Molecular regulation of mesothelial EMT in avian chorioallantoic fusion

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02452
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 44020:Developmental biology-related
• Research Institution: Kumamoto University
• Principal Investigator: Sheng Guojun 熊本大学, 国際先端医学研究機構, 特別招聘教授 (20399439)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: mesothelium / chicken / chorion / allantois / EMT / cancer

Outline of Final Research Achievements

In this project, we investigated the early phase of the formation of chorioallantoic membrane, which serves as the embryonic lung in avian development and is the evolutionary origin for mammalian placenta. We narrowed down the timing of initial fusion to E3.75 to E4, a short window of about six hours. We performed cell biological (through immunofluorescence and EM analyses), molecular (through RNA-seq and RNA in situ analyses), embryological (through graft and chimera analyses) and perturbation (through overexpression and CRISPR-based gene activation/inhibition) experiments. We showed that chorioallantoic fusion involved EMT of both mesothelial layers. We also showed that the allantoic mesothelial layer EMT is an active process, whereas chorionic mesothelial layer EMT is passive. We showed that EMT transcription factors were involved in chorioallantoic membrane fusion EMT and that this EMT could be considered as partial EMT.

Free Research Field

developmental morphogenesis

Academic Significance and Societal Importance of the Research Achievements

This research has offered us better understanding of an important developmental process called "chorioallantoic fusion", the evolutionary precursor for mammalian placenta. Many pregnancy diseases are due to placental defects, of which this project helped us gain a better mechanistic understanding.