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Vicic N, Guo X, Chan D, Flanagan JG, Sigal IA, Sivak JM. Evidence of an Annexin A4 mediated plasma membrane repair response to biomechanical strain associated with glaucoma pathogenesis. J Cell Physiol 2022; 237:3687-3702. [PMID: 35862065 PMCID: PMC9891715 DOI: 10.1002/jcp.30834] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 07/04/2022] [Accepted: 07/06/2022] [Indexed: 02/03/2023]
Abstract
Glaucoma is a common neurodegenerative blinding disease that is closely associated with chronic biomechanical strain at the optic nerve head (ONH). Yet, the cellular injury and mechanosensing mechanisms underlying the resulting damage have remained critically unclear. We previously identified Annexin A4 (ANXA4) from a proteomic analyses of human ONH astrocytes undergoing pathological biomechanical strain that mimics glaucomatous conditions. Annexins are a family of calcium-dependent phospholipid binding proteins with key functions in plasma membrane repair (PMR); an active mechanism to limit and mend cellular injury that involves membrane and cytoskeletal reorganizations. However, a role for direct membrane damage and PMR has not been well studied in the context of biomechanical strain, such as that associated with glaucoma. Here we report that this moderate strain surprisingly damages cell membranes to increase permeability in a calcium-dependent manner, and induces rapid aggregation of ANXA4 at injury sites. ANXA4 loss-of-function increases permeability, while exogenous ANXA4 reduces it. Furthermore, ANXA4 aggregation is associated with F-actin dynamics in vitro, and remarkably this interaction and aggregation signature is also observed in the glaucomatous ONH in patient samples. Together these studies link moderate biomechanical strain with direct membrane damage and actin dynamics, and identify an active PMR role for ANXA4 in new model of cell injury associated with glaucoma pathogenesis.
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Affiliation(s)
- Nevena Vicic
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada,Department of Ophthalmology and Vision Science, University of Toronto School of Medicine, Toronto, Ontario, Canada,Department of Laboratory Medicine and Pathobiology, University of Toronto School of Medicine, Toronto, Ontario, Canada
| | - Xiaoxin Guo
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada,Department of Ophthalmology and Vision Science, University of Toronto School of Medicine, Toronto, Ontario, Canada
| | - Darren Chan
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada,Department of Ophthalmology and Vision Science, University of Toronto School of Medicine, Toronto, Ontario, Canada
| | - John G Flanagan
- The Herbert Wertheim School of Optometry and Vision Science, University of California Berkeley, Berkeley, California, USA
| | - Ian A. Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jeremy M. Sivak
- Donald K Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada,Department of Ophthalmology and Vision Science, University of Toronto School of Medicine, Toronto, Ontario, Canada,Department of Laboratory Medicine and Pathobiology, University of Toronto School of Medicine, Toronto, Ontario, Canada
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2
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Lichocka M, Krzymowska M, Górecka M, Hennig J. Arabidopsis annexin 5 is involved in maintenance of pollen membrane integrity and permeability. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:94-109. [PMID: 34522949 DOI: 10.1093/jxb/erab419] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
In Arabidopsis, a dry stigma surface enables a gradual hydration of pollen grains by a controlled release of water. Occasionally the grains may be exposed to extreme precipitations that cause rapid water influx and swelling, eventually leading to pollen membrane rupture. In metazoans, calcium- and phospholipid-binding proteins, referred to as annexins, participate in the repair of plasma membrane damages. It remains unclear, however, how this process is conducted in plants. Here, we examined whether plant annexin 5 (ANN5), the most abundant member of the annexin family in pollen, is involved in the restoration of pollen membrane integrity. We analyzed the cellular dynamics of ANN5 in pollen grains undergoing hydration in favorable or stress conditions. We observed a transient association of ANN5 with the pollen membrane during in vitro hydration that did not occur in the pollen grains being hydrated on the stigma. To simulate a rainfall, we performed spraying of the pollinated stigma with deionized water that induced ANN5 accumulation at the pollen membrane. Interestingly, calcium or magnesium application affected pollen membrane properties differently, causing rupture or shrinkage of pollen membrane, respectively. Both treatments, however, induced ANN5 recruitment to the pollen membrane. Our data suggest a model in which ANN5 is involved in the maintenance of membrane integrity in pollen grains exposed to osmotic or ionic imbalances.
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Affiliation(s)
- Małgorzata Lichocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Krzymowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Górecka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Jacek Hennig
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
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3
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Lin X, Li Y, Zhong W, Hong T, Li L, Song S, He D. Synthesis, Bioactivity, and QSAR Study of 3,4-Dichlorophenyl Isoxazole-Substituted Stilbene Derivatives against the Phytopathogenic Fungus Botrytis cinerea. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:9520-9528. [PMID: 34382783 DOI: 10.1021/acs.jafc.1c01816] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Gray mold, caused by Botrytis cinerea, is one of the most destructive fungal diseases in crops, responsible for significant economic losses. In search of natural product-based fungicides, we designed and synthesized a series of novel 3,4-dichlorophenyl isoxazole-substituted stilbene derivatives, and their in vivo antifungal activities against B. cinerea were evaluated. The results indicated that some of the target molecules demonstrated remarkable efficiency for the control of tomato gray mold. In particular, compound 5r displayed the highest fungicidal potency with an inhibition rate of 56.11% comparable to that of positive control boscalid (66.96%). Moreover, a hologram quantitative structure-activity relationship (HQSAR) model with good predictive capability was developed to provide in-depth insight into the activity profiles of these compounds. Preliminary mechanism studies suggested that compound 5r might exert its antifungal effect by changing hyphal morphology and increasing the membrane permeability. The present study contributes to the development of natural stilbene derivatives as alternative bioactive agents against B. cinerea.
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Affiliation(s)
- Xingdong Lin
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Yan Li
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Weiqiang Zhong
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Tian Hong
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Lihuang Li
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
| | - Shaoyun Song
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong 510006, People's Republic of China
| | - Daohang He
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, People's Republic of China
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4
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Detecting retinal cell stress and apoptosis with DARC: Progression from lab to clinic. Prog Retin Eye Res 2021; 86:100976. [PMID: 34102318 DOI: 10.1016/j.preteyeres.2021.100976] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 05/21/2021] [Accepted: 05/26/2021] [Indexed: 12/15/2022]
Abstract
DARC (Detection of Apoptosing Retinal Cells) is a retinal imaging technology that has been developed within the last 2 decades from basic laboratory science to Phase 2 clinical trials. It uses ANX776 (fluorescently labelled Annexin A5) to identify stressed and apoptotic cells in the living eye. During its development, DARC has undergone biochemistry optimisation, scale-up and GMP manufacture and extensive preclinical evaluation. Initially tested in preclinical glaucoma and optic neuropathy models, it has also been investigated in Alzheimer, Parkinson's and Diabetic models, and used to assess efficacy of therapies. Progression to clinical trials has not been speedy. Intravenous ANX776 has to date been found to be safe and well-tolerated in 129 patients, including 16 from Phase 1 and 113 from Phase 2. Results on glaucoma and AMD patients have been recently published, and suggest DARC with an AI-aided algorithm can be used to predict disease activity. New analyses of DARC in GA prediction are reported here. Although further studies are needed to validate these findings, it appears there is potential of the technology to be used as a biomarker. Much larger clinical studies will be needed before it can be considered as a diagnostic, although the relatively non-invasive nature of the nasal as opposed to intravenous administration would widen its acceptability in the future as a screening tool. This review describes DARC development and its progression into Phase 2 clinical trials from lab-based research. It discusses hypotheses, potential challenges, and regulatory hurdles in translating technology.
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Klenow MB, Heitmann ASB, Nylandsted J, Simonsen AC. Timescale of hole closure during plasma membrane repair estimated by calcium imaging and numerical modeling. Sci Rep 2021; 11:4226. [PMID: 33608587 PMCID: PMC7895973 DOI: 10.1038/s41598-021-82926-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/21/2021] [Indexed: 02/08/2023] Open
Abstract
Plasma membrane repair is essential for eukaryotic cell life and is triggered by the influx of calcium through membrane wounds. Repair consists of sequential steps, with closure of the membrane hole being the key event that allows the cell to recover, thus identifying the kinetics of hole closure as important for clarifying repair mechanisms and as a quantitative handle on repair efficiency. We implement calcium imaging in MCF7 breast carcinoma cells subject to laser damage, coupled with a model describing the spatio-temporal calcium distribution. The model identifies the time point of hole closure as the time of maximum calcium signal. Analysis of cell data estimates the closure time as: [Formula: see text] s and [Formula: see text] s using GCaMP6s-CAAX and GCaMP6s probes respectively. The timescale was confirmed by independent time-lapse imaging of a hole during sealing. Moreover, the analysis estimates the characteristic time scale of calcium removal, the penetration depth of the calcium wave and the diffusion coefficient. Probing of hole closure times emerges as a strong universal tool for quantification of plasma membrane repair.
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Affiliation(s)
- Martin Berg Klenow
- Department of Physics Chemistry and Pharmacy (FKF), Odense, Denmark
- University of Southern Denmark (SDU), Campusvej 55, 5230, Odense, Denmark
| | | | - Jesper Nylandsted
- Danish Cancer Society Research Center, Strandboulevarden 49, 2100, Copenhagen, Denmark
- Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3C, 2200, Copenhagen, Denmark
| | - Adam Cohen Simonsen
- Department of Physics Chemistry and Pharmacy (FKF), Odense, Denmark.
- University of Southern Denmark (SDU), Campusvej 55, 5230, Odense, Denmark.
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Narahari AK, Kreutzberger AJB, Gaete PS, Chiu YH, Leonhardt SA, Medina CB, Jin X, Oleniacz PW, Kiessling V, Barrett PQ, Ravichandran KS, Yeager M, Contreras JE, Tamm LK, Bayliss DA. ATP and large signaling metabolites flux through caspase-activated Pannexin 1 channels. eLife 2021; 10:e64787. [PMID: 33410749 PMCID: PMC7806264 DOI: 10.7554/elife.64787] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Pannexin 1 (Panx1) is a membrane channel implicated in numerous physiological and pathophysiological processes via its ability to support release of ATP and other cellular metabolites for local intercellular signaling. However, to date, there has been no direct demonstration of large molecule permeation via the Panx1 channel itself, and thus the permselectivity of Panx1 for different molecules remains unknown. To address this, we expressed, purified, and reconstituted Panx1 into proteoliposomes and demonstrated that channel activation by caspase cleavage yields a dye-permeable pore that favors flux of anionic, large-molecule permeants (up to ~1 kDa). Large cationic molecules can also permeate the channel, albeit at a much lower rate. We further show that Panx1 channels provide a molecular pathway for flux of ATP and other anionic (glutamate) and cationic signaling metabolites (spermidine). These results verify large molecule permeation directly through caspase-activated Panx1 channels that can support their many physiological roles.
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Affiliation(s)
- Adishesh K Narahari
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Alex JB Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Pablo S Gaete
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Yu-Hsin Chiu
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Susan A Leonhardt
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Christopher B Medina
- Department of Microbiology, Immunology, and Cancer Biology, University of VirginiaCharlottesvilleUnited States
| | - Xueyao Jin
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Patrycja W Oleniacz
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Paula Q Barrett
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer Biology, University of VirginiaCharlottesvilleUnited States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Jorge E Contreras
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Douglas A Bayliss
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
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7
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Korolkova OY, Widatalla SE, Williams SD, Whalen DS, Beasley HK, Ochieng J, Grewal T, Sakwe AM. Diverse Roles of Annexin A6 in Triple-Negative Breast Cancer Diagnosis, Prognosis and EGFR-Targeted Therapies. Cells 2020; 9:E1855. [PMID: 32784650 PMCID: PMC7465958 DOI: 10.3390/cells9081855] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/20/2022] Open
Abstract
The calcium (Ca2+)-dependent membrane-binding Annexin A6 (AnxA6), is a multifunctional, predominantly intracellular scaffolding protein, now known to play relevant roles in different cancer types through diverse, often cell-type-specific mechanisms. AnxA6 is differentially expressed in various stages/subtypes of several cancers, and its expression in certain tumor cells is also induced by a variety of pharmacological drugs. Together with the secretion of AnxA6 as a component of extracellular vesicles, this suggests that AnxA6 mediates distinct tumor progression patterns via extracellular and/or intracellular activities. Although it lacks enzymatic activity, some of the AnxA6-mediated functions involving membrane, nucleotide and cholesterol binding as well as the scaffolding of specific proteins or multifactorial protein complexes, suggest its potential utility in the diagnosis, prognosis and therapeutic strategies for various cancers. In breast cancer, the low AnxA6 expression levels in the more aggressive basal-like triple-negative breast cancer (TNBC) subtype correlate with its tumor suppressor activity and the poor overall survival of basal-like TNBC patients. In this review, we highlight the potential tumor suppressor function of AnxA6 in TNBC progression and metastasis, the relevance of AnxA6 in the diagnosis and prognosis of several cancers and discuss the concept of therapy-induced expression of AnxA6 as a novel mechanism for acquired resistance of TNBC to tyrosine kinase inhibitors.
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Affiliation(s)
- Olga Y. Korolkova
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Sarrah E. Widatalla
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Stephen D. Williams
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Diva S. Whalen
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Heather K. Beasley
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Josiah Ochieng
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia;
| | - Amos M. Sakwe
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN 37208, USA; (O.Y.K.); (S.E.W.); (S.D.W.); (D.S.W.); (H.K.B.); (J.O.)
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8
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Annexin A5 prevents amyloid-β-induced toxicity in choroid plexus: implication for Alzheimer's disease. Sci Rep 2020; 10:9391. [PMID: 32523019 PMCID: PMC7286910 DOI: 10.1038/s41598-020-66177-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/09/2020] [Indexed: 12/11/2022] Open
Abstract
In Alzheimer’s disease (AD) amyloid-β (Aβ) deposits may cause impairments in choroid plexus, a specialised brain structure which forms the blood–cerebrospinal fluid (CSF) barrier. We previously carried out a mass proteomic-based study in choroid plexus from AD patients and we found several differentially regulated proteins compared with healthy subjects. One of these proteins, annexin A5, was previously demonstrated implicated in blocking Aβ-induced cytotoxicity in neuronal cell cultures. Here, we investigated the effects of annexin A5 on Aβ toxicity in choroid plexus. We used choroid plexus tissue samples and CSF from mild cognitive impairment (MCI) and AD patients to analyse Aβ accumulation, cell death and annexin A5 levels compared with control subjects. Choroid plexus cell cultures from rats were used to analyse annexin A5 effects on Aβ-induced cytotoxicity. AD choroid plexus exhibited progressive reduction of annexin A5 levels along with progressive increased Aβ accumulation and cell death as disease stage was higher. On the other hand, annexin A5 levels in CSF from patients were found progressively increased as the disease stage increased in severity. In choroid plexus primary cultures, Aβ administration reduced endogenous annexin A5 levels in a time-course dependent manner and simultaneously increased annexin A5 levels in extracellular medium. Annexin A5 addition to choroid plexus cell cultures restored the Aβ-induced impairments on autophagy flux and apoptosis in a calcium-dependent manner. We propose that annexin A5 would exert a protective role in choroid plexus and this protection is lost as Aβ accumulates with the disease progression. Then, brain protection against further toxic insults would be jeopardised.
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Creutz CE. Expression of Metazoan Annexins in Yeast Provides Protection Against Deleterious Effects of the Biofuel Isobutanol. Sci Rep 2019; 9:18603. [PMID: 31819124 PMCID: PMC6901584 DOI: 10.1038/s41598-019-55169-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/23/2019] [Indexed: 02/08/2023] Open
Abstract
The ability of microorganisms to produce biofuels by fermentation is adversely affected by the perturbing effects of the hydrophobic biofuel on plasma membrane structure. It is demonstrated here that heterologous expression of metazoan, calcium-dependent, membrane-binding proteins of the annexin class can reduce deleterious effects of isobutanol on Saccharomyces cerevisiae viability and complex membrane functions. Therefore, expression of annexins in industrial strains of yeast or bacteria may prove beneficial in biofuel production.
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Affiliation(s)
- Carl E Creutz
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA.
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10
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Hermo L, Oliveira RL, Smith CE, Au CE, Bergeron JJM. Dark side of the epididymis: tails of sperm maturation. Andrology 2019; 7:566-580. [PMID: 31102346 DOI: 10.1111/andr.12641] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/25/2019] [Accepted: 03/30/2019] [Indexed: 01/08/2023]
Abstract
BACKGROUND The Hermes body (HB) previously called the cytoplasmic droplet is a focal distension of the flagellar cytoplasm of epididymal spermatozoa consisting mainly of isolated flattened Golgi cisternae. OBJECTIVE To define a functional role for the HB of epididymal spermatozoa. METHODS Isolated fractions of HBs of epididymal spermatozoa were prepared and by quantitative tandem mass spectrometry revealed 1511 proteins. RESULTS The glucose transporter GLUT-3 was the most abundant protein followed by hexokinase 1, which along with the presence of all glycolytic enzymes suggested a role for the HB in glycolysis. Several TMED/p24 Golgi trafficking proteins were abundant with TMED7/p27 and TMED2/p24 defining the identity of the flattened cisternae within the HB as Golgi, along with the known Golgi proteins, GBF1, GOLPH3, Man2α1, and ManIIX. The Golgi trafficking protein TMED7/p27 via small 50-nm vesicles emanating from the Golgi cisternae was proposed to transport GLUT-3 to the plasma membrane for ATP production related to sperm motility. The internal membranes revealed abundant proteins not only of Golgi cisternae, but also of endoplasmic reticulum and endosomes. COPI and COPII coats, clathrin, SNAREs, annexins, atlastins, and GTPases were identified for vesicular trafficking and membrane fusion, in addition to ribosomes, stress proteins for protection, proteasome proteins involved in degradation, and cytoskeletal elements for migration of the HB along the flagellum. The biogenesis of the HB occurring at step 19 spermatids of the testis just prior to their release was uncovered as a key step in germ cell differentiation, where several proteins were expressed, some for the first time. CONCLUSION As epididymal spermatozoa undergo remodeling of their protein makeup through selective degradation of sperm proteins during epididymal transit, then remodeling as a consequence of new protein synthesis is not excluded by our observations.
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Affiliation(s)
- L Hermo
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - R L Oliveira
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - C E Smith
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | - C E Au
- Department of Medicine, McGill University Hospital Research Institute, Montreal, QC, Canada
| | - J J M Bergeron
- Department of Medicine, McGill University Hospital Research Institute, Montreal, QC, Canada
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11
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Whalen DS, Widatalla SE, Korolkova OY, Nangami GS, Beasley HK, Williams SD, Virgous C, Lehmann BD, Ochieng J, Sakwe AM. Implication of calcium activated RasGRF2 in Annexin A6-mediated breast tumor cell growth and motility. Oncotarget 2019; 10:133-151. [PMID: 30719209 PMCID: PMC6349432 DOI: 10.18632/oncotarget.26512] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 12/16/2018] [Indexed: 01/10/2023] Open
Abstract
The role of AnxA6 in breast cancer and in particular, the mechanisms underlying its contribution to tumor cell growth and/or motility remain poorly understood. In this study, we established the tumor suppressor function of AnxA6 in triple negative breast cancer (TNBC) cells by showing that loss of AnxA6 is associated with early onset and rapid growth of xenograft TNBC tumors in mice. We also identified the Ca2+ activated RasGRF2 as an effector of AnxA6 mediated TNBC cell growth and motility. Activation of Ca2+ mobilizing oncogenic receptors such as epidermal growth factor receptor (EGFR) in TNBC cells or pharmacological stimulation of Ca2+ influx led to activation, subsequent degradation and altered effector functions of RasGRF2. Inhibition of Ca2+ influx or overexpression of AnxA6 blocked the activation/degradation of RasGRF2. We also show that AnxA6 acts as a scaffold for RasGRF2 and Ras proteins and that its interaction with RasGRF2 is modulated by GTP and/or activation of Ras proteins. Meanwhile, down-regulation of RasGRF2 and treatment of cells with the EGFR-targeted tyrosine kinase inhibitor (TKI) lapatinib strongly attenuated the growth of otherwise EGFR-TKI resistant AnxA6 high TNBC cells. These data not only suggest that AnxA6 modulated Ca2+ influx and effector functions of RasGRF2 underlie at least in part, the AnxA6 mediated TNBC cell growth and/or motility, but also provide a rationale to target Ras-driven TNBC with EGFR targeted therapies in combination with inhibition of RasGRF2.
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Affiliation(s)
- Diva S Whalen
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Sarrah E Widatalla
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Olga Y Korolkova
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Gladys S Nangami
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Heather K Beasley
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Stephen D Williams
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Carlos Virgous
- Animal Care Facility, Meharry Medical College, Nashville, TN, USA
| | - Brian D Lehmann
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
| | - Josiah Ochieng
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
| | - Amos M Sakwe
- Department of Biochemistry and Cancer Biology, School of Graduate Studies and Research, Meharry Medical College, Nashville, TN, USA
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12
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Yap TE, Donna P, Almonte MT, Cordeiro MF. Real-Time Imaging of Retinal Ganglion Cell Apoptosis. Cells 2018; 7:E60. [PMID: 29914056 PMCID: PMC6025611 DOI: 10.3390/cells7060060] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/06/2018] [Accepted: 06/14/2018] [Indexed: 02/07/2023] Open
Abstract
Monitoring real-time apoptosis in-vivo is an unmet need of neurodegeneration science, both in clinical and research settings. For patients, earlier diagnosis before the onset of symptoms provides a window of time in which to instigate treatment. For researchers, being able to objectively monitor the rates of underlying degenerative processes at a cellular level provides a biomarker with which to test novel therapeutics. The DARC (Detection of Apoptosing Retinal Cells) project has developed a minimally invasive method using fluorescent annexin A5 to detect rates of apoptosis in retinal ganglion cells, the key pathological process in glaucoma. Numerous animal studies have used DARC to show efficacy of novel, pressure-independent treatment strategies in models of glaucoma and other conditions where retinal apoptosis is reported, including Alzheimer’s disease. This may forge exciting new links in the clinical science of treating both cognitive and visual decline. Human trials are now underway, successfully demonstrating the safety and efficacy of the technique to differentiate patients with progressive neurodegeneration from healthy individuals. We review the current perspectives on retinal ganglion cell apoptosis, the way in which this can be imaged, and the exciting advantages that these future methods hold in store.
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Affiliation(s)
- Timothy E Yap
- The Western Eye Hospital, Imperial College Healthcare NHS Trust (ICHNT), London NW1 5QH, UK.
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London NW1 5QH, UK.
| | - Piero Donna
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London NW1 5QH, UK.
| | - Melanie T Almonte
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London NW1 5QH, UK.
| | - Maria Francesca Cordeiro
- The Western Eye Hospital, Imperial College Healthcare NHS Trust (ICHNT), London NW1 5QH, UK.
- The Imperial College Ophthalmic Research Group (ICORG), Imperial College London, London NW1 5QH, UK.
- Glaucoma and Retinal Neurodegeneration Group, Department of Visual Neuroscience, UCL Institute of Ophthalmology, London EC1V 9EL, UK.
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Abstract
Glaucoma is one of the leading causes of irreversible visual loss, which has been estimated to affect 3.5% of those over 40 years old and projected to affect a total of 112 million people by 2040. Such a dramatic increase in affected patients demonstrates the need for continual improvement in the way we diagnose and treat this condition. Annexin A5 is a 36 kDa protein that is ubiquitously expressed in humans and is studied as an indicator of apoptosis in several fields. This molecule has a high calcium-dependent affinity for phosphatidylserine, a cell membrane phospholipid externalized to the outer cell membrane in early apoptosis. The DARC (Detection of Apoptosing Retinal Cells) project uses fluorescently-labelled annexin A5 to assess glaucomatous degeneration, the inherent process of which is the apoptosis of retinal ganglion cells. Furthermore, this project has conducted investigation of the retinal apoptosis in the neurodegenerative conditions of the eye and brain. In this present study, we summarized the use of annexin A5 as a marker of apoptosis in the eye. We also relayed the progress of the DARC project, developing real-time imaging of retinal ganglion cell apoptosis in vivo from the experimental models of disease and identifying mechanisms underlying neurodegeneration and its treatments, which has been applied to the first human clinical trials. DARC has potential as a biomarker in neurodegeneration, especially in the research of novel treatments, and could be a useful tool for the diagnosis and monitoring of glaucoma.
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14
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When a transmembrane channel isn't, or how biophysics and biochemistry (mis)communicate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1099-1104. [PMID: 29408340 DOI: 10.1016/j.bbamem.2018.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 11/21/2022]
Abstract
Annexins are a family of soluble proteins that bind to acidic phospholipids such as phosphatidylserine in a calcium-dependent manner. The archetypical member of the annexin family is annexin A5. For many years, its function remained unknown despite the availability of a high-resolution structure. This, combined with the observations of specific ion conductance in annexin-bound membranes, fueled speculations about the possible membrane-spanning forms of annexins that functioned as ion channels. The channel hypothesis remained controversial and did not gather sufficient evidence to become accepted. Yet, it continues to draw attention as a framework for interpreting indirect (e.g., biochemical) data. The goal of the mini-review is to examine the data on annexin-lipid interactions from the last ~30 years from the point of view of the controversy between the two lines of inquiry: the well-characterized peripheral assembly of the annexins at membranes vs. their putative transmembrane insertion. In particular, the potential role of lipid rearrangements induced by annexin binding is highlighted.
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15
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Moncada RM, Blackshear KJ, Garrett TA. The Arabidopsis thaliana lysophospholipid acyltransferase At1g78690p acylates lysocardiolipins. Biochem Biophys Res Commun 2017; 493:340-345. [DOI: 10.1016/j.bbrc.2017.09.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 09/06/2017] [Indexed: 12/21/2022]
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16
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Keck M, Fournier A, Gualtieri F, Walker A, von Rüden EL, Russmann V, Deeg CA, Hauck SM, Krause R, Potschka H. A systems level analysis of epileptogenesis-associated proteome alterations. Neurobiol Dis 2017; 105:164-178. [PMID: 28576708 DOI: 10.1016/j.nbd.2017.05.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 05/22/2017] [Accepted: 05/29/2017] [Indexed: 12/18/2022] Open
Abstract
Despite intense research efforts, the knowledge about the mechanisms of epileptogenesis and epilepsy is still considered incomplete and limited. However, an in-depth understanding of molecular pathophysiological processes is crucial for the rational selection of innovative biomarkers and target candidates. Here, we subjected proteomic data from different phases of a chronic rat epileptogenesis model to a comprehensive systems level analysis. Weighted Gene Co-expression Network analysis identified several modules of interconnected protein groups reflecting distinct molecular aspects of epileptogenesis in the hippocampus and the parahippocampal cortex. Characterization of these modules did not only further validate the data but also revealed regulation of molecular processes not described previously in the context of epilepsy development. The data sets also provide valuable information about temporal patterns, which should be taken into account for development of preventive strategies in particular when it comes to multi-targeting network pharmacology approaches. In addition, principal component analysis suggests candidate biomarkers, which might inform the design of novel molecular imaging approaches aiming to predict epileptogenesis during different phases or confirm epilepsy manifestation. Further studies are necessary to distinguish between molecular alterations, which correlate with epileptogenesis versus those reflecting a mere consequence of the status epilepticus.
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Affiliation(s)
- Michael Keck
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany
| | - Anna Fournier
- Bioinformatics Core, Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, 4367 Belvaux, Luxembourg
| | - Fabio Gualtieri
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany
| | - Andreas Walker
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany
| | - Eva-Lotta von Rüden
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany
| | - Vera Russmann
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany
| | - Cornelia A Deeg
- Institute of Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany; Experimental Ophthalmology, Philipps University of Marburg, 35037 Marburg, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Roland Krause
- Bioinformatics Core, Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, 4367 Belvaux, Luxembourg.
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology and Pharmacy, Ludwig-Maximilians-University (LMU), 80539 Munich, Germany.
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17
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Enrich C, Rentero C, Meneses-Salas E, Tebar F, Grewal T. Annexins: Ca 2+ Effectors Determining Membrane Trafficking in the Late Endocytic Compartment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:351-385. [PMID: 29594868 DOI: 10.1007/978-3-319-55858-5_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Despite the discovery of annexins 40 years ago, we are just beginning to understand some of the functions of these still enigmatic proteins. Defined and characterized by their ability to bind anionic membrane lipids in a Ca2+-dependent manner, each annexin has to be considered a multifunctional protein, with a multitude of cellular locations and diverse activities. Underlying causes for this considerable functional diversity include their capability to associate with multiple cytosolic and membrane proteins. In recent years, the increasingly recognized establishment of membrane contact sites between subcellular compartments opens a new scenario for annexins as instrumental players to link Ca2+ signalling with the integration of membrane trafficking in many facets of cell physiology. In this chapter, we review and discuss current knowledge on the contribution of annexins in the biogenesis and functioning of the late endocytic compartment, affecting endo- and exocytic pathways in a variety of physiological consequences ranging from membrane repair, lysosomal exocytosis, to cell migration.
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Affiliation(s)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Elsa Meneses-Salas
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, Australia
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18
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Saleh HA, Kabeer BS. Microparticles: Biomarkers and effectors in the cardiovascular system. Glob Cardiol Sci Pract 2015. [DOI: 10.5339/gcsp.2015.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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19
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Dalal A, Vishwakarma A, Singh NK, Gudla T, Bhattacharyya MK, Padmasree K, Viehhauser A, Dietz KJ, Kirti PB. Attenuation of hydrogen peroxide-mediated oxidative stress byBrassica junceaannexin-3 counteracts thiol-specific antioxidant (TSA1) deficiency inSaccharomyces cerevisiae. FEBS Lett 2014; 588:584-93. [DOI: 10.1016/j.febslet.2014.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/15/2013] [Accepted: 01/02/2014] [Indexed: 01/23/2023]
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20
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Seok H, Park HJ, Lee BW, Kim JW, Jung M, Lee SR, Park KH, Park YG, Baik HH, Chung JH. Association of annexin A5 polymorphisms with obesity. Biomed Rep 2013; 1:654-658. [PMID: 24649004 DOI: 10.3892/br.2013.118] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 05/10/2013] [Indexed: 01/21/2023] Open
Abstract
Annexin A5 (ANXA5), which is known as a protein with anticoagulative function, may play a role in triglyceride biosynthesis. Triglycerides are involved in lipid and energy metabolism, which are important in the elucidation of obesity. To investigate the association between single-nucleotide polymorphisms (SNPs) of ANXA5 and obesity in a Korean population, 372 participants (213 overweight/obese individuals and 159 control subjects) were enrolled from the Kyung Hee University Medical Center and Keimyung University Dongsan Medical Center. The genotypes of five SNPs (rs12510548, rs4240260, rs3756281, rs13136094 and rs6534313) were evaluated in ANXA5 using the multiple logistic regression analysis with the codominant 1, codominant 2, dominant, recessive and log-additive models. The genotype and allele frequencies of the five investigated SNPs exhibited significant differences between the control and the overweight/obese groups: rs12510548 (P=0.004 in the codominant 2 model, P=0.0019 in the recessive model, P=0.027 in the log-additive model and P=0.026 in allele frequencies); rs4240260 (P=0.002 and Fisher's exact P=0.0006 in the codominant 2 model, P=0.0007 and Fisher's exact P=0.0007 in the recessive model, P=0.020 and Fisher's exact P=0.0019 in the log-additive model and P=0.020 in allele frequencies); rs3756281 (P=0.016 in the codominant 2 model and P=0.0094 in the recessive model); rs13136094 (P=0.0030 and Fisher's exact P=0.0011 in the codominant 2 model, P=0.0012 and Fisher's exact P=0.0013 in the recessive model, P=0.034 and Fisher's exact P=0.0035 in the log-additive model and P=0.024 in allele frequencies); and rs6534313 (P=0.0010 and Fisher's exact P=0.0003 in the codominant 2 model, P=0.0003 and Fisher's exact P=0.0003 in the recessive model, P=0.0075 and Fisher's exact P=0.0010 in the log-additive model and P=0.005 in allele frequencies). Two haplotypes were weakly associated with obesity (GGATG, P=0.037 and CAGCC, P=0.020). Results of the present study suggested that ANXA5 may be associated with the development of obesity in a Korean population.
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Affiliation(s)
- Hosik Seok
- Departments of Pharmacology and Kohwang Medical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Hae Jeong Park
- Departments of Pharmacology and Kohwang Medical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Byoung Wook Lee
- Biochemistry and Molecular Biology, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Jong Woo Kim
- Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Min Jung
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Seo Ra Lee
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Ki Ho Park
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Young Guk Park
- Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Hyung Hwan Baik
- Biochemistry and Molecular Biology, Kyung Hee University, Seoul 130-701, Republic of Korea
| | - Joo-Ho Chung
- Departments of Pharmacology and Kohwang Medical Research Institute, Kyung Hee University, Seoul 130-701, Republic of Korea
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Annexin-phospholipid interactions. Functional implications. Int J Mol Sci 2013; 14:2652-83. [PMID: 23358253 PMCID: PMC3588008 DOI: 10.3390/ijms14022652] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 01/12/2013] [Accepted: 01/15/2013] [Indexed: 02/03/2023] Open
Abstract
Annexins constitute an evolutionary conserved multigene protein superfamily characterized by their ability to interact with biological membranes in a calcium dependent manner. They are expressed by all living organisms with the exception of certain unicellular organisms. The vertebrate annexin core is composed of four (eight in annexin A6) homologous domains of around 70 amino acids, with the overall shape of a slightly bent ring surrounding a central hydrophilic pore. Calcium- and phospholipid-binding sites are located on the convex side while the N-terminus links domains I and IV on the concave side. The N-terminus region shows great variability in length and amino acid sequence and it greatly influences protein stability and specific functions of annexins. These proteins interact mainly with acidic phospholipids, such as phosphatidylserine, but differences are found regarding their affinity for lipids and calcium requirements for the interaction. Annexins are involved in a wide range of intra- and extracellular biological processes in vitro, most of them directly related with the conserved ability to bind to phospholipid bilayers: membrane trafficking, membrane-cytoskeleton anchorage, ion channel activity and regulation, as well as antiinflammatory and anticoagulant activities. However, the in vivo physiological functions of annexins are just beginning to be established.
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