RESUMEN
Prostate-specific membrane antigen (PSMA) is a transmembrane protein highly expressed in advanced and metastatic prostate cancers. The pathologic consequence of elevated PSMA expression in not known. Here, we report that PSMA is localized to a membrane compartment in the vicinity of mitotic spindle poles and associates with the anaphase-promoting complex (APC). PSMA-expressing cells prematurely degrade cyclin B and exit mitosis due to increased APC activity and incomplete inactivation of APC by the spindle assembly checkpoint. Further, expression of PSMA in a karyotypically stable cell line induces aneuploidy. Thus, these findings provide the first evidence that PSMA has a causal role in the induction of aneuploidy and might play an etiologic role in the progression of prostate cancer.
Asunto(s)
Inestabilidad Cromosómica , Antígeno Prostático Específico/metabolismo , Complejos de Ubiquitina-Proteína Ligasa/metabolismo , Ciclosoma-Complejo Promotor de la Anafase , Animales , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Centrosoma/efectos de los fármacos , Centrosoma/ultraestructura , Inestabilidad Cromosómica/efectos de los fármacos , Ciclina B/metabolismo , Ciclina B1 , Perros , Humanos , Nocodazol/farmacología , Antígeno Prostático Específico/ultraestructura , Unión Proteica/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , Huso Acromático/metabolismoRESUMEN
MAD2 is a key component of the spindle checkpoint that delays the onset of anaphase until all the kinetochores are attached to the spindle. It binds to human p55CDC and prevents it from promoting destruction of an anaphase inhibitor, securin. Here we report the characterization of a novel MAD2-binding protein, CMT2. Upon the completion of spindle attachment, formation of the CMT2-MAD2 complex coincides with dissociation of the p55CDC-MAD2 complex. Overexpression of CMT2 in cells arrested by the spindle checkpoint causes premature destruction of securin and allows exit from mitosis without chromosome segregation. Depletion of CMT2 induces cell death following a transient delay in the onset of anaphase. These results indicate that CMT2 interacts with the spindle checkpoint and coordinates cell cycle events in late mitosis.
Asunto(s)
Proteínas de Unión al Calcio/metabolismo , Proteínas Portadoras/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas Fúngicas/metabolismo , Mitosis/fisiología , Proteínas Adaptadoras Transductoras de Señales , Secuencia de Aminoácidos , Animales , Proteínas Portadoras/genética , Proteínas Cdc20 , Ciclo Celular/fisiología , Proteínas de Ciclo Celular/genética , Células HeLa , Humanos , Proteínas Mad2 , Ratones , Datos de Secuencia Molecular , Proteínas Nucleares , Proteínas/metabolismo , Alineación de Secuencia , Huso Acromático/metabolismoRESUMEN
Cdc20 is a substrate adaptor and activator of the anaphase-promoting complex/cyclosome (APC/C), the E3 ubiquitin ligase whose activity is required for anaphase onset and exit from mitosis. A green fluorescent protein derivative, Cdc20-GFP, bound to centrosomes throughout the cell cycle and to kinetochores from late prophase to late telophase. We mapped distinct domains of Cdc20 that are required for association with kinetochores and centrosomes. FRAP measurements revealed extremely rapid dynamics at the kinetochores (t1/2 = 5.1 s) and spindle poles (t1/2 = 4.7 s). This rapid turnover is independent of microtubules. Rapid transit of Cdc20 through kinetochores may ensure that spindle checkpoint signaling at unattached/relaxed kinetochores can continuously inhibit APC/CCdc20 targeting of anaphase inhibitors (securins) throughout the cell until all the chromosomes are properly attached to the mitotic spindle.