Assessment of X chromosome inactivation status in human blastoids

• Grant number: 22/02096-4
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Effective date (Start): August 15, 2022
• Effective date (End): February 14, 2023
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Lygia da Veiga Pereira
• Grantee: Ana Elisa Ribeiro Orsi
• Supervisor: Jun Wu
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Research place: University of Texas Southwestern Medical Center, Dallas (UT Southwestern), United States
• Associated to the scholarship: 20/16612-9 - Analysis of gene expression of human preimplantation embryos for the development of a strategy for maintenance of the morulas epigenetic stage, BP.MS

Abstract

In placental mammals, the inactivation of extra copies of the X chromosome is essential for the viability of female embryos. Despite being well described in the mouse, the X chromosome inactivation (XCI) process in preimplantation human embryos is yet to be elucidated. Due to the ethical and technical barriers associated with the use of human embryos in research, the development of a stem cell-based blastocyst model to be used in the study of embryonic dose compensation is desirable. While primed pluripotent stem cells (PSCs) are not suitable for this application, human naive PSCs possess two active X chromosomes and have the potential to generate extraembryonic trophoblast and hypoblast cells. Recently, naive hPSCs have been employed to generate blastoids, tridimensional structures similar to the human blastocyst. However, XCI status during conversion and maintenance of these structures has not been evaluated. Therefore, we propose a collaboration with Dr. Jun Wu and his group at the University of Texas Southwestern Medical Center, who pioneered the human blastoids. First, we will generate and culture naive hPSCs with XX and XY karyotypes. Then, these cells will be used for the generation of blastoids. During the process, XCI status and expression of X-linked genes will be assessed by RNA-FISH, qPCR and/or single-cell RNA-sequencing. In addition to contributing to the elucidation of the XCI process in human embryos, this project will help train a Brazilian scientist who can help establish the human blastoid technology in Brazilian laboratories. (AU)