Intracellular Remodeling during Early Development

Abstract Multicellular organisms are made of numerous types of cells. While all cells in the adult animal originate from the fertilized egg, cellular machinery and organelles are organized uniquely in different cell lineages. This allows different types of cells to carry out specific functions. For decades, scientists have been focusing on how gene regulatory networks and signaling pathways control lineage specification and differentiation. Much less attention has been given to the remodeling of the cellular machinery and organelles during development. Whether intracellular remodeling can influence cell fate determination and cellular differentiation represents a key knowledge gap. In an effort to understand the mechanisms governing the oocyte-to-embryo transition (OET), which is crucial for reproduction, we have discovered novel remodeling mechanisms that act on cellular organelles and mRNAs in the oocyte. These include relocation of the proteasome, remodeling of the endoplasmic reticulum (ER), regulated mRNA-ER association, and RNA phase transition during the OET. Based on these findings, we propose to investigate the impact of ER remodeling on cell fate determination during early embryonic development, mitochondria remodeling during oocyte maturation, and RNA phase transition during the OET. By studying the remodeling of organelles and RNAs during early development, the proposed studies will fill fundamentally important knowledge gaps and open a new dimension to study post-transcriptional regulation during development.