The Identification Of BRG1-HP1-H3K9me Complex As The Core Element Of Sahf

BackgroundOncogene-induced senescence(OIS)is one of the most important topics in today's aging and cancer research area.Senescence-associated heterochromatic foci(SAHF)plays an essential role in the initiation and maintenance of OIS.The mechanism of SAHF formation is a hot topic in today's OIS study.A major difference between SAHF and common heterochromatin is that the folding of the tightly packed structures of SAHF is irreversible,but the underlying mechanism resulting this phenomenon remains unknown.Basing on our previous studies and latest results,we hypothesize that BRG1-HP1-H3K9 me protein complexes exist in senescent cells,and these complexes are the core structures for SAHF formation.Methods and resultsIn this project,we overexpressed H-RASG12 V to induce cellular senescence and use a variety of methods to prove the existence of BRG1-HP1-H3K9 me complexes in senescent cells.Through immunofluorescence staining,we found that BRG1,HP1 and H3K9 me are colocalized in SAHF in RAS-overexpressed cells.Immunoprecipitation also showed that there are interactions among BRG1,HP1 and H3K9 me.In addition,the results of GST-Pull down assays confirmed that there are interactions between BRG1,HP1 and H3K9 me.Further more,we impaired the formation BRG1-HP1-H3K9 me complex by overexpressing BRG1(295-634AA)or BRG1(1223-1420AA)that in turns inhibited RAS-induced SAHF formation.We proved that BRG1-HP1-H3K9 me complexes are the core structures for SAHF.ConclusionIn this study,we confirm the existence of BRG1-HP1-H3K9 me protein complexes in Ras-induced senescent cells,and these complexes are the core structures for SAHF formation.These results will greatly contribute to the mechanism study of SAHF formation,and help researchers to profoundly understand the complicated OIS process.