Study On The Interaction Between SCF Complex Component Cullin1 And Rif Of Rho GTPase Family

Cullin1 is the scaffold protein of the E3 ubiquitin-ligase complex SCF and is one of the members of the CUL family.It interacts with the substrate to mediate the ubiquitination degradation.Rif is a member of the Rho GTPase family,which mainly regulates the cytoskeleton structure.Proteasome-mediated degradation of ubiquitinated proteins can regulate the expression levels of some Rho GTPases,including RhoA,Rac2,Rac3,and Cdc42.However,there are no relevant reports on Cullin1-mediated Rif ubiquitination degradation pathway.Our research found that Cullin1 and Rif could co-localize and interact with each other in the cell.Cullin1 is involved in the regulation of Rif stability.The disturbed Cullin1 reduces the expression of Rif and decreases the ubiquitination degradation of Rif.Furthermore,Rif is a short half-time protein that can be ubiquitinated by SCF complex and degraded in the proteasome in vitro and in vivo.Meanwhile,Cullin1 mediates degradation of Rif could control actin cytoskeleton structure formation in both normal and tumor cells,affecting the generation of actin stress fibers and filopodia.A comparative proteomic analysis of the cervical cancer cell line HeLa with knockdown of Cullin1 and control cells revealed that under the influence of Cullin1 knockdown,the expression of Rho GDP dissociation inhibitor Rho-GDI and cytoplasmic dynein 1(Dynein)were both down-regulated.Cullin1 may indirectly regulate tumor cytoskeleton structure by affecting the expression of these two proteins.Our research reveals a new mechanism for controlling Rif degradation,regulating Rif function and cytoskeletal structure through the Cullin1-mediated ubiquitination-proteasome pathway,which may provide new ideas for targeted therapy of cervical cancer.