The Study Of Nuclear Configuration In Senescent Mesenchymal Stromal Cell Induced By Inflammatory Factors

The inflammatory environment is a highly complex and dynamic process.MSCs have complex immune regulatory functions in inflammatory environment.The immune regulation functions of MSCs largely depends on amount of factors that regulated by gene expression by sensing diverse inflammatory environment.MSCs could alter it's fate while exerting immune regulatory functions in inflammatory environment.Heterochromatin is a tightly folded region of DNA that is generally considered to be an area of inactive transcription.In the inflammatory environment,the transcriptional profile of MSCs changes drastically,and a large number of genes with low transcriptional activity become highly expressed.As the main component of the nuclear membrane,the nuclear lamina not only maintains the stability of the nuclear morphology,but also regulates the heterochromatin distribution through the lamina associated domain to regulate gene expression.This study is mainly to use TNF-? and IFN-y to simulate the inflammatory environment in vitro to explore the lamina regulation mechanism and the fate of MSCs in the inflammatory environment and heterochromatin regulation.We found that the proliferation rate of MSCs significantly decreased in the inflammatory environment,the cell cycle arrested at G0/G1,and the senescence-associated secretory phenotype was upregulated.The confocal microscopy showed that the nuclear lamina was thinned resulting in nuclear expansion and accompany by the decline of heterochromatin in the inflammatory environment.We found that PML-NB is involved in the regulation of MSCs nuclear lamina conformational changes and heterochromatin decline in inflammatory environment by siPML.PML-NB is also involved in the regulation of some SASP expression.But knocking down PML does not change the cell proliferation of MSCs.In addition,we verified that the formation of PML-NB is independent of STAT1 by siSTAT.In summary,MSCs produce a large amount of PML-NB in the inflammatory environment to change the nuclear lamina configuration and decrease heterochromatin result in the senescence of MSCs.