RESUMO
Dysfunction of cellular homeostasis can lead to misfolding of proteins thus acquiring conformations prone to polymerization into pathological aggregates. This process is associated with several disorders, including neurodegenerative diseases, such as Parkinson's disease (PD), and endoplasmic reticulum storage disorders (ERSDs), like alpha-1-antitrypsin deficiency (AATD) and hereditary hypofibrinogenemia with hepatic storage (HHHS). Given the shared pathophysiological mechanisms involved in such conditions, it is necessary to deepen our understanding of the basic principles of misfolding and aggregation akin to these diseases which, although heterogeneous in symptomatology, present similarities that could lead to potential mutual treatments. Here, we review: (i) the pathological bases leading to misfolding and aggregation of proteins involved in PD, AATD, and HHHS: alpha-synuclein, alpha-1-antitrypsin, and fibrinogen, respectively, (ii) the evidence linking each protein aggregation to the stress mechanisms occurring in the endoplasmic reticulum (ER) of each pathology, (iii) a comparison of the mechanisms related to dysfunction of proteostasis and regulation of homeostasis between the diseases (such as the unfolded protein response and/or autophagy), (iv) and clinical perspectives regarding possible common treatments focused on improving the defensive responses to protein aggregation for diseases as different as PD, and ERSDs.
Assuntos
Afibrinogenemia/genética , Fibrinogênio/química , Doença de Parkinson/genética , Deficiência de alfa 1-Antitripsina/genética , alfa 1-Antitripsina/química , alfa-Sinucleína/química , Afibrinogenemia/tratamento farmacológico , Afibrinogenemia/metabolismo , Afibrinogenemia/patologia , Animais , Autofagia/efeitos dos fármacos , Autofagia/genética , Coagulantes/uso terapêutico , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/patologia , Fibrinogênio/genética , Fibrinogênio/metabolismo , Regulação da Expressão Gênica , Humanos , Fígado/metabolismo , Fígado/patologia , Fármacos Neuroprotetores/uso terapêutico , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Inibidores de Proteases/uso terapêutico , Agregados Proteicos/efeitos dos fármacos , Dobramento de Proteína/efeitos dos fármacos , Resposta a Proteínas não Dobradas/efeitos dos fármacos , alfa 1-Antitripsina/genética , alfa 1-Antitripsina/metabolismo , Deficiência de alfa 1-Antitripsina/tratamento farmacológico , Deficiência de alfa 1-Antitripsina/metabolismo , Deficiência de alfa 1-Antitripsina/patologia , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismoRESUMO
Turbidity analysis is widely used as a quantitative technique in hereditary dysfibrinogenemia. We aimed to compare several coagulation triggers in hereditary dysfibrinogenemia and control plasmas. We included 20 patients with hereditary dysfibrinogenemia, 19 with hotspot mutations Aα Arg35His (nâ=â9), Aα Arg35Cys (nâ=â2), γ Arg301His (nâ=â6), γ Arg301Cys (nâ=â2), and one with Aα Phe27Tyr, and a commercial pooled normal plasma. Fibrin polymerization was activated by bovine or human thrombin or tissue factor (TF), in the presence or absence of tissue type plasminogen activator. The lag time (min), slope (mOD/s), maximum absorbance (MaxAbs, mOD), and area under the curve (AUCp, ODâs) were calculated from the fibrin polymerization curves and the time for 50% clot degradation (T50, min), AUCf (ODâs) and the overall fibrinolytic potential from fibrinolysis curves. The lag time was significantly shorter and AUC increased in Aα Arg35His patients with bovine thrombin as compared with human thrombin. The MaxAbs and AUCp were significantly higher in γArg301His patients with bovine thrombin compared with human thrombin. Fibrin polymerization parameters of patients' samples were closer to those of control when assessed with TF compared with both human and bovine thrombin. T50 and overall fibrinolytic potential were similar in all samples regardless of the coagulation trigger used, however, with TF the AUCf of Aα Arg35His and γ Arg301His groups were significantly decreased compared with control. Bovine and human thrombin cannot be used equally for studying fibrin polymerization in hotspot hereditary dysfibrinogenemia or control plasmas.
Assuntos
Afibrinogenemia/sangue , Coagulação Sanguínea , Adolescente , Adulto , Afibrinogenemia/genética , Animais , Testes de Coagulação Sanguínea/métodos , Bovinos , Feminino , Fibrinogênio/genética , Humanos , Indicadores e Reagentes , Masculino , Pessoa de Meia-Idade , Mutação , Adulto JovemRESUMO
: Hypodysfibrinogenemia and protein C deficiency are coagulopathies and in this report, we describe a young patient with both defects confirmed by molecular genetic tests. The patient was a 24-year-old woman referred for recurrent thrombophlebitis and finally deep venous thrombosis. Routine coagulation studies revealed mild decrease of protein C (0.49âIU, reference values 0.7-1.40âIU) and hypodysfibrinogenemia (0.88âg/l and 1.83âg/l for activity and antigen, respectively, reference values 2.0-4.0âg/l). Direct sequencing analyses were performed on FGA, FGB, and FGG genes to confirm hypodysfibrinogenemia and on the protein C gene to confirm protein C deficiency. As a result, the patient was shown to be heterozygous p.Ala82Gly in the FGG gene (Fibrinogen Dunedin) and for compound heterozygous missense mutation in protein C gene. To our knowledge, this is the first report on a case of combined dysfibrinogenemia and protein C deficiency confirmed by molecular genetic tests.
Assuntos
Fibrinogênio/genética , Proteína C/genética , Tromboflebite/genética , Afibrinogenemia/genética , Argentina , Feminino , Heterozigoto , Humanos , Mutação de Sentido Incorreto , Recidiva , Análise de Sequência de DNA , Trombose Venosa/genética , Adulto JovemRESUMO
Identifying coagulation abnormalities in patients with combined bleeding and thrombosis history is clinically challenging. Our goal was to probe the complexity of dysregulated coagulation in humans by characterizing pathophysiologic mechanisms in a patient with both bleeding and thrombosis. The patient is a 56-year-old female with a history of haematomas, poor wound healing, and thrombosis (retinal artery occlusion and transient cerebral ischaemia). She had a normal activated partial thromboplastin time, prolonged thrombin and reptilase times, and decreased functional and antigenic fibrinogen levels, and was initially diagnosed with hypodysfibrinogenaemia. This diagnosis was supported by DNA analysis revealing a novel FGB mutation (c.656A>G) predicting a Q189R mutation in the mature chain that was present in the heterozygote state. However, turbidity analysis showed that purified fibrinogen polymerisation and degradation were indistinguishable from normal, and Bß chain subpopulations appeared normal by two-dimensional difference in-gel electrophoresis, indicating the mutated chain was not secreted. Interestingly, plasma thrombin generation testing revealed the patient's thrombin generation was higher than normal and could be attributed to elevated levels of factor VIII (FVIII, 163-225%). Accordingly, in an arterial injury model, hypofibrinogenaemic mice (Fgn(+/-)) infused with factor VIII demonstrated significantly shorter vessel occlusion times than saline-infused Fgn(+/-) mice. Together, these data associate the complex bleeding and thrombotic presentation with combined hypofibrinogenaemia plus plasma hypercoagulability. These findings suggest previous cases in which fibrinogen abnormalities have been associated with thrombosis may also be complicated by co-existing plasma hypercoagulability and illustrate the importance of "global" coagulation testing in patients with compound presentations.
Assuntos
Afibrinogenemia/genética , Fator VIII/análise , Fibrinogênio/genética , Transtornos Hemorrágicos/genética , Mutação de Sentido Incorreto , Mutação Puntual , Trombina/biossíntese , Trombofilia/genética , Afibrinogenemia/sangue , Afibrinogenemia/complicações , Substituição de Aminoácidos , Animais , Biopolímeros , Testes de Coagulação Sanguínea , Trombose das Artérias Carótidas/sangue , Trombose das Artérias Carótidas/genética , Modelos Animais de Doenças , Eletroforese em Gel Bidimensional , Fator VIII/toxicidade , Feminino , Fibrinogênio/química , Fibrinólise , Deleção de Genes , Transtornos Hemorrágicos/sangue , Transtornos Hemorrágicos/etiologia , Heterozigoto , Humanos , Ataque Isquêmico Transitório/etiologia , Camundongos , Camundongos Mutantes , Pessoa de Meia-Idade , Oclusão da Artéria Retiniana/etiologia , Trombofilia/sangue , Trombofilia/etiologiaAssuntos
Afibrinogenemia/genética , Fibrinogênios Anormais/genética , Afibrinogenemia/sangue , Substituição de Aminoácidos , Argentina , Biopolímeros/química , Biopolímeros/genética , Testes de Coagulação Sanguínea , Feminino , Fibrinogênios Anormais/química , Humanos , Pessoa de Meia-Idade , Mutação PuntualRESUMO
We report hypofibrinogenemia and massive hepatic storage of fibrinogen in a child with cryptogenic chronic liver disease. Fibrinogen gene analysis revealed a de novo Aguadilla (c.1201C>T; p.Arg375Trp) mutation. This mutation should be considered in childhood hypofibrinogenemia associated with chronic liver disease.
Assuntos
Afibrinogenemia/genética , Fibrinogênio/genética , Fibrinogênio/metabolismo , Fígado/metabolismo , Mutação , Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Criança , Consanguinidade , Humanos , Masculino , Tempo de Tromboplastina Parcial , Tempo de Protrombina , gama-Glutamiltransferase/sangueRESUMO
The complement system participates in both innate and acquired immune responses. Deficiencies in any of the protein components of this system are generally uncommon and require specialized services for diagnosis. Consequently, complement deficiencies are clinically underscored and may be more common than is normally estimated. As C3 is the major complement component and participates in all three pathways of activation, it is fundamental to understand all the clinical consequences observed in patients for which this protein is below normal concentration or absent in the serum. C3 deficiencies are generally associated with higher susceptibility to severe infections and in some cases with autoimmune diseases such as systemic lupus erythematosus. Here, we review the main clinical aspects and the molecular basis of primary C3 deficiency as well as the mutations in the regulatory proteins factor I and factor H that result in secondary C3 deficiencies. We also discuss the use of animal models to study these deficiencies.
Assuntos
Afibrinogenemia/genética , Complemento C3/deficiência , Fator H do Complemento/deficiência , Animais , Doenças Autoimunes/complicações , Ativação do Complemento , Complemento C3/genética , Fator H do Complemento/genética , Fibrinogênio/genética , Humanos , Síndromes de Imunodeficiência/complicações , Síndromes de Imunodeficiência/genética , Infecções/imunologia , Modelos AnimaisRESUMO
We have studied the molecular basis of factor I (fI) deficiency in two Brazilian sisters from a consanguineous family. By reverse transcription-polymerase chain reaction we observed that all fI cDNA amplified products from one sister had the same size as those of normal cDNA, however, they were significantly less intense. Sequencing analysis of subcloned cDNA revealed a dinucleotide insertion (AT) between positions 1204 and 1205 in the 11th exon that creates a stop codon 13 bp downstream of the insertion site. Genomic DNA sequencing and heteroduplex analysis confirmed that both probands are homozygous for this mutation, whereas their parents are heterozygous. The stop codon and the diminished amounts of fI cDNA could indicate increased fI mRNA instability, perhaps due to a mechanism of nonsense-mediated decay. This hypothesis is consistent with our observation that treatment with the translation inhibitor cycloheximide stabilized fI mRNA expression in proband's fibroblasts.
Assuntos
Afibrinogenemia/genética , Códon sem Sentido/genética , Fibrinogênio/genética , Homozigoto , Adulto , Sequência de Bases , Pré-Escolar , DNA Complementar/genética , Feminino , Humanos , Dados de Sequência Molecular , Linhagem , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Congenital afibrinogenemia is a rare coagulation disorder with autosomal recessive inheritance, characterized by the complete absence or extremely reduced levels of fibrinogen in patients' plasma and platelets. Eight afibrinogenemic probands, with very low plasma levels of immunoreactive fibrinogen were studied. Sequencing of the fibrinogen gene cluster of each proband disclosed 4 novel point mutations (1914C>G, 1193G>T, 1215delT, and 3075C>T) and 1 already reported (3192C>T). All mutations, localized within the first 4 exons of the A alpha-chain gene, were null mutations predicted to produce severely truncated A alpha-chains because of the presence of premature termination codons. Since premature termination codons are frequently known to affect the metabolism of the corresponding messenger RNAs (mRNAs), the degree of stability of each mutant mRNA was investigated. Cotransfection experiments with plasmids expressing the wild type and each of the mutant A alpha-chains, followed by RNA extraction and semiquantitative reverse-transcriptase-polymerase chain reaction analysis, demonstrated that all the identified null mutations escaped nonsense-mediated mRNA decay. Moreover, ex vivo analysis at the protein level demonstrated that the presence of each mutation was sufficient to abolish fibrinogen secretion.