Bleeding tendency and impaired platelet function in a patient carrying a heterozygous mutation in the thromboxane A2 receptor.
J Thromb Haemost
; 9(5): 1040-8, 2011 May.
Article
en En
| MEDLINE
| ID: mdl-21342433
BACKGROUND: Thromboxane A(2) receptor (TXA(2)R) abnormality appears to dominantly disturb platelet function. OBJECTIVES: To reveal a molecular genetic defect in a patient with TXA(2)R abnormality and investigate the mechanism for the impaired response to TXA(2). PATIENT: The proband (OSP-2, PT) was a 7-year-old Japanese girl, suffering from repeated mucocutaneous bleeding. METHODS AND RESULTS: U46619 (2.5 and 10 µm)-induced platelet aggregation was remarkably impaired in the proband and her father. Immunoblots showed that TXA(2)R expression levels in their platelets were approximately 50% of controls, and nucleotide sequence analysis revealed that they were heterozygous for a novel mutation, c.167dupG in the TXA(2)R cDNA. Expression studies using Chinese hamster ovary (CHO) cells indicated that the mutation is responsible for the expression defect in TXA(2)R. We then examined α(IIb)ß(3) activation by employing an initial velocity analysis and revealed that U46619 failed to induce a sustained α(IIb)ß(3) and Rap1B activation in the proband. In addition, platelet secretion as monitored by P-selectin expression was markedly impaired in response to U46619 but not to ADP. The interaction between secreted ADP and P2Y(12) has been shown to play a critical role in the sustained α(IIb)ß(3) activation (Kamae et al. J Thromb Haemost 2006; 4: 1379). As expected, small amounts of exogenous ADP (0.5 µm) partially restored the sustained α(IIb)ß(3) activation induced by U46619. CONCLUSION: Our present data strongly suggest that the impaired platelet activation in response to U46619 in the heterozygous subject for the TXA(2)R mutation is, at least in part, as a result of the decrease in ADP secretion.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Receptores de Tromboxano A2 y Prostaglandina H2
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Mutación
Límite:
Animals
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Child
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Female
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Humans
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Male
Idioma:
En
Revista:
J Thromb Haemost
Asunto de la revista:
HEMATOLOGIA
Año:
2011
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
Reino Unido