The Molecular Mechanism Of PRR11 Regulating Cytonucleoskeleton Assembly By Recruiting Arp2/3 Complex In Lung Cancer Cells

Cytoskeleton is an interconnected network of filamentous polymers and regulatory proteins,which plays a key role in maintaining cellular morphology and intracellular structure stability as well as involving in a variety of important intracellular activities.F-actin is one of the three forms of cytoskeleton,and its polymerization/depolymerization and organization are highly dynamic.Actin cytoskeletal assemblies are coupled to nuclear lamina integrity via LINC complex and involved in the regulation of nuclear stability,chromatin organization and gene expression,which plays an important role in normal physiological or pathological process.Previous studies have shown that the polymerization,depolymerization or disorder of F-actin play a key role in the development of malignant tumors,but the specific mechanism remains to be studied.We have previously demonstrated that PRR11 is implicated in nonsmall cell lung cancer development.However,the precise molecular mechanism behind PRR11-mediated cellular functions and tumorigenesis remains unclear.In this study,we utilize molecular biology,cell biology,biochemistry and other research methods to find that the cytoplasmic protein PRR11 in non-small cell lung cancer cells can promote F-actin polymerization and rearrangement to regulate nuclear lamina stability,chromatin remodeling and gene expression.Mechanical study suggests PRR11 in NSCLC recruits Arp2/3 complex,which stimulates branched F-actin polymerization.And recombinant PRR11 promotes the role of Arp2/3 complex in driving branched F-actin polymerization in vitro.PRR11 silencing in NSCLC significantly inhibits Factin polymerization and PRR11 overexpression induces F-actin overpolymerization and disordered rearrangement.The activity of Arp2/3complex is inhibited in si RNA knockdown or specific inhibitor treated cells,which rescues PRR11-induced F-actin polymerization and rearrangement.Meanwhile,we find that PRR11 regulates F-actin polymerization and rearrangement dependent on specific domains.N-termini(1-100 aa)and Ctermini(201-360 aa)of PRR11 are closely related to F-actin polymerization,but the middle region(101-200)is not involved in F-actin polymerization.In addition,the proline-rich 2 region(PR2)has close association with F-actin rearrangement.PRR11 ?100-184 and ?100-200 induce the formation of actin comet tail,which are implicated in phagocytosis and endocytosis of pathogenic microorganism and vesicle transport.Further study reveals that PRR11 overexpression induces disorganization or collapse of nuclear lamina and chromatin reorganization,but PRR11 depletion significantly improves the nuclear stability of lung cancer cells.Moreover,inhibition of the Arp2/3complex activity abolishes all of the irregular lamina assembly and chromatin reorganization resulted from PRR11 overexpression.These findings suggest that PRR11 regulates nuclear stability and chromatin organization via cyto-nucleoskeleton in NSCLS.Finally,online database analysis further shows that the expressions of PRR11 and Arp2/Arp3 are remarkably upregulated in lung cancer tissues and all proteins are significantly associated with poor survival of lung cancer patients.Our data collectively demonstrate for the first time that cytoplasmic PRR11 associates with and recruits Arp2/3 complex to stimulate F-actin polymerization and cytoskeleton rearrangement,consequently influencing nuclear lamina integrity and chromatin organization in lung cancer cells.Overexpression of PRR11 in lung cancer cells leads to aberrant nuclear lamina integrity and chromatin dynamics,which is tightly associated with altered gene expression and tumorigenesis.