RESUMEN
The cancer-associated, centrosomal adaptor protein TACC3 (transforming acidic coiled-coil 3) and its direct effector, the microtubule polymerase chTOG (colonic and hepatic tumor overexpressed gene), play a crucial function in centrosome-driven mitotic spindle assembly. It is unclear how TACC3 interacts with chTOG. Here, we show that the C-terminal TACC domain of TACC3 and a C-terminal fragment adjacent to the TOG domains of chTOG mediate the interaction between these two proteins. Interestingly, the TACC domain consists of two functionally distinct subdomains, CC1 (amino acids (aa) 414-530) and CC2 (aa 530-630). Whereas CC1 is responsible for the interaction with chTOG, CC2 performs an intradomain interaction with the central repeat region of TACC3, thereby masking the TACC domain before effector binding. Contrary to previous findings, our data clearly demonstrate that Aurora-A kinase does not regulate TACC3-chTOG complex formation, indicating that Aurora-A solely functions as a recruitment factor for the TACC3-chTOG complex to centrosomes and proximal mitotic spindles. We identified with CC1 and CC2, two functionally diverse modules within the TACC domain of TACC3 that modulate and mediate, respectively, TACC3 interaction with chTOG required for spindle assembly and microtubule dynamics during mitotic cell division.
Asunto(s)
Aurora Quinasa A/metabolismo , Proteínas Portadoras/metabolismo , Centrosoma/metabolismo , Proteínas Fetales/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Mitosis/fisiología , Animales , Aurora Quinasa A/genética , Proteínas Portadoras/genética , Proteínas Fetales/genética , Células HEK293 , Células HeLa , Humanos , Ratones , Proteínas Asociadas a Microtúbulos/genética , Complejos Multiproteicos/genética , Complejos Multiproteicos/metabolismo , Unión Proteica/fisiología , Estructura Terciaria de ProteínaRESUMEN
During the mitotic division cycle, cells pass through an extensive microtubule rearrangement process where microtubules forming the mitotic spindle apparatus are dynamically instable. Several centrosomal- and microtubule-associated proteins are involved in the regulation of microtubule dynamics and stability during mitosis. Here, we focus on members of the transforming acidic coiled coil (TACC) family of centrosomal adaptor proteins, in particular TACC3, in which their subcellular localization at the mitotic spindle apparatus is controlled by Aurora-A kinase-mediated phosphorylation. At the effector level, several TACC-binding partners have been identified and characterized in greater detail, in particular, the microtubule polymerase XMAP215/ch-TOG/CKAP5 and clathrin heavy chain (CHC). We summarize the recent progress in the molecular understanding of these TACC3 protein complexes, which are crucial for proper mitotic spindle assembly and dynamics to prevent faulty cell division and aneuploidy. In this regard, the (patho)biological role of TACC3 in development and cancer will be discussed.
Asunto(s)
Complejo 3 de Proteína Adaptadora/química , Centrosoma/química , Proteínas Asociadas a Microtúbulos/química , Mitosis , Complejo 3 de Proteína Adaptadora/genética , Complejo 3 de Proteína Adaptadora/fisiología , Animales , División Celular/genética , Centrosoma/patología , Centrosoma/fisiología , Humanos , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/fisiología , Mitosis/genética , Familia de Multigenes/genética , Estructura Terciaria de Proteína/genética , Huso Acromático/genéticaRESUMEN
Clathrin ensures mitotic spindle stability and efficient chromosome alignment, independently of its vesicle trafficking function. Although clathrin localizes to the mitotic spindle and kinetochore fiber microtubule bundles, the mechanisms by which clathrin stabilizes microtubules are unclear. We show that clathrin adaptor interaction sites on clathrin heavy chain (CHC) are repurposed during mitosis to directly recruit the microtubule-stabilizing protein GTSE1 to the spindle. Structural analyses reveal that these sites interact directly with clathrin-box motifs on GTSE1. Disruption of this interaction releases GTSE1 from spindles, causing defects in chromosome alignment. Surprisingly, this disruption destabilizes astral microtubules, but not kinetochore-microtubule attachments, and chromosome alignment defects are due to a failure of chromosome congression independent of kinetochore-microtubule attachment stability. GTSE1 recruited to the spindle by clathrin stabilizes microtubules by inhibiting the microtubule depolymerase MCAK. This work uncovers a novel role of clathrin adaptor-type interactions to stabilize nonkinetochore fiber microtubules to support chromosome congression, defining for the first time a repurposing of this endocytic interaction mechanism during mitosis.
Asunto(s)
Proteínas de Ciclo Celular/genética , Cadenas Pesadas de Clatrina/genética , Cinesinas/genética , Proteínas Asociadas a Microtúbulos/genética , Microtúbulos/genética , Mitosis/genética , Animales , Segregación Cromosómica/genética , Clatrina/genética , Humanos , Cinetocoros/metabolismo , Ratones , Células Madre Embrionarias de Ratones/metabolismo , Huso Acromático/genéticaRESUMEN
Altered cell division is associated with overproliferation and tumorigenesis, however, mitotic aberrations can also trigger antiproliferative responses leading to postmitotic cell cycle exit. Here, we focus on the role of the centrosome and in particular of centrosomal TACC (transforming acidic coiled coil) proteins in tumorigenesis and cellular senescence. We have complied recent evidence that inhibition or depletion of various mitotic proteins which take over key in centrosome and kinetochore integrity and mitotic checkpoint function in sufficient to activate a p53-p21(WAF) driven premature senescence phenotype. These findings have direct implications for proliferative tissue homeostasis as well as for cellular and organismal aging.