The Effect Of SETD4 Knockout On The Function Of Macrophages And Differentiation Of Immune Cells

The SET domain is a same DNA sequence at the carboxy terminus of the three regulatory factors Su(var)3-9,Enhancer of zeste,and Trithorax of Drosophila.Proteins containing the SET domain belong to the SET family proteins.It has been shown that SET family proteins generally have methyltransferase activity,which can transfer methyl groups of S-adenosyl-L-methionine(SAM/AdoMet)to histones or N-terminus of non-histones and regulate gene expression by altering the methylation modification mode and action site.More and more studies show that histone methylation modification plays an important role in the development of inflammation and tumor.Therefore,studying the function of SET family proteins helps us to clarify the pathogenesis of inflammatory diseases and find new therapeutic targets.SETD4(SET domain-containing protein 4)is a member of the SET family proteins.It is a differential protein screened by proteomics during exploring the mechanism of endotoxin shock.In order to further clarify the mechanism of SETD4,our team constructed a SETD4 gene knockout mouse(SETD4-/-)previously.The results showed that SETD4-/-macrophages treated with LPS had reduced inflammatory responses and down-regulated TNF-? and IL-6 mRNA levels when compared with SETD4+/+ mice.However,it is unclear whether SETD4 gene knockout has an effect on the differentiation,maturity and function of macrophages.To characterize this,we took SETD4+/+and SETD4-/-mice as research objects and investigated the effect of SETD4 knockout on the differentiation,maturity and function of macrophages,differentiation of immune cells in peripheral blood and spleen,and development of thymus and spleen.Furthermore,bioinformatics analysis and quantitative real-time PCR were utilized to study the expression of SETD4.The results show that SETD4 was differentially expressed in heart,liver,spleen,lung,kidney and testis,and the level of SETD4 mRNA was highest in liver of mice.The release of TNF-? and IL-6 were decreased in SETD4-/-macrophages compared with SETD4+/+ cells in response to LPS stimulation,while no significant difference could be detected in percentage,differentiation and maturity of macrophages.It had no significant difference on phagocytosis and migration between SETD4-/-and SETD4+/+macrophages.There was no significant difference in number and proportion of immune cells in peripheral blood and spleen from SETD4-/-and SETD4+/+ mice.The thymus and spleen indexes and structure of SETD4-/-mice were not significantly different from those of SETD4+1+mice.In conclusion,SETD4 is differentially expressed in various tissues.SETD4 has a positive role in the production of TNF-? and IL-6 from LPS stimulated macrophages,while it has no significant effect on the differentiation,maturity,phagocytosis and migration of macrophages.SETD4 knockout has no distinct effect on the differentiation of immune cells in peripheral blood and spleen,and the development of thymus and spleen.