Control Gene Expression Noise In Mammalian Cells With Optogenetics Tools

Gene expression noise is widespread in the gene expression of mammalian cells,mainly manifested as the difference in gene expression of cells of the same genotype in the cell population.Compared with the constant expression promoter,the inducing promoter can generate greater gene expression noise,resulting in the inability to accurately induce gene expression in mammalian cells.The existing methods of reducing gene expression noise have the disadvantages of poor applicability or overly complicated equipment,which limits the application of gene expression noise regulation in mammalian cell research.This paper discusses the regulation methods of gene expression noise with GAVPO light-induced expression system.In this paper,we use the monoclonal cell line which stable transfected fluorescent protein marked GAVPO light-inducible expression system to compare the gene expression control effects of amplitude modulation and pulse width modulation.For the first time,this paper shows pulse width modulation with high light intensity could reduce the gene expression noise under the same expression level.By constructing a mathematical model,this paper analyzes the causes of pulse width modulation noise reduction.It suggests that the concentration of activated GAVPO protein can switch between the region with very low expression and low noise and the region with high expression and low noise under this light condition,thereby maintaining the amount of gene expression and reducing the gene expression noise.In addition,this paper shows that the difference in GAVPO protein expression between cells did not affect gene expression noise as much as previously thought.With the help of Ch IP-Seq technology,ATAC-Seq and sc ATAC-Seq technologies,this paper discusses the H3K27 ac and chromatin accessibility around the light-induced promoter during the illumination.For the first time,it shows that the difference in the H3K27 ac and chromatin accessibility around the light-induced promoter is positively correlated with the difference in gene expression.It takes a long time for chromatin accessibility around the light-induced promoter after illumination to recover to the state before illumination.The long-period pulse width modulation method of the GAVPO light-induced expression system proposed in this paper can expand the application of gene expression noise regulation in mammalian cell research.The discussion of noise reduction mechanism,H3K27 ac and chromatin accessibility in this paper could promote our understanding ofgene expression noise and further the development of better methods for regulating gene expression noise.