Eliane Berrou1, Frédéric Adam1, Marilyne Lebret1, Virginie Planche1, Patricia Fergelot1, Odile Issertial1, Isabelle Coupry1, Jean-Claude Bordet1, Paquita Nurden1, Dominique Bonneau1, Estelle Colin1, Cyril Goizet1, Jean-Philippe Rosa1, Marijke Bryckaert2. 1. From the INSERM UMR_S 1176, Université Paris-Sud, Université Paris-Saclay, Le Kremlin Bicêtre, France (E.B., F.A., M.L., V.P., O.I., J.-P.R., M.B.); INSERM UMR_S 1211, Université de Bordeaux, CHU Bordeaux UNIV EA 4576, Place Aurélie Raba-Léon, France (P.F., I.C., C.G.); CHU Bordeaux, Centre de Référence Anomalies du Développement Embryonnaire, Service de Génétique Médicale, Hôpital Pellegrin, Place Aurélie Raba-Léon, France (P.F., C.G.); Unité d'Hémostase Biologique, Hospices Civils de Lyon, CBE Bron, EA4609 and CIQLE-Lyon Bio Image, Université Lyon, France (J.-C.B.); Institut Hospitalo-Universitaire LIRYC PTIB, Hôpital Xavier Arnozan, av du Haut Lévêque, Pessac, France (P.N.); and Département de Biochimie et Génétique, INSERM UMR_S 1083 - CNRS 6214, CHU Angers, Angers, France (D.B., E.C.). 2. From the INSERM UMR_S 1176, Université Paris-Sud, Université Paris-Saclay, Le Kremlin Bicêtre, France (E.B., F.A., M.L., V.P., O.I., J.-P.R., M.B.); INSERM UMR_S 1211, Université de Bordeaux, CHU Bordeaux UNIV EA 4576, Place Aurélie Raba-Léon, France (P.F., I.C., C.G.); CHU Bordeaux, Centre de Référence Anomalies du Développement Embryonnaire, Service de Génétique Médicale, Hôpital Pellegrin, Place Aurélie Raba-Léon, France (P.F., C.G.); Unité d'Hémostase Biologique, Hospices Civils de Lyon, CBE Bron, EA4609 and CIQLE-Lyon Bio Image, Université Lyon, France (J.-C.B.); Institut Hospitalo-Universitaire LIRYC PTIB, Hôpital Xavier Arnozan, av du Haut Lévêque, Pessac, France (P.N.); and Département de Biochimie et Génétique, INSERM UMR_S 1083 - CNRS 6214, CHU Angers, Angers, France (D.B., E.C.). marijke.bryckaert@inserm.fr.
Abstract
OBJECTIVE: Dominant mutations of the X-linked filamin A (FLNA) gene are responsible for filaminopathies A, which are rare disorders including brain periventricular nodular heterotopia, congenital intestinal pseudo-obstruction, cardiac valves or skeleton malformations, and often macrothrombocytopenia. APPROACH AND RESULTS: We studied a male patient with periventricular nodular heterotopia and congenital intestinal pseudo-obstruction, his unique X-linked FLNA allele carrying a stop codon mutation resulting in a 100-amino acid-long FLNa C-terminal extension (NP_001447.2: p.Ter2648SerextTer101). Platelet counts were normal, with few enlarged platelets. FLNa was detectable in all platelets but at 30% of control levels. Surprisingly, all platelet functions were significantly upregulated, including platelet aggregation and secretion, as induced by ADP, collagen, or von Willebrand factor in the presence of ristocetin, as well as thrombus formation in blood flow on a collagen or on a von Willebrand factor matrix. Most importantly, patient platelets stimulated with ADP exhibited a marked increase in αIIbβ3 integrin activation and a parallel increase in talin recruitment to β3, contrasting with normal Rap1 activation. These results are consistent with the mutant FLNa affecting the last step of αIIbβ3 activation. Overexpression of mutant FLNa in the HEL megakaryocytic cell line correlated with an increase (compared with wild-type FLNa) in PMA-induced fibrinogen binding to and in talin and kindlin-3 recruitment by αIIbβ3. CONCLUSIONS: Altogether, our results are consistent with a less binding of mutant FLNa to β3 and the facilitated recruitment of talin by β3 on platelet stimulation, explaining the increased αIIbβ3 activation and the ensuing gain-of-platelet functions.
OBJECTIVE: Dominant mutations of the X-linked filamin A (FLNA) gene are responsible for filaminopathies A, which are rare disorders including brain periventricular nodular heterotopia, congenital intestinal pseudo-obstruction, cardiac valves or skeleton malformations, and often macrothrombocytopenia. APPROACH AND RESULTS: We studied a male patient with periventricular nodular heterotopia and congenital intestinal pseudo-obstruction, his unique X-linked FLNA allele carrying a stop codon mutation resulting in a 100-amino acid-long FLNa C-terminal extension (NP_001447.2: p.Ter2648SerextTer101). Platelet counts were normal, with few enlarged platelets. FLNa was detectable in all platelets but at 30% of control levels. Surprisingly, all platelet functions were significantly upregulated, including platelet aggregation and secretion, as induced by ADP, collagen, or von Willebrand factor in the presence of ristocetin, as well as thrombus formation in blood flow on a collagen or on a von Willebrand factor matrix. Most importantly, patient platelets stimulated with ADP exhibited a marked increase in αIIbβ3 integrin activation and a parallel increase in talin recruitment to β3, contrasting with normal Rap1 activation. These results are consistent with the mutant FLNa affecting the last step of αIIbβ3 activation. Overexpression of mutant FLNa in the HEL megakaryocytic cell line correlated with an increase (compared with wild-type FLNa) in PMA-induced fibrinogen binding to and in talin and kindlin-3 recruitment by αIIbβ3. CONCLUSIONS: Altogether, our results are consistent with a less binding of mutant FLNa to β3 and the facilitated recruitment of talin by β3 on platelet stimulation, explaining the increased αIIbβ3 activation and the ensuing gain-of-platelet functions.
Authors: Hong S Lu; Ann Marie Schmidt; Robert A Hegele; Nigel Mackman; Daniel J Rader; Christian Weber; Alan Daugherty Journal: Arterioscler Thromb Vasc Biol Date: 2018-10 Impact factor: 8.311
Authors: A Fernández-Marmiesse; M S Pérez-Poyato; A Fontalba; E Marco de Lucas; M T Martínez; M J Cabero Pérez; M L Couce Journal: BMC Med Genet Date: 2019-06-24 Impact factor: 2.103