1
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Garcia-Ovejero D, Beyerer E, Mach O, Leister I, Strowitzki M, Wutte C, Maier D, Kramer JL, Aigner L, Arevalo-Martin A, Grassner L. Untargeted blood serum proteomics identifies novel proteins related to neurological recovery after human spinal cord injury. J Transl Med 2024; 22:666. [PMID: 39020346 PMCID: PMC11256486 DOI: 10.1186/s12967-024-05344-y] [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: 03/09/2024] [Accepted: 05/24/2024] [Indexed: 07/19/2024] Open
Abstract
BACKGROUND The discovery of new prognostic biomarkers following spinal cord injury (SCI) is a rapidly growing field that could help uncover the underlying pathological mechanisms of SCI and aid in the development of new therapies. To date, this search has largely focused on the initial days after the lesion. However, during the subacute stage of SCI (weeks to months after the injury), there remains potential for sensorimotor recovery, and numerous secondary events develop in various organs. Additionally, the confounding effects of early interventions after the injury are less likely to interfere with the results. METHODS In this study, we conducted an untargeted proteomics analysis to identify biomarkers of recovery in blood serum samples during the subacute phase of SCI patients, comparing those with strong recovery to those with no recovery between 30 and 120 days. We analyzed the fraction of serum that is depleted of the most abundant proteins to unmask proteins that would otherwise go undetected. Linear models were used to identify peptides and proteins related to neurological recovery and we validated changes in some of these proteins using Enzyme-linked Immunosorbent Assay (ELISA). RESULTS Our findings reveal that differences in subacute recovery after SCI (from 30 to 120 days) are associated with an enrichment in proteins involved in inflammation, coagulation, and lipid metabolism. Technical validation using commercial ELISAs further confirms that high levels of SERPINE1 and ARHGAP35 are associated with strong neurological recovery, while high levels of CD300a and DEFA1 are associated with a lack of recovery. CONCLUSIONS Our study identifies new candidates for biomarkers of neurological recovery and for novel therapeutic targets after SCI.
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Affiliation(s)
- Daniel Garcia-Ovejero
- Laboratory of Neuroinflammation, Hospital Nacional de Paraplejicos, SESCAM, Toledo, Spain
| | - Evelyn Beyerer
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Orpheus Mach
- Spinal Cord Injury Center, BG Trauma Center, Murnau, Germany
- ParaMove, SCI Research Unit, BG Tauma Center Murnau, Germany and Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Iris Leister
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury Center, BG Trauma Center, Murnau, Germany
- ParaMove, SCI Research Unit, BG Tauma Center Murnau, Germany and Paracelsus Medical University Salzburg, Salzburg, Austria
| | | | - Christof Wutte
- Department of Neurosurgery, BG Trauma Center, Murnau, Germany
| | - Doris Maier
- Spinal Cord Injury Center, BG Trauma Center, Murnau, Germany
- ParaMove, SCI Research Unit, BG Tauma Center Murnau, Germany and Paracelsus Medical University Salzburg, Salzburg, Austria
| | - John Lk Kramer
- International Collaboration on Repair Discoveries, ICORD, University of British Columbia, Vancouver, Canada
- Department of Anesthesiology, Pharmacology & Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Ludwig Aigner
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria
- ParaMove, SCI Research Unit, BG Tauma Center Murnau, Germany and Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Angel Arevalo-Martin
- Laboratory of Neuroinflammation, Hospital Nacional de Paraplejicos, SESCAM, Toledo, Spain.
| | - Lukas Grassner
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria.
- Spinal Cord Injury Center, BG Trauma Center, Murnau, Germany.
- ParaMove, SCI Research Unit, BG Tauma Center Murnau, Germany and Paracelsus Medical University Salzburg, Salzburg, Austria.
- Department of Neurosurgery, Christian Doppler Clinic, Paracelsus Medical University, Salzburg, Austria.
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2
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Li Y, Sun S, Zhang H, Jing Y, Ji X, Wan Q, Liu Y. CALU promotes lung adenocarcinoma progression by enhancing cell proliferation, migration and invasion. Respir Res 2024; 25:267. [PMID: 38970088 PMCID: PMC11227236 DOI: 10.1186/s12931-024-02901-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 06/29/2024] [Indexed: 07/07/2024] Open
Abstract
BACKGROUND Lung cancer is the second most common cancer with the highest mortality in the world. Calumenin as a molecular chaperone that not only binds various proteins within the endoplasmic reticulum but also plays crucial roles in diverse processes associated with tumor development. However, the regulatory mechanism of calumenin in lung adenocarcinoma remains elusive. Here, we studied the impact of calumenin on lung adenocarcinoma and explored possible mechanisms. METHODS 5-ethynyl-2'-deoxyuridine assay, colony formation, transwell and wound healing assays were performed to explore the effects of calumenin on the proliferation and migration of lung adenocarcinoma cells. To gain insights into the underlying mechanisms through which calumenin knockdown inhibits the migration and proliferation of lung adenocarcinoma, we performed Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Gene Set Enrichment Analysis and Ingenuity Pathway Analysis based on transcriptomics by comparing calumenin knockdown with normal A549 cells. RESULTS The mRNA and protein levels of calumenin in lung adenocarcinoma are highly expressed and they are related to an unfavorable prognosis in this disease. Calumenin enhances the proliferation and migration of A549 and H1299 cells. Gene Set Enrichment Analysis revealed that knockdown of calumenin in A549 cells significantly inhibited MYC and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog signaling pathways while activating interferon signals, inflammatory signals, and p53 pathways. Ingenuity pathway analysis provided additional insights, indicating that the interferon and inflammatory pathways were prominently activated upon calumenin knockdown in A549 cells. CONCLUSIONS The anti-cancer mechanism of calumenin knockdown might be related to the inhibition of MYC and KRAS signals but the activation of interferon signals, inflammatory signals and p53 pathways.
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Affiliation(s)
- Yan Li
- Department of Pulmonary and Critical Care Medicine, The Second Hospital of Shandong University, Jinan, Shandong, 250033, China
| | - Shengnan Sun
- Key Laboratory of Cell Metabolism in Medical and Health of Shandong Provincial Health Commission, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
| | - Hui Zhang
- Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, 250021, China
| | - Yongjian Jing
- The First People's Hospital of Pingyuan County, Dezhou, Shandong, 253100, China
| | - Xingzhao Ji
- Key Laboratory of Cell Metabolism in Medical and Health of Shandong Provincial Health Commission, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China
- Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital, Shandong First Medical University, Jinan, Shandong, 250021, China
| | - Qiang Wan
- Key Laboratory of Cell Metabolism in Medical and Health of Shandong Provincial Health Commission, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China.
| | - Yi Liu
- Key Laboratory of Cell Metabolism in Medical and Health of Shandong Provincial Health Commission, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, China.
- Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital, Shandong University, Jinan, Shandong, 250021, China.
- Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital, Shandong First Medical University, Jinan, Shandong, 250021, China.
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3
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Yadav MP, Narayanasamy S, Aradhyam GK. Structural Plasticity Allows Calumenin-1 to Moonlight as a Ca 2+-Independent Chaperone: Pb 2+ Enables Probing Alternate Inhibitory Conformation. Biochemistry 2024; 63:69-81. [PMID: 38100476 DOI: 10.1021/acs.biochem.3c00326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Human calumenin-1 (HsCalu-1) is an endoplasmic reticulum (ER) and Golgi-resident Ca2+-binding protein of the hepta-EF-hand superfamily that plays a vital role in maintaining the cytoplasmic Ca2+ concentration below toxic levels by interacting with Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and ryanodine receptors (RyR), indicating its role in Ca2+ homeostasis in the ER. HsCalu-1 seems to be able to exhibit structural plasticity to achieve its plethora of functions. In this study, we demonstrate that HsCalu-1 acts as a chaperone in both its intrinsically disordered state (apo form) and the structured state (Ca2+-bound form). HsCalu-1 chaperone activity is independent of Ca2+ and Pb2+ binding attenuating its chaperone-like activity. Incidentally, Pb2+ binds to HsCalu-1 with lower affinity (KD = 38.46 μM) (compared to Ca2+-binding), leading to the formation of a less-stable conformation as observed by a sharp drop in its melting temperature Tm from 67 °C in the Ca2+-bound form to 43 °C in the presence of Pb2+. The binding site for Pb2+ was mapped as being in the EF-Hand-234 domain of HsCalu-1, a region that overlaps with the Ca2+-dependent initiator of its functional fold. A change in the secondary and tertiary structure, leading to a less-stable but compact conformation upon Pb2+ binding, is the mechanism by which the chaperone-like activity of HsCalu-1 is diminished. Our results not only demonstrate the chaperone activity by a protein in its disordered state but also explain, using Pb2+ as a probe, that the multiple functions of calumenin are due to its ability to adopt a quasi-stable conformation.
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Affiliation(s)
- Manoj Padamsing Yadav
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sasirekha Narayanasamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Gopala Krishna Aradhyam
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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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: 18] [Impact Index Per Article: 18.0] [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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5
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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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6
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Xu C, Meng LB, Duan YC, Cheng YJ, Zhang CM, Zhou X, Huang CB. Screening and identification of biomarkers for systemic sclerosis via microarray technology. Int J Mol Med 2019; 44:1753-1770. [PMID: 31545397 PMCID: PMC6777682 DOI: 10.3892/ijmm.2019.4332] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 08/13/2019] [Indexed: 12/25/2022] Open
Abstract
Systemic sclerosis (SSc) is a complex autoimmune disease. The pathogenesis of SSc is currently unclear, although like other rheumatic diseases its pathogenesis is complicated. However, the ongoing development of bioinformatics technology has enabled new approaches to research this disease using microarray technology to screen and identify differentially expressed genes (DEGs) in the skin of patients with SSc compared with individuals with healthy skin. Publicly available data were downloaded from the Gene Expression Omnibus (GEO) database and intra-group data repeatability tests were conducted using Pearson's correlation test and principal component analysis. DEGs were identified using an online tool, GEO2R. Functional annotation of DEGs was performed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Finally, the construction and analysis of the protein-protein interaction (PPI) network and identification and analysis of hub genes was carried out. A total of 106 DEGs were detected by the screening of SSc and healthy skin samples. A total of 10 genes [interleukin-6, bone morphogenetic protein 4, calumenin (CALU), clusterin, cysteine rich angiogenic inducer 61, serine protease 23, secretogranin II, suppressor of cytokine signaling 3, Toll-like receptor 4 (TLR4), tenascin C] were identified as hub genes with degrees ≥10, and which could sensitively and specifically predict SSc based on receiver operator characteristic curve analysis. GO and KEGG analysis showed that variations in hub genes were mainly enriched in positive regulation of nitric oxide biosynthetic processes, negative regulation of apoptotic processes, extracellular regions, extracellular spaces, cytokine activity, chemo-attractant activity, and the phosphoinositide 3 kinase-protein kinase B signaling pathway. In summary, bioinformatics techniques proved useful for the screening and identification of biomarkers of disease. A total of 106 DEGs and 10 hub genes were linked to SSc, in particular the TLR4 and CALU genes.
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Affiliation(s)
- Chen Xu
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Ling-Bing Meng
- Department of Neurology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Yu-Chen Duan
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Yong-Jing Cheng
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Chun-Mei Zhang
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Xing Zhou
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Ci-Bo Huang
- Department of Rheumatology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
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7
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Choi TW, Cho JH, Ahnn J, Song HO. Novel Findings of Anti-Filarial Drug Target and Structure-Based Virtual Screening for Drug Discovery. Int J Mol Sci 2018; 19:E3579. [PMID: 30428563 PMCID: PMC6274684 DOI: 10.3390/ijms19113579] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/01/2018] [Accepted: 11/10/2018] [Indexed: 12/22/2022] Open
Abstract
Lymphatic filariasis and onchocerciasis caused by filarial nematodes are important diseases leading to considerable morbidity throughout tropical countries. Diethylcarbamazine (DEC), albendazole (ALB), and ivermectin (IVM) used in massive drug administration are not highly effective in killing the long-lived adult worms, and there is demand for the development of novel macrofilaricidal drugs affecting new molecular targets. A Ca2+ binding protein, calumenin, was identified as a novel and nematode-specific drug target for filariasis, due to its involvement in fertility and cuticle development in nematodes. As sterilizing and killing effects of the adult worms are considered to be ideal profiles of new drugs, calumenin could be an eligible drug target. Indeed, the Caenorhabditis elegans mutant model of calumenin exhibited enhanced drug acceptability to both microfilaricidal drugs (ALB and IVM) even at the adult stage, proving the roles of the nematode cuticle in efficient drug entry. Molecular modeling revealed that structural features of calumenin were only conserved among nematodes (C. elegans, Brugia malayi, and Onchocerca volvulus). Structural conservation and the specificity of nematode calumenins enabled the development of drugs with good target selectivity between parasites and human hosts. Structure-based virtual screening resulted in the discovery of itraconazole (ITC), an inhibitor of sterol biosynthesis, as a nematode calumenin-targeting ligand. The inhibitory potential of ITC was tested using a nematode mutant model of calumenin.
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Affiliation(s)
- Tae-Woo Choi
- Department of Life Science, Hanyang University, Seoul 04763, Korea.
| | - Jeong Hoon Cho
- Department of Biology Education, College of Education, Chosun University, Gwangju 61452, Korea.
| | - Joohong Ahnn
- Department of Life Science, Hanyang University, Seoul 04763, Korea.
| | - Hyun-Ok Song
- Department of Infection Biology, Wonkwang University School of Medicine, Iksan 54538, Korea.
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8
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Narayanasamy S, Aradhyam GK. The Differential Response to Ca 2+ from Vertebrate and Invertebrate Calumenin Is Governed by a Single Amino Acid Residue. Biochemistry 2018; 57:722-731. [PMID: 29319298 DOI: 10.1021/acs.biochem.7b00762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calumenin (Calu) is a well-conserved multi-EF-hand-containing Ca2+-binding protein. In this work, we focused on the alterations that calumenin has undergone during evolution. We demonstrate that vertebrate calumenin is significantly different from its invertebrate homologues with respect to its response to Ca2+ binding. Human calumenin (HsCalu1) is intrinsically unstructured in the Ca2+ free form and responds to Ca2+ with a dramatic gain in structure. Calumenin from Caenorhabditis elegans (CeCalu) is structured even in the apo form, with no conformational change upon binding of Ca2+. We decode this structural and functional distinction by identifying a single "Leu" residue-based switch located in the fourth EF-hand of HsCalu1, occupied by "Gly" in the invertebrate homologues. We demonstrate that replacing Leu with Gly (L150G) in HsCalu1 enables the protein to adopt a structural fold even in the Ca2+ free form, similar to CeCalu, leading to ligand compensation (adoption of structure in the absence of Ca2+). The fourth (of seven) EF-hand of HsCalu1 nucleates the structural fold of the protein depending on the switch residue (Gly or Leu). Our analyses reveal that the Leu that replaced Gly from fishes onward is absolutely conserved in higher vertebrates, while lower organisms have Gly, not only enlarging the scope of Ca2+-dependent structural transitions but also drawing a boundary between the invertebrate and vertebrate calumenin. The evolutionary selection of the switch residue strongly corroborates the change in the structure of the protein and its pleiotropic functions and seems like it can be extended to the presence or absence of a heart in that organism.
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Affiliation(s)
- Sasirekha Narayanasamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras , Chennai 600036, India
| | - Gopala Krishna Aradhyam
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras , Chennai 600036, India
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9
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Blank B, von Blume J. Cab45-Unraveling key features of a novel secretory cargo sorter at the trans-Golgi network. Eur J Cell Biol 2017; 96:383-390. [PMID: 28372832 DOI: 10.1016/j.ejcb.2017.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/27/2017] [Accepted: 03/02/2017] [Indexed: 12/15/2022] Open
Abstract
The accurate and efficient delivery of proteins to specific domains of the plasma membrane or to the extracellular space is critical for the ordered function of surface receptors and proteins such as insulin, collagens, antibodies, extracellular proteases. The trans-Golgi network is responsible for sorting proteins onto specific carriers for transport to their final destination. The role of the mannose-6-phosphate receptor in the sorting of hydrolases destined for lysosomes has been studied extensively, but the sorting mechanisms for secreted proteins remains poorly understood. We recently described a novel process that links the cytoplasmic actin cytoskeleton to the membrane-anchored Ca2+ ATPase SPCA1 and the lumenal Ca2+-binding protein Cab45, which mediates sorting of a subset of secretory proteins at the TGN. In response to Ca2+ influx, Cab45 forms oligomers, enabling it to bind a variety of specific cargo molecules. Thus, we suggest that this represents a novel way to export cargo molecules without the need for a bona fide transmembrane cargo receptor. This review focuses on Cab45's molecular function and highlights its possible role in disease.
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Affiliation(s)
- Birgit Blank
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Julia von Blume
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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10
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Abstract
Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range.
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11
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Aune Westergaard Hansen G, Ludvigsen M, Jacobsen C, Cangemi C, Melholt Rasmussen L, Vorum H, Honoré B. Fibulin-1C, C1 Esterase Inhibitor and Glucose Regulated Protein 75 Interact with the CREC Proteins, Calumenin and Reticulocalbin. PLoS One 2015; 10:e0132283. [PMID: 26161649 PMCID: PMC4498735 DOI: 10.1371/journal.pone.0132283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 06/11/2015] [Indexed: 01/12/2023] Open
Abstract
Affinity purification, immunoprecipitation, gel electrophoresis and mass spectrometry were used to identify fibulin-1C, C1 esterase inhibitor and glucose regulated protein 75, grp75, as binding partners of the CREC proteins, calumenin and reticulocalbin. Surface plasmon resonance was used to verify the interaction of all three proteins with each of the CREC proteins. Fibulin-1C interacts with calumenin and reticulocalbin with an estimated dissociation constant around 50-60 nM. The interaction, at least for reticulocalbin, was not dependent upon the presence of Ca2+. C1 esterase inhibitor interacted with both proteins with an estimated dissociation constant at 1 μM for reticulocalbin and 150 nM for calumenin. The interaction, at least for calumenin, was dependent upon the presence of Ca2+ with strong interaction at 3.5 mM while no detectable interaction could be found at 0.1 mM. Grp75 binds with an affinity of approximately 3-7 nM with reticulocalbin as well as with calumenin. These interactions suggest functional participation of the CREC proteins in chaperone activity, cell proliferation and transformation, cellular aging, haemostasis and thrombosis as well as modulation of the complement system in fighting bacterial infection.
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Affiliation(s)
| | - Maja Ludvigsen
- Department of Biomedicine, Ole Worms Allé 3, Building 1182, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Christian Jacobsen
- Department of Biomedicine, Ole Worms Allé 3, Building 1182, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Claudia Cangemi
- Department of Clinical Biochemistry and Pharmacology, Center for Individualized Medicine in Arterial Diseases (CIMA), Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark
| | - Lars Melholt Rasmussen
- Department of Clinical Biochemistry and Pharmacology, Center for Individualized Medicine in Arterial Diseases (CIMA), Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C, Denmark
| | - Henrik Vorum
- Department of Ophthalmology, Aalborg University Hospital, Hobrovej 18–22, 9100 Aalborg, Denmark
| | - Bent Honoré
- Department of Biomedicine, Ole Worms Allé 3, Building 1182, Aarhus University, DK-8000 Aarhus C, Denmark
- * E-mail:
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12
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Daskalopoulos EP. CALibrating the CALumenin gene: New insights in overcoming the vascular CALcification CALamity? J Mol Cell Cardiol 2015; 84:81-3. [PMID: 25912188 DOI: 10.1016/j.yjmcc.2015.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 04/15/2015] [Accepted: 04/16/2015] [Indexed: 11/13/2022]
Affiliation(s)
- Evangelos P Daskalopoulos
- Pôle de Recherche Cardiovasculaire (CARD), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Brussels, Belgium; Cardiovascular Research (Care) Institute, Athens & Ioannina, Greece.
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13
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Regulation of neuronal survival and morphology by the E3 ubiquitin ligase RNF157. Cell Death Differ 2014; 22:626-42. [PMID: 25342469 DOI: 10.1038/cdd.2014.163] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 08/19/2014] [Accepted: 08/29/2014] [Indexed: 01/03/2023] Open
Abstract
Neuronal health is essential for the long-term integrity of the brain. In this study, we characterized the novel E3 ubiquitin ligase ring finger protein 157 (RNF157), which displays a brain-dominant expression in mouse. RNF157 is a homolog of the E3 ligase mahogunin ring finger-1, which has been previously implicated in spongiform neurodegeneration. We identified RNF157 as a regulator of survival in cultured neurons and established that the ligase activity of RNF157 is crucial for this process. We also uncovered that independently of its ligase activity, RNF157 regulates dendrite growth and maintenance. We further identified the adaptor protein APBB1 (amyloid beta precursor protein-binding, family B, member 1 or Fe65) as an interactor and proteolytic substrate of RNF157 in the control of neuronal survival. Here, the nuclear localization of Fe65 together with its interaction partner RNA-binding protein SART3 (squamous cell carcinoma antigen recognized by T cells 3 or Tip110) is crucial to trigger apoptosis. In summary, we described that the E3 ligase RNF157 regulates important aspects of neuronal development.
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Wang Q, Shen B, Chen L, Zheng P, Feng H, Hao Q, Liu X, Liu L, Xu S, Chen J, Teng J. Extracellular calumenin suppresses ERK1/2 signaling and cell migration by protecting fibulin-1 from MMP-13-mediated proteolysis. Oncogene 2014; 34:1006-18. [DOI: 10.1038/onc.2014.52] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/06/2014] [Accepted: 01/20/2014] [Indexed: 01/04/2023]
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15
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Gharesi-Fard B, Zolghadri J, Kamali-Sarvestani E. Alteration in the expression of proteins in unexplained recurrent pregnancy loss compared with in the normal placenta. J Reprod Dev 2014; 60:261-7. [PMID: 24621454 PMCID: PMC4139499 DOI: 10.1262/jrd.2013-096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The placenta is a unique pregnancy-related tissue and plays a key role in occurrence of unexplained recurrent pregnancy loss
(URPL). Abnormal placentation might play a key role in occurrence of URPL. Therefore, the purpose of this study was to compare the
human placental proteome between URPL placentas and normal placental matched for gestational week. Total placental proteins were
extracted, and the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique was used for separation of the placental
proteomes. Protein spots differentially expressed between URPL and normal placentas were selected and identified by the
matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF/TOF) technique after being digested in the
gel. Moreover, quantitative real-time PCR and Western blot techniques were used to confirm the differential expression mass
results for some differentially expressed proteins. The results indicated that at least 19 protein spots were differentially
expressed between URPL and normal placentas (P < 0.05), and twelve of them were successfully identified. While only two
proteins were downregulated (calumenin and enolase 1), the remaining ten spots (actin gamma 1 propeptide, cathepsin D
prepropeptide, heat shock protein gp96, tubulin beta, tubulin alpha 1, glutathione S-transferase, vitamin D binding protein,
prohibitin, actin beta, apolipoprotein A-I) showed increased expression in URPL cases in comparison with normal placentas.
Real-time PCR also confirmed the downregulation of calumenin and upregulation of prohibitin and apolipoprotein A-I at the mRNA
levels. In conclusion, the results of the present study showed that alteration in the expression of proteins involved in
proliferation and migration of endothelial cells as well as control of coagulation by these cells might play an important role in
the pathogenesis of URPL.
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Suzuki N, Ban S, Itoh E, Chen S, Imai FL, Sawano Y, Miyakawa T, Tanokura M, Yonezawa N. Calcium-dependent structural changes in human reticulocalbin-1. J Biochem 2014; 155:281-93. [PMID: 24451493 DOI: 10.1093/jb/mvu003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human reticulocalbin-1 (hRCN1) has six EF-hand motifs and binds Ca(2+). hRCN1 is a member of the CREC family localized in the secretory pathway, and its cellular function remains unclear. In this study, we established a new bacterial expression and purification procedure for hRCN1. We observed that hRCN1 binds Ca(2+) in a cooperative manner and the Ca(2+) binding caused an increase in the α-helix content of hRCN1. On the other hand, hRCN1 did not change the structure with Mg(2+) loading. hRCN1 is a monomeric protein, and its overall structure became more compact upon Ca(2+) binding, as revealed by gel-filtration column chromatography and small-angle X-ray scattering. This is the first report of conformational changes in the CREC family upon Ca(2+) binding. Our data suggest that CREC family member interactions with target proteins are regulated in the secretory pathway by conformational changes upon Ca(2+) binding.
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Affiliation(s)
- Nanao Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan; and Laboratory of Chemistry, College of Liberal and Sciences, Tokyo Medical and Dental University, Chiba 272-0827, Japan
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Feng H, Chen L, Wang Q, Shen B, Liu L, Zheng P, Xu S, Liu X, Chen J, Teng J. Calumenin-15 facilitates filopodia formation by promoting TGF-β superfamily cytokine GDF-15 transcription. Cell Death Dis 2013; 4:e870. [PMID: 24136234 PMCID: PMC3920949 DOI: 10.1038/cddis.2013.403] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/04/2013] [Accepted: 09/11/2013] [Indexed: 12/12/2022]
Abstract
Filopodia, which are actin-rich finger-like membrane protrusions, have an important role in cell migration and tumor metastasis. Here we identify 13 novel calumenin (Calu) isoforms (Calu 3-15) produced by alternative splicing, and find that Calu-15 promotes filopodia formation and cell migration. Calu-15 shuttles between the nucleus and cytoplasm through interacting with importin α, Ran GTPase, and Crm1. The phosphorylation of the threonine at position 73 (Thr-73) by casein kinase 2 (CK2) is essential for the nuclear import of Calu-15, and either Thr-73 mutation or inhibition of CK2 interrupts its nuclear localization. In the nucleus, Calu-15 increases the transcription of growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β (TGF-β) superfamily, via binding to its promoter region. Furthermore, Calu-15 induces filopodia formation mediated by GDF-15. Together, we identify that Calu-15, a novel isoform of Calu with phosphorylation-dependent nuclear localization, has a critical role in promoting filopodia formation and cell migration by upregulating the GDF-15 transcription.
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Affiliation(s)
- H Feng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - L Chen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Q Wang
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - B Shen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - L Liu
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - P Zheng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - S Xu
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - X Liu
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - J Chen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
- Center for Quantitative Biology, Peking University, Beijing, China
| | - J Teng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering, Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
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18
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Wang Q, Feng H, Zheng P, Shen B, Chen L, Liu L, Liu X, Hao Q, Wang S, Chen J, Teng J. The intracellular transport and secretion of calumenin-1/2 in living cells. PLoS One 2012; 7:e35344. [PMID: 22514732 PMCID: PMC3325945 DOI: 10.1371/journal.pone.0035344] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 03/14/2012] [Indexed: 01/05/2023] Open
Abstract
Calumenin isoforms 1 and 2 (calu-1/2), encoded by the CALU gene, belong to the CREC protein family. Calu-1/2 proteins are secreted into the extracellular space, but the secretory process and regulatory mechanism are largely unknown. Here, using a time-lapse imaging system, we visualized the intracellular transport and secretory process of calu-1/2-EGFP after their translocation into the ER lumen. Interestingly, we observed that an abundance of calu-1/2-EGFP accumulated in cellular processes before being released into the extracellular space, while only part of calu-1/2-EGFP proteins were secreted directly after attaching to the cell periphery. Moreover, we found the secretion of calu-1/2-EGFP required microtubule integrity, and that calu-1/2-EGFP-containing vesicles were transported by the motor proteins Kif5b and cytoplasmic dynein. Finally, we determined the export signal of calu-1/2-EGFP (amino acid positions 20–46) and provided evidence that the asparagine at site 131 was indispensable for calu-1/2-EGFP stabilization. Taken together, we provide a detailed picture of the intracellular transport of calu-1/2-EGFP, which facilitates our understanding of the secretory mechanism of calu-1/2.
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Affiliation(s)
- Qiao Wang
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Hui Feng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Pengli Zheng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Birong Shen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Liang Chen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Lin Liu
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Xiao Liu
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Qingsong Hao
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Shunchang Wang
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Jianguo Chen
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
- Center for Theoretical Biology, Peking University, Beijing, China
| | - Junlin Teng
- State Key Laboratory of Bio-membrane and Membrane Bio-engineering and Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing, China
- * E-mail:
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19
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Vasiljevic M, Heisler FF, Hausrat TJ, Fehr S, Milenkovic I, Kneussel M, Sieghart W. Spatio-temporal expression analysis of the calcium-binding protein calumenin in the rodent brain. Neuroscience 2011; 202:29-41. [PMID: 22178608 PMCID: PMC3270221 DOI: 10.1016/j.neuroscience.2011.11.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 11/29/2011] [Accepted: 11/29/2011] [Indexed: 11/25/2022]
Abstract
Calumenin is a Ca2+-binding protein that belongs to the CREC superfamily. It contains six EF-hand domains that exhibit a low affinity for Ca2+ as well as an endoplasmic reticulum retention signal. Calumenin exhibits a broad and relatively high expression in various brain regions during development as demonstrated by in situ hybridization. Signal intensity of calumenin is highest during the early development and then declines over time to reach a relatively low expression in adult animals. Immunohistochemistry indicates that at the P0 stage, calumenin expression is most abundant in migrating neurons in the zones around the lateral ventricle. In the brain of adult animals, it is expressed in various glial and neuronal cell types, including immature neurons in subgranular zone of hippocampal dentate gyrus. At the subcellular level, calumenin is identified in punctuate and diffuse distribution mostly in somatic regions where it co-localizes with endoplasmic reticulum (ER) and partially Golgi apparatus. Upon subcellular fractionation, calumenin is enriched in fractions containing membranes and is only weakly present in soluble fractions. This study points to a possible important role of calumenin in migration and differentiation of neurons, and/or in Ca2+ signaling between glial cells and neurons.
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Affiliation(s)
- M Vasiljevic
- Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria
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Song DW, Lee JG, Youn HS, Eom SH, Kim DH. Ryanodine receptor assembly: A novel systems biology approach to 3D mapping. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 105:145-61. [DOI: 10.1016/j.pbiomolbio.2010.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 09/14/2010] [Accepted: 09/28/2010] [Indexed: 10/19/2022]
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22
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Voora D, Koboldt DC, King CR, Lenzini PA, Eby CS, Porche-Sorbet R, Deych E, Crankshaw M, Milligan PE, McLeod HL, Patel SR, Cavallari LH, Ridker PM, Grice GR, Miller RD, Gage BF. A polymorphism in the VKORC1 regulator calumenin predicts higher warfarin dose requirements in African Americans. Clin Pharmacol Ther 2010; 87:445-51. [PMID: 20200517 DOI: 10.1038/clpt.2009.291] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Warfarin demonstrates a wide interindividual variability in response that is mediated partly by variants in cytochrome P450 2C9 (CYP2C9) and vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1). It is not known whether variants in calumenin (CALU) (vitamin K reductase regulator) have an influence on warfarin dose requirements. We resequenced CALU regions in a discovery cohort of dose outliers: patients with high (>90th percentile, n = 55) or low (<10th percentile, n = 53) warfarin dose requirements (after accounting for known genetic and nongenetic variables). One CALU variant, rs339097, was associated with high doses (P = 0.01). We validated this variant as a predictor of higher warfarin doses in two replication cohorts: (i) 496 patients of mixed ethnicity and (ii) 194 African-American patients. The G allele of rs339097 (the allele frequency was 0.14 in African Americans and 0.002 in Caucasians) was associated with the requirement for a 14.5% (SD +/- 7%) higher therapeutic dose (P = 0.03) in the first replication cohort and a higher-than-predicted dose in the second replication cohort (allele frequency 0.14, one-sided P = 0.03). CALU rs339097 A>G is associated with higher warfarin dose requirements, independent of known genetic and nongenetic predictors of warfarin dose in African Americans.
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Affiliation(s)
- D Voora
- Department of Medicine, Washington University in St Louis, St Louis, Missouri, USA
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23
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Ludvigsen M, Østergaard M, Vorum H, Jacobsen C, Honoré B. Identification and characterization of endonuclein binding proteins: evidence of modulatory effects on signal transduction and chaperone activity. BMC BIOCHEMISTRY 2009; 10:34. [PMID: 20028516 PMCID: PMC2810291 DOI: 10.1186/1471-2091-10-34] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 12/22/2009] [Indexed: 11/10/2022]
Abstract
Background We have previously identified endonuclein as a cell cycle regulated WD-repeat protein that is up-regulated in adenocarcinoma of the pancreas. Now, we aim to investigate its biomedical functions. Results Using the cDNA encoding human endonuclein, we have expressed and purified the recombinant protein from Escherichia coli using metal affinity chromatography. The recombinant protein was immobilized to a column and by affinity chromatography several interacting proteins were purified from several litres of placenta tissue extract. After chromatography the eluted proteins were further separated by two-dimensional gel electrophoresis and identified by tandem mass spectrometry. The interacting proteins were identified as; Tax interaction protein 1 (TIP-1), Aα fibrinogen transcription factor (P16/SSBP1), immunoglobulin heavy chain binding protein (BiP), human ER-associated DNAJ (HEDJ/DNAJB11), endonuclein interaction protein 8 (EIP-8), and pregnancy specific β-1 glycoproteins (PSGs). Surface plasmon resonance analysis and confocal fluorescence microscopy were used to further characterize the interactions. Conclusions Our results demonstrate that endonuclein interacts with several proteins indicating a broad function including signal transduction and chaperone activity.
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Affiliation(s)
- Maja Ludvigsen
- Department of Medical Biochemistry, Aarhus University, Ole Worms Allé 3, Building 1170, Aarhus, DK-8000 Aarhus C, Denmark.
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24
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Ludvigsen M, Jacobsen C, Maunsbach AB, Honoré B. Identification and characterization of novel ERC-55 interacting proteins: Evidence for the existence of several ERC-55 splicing variants; including the cytosolic ERC-55-C. Proteomics 2009; 9:5267-87. [DOI: 10.1002/pmic.200900321] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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25
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Sahoo SK, Kim T, Kang GB, Lee JG, Eom SH, Kim DH. Characterization of calumenin-SERCA2 interaction in mouse cardiac sarcoplasmic reticulum. J Biol Chem 2009; 284:31109-21. [PMID: 19740751 DOI: 10.1074/jbc.m109.031989] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calumenin is a multiple EF-hand Ca(2+)-binding protein localized in the sarcoplasmic reticulum (SR) with C-terminal SR retention signal HDEF. Recently, we showed evidence that calumenin interacts with SERCA2 in rat cardiac SR (Sahoo, S. K., and Kim, D. H. (2008) Mol. Cells 26, 265-269). The present study was undertaken to further characterize the association of calumenin with SERCA2 in mouse heart by various gene manipulation approaches. Immunocytochemical analysis showed that calumenin and SERCA2 were partially co-localized in HL-1 cells. Knockdown (KD) of calumenin was conducted in HL-1 cells and 80% reduction of calumenin did not induce any expressional changes of other Ca(2+)-cycling proteins. But it enhanced Ca(2+) transient amplitude and showed shortened time to reach peak and decreased time to reach 50% of baseline. Oxalate-supported Ca(2+) uptake showed increased Ca(2+) sensitivity of SERCA2 in calumenin KD HL-1 cells. Calumenin and SERCA2 interaction was significantly lower in the presence of thapsigargin, vanadate, or ATP, as compared with 1.3 mum Ca(2+), suggesting that the interaction is favored in the E1 state of SERCA2. A glutathione S-transferase-pulldown assay of calumenin deletion fragments and SERCA2 luminal domains suggested that regions of 132-222 amino acids of calumenin and 853-892 amino acids of SERCA2-L4 are the major binding partners. On the basis of our in vitro binding data and available information on three-dimensional structure of Ca(2+)-ATPases, a molecular model was proposed for the interaction between calumenin and SERCA2. Taken together, the present results suggest that calumenin is a novel regulator of SERCA2, and its expressional changes are tightly coupled with Ca(2+)-cycling of cardiomyocytes.
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Affiliation(s)
- Sanjaya Kumar Sahoo
- Department of Life Science and Systems Biology Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
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26
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Honoré B. The rapidly expanding CREC protein family: members, localization, function, and role in disease. Bioessays 2009; 31:262-77. [PMID: 19260022 DOI: 10.1002/bies.200800186] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although many aspects of the physiological and pathophysiological mechanisms remain unknown, recent advances in our knowledge suggest that the CREC proteins are promising disease biomarkers or targets for therapeutic intervention in a variety of diseases. The CREC family of low affinity, Ca2+-binding, multiple EF-hand proteins are encoded by five genes, RCN1, RCN2, RCN3, SDF4, and CALU, resulting in reticulocalbin, ER Ca2+-binding protein of 55 kDa (ERC-55), reticulocalbin-3, Ca2+-binding protein of 45 kDa (Cab45), and calumenin. Alternative splicing increases the number of gene products. The proteins are localized in the cytosol, in various parts of the secretory pathway, secreted to the extracellular space or localized on the cell surface. The emerging functions appear to be highly diverse. The proteins interact with several different ligands. Rather well-described functions are attached to calumenin with the inhibition of several proteins in the endoplasmic or sarcoplasmic reticulum membrane, the vitamin K(1) 2,3-epoxide reductase, the gamma-carboxylase, the ryanodine receptor, and the Ca2+-transporting ATPase. Other functions concern participation in the secretory process, chaperone activity, signal transduction as well as participation in a large variety of disease processes.
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Affiliation(s)
- Bent Honoré
- Department of Medical Biochemistry, Aarhus University, Aarhus C, Denmark.
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27
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Cho JH, Song HO, Singaravelu G, Sung H, Oh WC, Kwon S, Kim DH, Ahnn J. Pleiotropic roles of calumenin (calu-1), a calcium-binding ER luminal protein, inCaenorhabditis elegans. FEBS Lett 2009; 583:3050-6. [DOI: 10.1016/j.febslet.2009.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 08/11/2009] [Accepted: 08/13/2009] [Indexed: 11/29/2022]
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28
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Zhu Y, Wang Q, Xu W, Li S. The ethanol response gene Cab45 can modulate the impairment elicited by ethanol and ultraviolet in PC12 cells. J Genet Genomics 2009; 35:153-61. [PMID: 18355758 DOI: 10.1016/s1673-8527(08)60021-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 11/27/2007] [Accepted: 12/07/2007] [Indexed: 11/30/2022]
Abstract
High consumption of ethanolic beverages facilitates neurodegeneration, but the mechanism of this process still remained elusive. Suppression subtractive hybridization (SSH) is a technique for detection of rare transcripts. With SSH approach, we identified one ethanol response gene Cab45, which was down-regulated by ethanol with time-dependent manner in B104 cells. The full-length sequence of Cab45 gene was obtained by 5' -RACE (5' Rapid Amplification of cDNA Ends) for the first time in rat. Based on the sequence of deduced amino acid of rat Cab45, the alignment was conducted with its counterparts in different species and displayed a high conservation. Using different tissues in rat and cell lines, Cab45 was characterized by a ubiquitous expression and differentiation dependent down-regulation. Given that ethanol facilitates some cell differentiation, we hypothesize that Cab45 is involved in ethanol-mediated differentiation. With transient transfection, the function of Cab45 was investigated by up-regulation and down-regulation in PC12 cells. Ethanol treatment and UV exposure were conducted subsequently and cell proliferations were detected by MTT (Methyl Thiazolyl Tetrazolium) approach. It revealed that the up-regulation of Cab45 modulated the impairment elicited by ethanol and UV in transfected cells. As a member of new calcium binding protein family, the exact role of Cab45 still remains unclear.
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Affiliation(s)
- Yunfeng Zhu
- Department of Oncology in Beijing 307 Hospital, Fengtai District, Beijing 100071, China.
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29
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Hansen GAW, Vorum H, Jacobsen C, Honoré B. Calumenin but not reticulocalbin forms a Ca2+-dependent complex with thrombospondin-1. A potential role in haemostasis and thrombosis. Mol Cell Biochem 2008; 320:25-33. [DOI: 10.1007/s11010-008-9895-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 07/25/2008] [Indexed: 10/21/2022]
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30
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Ostergaard M, Hansen GAW, Vorum H, Honoré B. Proteomic profiling of fibroblasts reveals a modulating effect of extracellular calumenin on the organization of the actin cytoskeleton. Proteomics 2006; 6:3509-19. [PMID: 16691550 DOI: 10.1002/pmic.200500686] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
CREC proteins constitute a family of EF-hand calcium binding proteins localized to the secretory pathway. Calumenin is the only member known to be secreted. Recently, it was shown that thrombin-activated thrombocytes liberate calumenin, which also is found in atherosclerotic lesions but not in normal vasculature. To study the possible effects of calumenin extracellularly, we used proteomic profiling of fibroblasts cultured in absence and in presence of calumenin. Using 2-DE and MS/MS, we show that normal fibroblasts contain several 28-29-kDa N-terminal and a 16-kDa C-terminal fragment of beta- or gamma-actin. Extracellularly added calumenin decreases the levels of both the N-terminal and C-terminal actin fragments, and, in addition, decreases the expression level of septin 2, which interacts with the actin cytoskeleton and is involved in cytokinesis. Labeling of S-phase fibroblasts with bromo-2'deoxy-uridine indicates that calumenin added to the medium also modulates the cell cycle. Our study thus indicates that calumenin may have an autocrine or a paracrine effect on the cells in its vicinity, and, therefore, may be involved in the pathophysiology of thrombosis or in wound healing.
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Affiliation(s)
- Morten Ostergaard
- Institute of Medical Biochemistry, Ole Worms Allé, University of Aarhus, Denmark
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31
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Jung DH, Mo SH, Kim DH. Calumenin, a multiple EF-hands Ca2+-binding protein, interacts with ryanodine receptor-1 in rabbit skeletal sarcoplasmic reticulum. Biochem Biophys Res Commun 2006; 343:34-42. [PMID: 16527250 DOI: 10.1016/j.bbrc.2006.02.115] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 02/17/2006] [Indexed: 11/20/2022]
Abstract
Calumenin is a multiple EF-hand Ca2+-binding protein located in endo/sarcoplasmic reticulum of mammalian tissues. In the present study, we cloned two rabbit calumenin isoforms (rabbit calumenin-1 and -2, GenBank Accession Nos. SY225335 and AY225336, respectively) by RT-PCR. Both isoforms contain a 19 aa N-terminal signal sequence, 6 EF-hand domains, and a C-terminal ER/SR retrieval signal, HDEF. Both calumenin isoforms exist in rabbit cardiac and skeletal muscles, but calumenin-2 is the main isoform in skeletal muscle. Presence of calumenin in rabbit sarcoplasmic reticulum (SR) was identified by Western blot analysis. GST-pull down and co-immunoprecipitation experiments showed that ryanodine receptor 1 (RyR1) interacted with calumenin-2 in millimolar Ca2+ concentration range. Experiments of gradual EF-hand deletions suggest that the second EF-hand domain is essential for calumenin binding to RyR1. Adenovirus-mediated overexpression of calumenin-2 in C2C12 myotubes led to increased caffeine-induced Ca2+ release, but decreased depolarization-induced Ca2+ release. Taken together, we propose that calumenin-2 in the SR lumen can directly regulate the RyR1 activity in Ca2+-dependent manner.
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Affiliation(s)
- Dai Hyun Jung
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
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32
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Kollers S, Blott SC, Rocha D. Confirmation of the mapping of the porcine calumenin gene (CALU ) to chromosome 18. Anim Genet 2005; 36:177-8. [PMID: 15771739 DOI: 10.1111/j.1365-2052.2005.01251.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- S Kollers
- Sygen International plc, Cambridge Laboratory, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
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33
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Whitaker HC, Hanrahan S, Totty N, Gamble SC, Waxman J, Cato ACB, Hurst HC, Bevan CL. Androgen receptor is targeted to distinct subcellular compartments in response to different therapeutic antiandrogens. Clin Cancer Res 2005; 10:7392-401. [PMID: 15534116 DOI: 10.1158/1078-0432.ccr-04-0388] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Antiandrogens are routinely used in the treatment of prostate cancer. Although they are known to prevent activation of the androgen receptor (AR), little is known about the mechanisms involved. This report represents the first study of the localization of wild-type AR following expression at physiologic relevant levels in prostate cells and treatment with androgen and antiandrogens. EXPERIMENTAL DESIGN We have characterized a cellular model for prostate cancer using in situ cellular fractionation, proteomics, and confocal microscopy and investigated the effect of antiandrogens in clinical use on the subcellular localization of the AR. RESULTS Different antiandrogens have diverse effects on the subcellular localization of the AR. Treatment with androgen results in translocation from the cytoplasm to the nucleoplasm, whereas the antiandrogens hydroxyflutamide and bicalutamide lead to reversible association with the nuclear matrix. In contrast, treatment with the antiandrogen cyproterone acetate results in AR association with cytoplasmic membranes and irreversible retention within the cytoplasm. In addition, we demonstrate that AR translocation requires ATP and the cytoskeleton, regardless of ligand. CONCLUSIONS These results reveal that not all antiandrogens work via the same mechanism and suggest that an informed sequential treatment regime may benefit prostate cancer patients. The observed subnuclear and subcytoplasmic associations of the AR suggest new areas of study to investigate the role of the AR in the response and resistance of prostate cancer to antiandrogen therapy.
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Affiliation(s)
- Hayley C Whitaker
- Prostate Cancer Research Group, Department of Cancer Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
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34
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Pocernich CB, Boyd-Kimball D, Poon HF, Thongboonkerd V, Lynn BC, Klein JB, Calebrese V, Nath A, Butterfield DA. Proteomics analysis of human astrocytes expressing the HIV protein Tat. ACTA ACUST UNITED AC 2005; 133:307-16. [PMID: 15710248 DOI: 10.1016/j.molbrainres.2004.10.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2004] [Indexed: 10/26/2022]
Abstract
Astrocyte infection in HIV has been associated with rapid progression of dementia in a subset of HIV/AIDS patients. Astrogliosis and microglial activation are observed in areas of axonal and dendritic damage in HIVD. In HIV-infected astrocytes, the regulatory gene tat is over expressed and mRNA levels for Tat are elevated in brain extracts from individuals with HIV-1 dementia. Tat can be detected in HIV-infected astrocytes in vivo. The HIV-1 protein Tat transactivates viral and cellular gene expression, is actively secreted mainly from astrocytes, microglia and macrophages, into the extracellular environment, and is taken up by neighboring uninfected cells such as neurons. The HIV-1 protein Tat released from astrocytes reportedly produces trimming of neurites, mitochondrial dysfunction and cell death in neurons, while protecting its host, the astrocyte. We utilized proteomics to investigate protein expression changes in human astrocytes intracellularly expressing Tat (SVGA-Tat). By coupling 2D fingerprinting and identification of proteins by mass spectrometry, we identified phosphatase 2A, isocitrate dehydrogenase, nuclear ribonucleoprotein A1, Rho GDP dissociation inhibitor alpha, beta-tubulin, crocalbin like protein/calumenin, and vimentin/alpha-tubulin to have decreased protein expression levels in SVGA-Tat cells compared to the SVGA-pcDNA cells. Heat shock protein 70, heme oxygenase-1, and inducible nitric oxide synthase were found to have increased protein expression in SVGA-Tat cells compared to controls by slotblot technique. These findings are discussed with reference to astrocytes serving as a reservoir for the HIV virus and how Tat promotes survival of the astrocytic host.
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Affiliation(s)
- Chava B Pocernich
- Department of Chemistry and Center of Membrane Sciences, 125 Chemistry-Physics Building, University of Kentucky, Lexington, KY 40506, USA
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35
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Zurabian R, Carrero JC, Rodríguez-Contreras D, Willms K, Laclette JP. Antigenic Proteins Associated with Calcareous Corpuscules of Taenia solium: Partial Characterization of a Calcium-Binding Protein. Arch Med Res 2005; 36:4-9. [PMID: 15777987 DOI: 10.1016/j.arcmed.2004.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 09/27/2004] [Indexed: 11/25/2022]
Abstract
BACKGROUND A protein fraction was isolated from calcareous corpuscles of Taenia solium cysticerci. The antigens in this fraction were recognized in ELISA and Western blot assays by all sera from a group of patients with active neurocysticercosis (NC) and were not recognized by the sera from patients with other neurological disorders. Western blot analysis also showed that several high molecular weight proteins were strongly recognized by antibodies in all the neurocysticercotic patient sera, suggesting a potential for serological diagnosis of neurocysticercosis. METHODS In order to characterize these antigenic proteins, we used a monoclonal antibody raised against a high MW calcium-binding protein associated with calcareous corpuscles of Echinococcus granulosus (EgCaBP1). RESULTS Western blot assays revealed the recognition of a protein band of about 260 kDa, appearing within the range of the high MW antigens recognized by the NC sera. Several cDNA clones were isolated through screening of a T. solium metacestode library with a DNA probe for EgCaBP1, containing partial coding sequences showing about 88% identity with the protein of E. granulosus. Moreover, a recombinant product expressed in bacteria from the partial coding sequence of T. solium showed the ability to bind Ca2+ and was recognized by the monoclonal antibody. This recombinant calcium-binding protein of T. solium was not recognized by the NC patient sera by ELISA and Western blot. CONCLUSIONS Antigenic proteins in the calcareous corpuscles of T. solium metacestodes deserve further analysis as candidates in the development of diagnostic tools for neurocysticercosis.
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Affiliation(s)
- Rimma Zurabian
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, D.F
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36
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Wajih N, Sane DC, Hutson SM, Wallin R. The inhibitory effect of calumenin on the vitamin K-dependent gamma-carboxylation system. Characterization of the system in normal and warfarin-resistant rats. J Biol Chem 2004; 279:25276-83. [PMID: 15075329 DOI: 10.1074/jbc.m401645200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vitamin K-dependent gamma-carboxylation system is responsible for post-translational modification of vitamin K-dependent proteins, converting them to Gla-containing proteins. The system consists of integral membrane proteins located in the endoplasmic reticulum membrane and includes the gamma-carboxylase and the warfarin-sensitive enzyme vitamin K(1) 2,3-epoxide reductase (VKOR), which provides gamma-carboxylase with reduced vitamin K(1) cofactor. In this work, an in vitro gamma-carboxylation system was designed and used to understand how VKOR and gamma-carboxylase work together as a system and to identify factors that can regulate the activity of the system. Results are presented that demonstrate that the endoplasmic reticulum chaperone protein calumenin is associated with gamma-carboxylase and inhibits its activity. Silencing of the calumenin gene with siRNA resulted in a 5-fold increase in gamma-carboxylase activity. The results provide the first identification of a protein that can regulate the activity of the gamma-carboxylation system. The propeptides of vitamin K-dependent proteins stimulate gamma-carboxylase activity. Here we show that the factor X and prothrombin propeptides do not increase reduced vitamin K(1) cofactor production by VKOR in the system where VKOR is the rate-limiting step for gamma-carboxylation. These findings put calumenin in a central position concerning regulation of gamma-carboxylation of vitamin K-dependent proteins. Reduced vitamin K(1) cofactor transfer between VKOR and gamma-carboxylase is shown to be significantly impaired in the in vitro gamma-carboxylation system prepared from warfarin-resistant rats. Furthermore, the sequence of the 18-kDa subunit 1 of the VKOR enzyme complex was found to be identical in the two rat strains. This finding supports the notion that different forms of genetic warfarin resistance exist.
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Affiliation(s)
- Nadeem Wajih
- Departments of Internal Medicine and Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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37
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Jung DH, Kim DH. Characterization of isoforms and genomic organization of mouse calumenin. Gene 2004; 327:185-94. [PMID: 14980715 DOI: 10.1016/j.gene.2003.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 09/23/2003] [Accepted: 10/15/2003] [Indexed: 11/21/2022]
Abstract
Calumenin is a multiple EF-hand protein located in endo/sarcoplasmic reticulum of mammalian heart and other tissues [J. Biol. Chem. 272 (1997) 18232; Genomics 49 (1998) 331; Biochim. Biophys. Acta 1386 (1998) 121]. In the present study, a new isoform of mouse calumenin (mouse calumenin 2) was cloned by RT-PCR and genomic DNA PCR. The deduced amino acid sequence of mouse calumenin 2 is 315 aa long with the calculated MW of 37,064 and pI of 4.26. It has 92% aa sequence identity to previously identified mouse calumenin [J. Biol. Chem. 272 (1997) 18232] (mouse calumenin 1). The difference in the aa sequence was restricted to the first two EF-hand regions (residues 74-138). Northern blot analysis shows that mouse calumenin 2 is highly expressed in heart, lung, testis and unpregnant uterus. The expression of mouse calumenin 2 appears to decrease when fetal development is progressed. Genomic DNA PCR, sequencing and data mining of mouse genome database were utilized to examine the exon-intron boundaries of mouse calumenin genes. Both mouse calumenin 1 and 2 genes encompass six exons, and five of them (Exon1, 3, 4, 5 and 6) are identical. However, mouse calumenin 1 contains Exon2-1, whereas mouse calumenin 2 contains a neighboring Exon2-2. The calumenin genes are localized on mouse chromosome 6 having conserved synteny with human chromosome 7q32. For comparison, the genomic organization of human calumenin was also examined using the published human genome database (UCSC Genome Bioinformatics at ). Like mouse calumenin genes, two human calumenin genes also consist of five identical exons (Exon1, 3, 4, 5 and 6) and a different Exon2. The present study suggests that the genomic organization of calumenin genes is well conserved between human and mouse.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Calcium-Binding Proteins/genetics
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Embryo, Mammalian/metabolism
- Evolution, Molecular
- Exons
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Genes/genetics
- Humans
- Introns
- Male
- Molecular Sequence Data
- Muscle, Skeletal/metabolism
- Myocardium/metabolism
- Protein Isoforms/genetics
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Dai Hyun Jung
- Department of Life Science, Kwangju Institute of Science and Technology, 1 Oryong-dong, Puk-gu, Gwangju, 500-712, South Korea
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38
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Andersen OM, Vorum H, Honoré B, Thøgersen HC. Ca2+ binding to complement-type repeat domains 5 and 6 from the low-density lipoprotein receptor-related protein. BMC BIOCHEMISTRY 2003; 4:7. [PMID: 12921543 PMCID: PMC194729 DOI: 10.1186/1471-2091-4-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2003] [Accepted: 08/18/2003] [Indexed: 11/23/2022]
Abstract
BACKGROUND The binding of ligands to clusters of complement-type repeat (CR)-domains in proteins of the low-density lipoprotein receptor (LDLR) family is dependent on Ca2+ ions. One reason for this cation requirement was identified from the crystal structure data for a CR-domain from the prototypic LDLR, which showed the burial of a Ca2+ ion as a necessity for correct folding and stabilization of this protein module. Additional Ca2+ binding data to other CR-domains from both LDLR and the LDLR-related protein (LRP) have suggested the presence of a conserved Ca2+ cage within CR-domains from this family of receptors that function in endocytosis and signalling. RESULTS We have previously described the binding of several ligands to a fragment comprising the fifth and the sixth CR-domain (CR56) from LRP, as well as qualitatively described the binding of Ca2+ ions to this CR-domain pair. In the present study we have applied the rate dialysis method to measure the affinity for Ca2+, and show that CR56 binds 2 Ca2+ ions with an average affinity of KD = 10.6 microM, and there is no indication of additional Ca2+ binding sites within this receptor fragment. CONCLUSIONS Both CR-domains of CR56 bind a single Ca2+ ion with an affinity of 10.6 microM within the range of affinities demonstrated for several other CR-domains.
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Affiliation(s)
- Olav M Andersen
- Laboratory of Gene Expression, Department of Molecular and Structural Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Henrik Vorum
- Department of Medical Biochemistry, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Bent Honoré
- Department of Medical Biochemistry, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Hans C Thøgersen
- Laboratory of Gene Expression, Department of Molecular and Structural Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
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39
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Andersen OM, Yeung CH, Vorum H, Wellner M, Andreassen TK, Erdmann B, Mueller EC, Herz J, Otto A, Cooper TG, Willnow TE. Essential role of the apolipoprotein E receptor-2 in sperm development. J Biol Chem 2003; 278:23989-95. [PMID: 12695510 DOI: 10.1074/jbc.m302157200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The apolipoprotein (apo) E receptor-2 (apoER2) is a member of the low density lipoprotein receptor gene family and an important regulator of neuronal migration. It acts as a receptor for the signaling factor Reelin and provides positional cues to neurons that migrate to their proper position in the developing brain. Besides brain formation defects, apoER2-deficient mice also exhibit male infertility. The role of the receptor in male reproduction, however, remained unclear. Here we demonstrate that apoER2 is highly expressed in the initial segment of the epididymis, where it affects the functional expression of clusterin and phospholipid hydroperoxide glutathione peroxidase (PHGPx), two proteins required for sperm maturation. Reduced PHGPx expression in apoER2 knockout mice results in the inability of the sperm to regulate the cell volume and in abnormal sperm morphology and immotility. Because insufficient expression of PHGPx is a major cause of infertility in men, these findings not only highlight an important new function for apoER2 that is unrelated to neuronal migration, but they also suggest a possible role for apoER2 in human infertility.
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Affiliation(s)
- Olav M Andersen
- Max-Delbrueck-Center for Molecular Medicine and Medical Faculty of the Free University, D-13125 Berlin, Germany
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40
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Zhang R, Tremblay TL, McDermid A, Thibault P, Stanimirovic D. Identification of differentially expressed proteins in human glioblastoma cell lines and tumors. Glia 2003; 42:194-208. [PMID: 12655603 DOI: 10.1002/glia.10222] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An in-frame deletion of 801 bp in exons 2-7 (type III mutation) of the epidermal growth factor receptor (EGFR) is detected at high incidence in primary glioblastoma tumors. A proteomic approach was used to generate differential protein expression maps of fetal human astrocytes (FHA), human glioblastoma cell lines U87MG and U87MG expressing type III EGFR deletion (U87MGdeltaEGFR) that confers high malignancy to tumor cells. Two-dimensional gel electrophoresis followed by in-gel digestion of separated spots and protein identification by LC-MS-MS and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) identified 23 proteins expressed at higher levels or exclusively in FHA and 29 proteins expressed at higher levels or exclusively in U87MG cells. Three proteins, ubiquitin, cystatin B, and tissue transglutaminase (TTG), were upregulated in U87MGdeltaEGFR relative to U87MG. Four proteins highly expressed by U87MG cells, Hsp27, major vault protein, TTG, and cystatin B, were analyzed by Western blot, ELISA, or RT-PCR in cell extracts and in tissue samples of glioblastoma multiforme (GBM; grade IV), low-grade astrocytomas (grades I and II), and nonmalignant brain lesions. All four proteins were highly expressed in GBM tissues compared to nonmalignant brain. These proteins may be used as diagnostic or functional (e.g., multiple drug resistance, invasiveness) markers for glioblastoma tumors.
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Affiliation(s)
- Rulin Zhang
- Institute for Biological Sciences, National Research Council, Ottawa, Canada
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41
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Miwa N, Kawamura S. Frog p26olf, a molecule with two S100-like regions in a single peptide. Microsc Res Tech 2003; 60:593-9. [PMID: 12645007 DOI: 10.1002/jemt.10301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An S100-like calcium-binding protein, p26olf, was originally isolated from the frog (Rana Catesbeiana) olfactory epithelium with four chromatographical steps. The primary structure of p26olf contains two S100-like regions aligned in tandem with four functional EF-hands. At 100 mM K(+), wild-type p26olf binds Ca(2+) with a Kd value of 22 microM and a Hill coefficient of 2.0. Each EF-hand seems to have different affinity for Ca(2+): it is high in EF-A and -B and low in EF-C and -D. In our Ca(2+)-binding model, the order of Ca(2+)-binding to p26olf is EF-B, EF-A, EF-C, and EF-D. Expression of mRNA of p26olf is detected in various frog tissues: it is high in the olfactory epithelium, lung, and spleen, moderate in brain, retina, heart, and kidney, and low in liver and muscle. Immunohistochemical studies revealed that p26olf is prominently localized in the cilia of both olfactory and lung respiratory epithelium and especially enriched in the distal segment of the olfactory cilia. Several proteins in the olfactory cilia bind to p26olf in the presence of Ca(2+), suggesting that they are possible target proteins of p26olf. One of these target proteins is immunologically identified as a beta-adrenergic receptor kinase-like protein. In the olfactory cilia, p26olf may have some roles in the olfactory transduction or adaptation through interaction with this beta-adrenergic receptor kinase-like protein.
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Affiliation(s)
- Naofumi Miwa
- Department of Biology, Graduate School of Science, Osaka University, Osaka 560-0043, Japan.
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42
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Honoré B, Baandrup U, Nielsen S, Vorum H. Endonuclein is a cell cycle regulated WD-repeat protein that is up-regulated in adenocarcinoma of the pancreas. Oncogene 2002; 21:1123-9. [PMID: 11850830 DOI: 10.1038/sj.onc.1205186] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2001] [Revised: 11/22/2001] [Accepted: 11/26/2001] [Indexed: 11/09/2022]
Abstract
The transcript encoding endonuclein, the human homolog of yeast PWP1, was previously found up-regulated in pancreatic cancer tissue. By immunohistochemistry we detected a ubiquitous presence in several tissues examined: skin, liver, thyroid gland, heart muscle, neurons, kidney, bladder, pancreas, adrenal gland, ovary, uterus, testis and prostate gland. We especially noticed that normal pancreatic exocrine cells exhibited low protein levels while pancreatic adenocarcinoma cells revealed high levels. We found a heterogeneous subcellular distribution, especially with varying nuclear levels. In proliferating cells endonuclein protein expression and localization was cell cycle dependent, with increasing levels and nuclear focusing during the interphase toward mitosis. Ultrastructural analysis revealed ER and nuclear localization. Endonuclein contains five WD-repeats, indicating a putative role in crucial regulatory activities in the nucleus as well as in the ER.
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Affiliation(s)
- Bent Honoré
- Department of Medical Biochemistry, Ole Worms Allé, Building 170, University of Aarhus, DK-8000 Aarhus C, Denmark.
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43
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Morel-Huaux VM, Pypaert M, Wouters S, Tartakoff AM, Jurgan U, Gevaert K, Courtoy PJ. The calcium-binding protein p54/NEFA is a novel luminal resident of medial Golgi cisternae that traffics independently of mannosidase II. Eur J Cell Biol 2002; 81:87-100. [PMID: 11893086 DOI: 10.1078/0171-9335-00224] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A new Golgi resident, p54, has been demonstrated in several eukaryotic species and in multiple organs. Based on Triton X-114 partition, carbonate extraction and trypsin protection assays, p54 behaved as an extrinsic membrane protein, facing the luminal compartment. p54 was purified by two-dimensional electrophoresis and identified by matrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometry as NEFA, a calcium-binding protein (Barnikol-Watanabe et al., 1994, Biol. Chem. Hoppe Seyler, 375, 497-512). By immunofluorescence, p54/NEFA essentially colocalized with the medial Golgi marker mannosidase II, and did not overlap with the cis-Golgi marker p58, nor with the trans-Golgi network (TGN) marker TGN38. By immuno-electron microscopy, p54/NEFA localized in the medial cisternae and in Golgi-associated vesicles. p54/NEFA remained associated with mannosidase II despite Golgi disruption by nocodazole, caffeine, or, to some extent, potassium depletion (a new procedure to induce Golgi disassembly), but the two markers rapidly dissociated upon brefeldin A treatment and at metaphase, and reassociated upon drug removal and at the end of anaphase. Since p54/NEFA is a peripheral luminal membrane constituent, its distinct trafficking from the transmembrane marker mannosidase II suggests a novel Golgi retention mechanism, by strong association of this soluble protein with another integral transmembrane resident.
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Affiliation(s)
- Valérie M Morel-Huaux
- Cell Biology Unit, Christian de Duve Institute of Cellular Pathology and Université catholique de Louvain, Brussels, Belgium
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44
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Hilpert J, Vorum H, Burmeister R, Spoelgen R, Grishkovskaya I, Misselwitz R, Nykjaer A, Willnow TE. Efficient eukaryotic expression system for authentic human sex hormone-binding globulin. Biochem J 2001; 360:609-15. [PMID: 11736650 PMCID: PMC1222263 DOI: 10.1042/0264-6021:3600609] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sex hormone-binding globulin (SHBG) is the main carrier for androgens and oestrogens in humans. It mediates the transport of steroid hormones in the circulation and testicular fluid, and regulates their bioavailability to steroid-responsive tissues. In addition, the protein interacts with membrane receptors expressed in target tissues. Binding to the receptors is suspected to facilitate the uptake of steroid hormones and/or elicit cellular signal transduction. The identity of the SHBG receptor has not yet been resolved, in part due to a lack of sufficient quantities of authentic SHBG for receptor purification and molecular characterization. We have successfully addressed this problem by establishing an episomal expression system in human embryonic kidney cells that produces 5 mg of fully active human SHBG per litre. The recombinant protein resembles native SHBG in terms of structure, glycosylation pattern and steroid-binding activity. Moreover, the protein interacts with plasma membranes in steroid target tissues, an activity not observed with SHBG from other recombinant expression systems. Thus our studies have removed an important obstacle to the further elucidation of the role SHBG plays in steroid hormone action.
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Affiliation(s)
- J Hilpert
- Max-Delbrueck-Center for Molecular Medicine, Robert-Roessle-Strasse 10, D-13125 Berlin, Germany
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45
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Wallin R, Hutson SM, Cain D, Sweatt A, Sane DC. A molecular mechanism for genetic warfarin resistance in the rat. FASEB J 2001; 15:2542-4. [PMID: 11641264 DOI: 10.1096/fj.01-0337fje] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Warfarin targets vitamin K 2,3-epoxide reductase (VKOR), the enzyme that produces reduced vitamin K, a required cofactor for g-carboxylation of vitamin K-dependent proteins. To identify VKOR, we used 4'-azido-warfarin-3H-alcohol as an affinity label. When added to a partially purified preparation of VKOR, two proteins were identified by mass spectrometry as calumenin and cytochrome B5. Rat calumenin was cloned and sequenced and the recombinant protein was produced. When added to an in vitro test system, the 47 kDa recombinant protein was found to inhibit VKOR activity and to protect the enzyme from warfarin inhibition. Calumenin was also shown to inhibit the overall activity of the complete vitamin K-dependent g-carboxylation system. The results were repeated in COS-1 cells overexpressing recombinant calumenin. By comparing calumenin mRNA levels in various tissues from normal rats and warfarin-resistant rats, only the livers from resistant rats were different from normal rats by showing increased levels. Partially purified VKOR from resistant and normal rat livers showed no differences in Km-values, specific activity, and sensitivity to warfarin. A novel model for genetic warfarin resistance in the rat is proposed, whereby the concentration of calumenin in liver determines resistance.
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Affiliation(s)
- R Wallin
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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Sagi M, Fluhr R. Superoxide production by plant homologues of the gp91(phox) NADPH oxidase. Modulation of activity by calcium and by tobacco mosaic virus infection. PLANT PHYSIOLOGY 2001; 126:1281-90. [PMID: 11457979 PMCID: PMC116485 DOI: 10.1104/pp.126.3.1281] [Citation(s) in RCA: 365] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2000] [Revised: 03/11/2001] [Accepted: 04/20/2001] [Indexed: 05/17/2023]
Abstract
Genes encoding homologs of the gp91(phox) subunit of the plasma membrane NADPH oxidase complex have been identified in plants and are hypothesized to be a source of reactive oxygen species during defense responses. However, the direct involvement of the gene products in superoxide (O(2)(-)) production has yet to be shown. A novel activity gel assay based on protein fractionation in native or sodium dodecyl sulfate (SDS)-denaturing polyacrylamide gels was developed. In native polyacrylamide gel electrophoresis, one or two major O(2)(-)-producing formazan bands were detected in tomato (Lycopersicum esculentum Mill. cv Moneymaker) and tobacco (Nicotiana tabacum var. Samsun, NN) plasma membranes, respectively. Denaturing fractionation of tomato and tobacco plasma membrane in SDS-polyacrylamide gel electrophoresis, followed by regeneration of the in-gel activity, revealed NADPH-dependent O(2)(-)-producing formazan bands of 106-, 103-, and 80- to 75-kD molecular masses. The SDS and native activity bands were dependent on NADPH and completely inhibited by diphenylene iodonium or CuZn- O(2)(-) dismutase, indicating that the formazan precipitates were due to reduction by O(2)(-) radicals catalyzed by an NADPH-dependent flavin containing enzyme. The source of the plasma membrane activity bands was confirmed by their cross-reaction with antibody prepared from the C terminus of the tomato gp91(phox) homolog. Membrane extracts as well as the in-gel NADPH oxidase activities were stimulated in the presence of Ca(2+). In addition, the relative activity of the gp91(phox) homolog was enhanced in the plasma membrane of tobacco mosaic virus-infected leaves. Thus, in contrast to the mammalian gp91(phox), the plant homolog can produce O(2)(-) in the absence of additional cytosolic components and is stimulated directly by Ca(2+).
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Affiliation(s)
- M Sagi
- Department of Plant Science, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
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Yuasa K, Maeshima M. Purification, properties, and molecular cloning of a novel Ca(2+)-binding protein in radish vacuoles. PLANT PHYSIOLOGY 2000; 124:1069-78. [PMID: 11080284 PMCID: PMC59206 DOI: 10.1104/pp.124.3.1069] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2000] [Accepted: 08/04/2000] [Indexed: 05/19/2023]
Abstract
To understand the roles of plant vacuoles, we have purified and characterized a major soluble protein from vacuoles of radish (Raphanus sativus cv Tokinashi-daikon) taproots. The results showed that it is a novel radish vacuole Ca(2+)-binding protein (RVCaB). RVCaB was released from the vacuolar membrane fraction by sonication, and purified by ion exchange and gel filtration column chromatography. RVCaB is an acidic protein and migrated on sodium dodecyl sulfate-polyacrylamide gel with an apparent molecular mass of 43 kD. The Ca(2+)-binding activity was confirmed by the (45)Ca(2+)-overlay assay. RVCaB was localized in the lumen, as the protein was recovered in intact vacuoles prepared from protoplasts and was resistant to trypsin digestion. Plant vacuoles store Ca(2+) using two active Ca(2+) uptake systems, namely Ca(2+)-ATPase and Ca(2+)/H(+) antiporter. Vacuolar membrane vesicles containing RVCaB accumulated more Ca(2+) than sonicated vesicles depleted of the protein at a wide range of Ca(2+) concentrations. A cDNA (RVCaB) encoding a 248-amino acid polypeptide was cloned. Its deduced sequence was identical to amino acid sequences obtained from several peptide fragments of the purified RVCaB. The deduced sequence is not homologous to that of other Ca(2+)-binding proteins such as calreticulin. RVCaB has a repetitive unique acidic motif, but not the EF-hand motif. The recombinant RVCaB expressed in Escherichia coli-bound Ca(2+) as evidenced by staining with Stains-all and migrated with an apparent molecular mass of 44 kD. These results suggest that RVCaB is a new type Ca(2+)-binding protein with high capacity and low affinity for Ca(2+) and that the protein could function as a Ca(2+)-buffer and/or Ca(2+)-sequestering protein in the vacuole.
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Affiliation(s)
- K Yuasa
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Honoré B, Vorum H. The CREC family, a novel family of multiple EF-hand, low-affinity Ca(2+)-binding proteins localised to the secretory pathway of mammalian cells. FEBS Lett 2000; 466:11-8. [PMID: 10648803 DOI: 10.1016/s0014-5793(99)01780-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The CREC family consists of a number of recently discovered multiple (up to seven) EF-hand proteins that localise to the secretory pathway of mammalian cells. At present, the family includes reticulocalbin, ERC-55/TCBP-49/E6BP, Cab45, calumenin and crocalbin/CBP-50. Similar proteins are found in quite diverse invertebrate organisms such as DCB-45 and SCF in Drosophila melanogaster, SCF in Bombyx mori, CCB-39 in Caenorhabditis elegans and Pfs40/PfERC in Plasmodium falciparum. The Ca(2+) affinity is rather low with dissociation constants around 10(-4)-10(-3) M. The proteins may participate in Ca(2+)-regulated activities. Recent evidence has been obtained that some CREC family members are involved in pathological activities such as malignant cell transformation, mediation of the toxic effects of snake venom toxins and putative participation in amyloid formation.
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Affiliation(s)
- B Honoré
- Department of Medical Biochemistry, University of Aarhus, Ole Worms Allé, Building 170, DK-8000, Aarhus, Denmark.
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Abstract
We recently reported the identification of human calumenin, a novel Ca(2+) binding, transformation-sensitive and secreted protein [Vorum et al. (1998) Biochim. Biophys. Acta 1386, 121-131; Vorum et al. (1999) Exp. Cell Res. 248, 473-481] belonging to the family of multiple EF-hand proteins of the secretory pathway that include reticulocalbin, ERC-55, Cab45 and crocalbin. In order to further investigate the extracellular functions of calumenin we immobilized the recombinant protein to a column. After application of a placental tissue extract we were able to elute one protein that interacts with calumenin in the presence of Ca(2+). Amino acid sequencing identified this protein as serum amyloid P component (SAP). Furthermore, we verified and characterized the calumenin-SAP interaction by the surface plasmon resonance technique. The findings indicate that calumenin may participate in the immunological defense system and could be involved in the pathological process of amyloidosis that leads to formation of amyloid deposits seen in different types of tissues.
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Affiliation(s)
- H Vorum
- Department of Medical Biochemistry, Ole Worms Allé, Building 170, University of Aarhus, DK-8000, Aarhus C, Denmark
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Leheste JR, Rolinski B, Vorum H, Hilpert J, Nykjaer A, Jacobsen C, Aucouturier P, Moskaug JO, Otto A, Christensen EI, Willnow TE. Megalin knockout mice as an animal model of low molecular weight proteinuria. THE AMERICAN JOURNAL OF PATHOLOGY 1999; 155:1361-70. [PMID: 10514418 PMCID: PMC1867027 DOI: 10.1016/s0002-9440(10)65238-8] [Citation(s) in RCA: 327] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/10/1999] [Indexed: 11/24/2022]
Abstract
Megalin is an endocytic receptor expressed on the luminal surface of the renal proximal tubules. The receptor is believed to play an important role in the tubular uptake of macromolecules filtered through the glomerulus. To elucidate the role of megalin in vivo and to identify its endogenous ligands, we analyzed the proximal tubular function in mice genetically deficient for the receptor. We demonstrate that megalin-deficient mice exhibit a tubular resorption deficiency and excrete low molecular weight plasma proteins in the urine (low molecular weight proteinuria). Proteins excreted include small plasma proteins that carry lipophilic compounds including vitamin D-binding protein, retinol-binding protein, alpha(1)-microglobulin and odorant-binding protein. Megalin binds these proteins and mediates their cellular uptake. Urinary loss of carrier proteins in megalin-deficient mice results in concomitant loss of lipophilic vitamins bound to the carriers. Similar to megalin knockout mice, patients with low molecular weight proteinuria as in Fanconi syndrome are also shown to excrete vitamin/carrier complexes. Thus, these results identify a crucial role of the proximal tubule in retrieval of filtered vitamin/carrier complexes and the central role played by megalin in this process.
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Affiliation(s)
- J R Leheste
- Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
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