Proteasome Mediated Degradation Of Small Gtpase Rif And Lncrna Exprssion Files In Gastric Cancer Cells

The small Rho GTPase Rif controls essential aspects of cell biology and is cycled between an inactive GDP-bound form and an active GTP-bound form.In recent years,the study found that the activity of small Rho GTPases can also be regulated by ubiquitylation-mediated proteasome degradation.However,the ubiquitylation regulation of Rif has not been explored before.Here,we showed that Rif interacted with SCF complex scaffold protein Cullinl in a nucleotide-independent manner,and co-expression of Rif relocated SCF regulation protein NEDD8 from nucleus to cytoplasm.Also,we found that Rif is a short half-time protein and its expression level was downregulated by Cullinl expression.Moreover,Rif could be degradated at the proteasome in vitro and in vivo.In gastric cancer cells,Rif inhibition led to an increased expression of the cell cycle inhibitor p27,indicating that its proteasomal degradation might contribute to inhibition of gastric cancer cell proliferation.In addition,the expression profile of specific mRNA and IncRNA in DNA replication phase of gastric cancer cells was analyzed by a microarray assay,and the difference of expression profile of gastric cancer cells relative to normal gastric epithelial cells in S phase was found out.Our results reveal a previously unknown mechanism for controlling Rif degradation and regulating gastric cancer cell proliferation.Also,we filtered the IncRNA and mRNA combinations specific for DNA replication in gastric cancer cells,which laid the foundation for the detailed study of DNA replication regulation of gastric cancer.