Modulation of STI1 expression: Effects on the pluripotency status mediated by the Wnt signaling pathway

• Grant number: 24/07492-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: September 01, 2024
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Marilene Hohmuth Lopes
• Grantee: Samuel Ribeiro Soares
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 18/15557-4 - Prion protein and its partners: emerging targets for glioblastoma stem cell based-therapy, AP.JP2

Abstract

Mouse embryonic stem cells (mESCs) have long been the subject of biomedical research due to their pluripotency, the ability to give rise to the three embryonic germ layers. Pluripotent status is finely regulated by a complex network of transcription factors, such as the central triad of Oct4, Sox2 and Nanog, as well as by extensive secondary networks that assume a supporting role according to the metastate (naïve or primed) of pluripotency the cell is under. Pluripotency is further influenced by several regulators of protein homeostasis, such as heat shock proteins (HSPs) and their partners. In this context of protein homeostasis, a co-chaperone of HSP70/90, STI1/Stip1 (stress inducible phophoprotein 1), was recently described as an essential component of early embryonic development, as evidenced by its lethal phenotype after deletion in mouse embryos, which is still poorly characterized regarding its mechanism of action. Our initial RNA sequencing analysis, as well as growing evidence from cancer models, pointed to positive correlations between Stip1 and key components of the Wnt signaling pathway and the pluripotency network. Therefore, we aim to characterize the molecular interactions between Stip1 and Wnt signaling in our CTEm model, in order to further evaluate the role of this co-chaperone in early mammalian development. CTEm with differential expression of STI1 will be used in RT-qPCR and Western blotting assays to characterize differences in gene and protein expression of the main canonical components of the WNT signaling pathway and pluripotency markers. We will also evaluate phenotypic aspects such as cell proliferation and survival and the formation of blastoids (structures that mimic blastocysts) to better understand the changes caused by STI1 modulation at early stages of development. Furthermore, we intend to characterize protein interactions between Stip1 and key components of Wnt signaling that may explain the preliminary data collected, as well as investigate the possibility of a role for this co-chaperone as a transcription factor through chromatin immunoprecipitation analysis. Therefore, this study aims to elucidate molecular aspects of the fundamental role of Stip1 in preimplantation embryogenesis.