RESUMO
Human Cep57 is a coiled-coil scaffold at the pericentriolar matrix (PCM), controlling centriole duplication and centrosome maturation for faithful cell division. Genetic truncation mutations of Cep57 are associated with the mosaic-variegated aneuploidy (MVA) syndrome. During interphase, Cep57 forms a complex with Cep63 and Cep152, serving as regulators for centrosome maturation. However, the molecular interplay of Cep57 with these essential scaffolding proteins remains unclear. Here, we demonstrate that Cep57 undergoes liquid-liquid phase separation (LLPS) driven by three critical domains (NTD, CTD, and polybasic LMN). In vitro Cep57 condensates catalyze microtubule nucleation via the LMN motif-mediated tubulin concentration. In cells, the LMN motif is required for centrosomal microtubule aster formation. Moreover, Cep63 restricts Cep57 assembly, expansion, and microtubule polymerization activity. Overexpression of competitive constructs for multivalent interactions, including an MVA mutation, leads to excessive centrosome duplication. In Cep57-depleted cells, self-assembly mutants failed to rescue centriole disengagement and PCM disorganization. Thus, Cep57's multivalent interactions are pivotal for maintaining the accurate structural and functional integrity of human centrosomes.
Assuntos
Proteínas de Ciclo Celular , Centríolos , Centrossomo , Microtúbulos , Humanos , Centrossomo/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Microtúbulos/metabolismo , Centríolos/metabolismo , Centríolos/genética , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/genética , Mutação , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Associadas aos Microtúbulos/genética , Ligação Proteica , Proteínas NuclearesRESUMO
OBJECTIVES: The aim of the study was to validate the use of the ABCD(2) score for the prediction of stroke after transient ischemic attack (TIA) in patients presenting to the emergency department (ED). The ABCD(2) scoring is based on 5 factors as follows: age of at least 60 years; blood pressure of at least 140/90 mm Hg; clinical features such as unilateral weakness and speech impairment alone; duration of at least 60 minutes or 10 to 59 minutes; and diabetes. METHODS: The authors conducted a retrospective observational study of all patients presented to the ED for TIA, as diagnosed by the attending emergency physicians, for a 2-year period. Sensitivity, specificity, and negative predictive value (NPV) were calculated for risk of stroke at 2, 7, 30, and 90 days after presentation. RESULTS: From January 1, 2005, to December 31, 2006, there were 470 patients diagnosed with TIA at the ED. Mean age was 61.0 years (SD, 13.2), with 63.3% males. Age of at least 60 years, unilateral weakness, and duration of at least 60 minutes were found to be significant predictors of stroke at 2 days. An admission rule based on an ABCD(2) score of at least 4 showed sensitivity of 86.4% and NPV of 91.7% for stroke at 7 days. Admission based on a score of at least 3 showed sensitivity of 96.6% and NPV of 96.1%. Admission rate was 69.1% and. 83.6%, respectively. CONCLUSION: The ABCD(2) rule showed good sensitivity and NPV for stroke at 7 days. However, NPV was not 100%, and there would still be patients being discharged from the ED and returning with a stroke if this cutoff was implemented in our setting.
