RESUMEN
Tyrosine phosphatases play a critical role in many cellular processes and pathogenesis, yet comprehensive analysis of their functional interacting proteins in the cell is limited. By utilizing a proteomic approach, here we present an interaction network of 81 human tyrosine phosphatases built on 1884 high-confidence interactions of which 85% are unreported. Our analysis has linked several phosphatases with new cellular processes and unveiled protein interactions genetically linked to various human diseases including cancer. We validated the functional importance of an identified interaction network by characterizing a distinct novel interaction between PTPN5 and Mob1a. PTPN5 dephosphorylates Mob1a at Y26 residue. Further, we identify that PTPN5 is required for proper midbody abscission during cytokinesis through regulation of Mob1a dephosphorylation. In conclusion, our study provides a valuable resource of tyrosine phosphatase interactions, which can be further utilized to dissect novel cellular functions of these enzymes.
Asunto(s)
Mapas de Interacción de Proteínas/fisiología , Proteínas Tirosina Fosfatasas/metabolismo , Proteómica/métodos , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Citocinesis , Humanos , Fosforilación , Mapeo de Interacción de Proteínas/métodos , Proteínas Tirosina Fosfatasas no Receptoras/metabolismoRESUMEN
Mitotic progression is regulated by co-ordinated action of several proteins and is crucial for the maintenance of genomic stability. CHFR (Check point protein with FHA and RING domains) is an E3 ubiquitin ligase and a checkpoint protein that regulates entry into mitosis. But the molecular players involved in CHFR mediated mitotic checkpoint are not completely understood. In this study, we identified TOPK/PBK, a serine/threonine kinase and PTEN, a lipid phosphatase to play an important role in CHFR mediated mitotic transitions. We demonstrated that CHFR ubiquitinates and regulates TOPK levels, which is essential for its checkpoint function. Moreover, TOPK phosphorylates and inactivates PTEN, which in turn activates Akt that leads to proper G2/M progression. Collectively, our results reveal TOPK and PTEN as new players in CHFR mediated mitotic checkpoint.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Mitosis , Proteínas de Neoplasias/metabolismo , Fosfohidrolasa PTEN/metabolismo , Células HeLa , Humanos , Puntos de Control de la Fase M del Ciclo Celular , Fosforilación , Proteínas de Unión a Poli-ADP-Ribosa , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligasas , UbiquitinaciónRESUMEN
PTEN is a well-defined tumor suppressor gene that antagonizes the PI3K/Akt pathway to regulate a multitude of cellular processes, such as survival, growth, motility, invasiveness, and angiogenesis. While the functions of PTEN have been studied extensively, the regulation of its activity during normal and disease conditions still remains incompletely understood. In this study, we identified the protein phosphatase-1 nuclear targeting subunit PNUTS (PPP1R10) as a PTEN-associated protein. PNUTS directly interacted with the lipid-binding domain (C2 domain) of PTEN and sequestered it in the nucleus. Depletion of PNUTS leads to increased apoptosis and reduced cellular proliferation in a PTEN-dependent manner. PNUTS expression was elevated in certain cancers compared with matched normal tissues. Collectively, our studies reveal PNUTS as a novel PTEN regulator and a likely oncogene.