RESUMO
Rich1, a previously identified Rho GTPase-activating protein (RhoGAP), was found to have close relationship with Rho GTPase family members in multiple cellular processes in nervous cells and platelets. But the exact role of Rich1 in epithelial cells remains obscure. The present investigation demonstrated that up-regulation of Rich1 could cause S-phase arrest, proliferation inhibition and adhesion decline with F-actin amount decrease in epithelial cells. Further exploration in hepatocyte HL7702 revealed that overexpression of Rich1 could greatly elevate the intrinsic GTPase activities on both of CDC42 and RAC1 by stimulating GTP hydrolysis, which consequently attenuated the activities of the Rho proteins and the phosphorylation level of those in PAK1-ERK1/2 signaling cascade. While the GAP domain deleted Rich1 variant or silence of endogenous Rich1 expression could not result in any of the biological effects. It is indicated that Rich1, completely different from in other types of cells, might act as a crucial upstream negative regulator via its GAP domain in control of epithelial cell cycle, proliferation and focal adhesion through CDC42/RAC1-PAK1-ERK1/2 signaling pathway and F-actin dynamics.
Assuntos
Ciclo Celular/fisiologia , Células Epiteliais/metabolismo , Proteínas Ativadoras de GTPase/metabolismo , Sistema de Sinalização das MAP Quinases/fisiologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo , Quinases Ativadas por p21/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Adesão Celular/fisiologia , Células Epiteliais/citologia , Proteínas Ativadoras de GTPase/genética , Humanos , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína cdc42 de Ligação ao GTP/genética , Quinases Ativadas por p21/genética , Proteínas rac1 de Ligação ao GTP/genéticaRESUMO
Uptake 14CO2 from air and accumulation of 14C in the Chinese cabbage were studied by using the isotope-tracer techniques in order to get a better understanding of the environmental behavior of 14CO. The results show that the 14CO2, which was uptaken from the air by the leaf photosynthesis, would be sent to the other part of the Chinese cabbage and form a accumulating trend. The specific activity of 14C in every tissue increases linearly with time, and the increasing rate is in the range of 95.3 - 270.2 Bq/(g x d). The order of rate in tissues is as below: cabbage heart > leaf blade > leaf stalk > basal plate > root. The Chinese cabbage has an intensive concentration of 14CO2, and the concentration factor values increase rapidly with time. The concentration factor values in the cabbage heart reach the highest level (156.4 in 48 days) and following with the leaf blade (135.6 in 48 days). The specific activity in each part of the Chinese cabbage also increases with the introduction times of the 14CO2. Regression analysis has proved that the specific activity (C) of every part is positively correlated to the introducing times (N). Owing to its high accumulation of 14CO2, Chinese cabbage can be used as the indicator plant in the supervisor of 14CO2 air pollution.
