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Hernandez-Suarez L, Diez-Martin E, Egiguren-Ortiz J, Fernandez R, Etxebarria A, Astigarraga E, Miguelez C, Ramirez-Garcia A, Barreda-Gómez G. Serological Antibodies against Kidney, Liver, and Spleen Membrane Antigens as Potential Biomarkers in Patients with Immune Disorders. Int J Mol Sci 2024; 25:2025. [PMID: 38396703 PMCID: PMC10888476 DOI: 10.3390/ijms25042025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/30/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Immune disorders arise from complex genetic and environmental factors, which lead to dysregulation at the cellular and inflammatory levels and cause tissue damage. Recent research highlights the crucial role of reactive antibodies in autoimmune diseases and graft rejection, but their complex determination poses challenges for clinical use. Therefore, our study aimed to ascertain whether the presence of reactive antibodies against membrane antigens in tissues from both animal models and humans could serve as biomarkers in patients with autoimmune disorders. To address this issue, we examined the binding profile of serological antibodies against a diverse panel of cell membranes from the spleen, liver, and kidney tissues of monkeys, rats, and humans. After developing the cell membrane microarrays, human sera were immunologically assayed. The study was first conducted on sera from two groups, healthy subjects and patients with inflammatory and autoimmune disorders, and then optimized for kidney transplant patient sera. A significant increase in antibody reactivity against specific monkey kidney and spleen membranes was observed in the serum of patients with lupus nephritis, while kidney transplant patients showed a significant enhancement against human tissues and human embryonic kidney 293 cells. These results show the potential importance for clinical and basic research purposes of studying the presence of specific IgG against membrane antigens in patients' serum as potential biomarkers of immune disorders. However, it is important to note that these results need to be verified in further studies with a larger sample size to confirm their relevance.
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Affiliation(s)
- Leidi Hernandez-Suarez
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
- Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain;
| | - Eguzkiñe Diez-Martin
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
- Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain;
| | - June Egiguren-Ortiz
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain;
| | - Roberto Fernandez
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
| | - Aitor Etxebarria
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
| | - Egoitz Astigarraga
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
| | - Cristina Miguelez
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain;
- Neurodegenerative Diseases Group, BioBizkaia Health Research Institute, 48940 Barakaldo, Spain
| | - Andoni Ramirez-Garcia
- Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain;
| | - Gabriel Barreda-Gómez
- Department of Research and Development, IMG Pharma Biotech S.L., 48170 Zamudio, Spain; (L.H.-S.); (E.D.-M.); (J.E.-O.); (R.F.); (A.E.); (E.A.)
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Di Taranto MD, Benito-Vicente A, Giacobbe C, Uribe KB, Rubba P, Etxebarria A, Guardamagna O, Gentile M, Martín C, Fortunato G. Identification and in vitro characterization of two new PCSK9 Gain of Function variants found in patients with Familial Hypercholesterolemia. Sci Rep 2017; 7:15282. [PMID: 29127338 PMCID: PMC5681505 DOI: 10.1038/s41598-017-15543-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/30/2017] [Indexed: 11/16/2022] Open
Abstract
Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by pathogenic variants in genes encoding for LDL receptor (LDLR), Apolipoprotein B and Proprotein convertase subtilisin/kexin type 9 (PCSK9). Among PCSK9 variants, only Gain-of- Function (GOF) variants lead to FH. Greater attention should be paid to the classification of variants as pathogenic. Two hundred sixty nine patients with a clinical suspect of FH were screened for variants in LDLR and the patients without pathogenic variants were screened for variants in PCSK9 and APOB. Functional characterization of PCSK9 variants was performed by assessment of protein secretion, of LDLR activity in presence of PCSK9 variant proteins as well as of the LDLR affinity of the PCSK9 variants. Among 81 patients without pathogenic variants in LDLR, 7 PCSK9 heterozygotes were found, 4 of whom were carriers of variants whose role in FH pathogenesis is still unknown. Functional characterization revealed that two variants (p.(Ser636Arg) and p.(Arg357Cys)) were GOF variants. In Conclusions, we demonstrated a GOF effect of 2 PCSK9 variants that can be considered as FH-causative variants. The study highlights the important role played by functional characterization in integrating diagnostic procedures when the pathogenicity of new variants has not been previously demonstrated.
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Affiliation(s)
- Maria Donata Di Taranto
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli and CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy
| | - Asier Benito-Vicente
- Biofisika Institute (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080, Bilbao, Spain
| | - Carola Giacobbe
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli and CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy
| | - Kepa Belloso Uribe
- Biofisika Institute (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080, Bilbao, Spain
| | - Paolo Rubba
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Aitor Etxebarria
- Biofisika Institute (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080, Bilbao, Spain
| | - Ornella Guardamagna
- Dipartimento di Scienze della Sanità Pubblica e Pediatriche, Università degli Studi di Torino, Torino, Italy
| | - Marco Gentile
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy
| | - Cesar Martín
- Biofisika Institute (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080, Bilbao, Spain.
| | - Giuliana Fortunato
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Napoli and CEINGE S.C.a r.l. Biotecnologie Avanzate, Napoli, Italy.
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Garcia UG, Vicente AB, Etxebarria A, Palacios L, Cenarro A, Calle X, Uribe KB, Sánchez-Hernández RM, Stef M, Lambert G, Civeira F, Ostolaza H, Martín C. The leucine stretch length of PCSK9 signal peptide and its role in development of autosomal dominant hypercholesterolaemia: Unravelling the activities of P.LEU23DEL and P.LEU22_LEU23DUP variants. Atherosclerosis 2017. [DOI: 10.1016/j.atherosclerosis.2017.06.138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Jiang L, Benito-Vicente A, Tang L, Etxebarria A, Cui W, Uribe KB, Pan XD, Ostolaza H, Yang SW, Zhou YJ, Martin C, Wang LY. Analysis of LDLR variants from homozygous FH patients carrying multiple mutations in the LDLR gene. Atherosclerosis 2017. [DOI: 10.1016/j.atherosclerosis.2017.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Alves A, Azevedo S, Benito-Vicente A, Etxebarria A, Barros P, Medeiros A, Martin C, Bourbon M. Functionally characterization of LDLR missense alterations found in clinical FH patients. Atherosclerosis 2016. [DOI: 10.1016/j.atherosclerosis.2016.07.383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Benito-Vicente A, Fernández-Higuero J, Milicua J, Etxebarria A, Ostolaza H, Arrondo J, Martin C. Structural changes induced by acidic pH in human apolipoprotein B-100. Atherosclerosis 2016. [DOI: 10.1016/j.atherosclerosis.2016.07.579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Etxebarria A, Moreno X, Benito-Vicente A, Jebari S, Galicia U, Ostolaza H, Martin C. Statins upregulate microRNA-122 in HEPG2 cells. Atherosclerosis 2016. [DOI: 10.1016/j.atherosclerosis.2016.07.478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cenarro A, Etxebarria A, de Castro-Orós I, Stef M, Bea AM, Palacios L, Mateo-Gallego R, Benito-Vicente A, Ostolaza H, Tejedor T, Martín C, Civeira F. The p.Leu167del Mutation in APOE Gene Causes Autosomal Dominant Hypercholesterolemia by Down-regulation of LDL Receptor Expression in Hepatocytes. J Clin Endocrinol Metab 2016; 101:2113-21. [PMID: 27014949 DOI: 10.1210/jc.2015-3874] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
CONTEXT The p.Leu167del mutation in the APOE gene has been associated with hyperlipidemia. OBJECTIVES Our objective was to determine the frequency of p.Leu167del mutation in APOE gene in subjects with autosomal dominant hypercholesterolemia (ADH) in whom LDLR, APOB, and PCSK9 mutations had been excluded and to identify the mechanisms by which this mutant apo E causes hypercholesterolemia. DESIGN The APOE gene was analyzed in a case-control study. SETTING The study was conducted at a University Hospital Lipid Clinic. PATIENTS OR OTHER PARTICIPANTS Two groups (ADH, 288 patients; control, 220 normolipidemic subjects) were included. INTERVENTION We performed sequencing of APOE gene and proteomic and cellular experiments. MAIN OUTCOME MEASURE To determine the frequency of the p.Leu167del mutation and the mechanism by which it causes hypercholesterolemia. RESULTS In the ADH group, nine subjects (3.1%) were carriers of the APOE c.500_502delTCC, p.Leu167del mutation, cosegregating with hypercholesterolemia in studied families. Proteomic quantification of wild-type and mutant apo E in very low-density lipoprotein (VLDL) from carrier subjects revealed that apo E3 is almost a 5-fold increase compared to mutant apo E. Cultured cell studies revealed that VLDL from mutation carriers had a significantly higher uptake by HepG2 and THP-1 cells compared to VLDL from subjects with E3/E3 or E2/E2 genotypes. Transcriptional down-regulation of LDLR was also confirmed. CONCLUSIONS p.Leu167del mutation in APOE gene is the cause of hypercholesterolemia in the 3.1% of our ADH subjects without LDLR, APOB, and PCSK9 mutations. The mechanism by which this mutation is associated to ADH is that VLDL carrying the mutant apo E produces LDLR down-regulation, thereby raising plasma low-density lipoprotein cholesterol levels.
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Affiliation(s)
- Ana Cenarro
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Aitor Etxebarria
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Isabel de Castro-Orós
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Marianne Stef
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Ana M Bea
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Lourdes Palacios
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Rocío Mateo-Gallego
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Asier Benito-Vicente
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Helena Ostolaza
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Teresa Tejedor
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - César Martín
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
| | - Fernando Civeira
- Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis (A.C., I.d.C.-O., A.M.B., R.M.-G., F.C.), Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón, Zaragoza, Spain; Unidad de Biofísica (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular (A.E., A.B.-V., H.O., C.M.), Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain; Progenika Biopharma (M.S., L.P.), a Grifols Company, Derio, Spain; and Departamento de Anatomía (T.T.), Embriología y Genética, Universidad de Zaragoza, Spain
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Alves AC, Etxebarria A, Medeiros AM, Benito-Vicente A, Thedrez A, Passard M, Croyal M, Martin C, Lambert G, Bourbon M. Characterization of the First PCSK9 Gain of Function Homozygote. J Am Coll Cardiol 2015; 66:2152-2154. [DOI: 10.1016/j.jacc.2015.08.871] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/05/2015] [Accepted: 08/31/2015] [Indexed: 12/19/2022]
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Martín C, Etxaniz A, Uribe KB, Etxebarria A, González-Bullón D, Arlucea J, Goñi FM, Aréchaga J, Ostolaza H. Adenylate Cyclase Toxin promotes bacterial internalisation into non phagocytic cells. Sci Rep 2015; 5:13774. [PMID: 26346097 PMCID: PMC4642564 DOI: 10.1038/srep13774] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 08/04/2015] [Indexed: 02/07/2023] Open
Abstract
Bordetella pertussis causes whooping cough, a respiratory infectious disease that is the fifth largest cause of vaccine-preventable death in infants. Though historically considered an extracellular pathogen, this bacterium has been detected both in vitro and in vivo inside phagocytic and non-phagocytic cells. However the precise mechanism used by B. pertussis for cell entry, or the putative bacterial factors involved, are not fully elucidated. Here we find that adenylate cyclase toxin (ACT), one of the important toxins of B. pertussis, is sufficient to promote bacterial internalisation into non-phagocytic cells. After characterization of the entry route we show that uptake of “toxin-coated bacteria” proceeds via a clathrin-independent, caveolae-dependent entry pathway, allowing the internalised bacteria to survive within the cells. Intracellular bacteria were found inside non-acidic endosomes with high sphingomyelin and cholesterol content, or “free” in the cytosol of the invaded cells, suggesting that the ACT-induced bacterial uptake may not proceed through formation of late endolysosomes. Activation of Tyr kinases and toxin-induced Ca2+-influx are essential for the entry process. We hypothesize that B. pertussis might use ACT to activate the endocytic machinery of non-phagocytic cells and gain entry into these cells, in this way evading the host immune system.
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Affiliation(s)
- César Martín
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Asier Etxaniz
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Kepa B Uribe
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Aitor Etxebarria
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - David González-Bullón
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Jon Arlucea
- Departamento de Biología Celular, Facultad de Medicina, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Félix M Goñi
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Juan Aréchaga
- Departamento de Biología Celular, Facultad de Medicina, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
| | - Helena Ostolaza
- Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain
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Benito-Vicente A, Etxebarria A, Stef M, Ostolaza H, Palacios L, Martín C. Activity-associated effect of LDL receptor missense variants located in the cysteine-rich repeats. Atherosclerosis 2015. [DOI: 10.1016/j.atherosclerosis.2015.04.414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Etxebarria A, Benito-Vicente A, Stef M, Ostolaza H, Palacios L, Martin C. Activity-associated effect of LDL receptor missense variants located in the cysteine-rich repeats. Atherosclerosis 2014; 238:304-12. [PMID: 25545329 DOI: 10.1016/j.atherosclerosis.2014.12.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 12/09/2014] [Accepted: 12/13/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND The LDL receptor (LDLR) is a Class I transmembrane protein critical for the clearance of cholesterol-containing lipoprotein particles. The N-terminal domain of the LDLR harbours the ligand-binding domain consisting of seven cysteine-rich repeats of approximately 40 amino acids each. Mutations in the LDLR binding domain may result in loss of receptor activity leading to familial hypercholesterolemia (FH). In this study the activity of six mutations located in the cysteine-rich repeats of the LDLR has been investigated. METHODS CHO-ldlA7 transfected cells with six different LDLR mutations have been used to analyse in vitro LDLR expression, lipoprotein binding and uptake. Immunoblotting of cell extracts, flow cytometry and confocal microscopy have been performed to determine the effects of these mutations. In silico analysis was also performed to predict the mutation effect. RESULTS AND CONCLUSION From the six mutations, p.Arg257Trp turned out to be a non-pathogenic LDLR variant whereas p.Cys116Arg, p.Asp168Asn, p.Asp172Asn, p.Arg300Gly and p.Asp301Gly were classified as binding-defective LDLR variants whose effect is not as severe as null allele mutations.
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Affiliation(s)
- A Etxebarria
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - A Benito-Vicente
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - M Stef
- Progenika Biopharma, a Grifols Company, Derio, Spain
| | - H Ostolaza
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - L Palacios
- Progenika Biopharma, a Grifols Company, Derio, Spain
| | - C Martin
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain.
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Etxebarria A, Benito-Vicente A, Palacios L, Stef M, Cenarro A, Civeira F, Ostolaza H, Martin C. Functional Characterization and Classification of Frequent Low-Density Lipoprotein Receptor Variants. Hum Mutat 2014; 36:129-41. [DOI: 10.1002/humu.22721] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/24/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | - Asier Benito-Vicente
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | | | | | - Ana Cenarro
- Unidad de Lípidos and Laboratorio de Investigación Molecular; Hospital Universitario Miguel Servet; Instituto Aragonés de Ciencias de la Salud (IACS); Zaragoza Spain
| | - Fernando Civeira
- Unidad de Lípidos and Laboratorio de Investigación Molecular; Hospital Universitario Miguel Servet; Instituto Aragonés de Ciencias de la Salud (IACS); Zaragoza Spain
| | - Helena Ostolaza
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
| | - Cesar Martin
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica; Universidad del País Vasco; Bilbao 48080 Spain
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Etxebarria A, Benito-Vicente A, Alves AC, Ostolaza H, Bourbon M, Martin C. Advantages and versatility of fluorescence-based methodology to characterize the functionality of LDLR and class mutation assignment. PLoS One 2014; 9:e112677. [PMID: 25386756 PMCID: PMC4227843 DOI: 10.1371/journal.pone.0112677] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 10/10/2014] [Indexed: 12/16/2022] Open
Abstract
Familial hypercholesterolemia (FH) is a common autosomal codominant disease with a frequency of 1:500 individuals in its heterozygous form. The genetic basis of FH is most commonly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR activity ex vivo are based on the analysis of 125I-labeled lipoproteins (reference method) or fluorescent-labelled LDL. The main purpose of this study was to compare the effectiveness of these two methods to assess LDLR functionality in order to validate a functional assay to analyse LDLR mutations. LDLR activity of different variants has been studied by flow cytometry using FITC-labelled LDL and compared with studies performed previously with 125I-labeled lipoproteins. Flow cytometry results are in full agreement with the data obtained by the 125I methodology. Additionally confocal microscopy allowed the assignment of different class mutation to the variants assayed. Use of fluorescence yielded similar results than 125I-labeled lipoproteins concerning LDLR activity determination, and also allows class mutation classification. The use of FITC-labelled LDL is easier in handling and disposal, cheaper than radioactivity and can be routinely performed by any group doing LDLR functional validations.
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Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - Asier Benito-Vicente
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - Ana C. Alves
- Grupo de Investigação Cardiovascular, Unidade I&D, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa 1649-040, Portugal
- Centre for Biodiversity, Functional and Integrative Genomics, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Helena Ostolaza
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
| | - Mafalda Bourbon
- Grupo de Investigação Cardiovascular, Unidade I&D, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa 1649-040, Portugal
- Centre for Biodiversity, Functional and Integrative Genomics, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Cesar Martin
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
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Etxebarria A, Fernández-Higuero J, Benito-Vicente A, Alves A, Bourbon M, Ostolaza H, Martin C. Differences in secondary structure of p.arg1164thr and p.gln4494del, two novel ApoB-100 mutants. Atherosclerosis 2014. [DOI: 10.1016/j.atherosclerosis.2014.05.098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Benito-Vicente A, Etxebarria A, Alves A, Bourbon M, Martin C. Radioactivity assay vs. cytometry: a comparison study for ldlr functionality determination. Atherosclerosis 2014. [DOI: 10.1016/j.atherosclerosis.2014.05.514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Benito-Vicente A, Etxebarria A, Palacios L, Stef M, Ostolaza H, Martin C. Role of type class defect on ldl receptor activity. Atherosclerosis 2014. [DOI: 10.1016/j.atherosclerosis.2014.05.513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Ostolaza H, Uribe KB, Martin C, Etxebarria A, Gonzalez-Bullon D. Ca2+ Influx and Tyr Kinases Trigger Bordetella Cyaa Endocytosis. Cell Physiology and Expression of the CD11B/CD18 Integrin, Major Determinants of the Entry Route. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Alves AC, Etxebarria A, Soutar AK, Martin C, Bourbon M. Novel functional APOB mutations outside LDL-binding region causing familial hypercholesterolaemia. Hum Mol Genet 2013; 23:1817-28. [DOI: 10.1093/hmg/ddt573] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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20
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Uribe KB, Martín C, Etxebarria A, González-Bullón D, Gómez-Bilbao G, Ostolaza H. Ca2+ influx and tyrosine kinases trigger Bordetella adenylate cyclase toxin (ACT) endocytosis. Cell physiology and expression of the CD11b/CD18 integrin major determinants of the entry route. PLoS One 2013; 8:e74248. [PMID: 24058533 PMCID: PMC3772820 DOI: 10.1371/journal.pone.0074248] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/31/2013] [Indexed: 12/12/2022] Open
Abstract
Humans infected with Bordetella pertussis, the whooping cough bacterium, show evidences of impaired host defenses. This pathogenic bacterium produces a unique adenylate cyclase toxin (ACT) which enters human phagocytes and catalyzes the unregulated formation of cAMP, hampering important bactericidal functions of these immune cells that eventually cause cell death by apoptosis and/or necrosis. Additionally, ACT permeabilizes cells through pore formation in the target cell membrane. Recently, we demonstrated that ACT is internalised into macrophages together with other membrane components, such as the integrin CD11b/CD18 (CR3), its receptor in these immune cells, and GM1. The goal of this study was to determine whether ACT uptake is restricted to receptor-bearing macrophages or on the contrary may also take place into cells devoid of receptor and gain more insights on the signalling involved. Here, we show that ACT is rapidly eliminated from the cell membrane of either CR3-positive as negative cells, though through different entry routes, which depends in part, on the target cell physiology and characteristics. ACT-induced Ca(2+) influx and activation of non-receptor Tyr kinases into the target cell appear to be common master denominators in the different endocytic strategies activated by this toxin. Very importantly, we show that, upon incubation with ACT, target cells are capable of repairing the cell membrane, which suggests the mounting of an anti-toxin cell repair-response, very likely involving the toxin elimination from the cell surface.
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Affiliation(s)
- Kepa B. Uribe
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
| | - César Martín
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
| | - Aitor Etxebarria
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
| | - David González-Bullón
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
| | - Geraxane Gómez-Bilbao
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
| | - Helena Ostolaza
- Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, UPV/EHU, Bilbao, Spain
- * E-mail:
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Uribe KB, Etxebarria A, Martín C, Ostolaza H. Calpain-Mediated Processing of Adenylate Cyclase Toxin Generates a Cytosolic Soluble Catalytically Active N-Terminal Domain. PLoS One 2013; 8:e67648. [PMID: 23840759 PMCID: PMC3694075 DOI: 10.1371/journal.pone.0067648] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/21/2013] [Indexed: 11/17/2022] Open
Abstract
Bordetella pertussis, the whooping cough pathogen, secretes several virulence factors among which adenylate cyclase toxin (ACT) is essential for establishment of the disease in the respiratory tract. ACT weakens host defenses by suppressing important bactericidal activities of the phagocytic cells. Up to now, it was believed that cell intoxication by ACT was a consequence of the accumulation of abnormally high levels of cAMP, generated exclusively beneath the host plasma membrane by the toxin N-terminal catalytic adenylate cyclase (AC) domain, upon its direct translocation across the lipid bilayer. Here we show that host calpain, a calcium-dependent Cys-protease, is activated into the phagocytes by a toxin-triggered calcium rise, resulting in the proteolytic cleavage of the toxin N-terminal domain that releases a catalytically active "soluble AC". The calpain-mediated ACT processing allows trafficking of the "soluble AC" domain into subcellular organella. At least two strategic advantages arise from this singular toxin cleavage, enhancing the specificity of action, and simultaneously preventing an indiscriminate activation of cAMP effectors throughout the cell. The present study provides novel insights into the toxin mechanism of action, as the calpain-mediated toxin processing would confer ACT the capacity for a space- and time-coordinated production of different cAMP "pools", which would play different roles in the cell pathophysiology.
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Affiliation(s)
- Kepa B Uribe
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco UPV/EHU, Bilbao, Spain
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Etxebarria A, Palacios L, Stef M, Tejedor D, Uribe KB, Oleaga A, Irigoyen L, Torres B, Ostolaza H, Martin C. Functional characterization of splicing and ligand-binding domain variants in the LDL receptor. Hum Mutat 2011; 33:232-43. [PMID: 21990180 DOI: 10.1002/humu.21630] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/26/2011] [Indexed: 12/11/2022]
Abstract
Familial hypercholesterolemia (FH) is an autosomal dominant disorder mostly caused by mutations in the LDLR gene. Although the detection of functional mutations in the LDLR gene provides an unequivocal diagnosis of the FH condition, there are many variants whose pathogenicity is still unknown. The aims of this study were to set up a rapid method to determine the effect of LDLR mutations, thereby providing an accurate diagnosis of FH, and to functionally characterize six LDLR mutations detected at high frequency by the LIPOchip(®) platform (Progenika Biopharma, Spain) in the Spanish population. LDLR expression and activity were analyzed by one-single-step flow cytometry assay and confocal microscopy. Splicing effects were determined by sequencing reverse transcription polymerase chain reaction products. The analysis of three heterozygous variants with a single point mutation within the low-density lipoprotein binding domain allowed us to classify the c.806G>A variant as nonpathogenic, and c.862G>A and c.895G>A variants as causative of FH. The results obtained for three variants affecting donor splice sites of the LDLR mRNA, c.313+2dupT, c.1186+5G>A, and c.1845+1G>C, demonstrated that these mutations are pathogenic. These results expand our knowledge of mutations responsible for FH, providing an accurate diagnosis and leading to early treatment to reduce the risk of premature cardiovascular events.
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Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
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Etxebarria A, Palacios L, Stef M, Tejedor D, Oleaga A, Irigoyen L, Torres B, Ostolaza H, Martin C. 845 FLOW CYTOMETRY-BASED FUNCTIONAL VALIDATION OF LDLR MUTATIONS FOR AN ACCURATE DIAGNOSIS OF FAMILIAL HYPERCHOLESTEROLEMIA. ATHEROSCLEROSIS SUPP 2011. [DOI: 10.1016/s1567-5688(11)70846-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Etxebarria A, Terrones O, Yamaguchi H, Landajuela A, Landeta O, Antonsson B, Wang HG, Basañez G. Endophilin B1/Bif-1 stimulates BAX activation independently from its capacity to produce large scale membrane morphological rearrangements. J Biol Chem 2008; 284:4200-12. [PMID: 19074440 DOI: 10.1074/jbc.m808050200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Endophilin B1/BAX-interacting factor 1 (Bif-1) is a protein that cooperates with dynamin-like protein 1 (DLP1/Drp1) to maintain normal mitochondrial outer membrane (MOM) dynamics in healthy cells and also contributes to BAX-driven MOM permeabilization (MOMP), the irreversible commitment point to cell death for the majority of apoptotic stimuli. However, despite its importance, exactly how Bif-1 fulfils its proapoptotic role is unknown. Here, we demonstrate that the stimulatory effect of Bif-1 on BAX-driven MOMP and on BAX conformational activation observed in intact cells during apoptosis can be recapitulated in a simplified system consisting of purified proteins and MOM-like liposomes. In this reconstituted model system the N-BAR domain of Bif-1 reproduced the stimulatory effect of Bif-1 on functional BAX activation. This process was dependent on physical interaction between Bif-1 N-BAR and BAX as well as on the presence of the mitochondrion-specific lipid cardiolipin. Despite that Bif-1 N-BAR produced large scale morphological rearrangements in MOM-like liposomes, this phenomenon could be separated from functional BAX activation. Furthermore, DLP1 also caused global morphological changes in MOM-like liposomes, but DLP1 did not stimulate BAX-permeabilizing function in the absence or presence of Bif-1. Taken together, our findings not only provide direct evidence for a functional interplay between Bif-1, BAX, and cardiolipin during MOMP but also add significantly to the growing body of evidence indicating that components of the mitochondrial morphogenesis machinery possess proapoptotic functions that are independent from their recognized roles in normal mitochondrial dynamics.
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Affiliation(s)
- Aitor Etxebarria
- Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Cientificas, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, 48080 Bilbao, Spain
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Terrones O, Etxebarria A, Landajuela A, Landeta O, Antonsson B, Basañez G. BIM and tBID Are Not Mechanistically Equivalent When Assisting BAX to Permeabilize Bilayer Membranes. J Biol Chem 2008; 283:7790-803. [DOI: 10.1074/jbc.m708814200] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Polster BM, Basañez G, Etxebarria A, Hardwick JM, Nicholls DG. Calpain I induces cleavage and release of apoptosis-inducing factor from isolated mitochondria. J Biol Chem 2005; 280:6447-54. [PMID: 15590628 DOI: 10.1074/jbc.m413269200] [Citation(s) in RCA: 309] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The translocation of apoptosis-inducing factor (AIF) from mitochondria to the nucleus has been implicated in the mechanism of glutamate excitotoxicity in cortical neurons and has been observed in vivo following acute rodent brain injuries. However, the mechanism and time course of AIF redistribution to the nucleus is highly controversial. Because elevated intracellular calcium is one of the most ubiquitous features of neuronal cell death, this study tested the hypothesis that cleavage of AIF by the calcium-activated protease calpain mediates its release from mitochondria. Both precursor and mature forms of recombinant AIF were cleaved near the amino terminus by calpain I in vitro. Mitochondrial outer membrane permeabilization by truncated Bid induced cytochrome c release from isolated liver or brain mitochondria but only induced AIF release in the presence of active calpain. Enzymatic inhibition of calpain by calpeptin precluded AIF release, demonstrating that proteolytic activity was required for release. Calpeptin and the mitochondrial permeability transition pore antagonist cyclosporin A also inhibited calcium-induced AIF release from mouse liver mitochondria, implicating the involvement of an endogenous mitochondrial calpain in release of AIF during permeability transition. Cleavage of AIF directly decreased its association with pure lipid vesicles of mitochondrial inner membrane composition. Taken together, these results define a novel mechanism of AIF release involving calpain processing and identify a potential molecular checkpoint for cytoprotective interventions.
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Affiliation(s)
- Brian M Polster
- The Buck Institute for Age Research, Novato, California 94945, USA.
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