Triiodothyronine induces changes in the proteome and transcriptome of ecc1 cell line

Abstract

During women´s reproductive life, steroid hormones govern the periodic changes of the endometrium. Estradiol (E2) and progesterone (P4) are essential to regenerate and differentiate the endometrium after menses, in order to provide an adequate milieu for embryo implantation. Both implantation and maintenance of pregnancy depend on the correct function and interaction between the corpus luteum, the receptivity and functionality of the uterus, and the action of thyroid hormones (THs). THs dysfunction causes irregularities during the menstrual cycle, failure of implantation and early pregnancy loss. Therefore, we hypothesize that interaction between THs, E2, and P4 in the endometrium are fundamental for development and differentiation, providing the right environment for implantation. The goal of this study was to investigate how endometrial cells respond to HTs-controlled signaling, through the analysis of the genomic and proteomic expression pattern. For this purpose, the human endometrial ECC1 cell line was used to determine the expression of E2 (ERS1 and ERS2), P4 (PGR) and TH (TRα and TRβ) receptors and also how it responds to E2, P4, and triiodothyronine (T3) stimulation. Besides, the pattern of protein and genomic expression in response to the combination of E2 and P4, with or without T3 was analyzed. The protein identification was performed by LC and tandem mass spectrometry. The data were analyzed using Mascot server, followed by PROTEOIQ (Premier Biosoft) and Functional Enrichment analysis tool (FunRich) software. The relative expression of mRNA was analyzed by RT-qPCR. The mRNA analysis confirmed the expression of PGR, ERS1, ERS2 and TRα, TRβ in ECC1 endometrial cells. The mRNA expression of PGR increased significantly (p <0.05) with T3. The proteomic analysis showed that cells treated with E2 and P4 present a greater amount of proteins involved in biological processes such as energy metabolism; protein transport; and cell growth. Whereas the combination with T3 expressed a greater amount of proteins involved in immune response and signal transduction. This work elucidates that ECC1 cells respond differentially to the hormonal treatments with E2, P4, and T3, showing that these cells are good model for the study of the interaction between steroid and THs. On the other hand, the proteomic analysis allowed us to infer that T3 induces changes in the relative expression of proteins when it interacts with maternal hormones. Altogether, the changes observed, demonstrated that the presence of THs is essential to provide an optimal environment for embryo implantation and growth.