RESUMO
Prolactin (PRL) stimulates the cytoskeletal re-organization and motility of breast cancer cells. During PRL receptor signaling, Vav2 becomes phosphorylated and activated, an event regulated by the serine/threonine kinase Nek3. Given the regulatory role of Vav2, the function of Nek3 in PRL-mediated motility and invasion was examined. Overexpression of Nek3 in Chinese hamster ovary transfectants potentiated cytoskeletal re-organization in response to PRL. In contrast, downregulation of Nek3 expression by small-interfering RNA (siRNA) attenuated PRL-mediated cytoskeletal reorganization, activation of GTPase Rac1, cell migration and invasion of T47D cells. In addition, PRL stimulation induced an interaction between Nek3 and paxillin and significantly increased paxillin serine phosphorylation, whereas Nek3 siRNA-transfected cells showed a marked reduction in paxillin phosphorylation. Analysis of breast tissue microarrays also demonstrated a significant up-regulation of Nek3 expression in malignant versus normal specimens. These data suggest that Nek3 contributes to PRL-mediated breast cancer motility through mechanisms involving Rac1 activation and paxillin phosphorylation.
Assuntos
Neoplasias da Mama/patologia , Movimento Celular , Citoesqueleto/ultraestrutura , Proteínas Serina-Treonina Quinases/fisiologia , Animais , Neoplasias da Mama/enzimologia , Células CHO , Linhagem Celular Tumoral , Cricetinae , Cricetulus , Citoesqueleto/efeitos dos fármacos , Feminino , Humanos , Quinases Relacionadas a NIMA , Invasividade Neoplásica , Paxilina/metabolismo , Fosforilação , Prolactina/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas c-vav/metabolismo , RNA Interferente Pequeno/farmacologia , Serina/metabolismo , Transfecção , Proteínas rac1 de Ligação ao GTP/metabolismoAssuntos
Artrite/fisiopatologia , Lipoxinas/fisiologia , Artrite/imunologia , Citocinas/biossíntese , Humanos , NF-kappa B/metabolismo , Receptores de Lipoxinas/metabolismo , Transdução de Sinais , Membrana Sinovial/fisiopatologia , Fator de Transcrição AP-1/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
In Eubacteria, de novo translation of some internal cistrons may be inefficient or impossible unless the 5' neighboring cistron is also translated (translational coupling). Translation reinitiation is an extreme case of translational coupling in which translation of a message depends entirely on the presence of a nearby terminating ribosome. In this work, the characteristics of mRNA cis-elements inducing the reinitiation process in Escherichia coli have been investigated using a combinatorial approach. A number of novel translational reinitiation sequences (TRSs) were thus identified, which show a wide range of reinitiation activities fully dependent on a translational coupling event and unrelated to the presence/absence of secondary structure or mRNA stability. Moreover, some of the isolated TRSs are similar to intercistronic sequences present in the E. coli genome.
