The Effect Of RanBP1 On Cell Division

Ran binding protein 1?RanBP1?is a key regulator of the RanGTPase cycle,which plays an important role in nucleocytoplasmic transport,centrosome assembly,microtubule polymerization,spindle assembly and apoptosis.Recently,it has been found that the RanGTP played an important role in the MI spindle assembly of human and mouse.In this study,the results showed that RanBP1 was expressed in all stages of oocyte maturation and early embryonic development.RanBP1 is distributed in the whole cytoplasm and the concentration is low in the region of nucleus and chromosomes by immunofluorescence.Although the oocytes could develope into MII stage,but the abnormal rate of spindle morphology and the ratio of the huge polar body significant increased.In summary,RanBP1 plays an important role in the oocyte maturation,meiotic spindle assembly and chromosome correct segregation.Recent studies show that RanBP1 participates in the self-renewal of hematopoietic stem cells and maintains the ability of differentiation.Tobacco RanBP1is involved in mRNA transport and is an important target of tobacco resistance to potato disease.The expression of RanBP1 was abnormal in a variety of cancer cells.So we thought that RanBP1 might have some other undiscovered functions.The expression vectors of main member protein in the RanGTPase cycle such as RanBP1,Ran,RCC1,RanGAP1 and CRM1 have been constructed and transfection into the 293T cell by liposome respectively.The results showed that upregulation of each protein in the RanGTPase cycle had due to block cell division or apoptosis.The mutual regulation of each protein in the RanGTPase cycle might be very complicated,and it could not achieve only though changing the expression of protein.The quantitative proteomics and phosphorylated proteomics were used to analyze the biologic function of RanBP1 by upregulation of RanBP1 in 293T cell.The differential expression proteins mainly participate in apoptosis,cell division G₂/M transformation,transcription,protein kinase binding and so on.The change of kinases is likely to cause differences of protein phosphorylation modification.By the phosphorylation proteomics experiments,the differential proteins are mainly involved in the splicing complex-mediated mRNA splicing and mRNA transcription process.We determined 99 proteins which mignt interact with RanBP1 by pulldown and CoIP expriments.These interacted proteins mainly include spliceosome comples proteins and ribosomal proteins except the proteins in the RanGTPase cycle.The abnormal expression of RanBP1 affects the assembly and morphology of the spindle and hinders cell division,even causing apoptosis.The results of proteomics experiments shown that the possible molecular mechanism might be that upregulation of RanBP1 affected the activity of kinases and changed phosphorylation modification of protein,which misregulated the mRNA splicing and transcription process.The proteins related with spindle assembly,mRNA splicing and transcription process of cell division proteins were affected causing abnormal cell division.