1
|
Fernandez DI, Provenzale I, Canault M, Fels S, Lenz A, Andresen F, Krümpel A, Dupuis A, Heemskerk JWM, Boeckelmann D, Zieger B. High-throughput microfluidic blood testing to phenotype genetically linked platelet disorders: an aid to diagnosis. Blood Adv 2023; 7:6163-6177. [PMID: 37389831 PMCID: PMC10582840 DOI: 10.1182/bloodadvances.2023009860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/12/2023] [Accepted: 05/30/2023] [Indexed: 07/01/2023] Open
Abstract
Linking the genetic background of patients with bleeding diathesis and altered platelet function remains challenging. We aimed to assess how a multiparameter microspot-based measurement of thrombus formation under flow can help identify patients with a platelet bleeding disorder. For this purpose, we studied 16 patients presenting with bleeding and/or albinism and suspected platelet dysfunction and 15 relatives. Genotyping of patients revealed a novel biallelic pathogenic variant in RASGRP2 (splice site c.240-1G>A), abrogating CalDAG-GEFI expression, compound heterozygosity (c.537del, c.571A>T) in P2RY12, affecting P2Y12 signaling, and heterozygous variants of unknown significance in the P2RY12 and HPS3 genes. Other patients were confirmed to have Hermansky-Pudlak syndrome type 1 or 3. In 5 patients, no genetic variant was found. Platelet functions were assessed via routine laboratory measurements. Blood samples from all subjects and day controls were screened for blood cell counts and microfluidic outcomes on 6 surfaces (48 parameters) in comparison with those of a reference cohort of healthy subjects. Differential analysis of the microfluidic data showed that the key parameters of thrombus formation were compromised in the 16 index patients. Principal component analysis revealed separate clusters of patients vs heterozygous family members and control subjects. Clusters were further segregated based on inclusion of hematologic values and laboratory measurements. Subject ranking indicated an overall impairment in thrombus formation in patients carrying a (likely) pathogenic variant of the genes but not in asymptomatic relatives. Taken together, our results indicate the advantages of testing for multiparametric thrombus formation in this patient population.
Collapse
Affiliation(s)
- Delia I. Fernandez
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
- Platelet Proteomics Group, Center for Research in Molecular Medicine and Chronic Diseases, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
| | - Isabella Provenzale
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
- Institute for Cardiovascular and Metabolic Research, University of Reading, Reading, United Kingdom
| | - Matthias Canault
- Institut National de la Santé et de la Recherche Médicale, UMR_INRA 1260, Faculté de Medecine, Aix Marseille Université, Marseille, France
| | - Salome Fels
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Antonia Lenz
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Felicia Andresen
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Anne Krümpel
- Practice for Pediatric and Youth Medicine, Wettringen, Germany
| | - Arnaud Dupuis
- Université de Strasbourg, Etablissement Français du Sang Grand Est, UMR_S 1255, Fédération de Médecine Translationnelle de Strasbourg, Strasbourg, France
| | - Johan W. M. Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
- Synapse Research Institute, Maastricht, The Netherlands
| | - Doris Boeckelmann
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Barbara Zieger
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, University of Freiburg, Freiburg, Germany
| |
Collapse
|
2
|
Sun W, Hu J, Li M, Huo J, Zhu X. Stormorken syndrome caused by STIM1 mutation: A case report and literature review. MEDICINE INTERNATIONAL 2022; 2:29. [PMID: 36698909 PMCID: PMC9829216 DOI: 10.3892/mi.2022.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 09/16/2022] [Indexed: 06/17/2023]
Abstract
The aim of the present case study was to identify the genetic cause of a patient with a clinical presentation of tubular aggregate myopathy (TAM)/Stormorken syndrome (STRMK) and review the published clinical data of patients with TAM/STRMK. A child with thrombocytopenia and hyperCKemia at the Children's Hospital of Soochow University were recruited in the study. Peripheral blood samples of the infant and her parents were collected, and then whole-exome sequencing was performed. Detection of the stromal interaction molecule 1 (STIM1) level of the child was performed using western blot analysis. In addition, a literature review was performed based on a thorough retrieval of published literature from the PubMed database, as well as domestic databases. In the present study, the c.326A>G mutation in a STIM1 allele (p.H109R) was identified only in the child, as opposed to the unaffected parents. The level of STIM1 was not decreased in the child. Among the mutation sites identified in previous studies, there were 46 cases across 30 families of STIM1 EF-hand mutations, 21 cases across 14 families of STIM1 CC1 mutations and 20 cases across 8 families of calcium release-activated calcium channel protein 1 mutations, in which 7 parents had the same mutation site as the patient described herein. On the whole, it is demonstrated that TAM/STRMK is an extremely rare disease with autosomal dominant inheritance. Patients often have multisystemic signs. Gene detection at an early stage is helpful for diagnosis. Long-term exercise training may also have a certain curative effect.
Collapse
Affiliation(s)
- Wenqiang Sun
- Department of Neonatology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Jinhui Hu
- Department of Neonatology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Mengzhao Li
- Department of Neonatology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Jie Huo
- Department of Neonatology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| | - Xueping Zhu
- Department of Neonatology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215025, P.R. China
| |
Collapse
|
3
|
CRACking the Molecular Regulatory Mechanism of SOCE during Platelet Activation in Thrombo-Occlusive Diseases. Cells 2022; 11:cells11040619. [PMID: 35203269 PMCID: PMC8870035 DOI: 10.3390/cells11040619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 01/31/2022] [Accepted: 02/09/2022] [Indexed: 11/16/2022] Open
Abstract
Thrombo-occlusive diseases such as myocardial infarction, ischemic stroke and deep vein thrombosis with subsequent pulmonary embolism still represent a major health burden worldwide. Besides the cells of the vasculature or other hematopoietic cells, platelets are primarily responsible for the development and progression of an occluding thrombus. The activation and function of platelets crucially depend on free cytosolic calcium (Ca2+) as second messenger, which modulates platelet secretion, aggregation and thrombus formation. Ca2+ is elevated upon platelet activation by release of Ca2+ from intracellular stores thus triggering of the subsequent store-operated Ca2+ entry (SOCE), which is facilitated by Ca2+ release-activated channels (CRACs). In general, CRACs are assembled by the pore-forming unit Orai in the plasma membrane and the Ca2+-sensing stromal interaction molecule (STIM) in the endoplasmic reticulum after the depletion of internal Ca2+ stores. In the last few years, there is a growing body of the literature demonstrating the importance of STIM and Orai-mediated mechanism in thrombo-occlusive disorders. Thus, this review provides an overview of the recent understanding of STIM and Orai signaling in platelet function and its implication in the development and progression of ischemic thrombo-occlusive disorders. Moreover, potential pharmacological implications of STIM and Orai signaling in platelets are anticipated and discussed in the end.
Collapse
|
4
|
Silva-Rojas R, Laporte J, Böhm J. STIM1/ ORAI1 Loss-of-Function and Gain-of-Function Mutations Inversely Impact on SOCE and Calcium Homeostasis and Cause Multi-Systemic Mirror Diseases. Front Physiol 2020; 11:604941. [PMID: 33250786 PMCID: PMC7672041 DOI: 10.3389/fphys.2020.604941] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 10/15/2020] [Indexed: 12/19/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous and essential mechanism regulating Ca2+ homeostasis in all tissues, and controls a wide range of cellular functions including keratinocyte differentiation, osteoblastogenesis and osteoclastogenesis, T cell proliferation, platelet activation, and muscle contraction. The main SOCE actors are STIM1 and ORAI1. Depletion of the reticular Ca2+ stores induces oligomerization of the luminal Ca2+ sensor STIM1, and the oligomers activate the plasma membrane Ca2+ channel ORAI1 to trigger extracellular Ca2+ entry. Mutations in STIM1 and ORAI1 result in abnormal SOCE and lead to multi-systemic disorders. Recessive loss-of-function mutations are associated with CRAC (Ca2+ release-activated Ca2+) channelopathy, involving immunodeficiency and autoimmunity, muscular hypotonia, ectodermal dysplasia, and mydriasis. In contrast, dominant STIM1 and ORAI1 gain-of-function mutations give rise to tubular aggregate myopathy and Stormorken syndrome (TAM/STRMK), forming a clinical spectrum encompassing muscle weakness, thrombocytopenia, ichthyosis, hyposplenism, short stature, and miosis. Functional studies on patient-derived cells revealed that CRAC channelopathy mutations impair SOCE and extracellular Ca2+ influx, while TAM/STRMK mutations induce excessive Ca2+ entry through SOCE over-activation. In accordance with the opposite pathomechanisms underlying both disorders, CRAC channelopathy and TAM/STRMK patients show mirror phenotypes at the clinical and molecular levels, and the respective animal models recapitulate the skin, bones, immune system, platelet, and muscle anomalies. Here we review and compare the clinical presentations of CRAC channelopathy and TAM/STRMK patients and the histological and molecular findings obtained on human samples and murine models to highlight the mirror phenotypes in different tissues, and to point out potentially undiagnosed anomalies in patients, which may be relevant for disease management and prospective therapeutic approaches.
Collapse
Affiliation(s)
- Roberto Silva-Rojas
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
| | - Jocelyn Laporte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
| | - Johann Böhm
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
| |
Collapse
|
5
|
Role of STIM1/ORAI1-mediated store-operated Ca 2+ entry in skeletal muscle physiology and disease. Cell Calcium 2018; 76:101-115. [PMID: 30414508 DOI: 10.1016/j.ceca.2018.10.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/23/2018] [Accepted: 10/23/2018] [Indexed: 11/23/2022]
Abstract
Store-operated Ca2+ entry (SOCE) is a Ca2+ entry mechanism activated by depletion of intracellular Ca2+ stores. In skeletal muscle, SOCE is mediated by an interaction between stromal-interacting molecule-1 (STIM1), the Ca2+ sensor of the sarcoplasmic reticulum, and ORAI1, the Ca2+-release-activated-Ca2+ (CRAC) channel located in the transverse tubule membrane. This review focuses on the molecular mechanisms and physiological role of SOCE in skeletal muscle, as well as how alterations in STIM1/ORAI1-mediated SOCE contribute to muscle disease. Recent evidence indicates that SOCE plays an important role in both muscle development/growth and fatigue. The importance of SOCE in muscle is further underscored by the discovery that loss- and gain-of-function mutations in STIM1 and ORAI1 result in an eclectic array of disorders with clinical myopathy as central defining component. Despite differences in clinical phenotype, all STIM1/ORAI1 gain-of-function mutations-linked myopathies are characterized by the abnormal accumulation of intracellular membranes, known as tubular aggregates. Finally, dysfunctional STIM1/ORAI1-mediated SOCE also contributes to the pathogenesis of muscular dystrophy, malignant hyperthermia, and sarcopenia. The picture to emerge is that tight regulation of STIM1/ORAI1-dependent Ca2+ signaling is critical for optimal skeletal muscle development/function such that either aberrant increases or decreases in SOCE activity result in muscle dysfunction.
Collapse
|
6
|
Nagy M, Mastenbroek TG, Mattheij NJA, de Witt S, Clemetson KJ, Kirschner J, Schulz AS, Vraetz T, Speckmann C, Braun A, Cosemans JMEM, Zieger B, Heemskerk JWM. Variable impairment of platelet functions in patients with severe, genetically linked immune deficiencies. Haematologica 2017; 103:540-549. [PMID: 29242293 PMCID: PMC5830379 DOI: 10.3324/haematol.2017.176974] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/07/2017] [Indexed: 11/09/2022] Open
Abstract
In patients with dysfunctions of the Ca2+ channel ORAI1, stromal interaction molecule 1 (STIM1) or integrin-regulating kindlin-3 (FERMT3), severe immunodeficiency is frequently linked to abnormal platelet activity. In this paper, we studied platelet responsiveness by multiparameter assessment of whole blood thrombus formation under high-shear flow conditions in 9 patients, including relatives, with confirmed rare genetic mutations of ORAI1, STIM1 or FERMT3. In platelets isolated from 5 out of 6 patients with ORAI1 or STIM1 mutations, store-operated Ca2+ entry (SOCE) was either completely or partially defective compared to control platelets. Parameters of platelet adhesion and aggregation on collagen microspots were impaired for 4 out of 6 patients, in part related to a low platelet count. For 4 patients, platelet adhesion/aggregation and procoagulant activity on von Willebrand Factor (VWF)/rhodocytin and VWF/fibrinogen microspots were impaired independently of platelet count, and were partly correlated with SOCE deficiency. Measurement of thrombus formation at low shear rate confirmed a greater impairment of platelet functionality in the ORAI1 patients than in the STIM1 patient. For 3 patients/relatives with a FERMT3 mutation, all parameters of thrombus formation were strongly reduced regardless of the microspot. Bone marrow transplantation, required by 2 patients, resulted in overall improvement of platelet function. We concluded that multiparameter assessment of whole blood thrombus formation in a surface-dependent way can detect: i) additive effects of low platelet count and impaired platelet functionality; ii) aberrant ORAI1-mediated Ca2+ entry; iii) differences in platelet activation between patients carrying the same ORAI1 mutation; iv) severe platelet function impairment linked to a FERMT3 mutation and bleeding history.
Collapse
Affiliation(s)
- Magdolna Nagy
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | - Tom G Mastenbroek
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | - Nadine J A Mattheij
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | - Susanne de Witt
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | | | - Janbernd Kirschner
- Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Germany
| | - Ansgar S Schulz
- Department of Pediatrics and Adolescent Medicine, University Medical Centre Ulm, Germany
| | - Thomas Vraetz
- Department of Pediatrics and Adolescent Medicine, Medical Center-University of Freiburg, Faculty of Medicine, Germany
| | - Carsten Speckmann
- Center for Chronic Immunodeficiency and Department of Pediatrics and Adolescent Medicine, Medical Centre, University of Freiburg, Germany
| | - Attila Braun
- Institute of Experimental Biomedicine, University Hospital and Rudolf Virchow Centre, University of Würzburg, Germany
| | - Judith M E M Cosemans
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | - Barbara Zieger
- Center for Chronic Immunodeficiency and Department of Pediatrics and Adolescent Medicine, Medical Centre, University of Freiburg, Germany
| | - Johan W M Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| |
Collapse
|
7
|
Berna-Erro A, Jardín I, Smani T, Rosado JA. Regulation of Platelet Function by Orai, STIM and TRP. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:157-81. [PMID: 27161229 DOI: 10.1007/978-3-319-26974-0_8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Agonist-induced changes in cytosolic Ca(2+) concentration ([Ca(2+)]c) are central events in platelet physiology. A major mechanism supporting agonist-induced Ca(2+) signals is store-operated Ca(2+) entry (SOCE), where the Ca(2+) sensor STIM1 and the channels of the Orai family, as well as TRPC members are the key elements. STIM1-dependent SOCE plays a major role in collagen-stimulated Ca(2+) signaling, phosphatidylserine exposure and thrombin generation. Furthermore, studies involving Orai1 gain-of-function mutants and platelets from Orai1-deficient mice have revealed the importance of this channel in thrombosis and hemostasis to those found in STIM1-deficient mice indicating that SOCE might play a prominent role in thrombus formation. Moreover, increase in TRPC6 expression might lead to thrombosis in humans. The role of STIM1, Orai1 and TRPCs, and thus SOCE, in thrombus formation, suggests that therapies directed against SOCE and targeting these molecules during cardiovascular and cerebrovascular events could significantly improve traditional anti-thrombotic treatments.
Collapse
Affiliation(s)
- Alejandro Berna-Erro
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, 08003, Spain
| | - Isaac Jardín
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, Cáceres, 10003, Spain
| | - Tarik Smani
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
| | - Juan A Rosado
- Departamento de Fisiología, University of Extremadura, Cáceres, Spain.
| |
Collapse
|
8
|
Abstract
Ca(2+) release-activated Ca(2+) (CRAC) channels mediate a specific form of Ca(2+) influx called store-operated Ca(2+) entry (SOCE) that contributes to the function of many cell types. CRAC channels are composed of ORAI1 proteins located in the plasma membrane, which form its ion-conducting pore. ORAI1 channels are activated by stromal interaction molecule (STIM) 1 and STIM2 located in the endoplasmic reticulum. Loss- and gain-of-function gene mutations in ORAI1 and STIM1 in human patients cause distinct disease syndromes. CRAC channelopathy is caused by loss-of-function mutations in ORAI1 and STIM1 that abolish CRAC channel function and SOCE; it is characterized by severe combined immunodeficiency (SCID)-like disease, autoimmunity, muscular hypotonia, and ectodermal dysplasia, with defects in sweat gland function and dental enamel formation. The latter defect emphasizes an important role of CRAC channels in tooth development. By contrast, autosomal dominant gain-of-function mutations in ORAI1 and STIM1 result in constitutive CRAC channel activation, SOCE, and increased intracellular Ca(2+) levels that are associated with an overlapping spectrum of diseases, including nonsyndromic tubular aggregate myopathy (TAM) and York platelet and Stormorken syndromes. The latter two syndromes are defined, besides myopathy, by thrombocytopenia, thrombopathy, and bleeding diathesis. The fact that myopathy results from both loss- and gain-of-function mutations in ORAI1 and STIM1 highlights the importance of CRAC channels for Ca(2+) homeostasis in skeletal muscle function. The cellular dysfunction and clinical disease spectrum observed in mutant patients provide important information about the molecular regulation of ORAI1 and STIM1 proteins and the role of CRAC channels in human physiology.
Collapse
Affiliation(s)
- Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, New York
| |
Collapse
|
9
|
Store-operated calcium entry: Mechanisms and modulation. Biochem Biophys Res Commun 2015; 460:40-9. [PMID: 25998732 DOI: 10.1016/j.bbrc.2015.02.110] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 02/20/2015] [Indexed: 11/22/2022]
Abstract
Store-operated calcium entry is a central mechanism in cellular calcium signalling and in maintaining cellular calcium balance. This review traces the history of research on store-operated calcium entry, the discovery of STIM and ORAI as central players in calcium entry, and the role of STIM and ORAI in biology and human disease. It describes current knowledge of the basic mechanism of STIM-ORAI signalling and of the varied mechanisms by which STIM-ORAI signalling can be modulated.
Collapse
|
10
|
Morin G, Bruechle NO, Singh AR, Knopp C, Jedraszak G, Elbracht M, Brémond-Gignac D, Hartmann K, Sevestre H, Deutz P, Hérent D, Nürnberg P, Roméo B, Konrad K, Mathieu-Dramard M, Oldenburg J, Bourges-Petit E, Shen Y, Zerres K, Ouadid-Ahidouch H, Rochette J. Gain-of-Function Mutation in STIM1 (P.R304W) Is Associated with Stormorken Syndrome. Hum Mutat 2015; 35:1221-32. [PMID: 25044882 DOI: 10.1002/humu.22621] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 07/03/2014] [Indexed: 12/21/2022]
Abstract
Stormorken syndrome is a rare autosomal dominant disorder characterized by a phenotype that includes miosis, thrombocytopenia/thrombocytopathy with bleeding time diathesis, intellectual disability, mild hypocalcemia, muscle fatigue, asplenia, and ichthyosis. Using targeted sequencing and whole-exome sequencing, we identified the c.910C > T transition in a STIM1 allele (p.R304W) only in patients and not in their unaffected family members. STIM1 encodes stromal interaction molecule 1 protein (STIM1), which is a finely tuned endoplasmic reticulum Ca(2+) sensor. The effect of the mutation on the structure of STIM1 was investigated by molecular modeling, and its effect on function was explored by calcium imaging experiments. Results obtained from calcium imaging experiments using transfected cells together with fibroblasts from one patient are in agreement with impairment of calcium homeostasis. We show that the STIM1 p.R304W variant may affect the conformation of the inhibitory helix and unlock the inhibitory state of STIM1. The p.R304W mutation causes a gain of function effect associated with an increase in both resting Ca(2+) levels and store-operated calcium entry. Our study provides evidence that Stormorken syndrome may result from a single-gene defect, which is consistent with Mendelian-dominant inheritance.
Collapse
Affiliation(s)
- Gilles Morin
- Department of Molecular and Clinical Genetics, EA 4666, CHU d'Amiens, Université de Picardie Jules Verne, Amiens, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Dolan AT, Diamond SL. Systems modeling of Ca(2+) homeostasis and mobilization in platelets mediated by IP3 and store-operated Ca(2+) entry. Biophys J 2014; 106:2049-60. [PMID: 24806937 DOI: 10.1016/j.bpj.2014.03.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 11/17/2022] Open
Abstract
Resting platelets maintain a stable level of low cytoplasmic calcium ([Ca(2+)]cyt) and high dense tubular system calcium ([Ca(2+)]dts). During thrombosis, activators cause a transient rise in inositol trisphosphate (IP3) to trigger calcium mobilization from stores and elevation of [Ca(2+)]cyt. Another major source of [Ca(2+)]cyt elevation is store-operated calcium entry (SOCE) through plasmalemmal calcium channels that open in response to store depletion as [Ca(2+)]dts drops. A 34-species systems model employed kinetics describing IP3-receptor, DTS-plasmalemma puncta formation, SOCE via assembly of STIM1 and Orai1, and the plasmalemma and sarco/endoplasmic reticulum Ca(2+)-ATPases. Four constraints were imposed: calcium homeostasis before activation; stable in zero extracellular calcium; IP3-activatable; and functional SOCE. Using a Monte Carlo method to sample three unknown parameters and nine initial concentrations in a 12-dimensional space near measured or expected values, we found that model configurations that were responsive to stimuli and demonstrated significant SOCE required high inner membrane electric potential (>-70 mV) and low resting IP3 concentrations. The absence of puncta in resting cells was required to prevent spontaneous store depletion in calcium-free media. Ten-fold increases in IP3 caused saturated calcium mobilization. This systems model represents a critical step in being able to predict platelets' phenotypes during hemostasis or thrombosis.
Collapse
Affiliation(s)
- Andrew T Dolan
- Institute for Medicine and Engineering, Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Scott L Diamond
- Institute for Medicine and Engineering, Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania.
| |
Collapse
|