Transcriptome And Proteomic Analysis Of Effects Of 17β-estradiol On The Proliferation Of Mouse Thymic Epithelial Cells

The thymus is the primary lymphoid organ indispensable for the generation of T cells,which is pretty significant for organism immune.Thymocytes and thymic epithelial cells(TECs)are two major cell types of the thymus parenchyma.Particularly,TECs can provide unique microenvironment and signals for various stages of T-cell development and maturity.Studies have shown that thymus undergoes atrophy and phenotypic alterations with aging associated with the destruction of microenvironment.Furthermore,gonadal steroid hormones,including estrogens,are the key factors to promote thymic involution.It has also known that TECs are main target sites of estrogens with containing a large amount of estrogen receptor(ERα).However,the mechanism of estrogen acting on TECs is not fully clear.Therefore,it is fundamentally significant that exploring the mechanism of estrogen working on TECs to clarify the thymus involution.In this study,we investigated the effect of 17β-estradiol on the proliferation or apoptosis of mouse TEC1(MTEC1)and its underlying mechanism.Biological experiment methods including CCK-8,fluorescent staining,flow cytometry,qRT-PCR,western bloting,transcriptome,iTRAQ-based proteomic and bioinformatics analysis were employed to detect the effect of 17β-estradiol on MTEC1 cell proliferation,cell viability,cell apoptosis,cell cycle,as well as protein expression profile.Our results were as follows:(1)17β-estradiol could affect MTEC1 in a dose-dependent manner,including altering cell morphology,inhibiting cell proliferation,inducing G2/M phase arrest and leading to cell apoptosis.(2)17β-estradiol could cause the change of mRNA expression profile,especially the expression changes of cell cycle or apoptosis regulation related genes in MTEC1 cells.In addition,17β-estradiol might inhibit MTEC1 cell proliferation and induce cell apoptosis through the p53 signaling pathway.(3)17β-estradiol could induce the change of protein expression profile in MTEC1,including 61 up-regulated proteins such as GRP78,PDI,Calr etc.and 10 down-regulated proteins.These differentially expressed proteins were involved with cell proliferation,cell apoptosis,immunoreaction and other cellular processes,which indicated that endoplasmic reticulum stress(ER stress)signaling pathway may play a key role in the MTEC1 apoptosis induced by 17β-estradiol.Conclusion: 17β-estradiol could induce the change of gene and protein profile expression and cellular environmental homeostasis in MTEC1,inhibit cell proliferation and eventually lead to cell apoptosis through p53 signaling pathway and ER stress.