of surface CRT on ovarian cancer cells. The second aim of this work is to discuss and summarize the prognostic/predictive value of CRT in ovarian cancer patients.
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Affiliation(s)
- Michal Kielbik
- Institute of Medical Biology, Polish Academy of Sciences, 106 Lodowa Str., 93-232 Lodz, Poland; (I.S.-K.); (M.K.)
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18
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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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19
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Doğan C, Hänniger S, Heckel DG, Coutu C, Hegedus DD, Crubaugh L, Groves RL, Bayram Ş, Toprak U. Two calcium-binding chaperones from the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) involved in diapause. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 106:e21755. [PMID: 33118236 DOI: 10.1002/arch.21755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Molecular chaperones are crucial for the correct folding of newly synthesized polypeptides, in particular, under stress conditions. Various studies have revealed the involvement of molecular chaperones, such as heat shock proteins, in diapause maintenance and starvation; however, the role of other chaperones in diapause and starvation relatively is unknown. In the current study, we identified two lectin-type chaperones with calcium affinity, a calreticulin (LdCrT) and a calnexin (LdCnX), that were present in the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) during diapause. Both proteins possessed an N-globular domain, a P-arm domain, and a highly charged C-terminal domain, while an additional transmembrane domain was present in LdCnX. Phylogenetic analysis revealed distinction at the order level. Both genes were expressed in multiple tissues in larval and adult stages, and constitutively throughout development, though a starvation response was detected only for LdCrT. In females, diapause-related expression analysis in the whole body revealed an upregulation of both genes by post-diapause, but a downregulation by diapause only for LdCrT. By contrast, males revealed no alteration in their diapause-related expression pattern in the entire body for both genes. Fat body-specific expression analysis of both genes in relation to diapause revealed the same expression pattern with no alteration in females and downregulation in males by post-diapause. This study suggests that calcium-binding chaperones play similar and possibly gender-specific roles during diapause.
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Affiliation(s)
- Cansu Doğan
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sabine Hänniger
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Linda Crubaugh
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Şerife Bayram
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | - Umut Toprak
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
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20
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Adams BM, Canniff NP, Guay KP, Larsen ISB, Hebert DN. Quantitative glycoproteomics reveals cellular substrate selectivity of the ER protein quality control sensors UGGT1 and UGGT2. eLife 2020; 9:e63997. [PMID: 33320095 PMCID: PMC7771966 DOI: 10.7554/elife.63997] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/14/2020] [Indexed: 12/13/2022] Open
Abstract
UDP-glucose:glycoprotein glucosyltransferase (UGGT) 1 and 2 are central hubs in the chaperone network of the endoplasmic reticulum (ER), acting as gatekeepers to the early secretory pathway, yet little is known about their cellular clients. These two quality control sensors control lectin chaperone binding and glycoprotein egress from the ER. A quantitative glycoproteomics strategy was deployed to identify cellular substrates of the UGGTs at endogenous levels in CRISPR-edited HEK293 cells. The 71 UGGT substrates identified were mainly large multidomain and heavily glycosylated proteins when compared to the general N-glycoproteome. UGGT1 was the dominant glucosyltransferase with a preference toward large plasma membrane proteins whereas UGGT2 favored the modification of smaller, soluble lysosomal proteins. This study sheds light on differential specificities and roles of UGGT1 and UGGT2 and provides insight into the cellular reliance on the carbohydrate-dependent chaperone system to facilitate proper folding and maturation of the cellular N-glycoproteome.
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Affiliation(s)
- Benjamin M Adams
- Department of Biochemistry and Molecular Biology, University of MassachusettsAmherstUnited States
- Program in Molecular and Cellular Biology, University of MassachusettsAmherstUnited States
| | - Nathan P Canniff
- Department of Biochemistry and Molecular Biology, University of MassachusettsAmherstUnited States
- Program in Molecular and Cellular Biology, University of MassachusettsAmherstUnited States
| | - Kevin P Guay
- Department of Biochemistry and Molecular Biology, University of MassachusettsAmherstUnited States
- Program in Molecular and Cellular Biology, University of MassachusettsAmherstUnited States
| | - Ida Signe Bohse Larsen
- Department of Cellular and Molecular Medicine, University of CopenhagenCopenhagenDenmark
- Copenhagen Center for Glycomics, University of CopenhagenCopenhagenDenmark
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, University of MassachusettsAmherstUnited States
- Program in Molecular and Cellular Biology, University of MassachusettsAmherstUnited States
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21
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Preissler S, Rato C, Yan Y, Perera LA, Czako A, Ron D. Calcium depletion challenges endoplasmic reticulum proteostasis by destabilising BiP-substrate complexes. eLife 2020; 9:62601. [PMID: 33295873 PMCID: PMC7758071 DOI: 10.7554/elife.62601] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
The metazoan endoplasmic reticulum (ER) serves both as a hub for maturation of secreted proteins and as an intracellular calcium storage compartment, facilitating calcium-release-dependent cellular processes. ER calcium depletion robustly activates the unfolded protein response (UPR). However, it is unclear how fluctuations in ER calcium impact organellar proteostasis. Here, we report that calcium selectively affects the dynamics of the abundant metazoan ER Hsp70 chaperone BiP, by enhancing its affinity for ADP. In the calcium-replete ER, ADP rebinding to post-ATP hydrolysis BiP-substrate complexes competes with ATP binding during both spontaneous and co-chaperone-assisted nucleotide exchange, favouring substrate retention. Conversely, in the calcium-depleted ER, relative acceleration of ADP-to-ATP exchange favours substrate release. These findings explain the rapid dissociation of certain substrates from BiP observed in the calcium-depleted ER and suggest a mechanism for tuning ER quality control and coupling UPR activity to signals that mobilise ER calcium in secretory cells.
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Affiliation(s)
- Steffen Preissler
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Claudia Rato
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Yahui Yan
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Luke A Perera
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Aron Czako
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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22
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Mohan HM, Yang B, Dean NA, Raghavan M. Calreticulin enhances the secretory trafficking of a misfolded α-1-antitrypsin. J Biol Chem 2020; 295:16754-16772. [PMID: 32978262 PMCID: PMC7864070 DOI: 10.1074/jbc.ra120.014372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/12/2020] [Indexed: 01/24/2023] Open
Abstract
α1-antitrypsin (AAT) regulates the activity of multiple proteases in the lungs and liver. A mutant of AAT (E342K) called ATZ forms polymers that are present at only low levels in the serum and induce intracellular protein inclusions, causing lung emphysema and liver cirrhosis. An understanding of factors that can reduce the intracellular accumulation of ATZ is of great interest. We now show that calreticulin (CRT), an endoplasmic reticulum (ER) glycoprotein chaperone, promotes the secretory trafficking of ATZ, enhancing the media:cell ratio. This effect is more pronounced for ATZ than with AAT and is only partially dependent on the glycan-binding site of CRT, which is generally relevant to substrate recruitment and folding by CRT. The CRT-related chaperone calnexin does not enhance ATZ secretory trafficking, despite the higher cellular abundance of calnexin-ATZ complexes. CRT deficiency alters the distributions of ATZ-ER chaperone complexes, increasing ATZ-BiP binding and inclusion body formation and reducing ATZ interactions with components required for ER-Golgi trafficking, coincident with reduced levels of the protein transport protein Sec31A in CRT-deficient cells. These findings indicate a novel role for CRT in promoting the secretory trafficking of a protein that forms polymers and large intracellular inclusions. Inefficient secretory trafficking of ATZ in the absence of CRT is coincident with enhanced accumulation of ER-derived ATZ inclusion bodies. Further understanding of the factors that control the secretory trafficking of ATZ and their regulation by CRT could lead to new therapies for lung and liver diseases linked to AAT deficiency.
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Affiliation(s)
- Harihar Milaganur Mohan
- Department of Microbiology and Immunology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, 48109 USA
| | - Boning Yang
- Department of Microbiology and Immunology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, 48109 USA
| | - Nicole A Dean
- Department of Microbiology and Immunology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, 48109 USA
| | - Malini Raghavan
- Department of Microbiology and Immunology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, 48109 USA.
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23
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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: 89] [Impact Index Per Article: 22.3] [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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24
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Lee JS, Kim HY, Kim M, Lee YK. A Novel Pathogenic CALR Exon 9 Mutation in a Patient with Essential Thrombocythemia. Lab Med 2020; 51:306-309. [PMID: 31626697 DOI: 10.1093/labmed/lmz064] [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: 11/13/2022] Open
Abstract
The clinical phenotypes and prognoses of CALR-mutant myeloproliferative neoplasms depend on the mutation type. The 2 most common mutations, type 1 (52-bp deletion) and type 2 (5-bp insertion), account for 85% of CALR-mutated neoplasms. The former confers a myelofibrotic phenotype, and the latter is associated with a low risk of thrombosis and an indolent clinical course. Individual case reports for patients with novel pathogenic CALR mutations are rare. Herein, we present the first case in the literature, to our knowledge, of a 63-year old ethnic Korean man with essential thrombocythemia who was diagnosed with a novel +1-bp frameshift mutation in CALR, which was predicted to exhibit a type 2-like phenotype.
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Affiliation(s)
- Jee-Soo Lee
- Department of Laboratory Medicine, Hallym University Sacred Heart Hospital, Anyang, South Korea
| | - Ho Young Kim
- Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, South Korea
| | - Miyoung Kim
- Department of Laboratory Medicine, Hallym University Sacred Heart Hospital, Anyang, South Korea
| | - Young Kyung Lee
- Department of Laboratory Medicine, Hallym University Sacred Heart Hospital, Anyang, South Korea
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25
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Abstract
Calreticulin (CRT) is a pleiotropic and highly conserved molecule that is mainly localized in the endoplasmic reticulum. Recently, CRT has gained special interest for its functions outside the endoplasmic reticulum where it has immunomodulatory properties. CRT translocation to the cell membrane serves as an "eat me" signal and promotes efferocytosis of apoptotic cells and cancer cell removal with completely opposite outcomes. Efferocytosis results in a silenced immune response and homeostasis, while removal of dying cancer cells brought about by anthracycline treatment, ionizing-irradiation or photodynamic therapy results in immunogenic cell death with activation of the innate and adaptive immune responses. In addition, CRT impacts phagocyte activation and cytokine production. The effects of CRT on cytokine production depend on its conformation, species specificity, degree of oligomerization and/or glycosylation, as well as its cellular localization and the molecular partners involved. The controversial roles of CRT in cancer progression and the possible role of the CALR gene mutations in myeloproliferative neoplasms are also addressed. The release of CRT and its influence on the different cells involved during efferocytosis and immunogenic cell death points to additional roles of CRT besides merely acting as an "eat me" signal during apoptosis. Understanding the contribution of CRT in physiological and pathological processes could give us some insight into the potential of CRT as a therapeutic target.
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26
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Biwer LA, Askew-Page HR, Hong K, Milstein J, Johnstone SR, Macal E, Good ME, Bagher P, Sonkusare SK, Isakson BE. Endothelial calreticulin deletion impairs endothelial function in aged mice. Am J Physiol Heart Circ Physiol 2020; 318:H1041-H1048. [PMID: 32196361 PMCID: PMC7346539 DOI: 10.1152/ajpheart.00586.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Discrete calcium signals within the vascular endothelium decrease with age and contribute to impaired endothelial-dependent vasodilation. Calreticulin (Calr), a multifunctional calcium binding protein and endoplasmic reticulum (ER) chaperone, can mediate calcium signals and vascular function within the endothelial cells (ECs) of small resistance arteries. We found Calr protein expression significantly decreases with age in mesenteric arteries and examined the functional role of EC Calr in vasodilation and calcium mobilization in the context of aging. Third-order mesenteric arteries from mice with or without EC Calr knockdown were examined for calcium signals and constriction to phenylephrine (PE) or vasodilation to carbachol (CCh) after 75 wk of age. PE constriction in aged mice with or without EC Calr was unchanged. However, calcium signals and vasodilation to endothelial-dependent agonist carbachol were significantly impaired in aged EC Calr knockdown mice. Ex vivo incubation of arteries with the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) significantly improved vasodilation in mice lacking EC Calr. Our data suggests diminished vascular Calr expression with age can contribute to the detrimental effects of aging on endothelial calcium regulation and vasodilation.NEW & NOTEWORTHY Calreticulin (Calr) is responsible for key physiological processes in endoplasmic reticulum, especially in aging tissue. In particular, endothelial Calr is crucial to vascular function. In this study, we deleted Calr from the endothelium and aged the mice up to 75 wk to examine changes in vascular function. We found two key differences: 1) calcium events in endothelium were severely diminished after muscarinic stimulation, which 2) corresponded with a dramatic decrease in muscarinic vasodilation. Remarkably, we were able to rescue the effect of Calr deletion on endothelial-dependent vasodilatory function using tauroursodeoxycholic acid (TUDCA), an inhibitor of endoplasmic reticulum stress that is currently in clinical trials.
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Affiliation(s)
- Lauren A Biwer
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia.,Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts
| | - Henry R Askew-Page
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St. George's University of London, London, United Kingdom
| | - Kwangseok Hong
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Department of Physical Education, College of Education, Chung-Ang University, Seoul, South Korea
| | - Jenna Milstein
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Scott R Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Edgar Macal
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Miranda E Good
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts
| | - Pooneh Bagher
- Department of Medical Physiology, Texas A&M University Health Science Center, Bryan, Texas
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia.,Department of Molecular Physiology and Biophysics, University of Virginia School of Medicine, Charlottesville, Virginia
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27
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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: 46] [Impact Index Per Article: 11.5] [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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28
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Wang WA, Agellon LB, Michalak M. Organellar Calcium Handling in the Cellular Reticular Network. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a038265. [PMID: 31358518 DOI: 10.1101/cshperspect.a038265] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ca2+ is an important intracellular messenger affecting diverse cellular processes. In eukaryotic cells, Ca2+ is handled by a myriad of Ca2+-binding proteins found in organelles that are organized into the cellular reticular network (CRN). The network is comprised of the endoplasmic reticulum, Golgi apparatus, lysosomes, membranous components of the endocytic and exocytic pathways, peroxisomes, and the nuclear envelope. Membrane contact sites between the different components of the CRN enable the rapid movement of Ca2+, and communication of Ca2+ status, within the network. Ca2+-handling proteins that reside in the CRN facilitate Ca2+ sensing, buffering, and cellular signaling to coordinate the many processes that operate within the cell.
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Affiliation(s)
- Wen-An Wang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
| | - Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
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29
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Jia R, Kralovics R. Progress in elucidation of molecular pathophysiology of myeloproliferative neoplasms and its application to therapeutic decisions. Int J Hematol 2019; 111:182-191. [PMID: 31741139 DOI: 10.1007/s12185-019-02778-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 11/07/2019] [Indexed: 01/14/2023]
Abstract
Myeloproliferative neoplasms (MPNs) are hematological diseases that are driven by somatic mutations in hematopoietic stem and progenitor cells. These mutations include JAK2, CALR and MPL mutations as the main disease drivers, mutations driving clonal expansion, and mutations that contribute to progression of chronic MPNs to myelodysplasia and acute leukemia. JAK-STAT pathway has played a central role in the disease pathogenesis of MPNs. Mutant JAK2, CALR or MPL constitutively activates JAK-STAT pathway independent of the cytokine regulation. Symptomatic management is the primary goal of MPN therapy in ET and low-risk PV patients. JAK2 inhibitors and interferon-α are the established therapies in MF and high-risk PV patients.
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Affiliation(s)
- Ruochen Jia
- Department of Laboratory Medicine, Medical University of Vienna, 18-20 Währinger Gürtel, 1090, Vienna, Austria.,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Robert Kralovics
- Department of Laboratory Medicine, Medical University of Vienna, 18-20 Währinger Gürtel, 1090, Vienna, Austria. .,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
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30
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Adams BM, Ke H, Gierasch LM, Gershenson A, Hebert DN. Proper secretion of the serpin antithrombin relies strictly on thiol-dependent quality control. J Biol Chem 2019; 294:18992-19011. [PMID: 31662433 DOI: 10.1074/jbc.ra119.010450] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/24/2019] [Indexed: 01/04/2023] Open
Abstract
The protein quality control machinery of the endoplasmic reticulum (ERQC) ensures that client proteins are properly folded. ERQC substrates may be recognized as nonnative by the presence of exposed hydrophobic surfaces, free thiols, or processed N-glycans. How these features dictate which ERQC pathways engage a given substrate is poorly understood. Here, using metabolic labeling, immunoprecipitations, various biochemical assays, and the human serpin antithrombin III (ATIII) as a model, we explored the role of ERQC systems in mammalian cells. Although ATIII has N-glycans and a hydrophobic core, we found that its quality control depended solely on free thiol content. Mutagenesis of all six Cys residues in ATIII to Ala resulted in its efficient secretion even though the product was not natively folded. ATIII variants with free thiols were retained in the endoplasmic reticulum but not degraded. These results provide insight into the hierarchy of ERQC systems and reveal a fundamental vulnerability of ERQC in a case of reliance on the thiol-dependent quality control pathway.
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Affiliation(s)
- Benjamin M Adams
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Haiping Ke
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Lila M Gierasch
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003.,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003 .,Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003
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31
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Kotian V, Sarmah D, Kaur H, Kesharwani R, Verma G, Mounica L, Veeresh P, Kalia K, Borah A, Wang X, Dave KR, Yavagal DR, Bhattacharya P. Evolving Evidence of Calreticulin as a Pharmacological Target in Neurological Disorders. ACS Chem Neurosci 2019; 10:2629-2646. [PMID: 31017385 DOI: 10.1021/acschemneuro.9b00158] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Calreticulin (CALR), a lectin-like ER chaperone, was initially known only for its housekeeping function, but today it is recognized for many versatile roles in different compartments of a cell. Apart from canonical roles in protein folding and calcium homeostasis, it performs a variety of noncanonical roles, mostly in CNS development. In the past, studies have linked Calreticulin with various other biological components which are detrimental in deciding the fate of neurons. Many neurological disorders that differ in their etiology are commonly associated with aberrant levels of Calreticulin, that lead to modulation of apoptosis and phagocytosis, and impact on transcriptional pathways, impairment in proteostatis, and calcium imbalances. Such multifaceted properties of Calreticulin are the reason why it has been implicated in vital roles of the nervous system in recent years. Hence, understanding its role in the physiology of neurons would help to unearth its involvement in the spectrum of neurological disorders. This Review aims toward exploring the interplay of Calreticulin in neurological disorders which would aid in targeting Calreticulin for developing novel neurotherapeutics.
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Affiliation(s)
- Vignesh Kotian
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Deepaneeta Sarmah
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Harpreet Kaur
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Radhika Kesharwani
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Geetesh Verma
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Leela Mounica
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Pabbala Veeresh
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Kiran Kalia
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
| | - Anupom Borah
- Cellular and Molecular Neurobiology Laboratory, Department of Life Science and Bioinformatics, Assam University, Silchar, Assam 788011, India
| | - Xin Wang
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Kunjan R. Dave
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Dileep R. Yavagal
- Department of Neurology and Neurosurgery, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Pallab Bhattacharya
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar, Gujarat 382355, India
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32
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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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Paraquat-Mediated Oxidative Stress in Anopheles gambiae Mosquitoes Is Regulated by An Endoplasmic Reticulum (ER) Stress Response. Proteomes 2018; 6:proteomes6040047. [PMID: 30424486 PMCID: PMC6313908 DOI: 10.3390/proteomes6040047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/07/2018] [Accepted: 11/09/2018] [Indexed: 11/20/2022] Open
Abstract
Paraquat is a potent superoxide (O2−)-inducing agent that is capable of inducing an oxidative imbalance in the mosquito midgut. This oxidative imbalance can super-stress the malaria parasite, leading to arrested development in the mosquito midgut and reduced transmission. While several studies have explored the effect of paraquat on malaria parasites, a fundamental understanding of the mosquito response to this compound remains unknown. Here, we quantified the mosquito midgut proteomic response to a paraquat-laced sugar meal, and found that An. gambiae midguts were enriched in proteins that are indicative of cells under endoplasmic reticulum (ER) stress. We also carried out qRT-PCR analyses for nine prominent thioredoxin (Trx) and glutathione (GSH)-dependent genes in mosquito midguts post P. falciparum blood meal ingestion to evaluate the concordance between transcripts and proteins under different oxidative stress conditions. Our data revealed an absence of significant upregulation in the Trx and GSH-dependent genes following infected blood meal ingestion. These data suggest that the intrinsic tolerance of the mosquito midgut to paraquat-mediated oxidative stress is through an ER stress response. These data indicate that mosquitoes have at least two divergent pathways of managing the oxidative stress that is induced by exogenous compounds, and outline the potential application of paraquat-like drugs to act selectively against malaria parasite development in mosquito midguts, thereby blocking mosquito-to-human transmission.
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Morimoto M, Waller-Evans H, Ammous Z, Song X, Strauss KA, Pehlivan D, Gonzaga-Jauregui C, Puffenberger EG, Holst CR, Karaca E, Brigatti KW, Maguire E, Coban-Akdemir ZH, Amagata A, Lau CC, Chepa-Lotrea X, Macnamara E, Tos T, Isikay S, Nehrebecky M, Overton JD, Klein M, Markello TC, Posey JE, Adams DR, Lloyd-Evans E, Lupski JR, Gahl WA, Malicdan MCV. Bi-allelic CCDC47 Variants Cause a Disorder Characterized by Woolly Hair, Liver Dysfunction, Dysmorphic Features, and Global Developmental Delay. Am J Hum Genet 2018; 103:794-807. [PMID: 30401460 PMCID: PMC6218603 DOI: 10.1016/j.ajhg.2018.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/26/2018] [Indexed: 01/06/2023] Open
Abstract
Ca2+ signaling is vital for various cellular processes including synaptic vesicle exocytosis, muscle contraction, regulation of secretion, gene transcription, and cellular proliferation. The endoplasmic reticulum (ER) is the largest intracellular Ca2+ store, and dysregulation of ER Ca2+ signaling and homeostasis contributes to the pathogenesis of various complex disorders and Mendelian disease traits. We describe four unrelated individuals with a complex multisystem disorder characterized by woolly hair, liver dysfunction, pruritus, dysmorphic features, hypotonia, and global developmental delay. Through whole-exome sequencing and family-based genomics, we identified bi-allelic variants in CCDC47 that encodes the Ca2+-binding ER transmembrane protein CCDC47. CCDC47, also known as calumin, has been shown to bind Ca2+ with low affinity and high capacity. In mice, loss of Ccdc47 leads to embryonic lethality, suggesting that Ccdc47 is essential for early development. Characterization of cells from individuals with predicted likely damaging alleles showed decreased CCDC47 mRNA expression and protein levels. In vitro cellular experiments showed decreased total ER Ca2+ storage, impaired Ca2+ signaling mediated by the IP3R Ca2+ release channel, and reduced ER Ca2+ refilling via store-operated Ca2+ entry. These results, together with the previously described role of CCDC47 in Ca2+ signaling and development, suggest that bi-allelic loss-of-function variants in CCDC47 underlie the pathogenesis of this multisystem disorder.
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Affiliation(s)
- Marie Morimoto
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - Zineb Ammous
- The Community Health Clinic, Topeka, IN 46571, USA
| | - Xiaofei Song
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | - Charles R Holst
- BioElectron Technology Corporation, Mountain View, CA 94043, USA
| | - Ender Karaca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Emily Maguire
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - Zeynep H Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Akiko Amagata
- BioElectron Technology Corporation, Mountain View, CA 94043, USA
| | - C Christopher Lau
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xenia Chepa-Lotrea
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ellen Macnamara
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tulay Tos
- Department of Medical Genetics, Dr. Sami Ulus Research and Training Hospital of Women's and Children's Health and Diseases, Ankara 06080, Turkey
| | - Sedat Isikay
- Department of Physiotherapy and Rehabilitation, Hasan Kalyoncu University, School of Health Sciences, Gaziantep 27000, Turkey
| | - Michele Nehrebecky
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | - John D Overton
- Regeneron Genetics Center, Regeneron Pharmaceuticals Inc., Tarrytown, NY 10591, USA
| | - Matthew Klein
- BioElectron Technology Corporation, Mountain View, CA 94043, USA
| | - Thomas C Markello
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jennifer E Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - David R Adams
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA; Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - William A Gahl
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA; Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - May Christine V Malicdan
- National Institutes of Health Undiagnosed Diseases Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, MD 20892, USA; Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Study on the Role of Calreticulin Within Platelet from Adult Patients with Chronic Immune Thrombocytopenic Purpura. Indian J Hematol Blood Transfus 2018; 34:711-718. [PMID: 30369746 DOI: 10.1007/s12288-018-0955-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/28/2018] [Indexed: 02/05/2023] Open
Abstract
To observe the differences in proteins between adult patients with chronic immune thrombocytopenic purpura (ITP) and healthy adults. 30 patients with chronic ITP and 30 healthy controls were enrolled into the study. The platelet total protein was extracted from peripheral venous blood of 10 chronic ITP patients and 10 healthy controls respectively, and subjected to two-dimensional electrophoresis (2-DE) to find the differential protein spot between chronic ITP patients and healthy controls, then the differential protein spots were identified by mass spectrometry. Subsequently, platelets RNA and proteins were isolated from the other 20 chronic ITP patients and 20 healthy controls respectively, and used for confirming the 2-DE and mass spectrometry results by using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and enzyme linked immunosorbent assay (ELISA). 2-DE combined with mass spectrometry revealed that calreticulin (CRT) expressed normally within platelets from healthy controls, while it reduced within platelets from patients with chronic ITP. qPCR and ELISA confirmed that CRT was decreased at both RNA transcription and protein expression levels within platelets from chronic ITP patients compared with healthy controls. Decreased transcription and expression of CRT within platelets may play an important role in the pathogenesis of chronic ITP, which is worthy of further study.
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Yadav S, Prakash J, Saxena JK. Metal binding study of calreticulin: An immunomodulatory protein of human filarial parasite Brugia malayi. Int J Biol Macromol 2018; 117:1157-1168. [DOI: 10.1016/j.ijbiomac.2018.06.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/28/2018] [Accepted: 06/02/2018] [Indexed: 01/02/2023]
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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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Fucikova J, Kasikova L, Truxova I, Laco J, Skapa P, Ryska A, Spisek R. Relevance of the chaperone-like protein calreticulin for the biological behavior and clinical outcome of cancer. Immunol Lett 2017; 193:25-34. [PMID: 29175313 DOI: 10.1016/j.imlet.2017.11.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/17/2017] [Accepted: 11/19/2017] [Indexed: 12/26/2022]
Abstract
The death of cancer cells can be categorized as either immunogenic (ICD) or nonimmunogenic, depending on the initiating stimulus. The immunogenic processes of immunogenic cell death are mainly mediated by damage-associated molecular patterns (DAMPs), which include surface exposure of calreticulin (CRT), secretion of adenosine triphosphate (ATP), release of non-histone chromatin protein high-mobility group box 1 (HMGB1) and the production of type I interferons (IFNs). DAMPs are recognized by various receptors that are expressed by antigen-presenting cells (APCs) and potentiate the presentation of tumor antigens to T lymphocytes. Accumulating evidence indicates that CRT exposure constitutes one of the major checkpoints, that determines the immunogenicity of cell death both in vitro and in vivo in mouse models. Moreover, recent studies have identified CRT expression on tumor cells not only as a marker of ICD and active anti-tumor immune reactions but also as a major predictor of a better prognosis in various cancers. Here, we discuss the recent information on the CRT capacity to activate anticancer immune response as well as its prognostic and predictive role for the clinical outcome in cancer patients.
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Affiliation(s)
- Jitka Fucikova
- Department of Immunology, Charles University, 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic; Sotio, Prague, Czech Republic
| | - Lenka Kasikova
- Department of Immunology, Charles University, 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic; Sotio, Prague, Czech Republic
| | - Iva Truxova
- Department of Immunology, Charles University, 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic; Sotio, Prague, Czech Republic
| | - Jan Laco
- Fingerland Department of Pathology, Charles University Medical Faculty and University Hospital, Hradec Kralove, Czech Republic
| | - Petr Skapa
- Department of Immunology, Charles University, 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Ales Ryska
- Fingerland Department of Pathology, Charles University Medical Faculty and University Hospital, Hradec Kralove, Czech Republic
| | - Radek Spisek
- Department of Immunology, Charles University, 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic; Sotio, Prague, Czech Republic.
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Owusu BY, Zimmerman KA, Murphy-Ullrich JE. The role of the endoplasmic reticulum protein calreticulin in mediating TGF-β-stimulated extracellular matrix production in fibrotic disease. J Cell Commun Signal 2017; 12:289-299. [PMID: 29080087 DOI: 10.1007/s12079-017-0426-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 10/20/2017] [Indexed: 12/11/2022] Open
Abstract
Endoplasmic reticulum (ER) stress is a key factor contributing to fibrotic disease. Although ER stress is a short-term adaptive response, with chronic stimulation, it can activate pathways leading to fibrosis. ER stress can induce TGF-β signaling, a central driver of extracellular matrix production in fibrosis. This review will discuss the role of an ER protein, calreticulin (CRT), which has both chaperone and calcium regulatory functions, in fibrosis. CRT expression is upregulated in multiple different fibrotic diseases. The roles of CRT in regulation of fibronectin extracellular matrix assembly, extracellular matrix transcription, and collagen secretion and processing into the extracellular matrix will be discussed. Evidence for the importance of CRT in ER calcium release and NFAT activation downstream of TGF-β signaling will be presented. Finally, we will summarize evidence from animal models in which CRT expression is genetically reduced or experimentally downregulated in targeted tissues of adult animals and discuss how these models define a key role for CRT in fibrotic diseases.
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Affiliation(s)
- Benjamin Y Owusu
- Department of Pathology, University of Alabama at Birmingham, G001A Volker Hall, Birmingham, AL, 35294, USA
| | - Kurt A Zimmerman
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Joanne E Murphy-Ullrich
- Department of Pathology, University of Alabama at Birmingham, G001A Volker Hall, Birmingham, AL, 35294, USA. .,Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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Araki M, Komatsu N. Novel molecular mechanism of cellular transformation by a mutant molecular chaperone in myeloproliferative neoplasms. Cancer Sci 2017; 108:1907-1912. [PMID: 28741795 PMCID: PMC5623763 DOI: 10.1111/cas.13327] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 07/19/2017] [Indexed: 12/03/2022] Open
Abstract
Deregulation of the cytokine‐receptor signaling pathway plays a significant role in tumorigenesis. Such deregulation is frequently caused by alterations in the genes involved in the signaling pathway. At the end of 2013, recurrent somatic mutations in the calreticulin (CALR) gene that encodes a molecular chaperone were identified in a subset of patients with Philadelphia‐chromosome negative myeloproliferative neoplasms (MPN). The present review focuses on the role of CALR mutations in the oncogenic transformations observed in MPN. All the CALR mutations were found to generate a + 1 frameshift in the reading frame on exon 9, which encodes the carboxy (C)‐terminus end of CALR, and thus conferred a common mutant‐specific sequence in all the CALR mutants. The mutant CALR (but not the wild‐type) constitutively activates the thrombopoietin (TPO) receptor, myeloproliferative leukemia protein (MPL), even in the absence of TPO to induce cellular transformation. Preferential interaction between the mutant CALR and MPL is achieved by a presumptive conformational change induced by the mutant‐specific C‐terminus domain, which allows N‐domain binding to MPL. Even though mutant CALR is expressed on the cell surface and is secreted out of cells, it only presents autocrine capacity for MPL activation. These findings define a novel molecular mechanism by which the mutant molecular chaperone constitutively activates the cytokine receptor to induce cellular transformation.
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Affiliation(s)
- Marito Araki
- Department of Transfusion Medicine and Stem Cell Regulation, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Norio Komatsu
- Department of Hematology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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The Lectin Chaperone Calnexin Is Involved in the Endoplasmic Reticulum Stress Response by Regulating Ca 2+ Homeostasis in Aspergillus nidulans. Appl Environ Microbiol 2017; 83:AEM.00673-17. [PMID: 28550061 DOI: 10.1128/aem.00673-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/18/2017] [Indexed: 12/23/2022] Open
Abstract
The Ca2+-mediated signaling pathway is crucial for environmental adaptation in fungi. Here we show that calnexin, a molecular chaperone located in the endoplasmic reticulum (ER), plays an important role in regulating the cytosolic free calcium concentration ([Ca2+]c) in Aspergillus nidulans Inactivation of calnexin (ClxA) in A. nidulans caused severe defects in hyphal growth and conidiation under ER stress caused by the ER stress-inducing agent dithiothreitol (DTT) or high temperature. Importantly, defects in the ΔclxA mutant were restored by the addition of extracellular calcium. Furthermore, the CchA/MidA complex (the high-affinity Ca2+ channels), calcineurin (calcium/calmodulin-dependent protein phosphatase), and PmrA (secretory pathway Ca2+ ATPase) were required for extracellular calcium-based restoration of the DTT/thermal stress sensitivity in the ΔclxA mutant. Interestingly, the ΔclxA mutant exhibited markedly reduced conidium formation and hyphal growth defects under the low-calcium condition, which is similar to defects caused by mutations in MidA/CchA. Moreover, the phenotypic defects were further exacerbated in the ΔclxA ΔmidA ΔcchA mutant, which suggested that ClxA and MidA/CchA are both required under the calcium-limiting condition. Using the calcium-sensitive photoprotein aequorin to monitor [Ca2+]c in living cells, we found that ClxA and MidA/CchA complex synergistically coordinate transient increase in [Ca2+]c in response to extracellular calcium. Moreover, ClxA, in particular its luminal domain, plays a role in mediating the transient [Ca2+]c in response to DTT-induced ER stress in the absence of extracellular calcium, indicating ClxA may mediate calcium release from internal calcium stores. Our findings provide new insights into the role of calnexin in the regulation of calcium-mediated response in fungal ER stress adaptation.IMPORTANCE Calnexin is a well-known molecular chaperone conserved from yeast to humans. Although it contains calcium binding domains, little is known about the role of calnexin in Ca2+ regulation. In this study, we demonstrate that calnexin (ClxA) in the filamentous fungus Aspergillus nidulans, similar to the high-affinity calcium uptake system (HACS), is required for normal growth and conidiation under the calcium-limiting condition. The ClxA dysfunction decreases the transient cytosolic free calcium concentration ([Ca2+]c) induced by a high extracellular calcium or DTT-induced ER stress. Our findings provide the direct evidence that calnexin plays important roles in regulating Ca2+ homeostasis in addition to its role as a molecular chaperone in fungi. These results provide new insights into the roles of calnexin and expand knowledge of fungal stress adaptation.
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Wang G, Jiang Z, Yang N, Zhu D, Zhang M. Identification and characterization of a novel calreticulin involved in the immune response of the Zhikong scallop, Chlamys farreri. FISH & SHELLFISH IMMUNOLOGY 2017; 64:251-259. [PMID: 28323215 DOI: 10.1016/j.fsi.2017.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/09/2017] [Accepted: 03/16/2017] [Indexed: 06/06/2023]
Abstract
Calreticulin (CRT) is a multifunctional calcium-binding chaperone shared among vertebrates and invertebrates. In this study, a novel CRT (CfCRT) was identified in the Zhikong scallop Chlamys farreri by rapid amplification of cDNA ends. The full-length cDNA was composed of 1345 bp, which included a 1158 bp open reading frame, a 25 bp 5'-untranslated region (UTR) and a 162 bp 3'-UTR. The predicted molecular mass of CfCRT was 44.8 kDa. CfCRT contained three highly conserved domains (N-, P- and C-domains) essential to the function of CRT. BLAST analysis revealed significant sequence similarity (73%-92%) with CRT proteins from other mollusks. The mRNA transcripts of CfCRT were present in all the tested tissues of Zhikong scallops, with the higher expression level in the hemocytes and mantle. After stimulation by Vibrio anguillarum, the mRNA transcript of CfCRT in hemocytes was significantly upregulated. Recombinant plasmid pBCRT was successfully expressed in Escherichia coli BL21 (DE3). The recombinant (r)CfCRT protein could bind to the surface of several bacteria including the Gram-negative bacteria V. anguillarum, E. coli, and the Gram-positive bacterium Staphylococcus aureus. Moreover, rCfCRT was able to suppress their growth significantly. These results indicate that CfCRT might act as an immune effector in Zhikong scallop innate immunity.
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Affiliation(s)
- Guanghua Wang
- School of Marine Science, Ningbo University, Ningbo, 315211, China; Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China
| | - Zengjie Jiang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China; Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China
| | - Ning Yang
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China
| | - Dongfa Zhu
- School of Marine Science, Ningbo University, Ningbo, 315211, China.
| | - Min Zhang
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China
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Totani K, Yamaya K, Hirano M, Ito Y. Influence of aglycone structures on N -glycan processing reactions in the endoplasmic reticulum. Carbohydr Res 2017; 439:16-22. [DOI: 10.1016/j.carres.2016.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
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Quality control of glycoprotein folding and ERAD: the role of N-glycan handling, EDEM1 and OS-9. Histochem Cell Biol 2016; 147:269-284. [DOI: 10.1007/s00418-016-1513-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2016] [Indexed: 02/03/2023]
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45
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Ramírez-Toloza G, Abello P, Ferreira A. Is the Antitumor Property of Trypanosoma cruzi Infection Mediated by Its Calreticulin? Front Immunol 2016; 7:268. [PMID: 27462315 PMCID: PMC4939398 DOI: 10.3389/fimmu.2016.00268] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 06/27/2016] [Indexed: 12/31/2022] Open
Abstract
Eight to 10 million people in 21 endemic countries are infected with Trypanosoma cruzi. However, only 30% of those infected develop symptoms of Chagas' disease, a chronic, neglected tropical disease worldwide. Similar to other pathogens, T. cruzi has evolved to resist the host immune response. Studies, performed 80 years ago in the Soviet Union, proposed that T. cruzi infects tumor cells with similar capacity to that displayed for target tissues such as cardiac, aortic, or digestive. An antagonistic relationship between T. cruzi infection and cancer development was also proposed, but the molecular mechanisms involved have remained largely unknown. Probably, a variety of T. cruzi molecules is involved. This review focuses on how T. cruzi calreticulin (TcCRT), exteriorized from the endoplasmic reticulum, targets the first classical complement component C1 and negatively regulates the classical complement activation cascade, promoting parasite infectivity. We propose that this C1-dependent TcCRT-mediated virulence is critical to explain, at least an important part, of the parasite capacity to inhibit tumor development. We will discuss how TcCRT, by directly interacting with venous and arterial endothelial cells, inhibits angiogenesis and tumor growth. Thus, these TcCRT functions not only illustrate T. cruzi interactions with the host immune defensive strategies, but also illustrate a possible co-evolutionary adaptation to privilege a prolonged interaction with its host.
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Affiliation(s)
- Galia Ramírez-Toloza
- Faculty of Veterinary Medicine and Livestock Sciences, University of Chile , Santiago , Chile
| | - Paula Abello
- Program of Immunology, Faculty of Medicine, Institute of Biomedical Sciences (ICBM), University of Chile , Santiago , Chile
| | - Arturo Ferreira
- Program of Immunology, Faculty of Medicine, Institute of Biomedical Sciences (ICBM), University of Chile , Santiago , Chile
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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: 29] [Impact Index Per Article: 3.6] [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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Kim TK, Ibelli AMG, Mulenga A. Amblyomma americanum tick calreticulin binds C1q but does not inhibit activation of the classical complement cascade. Ticks Tick Borne Dis 2016; 6:91-101. [PMID: 25454607 DOI: 10.1016/j.ttbdis.2014.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/08/2014] [Accepted: 10/13/2014] [Indexed: 01/02/2023]
Abstract
In this study we characterized Amblyomma americanum (Aam) tick calreticulin (CRT) homolog in tick feeding physiology. In nature, different tick species can be found feeding on the same animal host. This suggests that different tick species found feeding on the same host can modulate the same host anti-tick defense pathways to successfully feed. From this perspective it's plausible that different tick species can utilize universally conserved proteins such as CRT to regulate and facilitate feeding. CRT is a multi-functional protein found in most taxa that is injected into the vertebrate host during tick feeding. Apart from it's current use as a biomarker for human tick bites, role(s) of this protein in tick feeding physiology have not been elucidated. Here we show that annotated functional CRT amino acid motifs are well conserved in tick CRT. However our data show that despite high amino acid identity levels to functionally characterized CRT homologs in other organisms, AamCRT is apparently functionally different. Pichia pastoris expressed recombinant (r) AamCRT bound C1q, the first component of the classical complement system, but it did not inhibit activation of this pathway. This contrast with reports of other parasite CRT that inhibited activation of the classical complement pathway through sequestration of C1q. Furthermore rAamCRT did not bind factor Xa in contrast to reports of parasite CRT binding factor Xa, an important protease in the blood clotting system. Consistent with this observation, rAamCRT did not affect plasma clotting or platelet aggregation. We discuss our findings in the context of tick feeding physiology.
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Affiliation(s)
- Tae Kwon Kim
- Texas A & M University AgriLife Research, Department of Entomology, 2475 TAMU, College Station, TX 77843, United States
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Wijeyesakere SJ, Bedi SK, Huynh D, Raghavan M. The C-Terminal Acidic Region of Calreticulin Mediates Phosphatidylserine Binding and Apoptotic Cell Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2016; 196:3896-3909. [PMID: 27036911 DOI: 10.4049/jimmunol.1502122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 02/23/2016] [Indexed: 12/22/2022]
Abstract
Calreticulin is a calcium-binding chaperone that is normally localized in the endoplasmic reticulum. Calreticulin is detectable on the surface of apoptotic cells under some apoptosis-inducing conditions, where it promotes the phagocytosis and immunogenicity of dying cells. However, the precise mechanism by which calreticulin, a soluble protein, localizes to the outer surface of the plasma membrane of dying cells is unknown, as are the molecular mechanisms that are relevant to calreticulin-induced cellular phagocytosis. Calreticulin comprises three distinct structural domains: a globular domain, an extended arm-like P-domain, and a C-terminal acidic region containing multiple low-affinity calcium binding sites. We show that calreticulin, via its C-terminal acidic region, preferentially interacts with phosphatidylserine (PS) compared with other phospholipids and that this interaction is calcium dependent. Additionally, exogenous calreticulin binds apoptotic cells via a higher-affinity calcium-dependent mode that is acidic region dependent. Exogenous calreticulin also binds live cells, including macrophages, via a second, lower-affinity P-domain and globular domain-dependent, but calcium-independent binding mode that likely involves its generic polypeptide binding site. Truncation constructs lacking the acidic region or arm-like P-domain of calreticulin are impaired in their abilities to induce apoptotic cell phagocytosis by murine peritoneal macrophages. Taken together, the results of this investigation provide the first molecular insights into the phospholipid binding site of calreticulin as a key anchor point for the cell surface expression of calreticulin on apoptotic cells. These findings also support a role for calreticulin as a PS-bridging molecule that cooperates with other PS-binding factors to promote the phagocytosis of apoptotic cells.
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Affiliation(s)
| | - Sukhmani Kaur Bedi
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
| | - David Huynh
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
| | - Malini Raghavan
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor MI 48109
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Eggleton P, Bremer E, Dudek E, Michalak M. Calreticulin, a therapeutic target? Expert Opin Ther Targets 2016; 20:1137-47. [DOI: 10.1517/14728222.2016.1164695] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Chen Y, Bharill S, Altun Z, O'Hagan R, Coblitz B, Isacoff EY, Chalfie M. Caenorhabditis elegans paraoxonase-like proteins control the functional expression of DEG/ENaC mechanosensory proteins. Mol Biol Cell 2016; 27:1272-85. [PMID: 26941331 PMCID: PMC4831881 DOI: 10.1091/mbc.e15-08-0561] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 02/23/2016] [Indexed: 12/22/2022] Open
Abstract
MEC-6 and POML-1 are similar proteins needed for touch sensitivity in Caenorhabditis elegans. These proteins reside primarily in the ER and affect the amount and localization of MEC-4, the DEG/ENaC mechanotransduction channel protein. MEC-6 also accelerates MEC-4 transport to the cell surface in vitro. Thus these proteins appear to act as MEC-4 chaperones. Caenorhabditis elegans senses gentle touch via a mechanotransduction channel formed from the DEG/ENaC proteins MEC-4 and MEC-10. An additional protein, the paraoxonase-like protein MEC-6, is essential for transduction, and previous work suggested that MEC-6 was part of the transduction complex. We found that MEC-6 and a similar protein, POML-1, reside primarily in the endoplasmic reticulum and do not colocalize with MEC-4 on the plasma membrane in vivo. As with MEC-6, POML-1 is needed for touch sensitivity, the neurodegeneration caused by the mec-4(d) mutation, and the expression and distribution of MEC-4 in vivo. Both proteins are likely needed for the proper folding or assembly of MEC-4 channels in vivo as measured by FRET. MEC-6 detectably increases the rate of MEC-4 accumulation on the Xenopus oocyte plasma membrane. These results suggest that MEC-6 and POML-1 interact with MEC-4 to facilitate expression and localization of MEC-4 on the cell surface. Thus MEC-6 and POML-1 act more like chaperones for MEC-4 than channel components.
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Affiliation(s)
- Yushu Chen
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Shashank Bharill
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Zeynep Altun
- Department of Neuroscience and Psychiatry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Robert O'Hagan
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Brian Coblitz
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - Martin Chalfie
- Department of Biological Sciences, Columbia University, New York, NY 10027
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