Understanding early vertebrate development: a CRISPR-Cas13d view [IRB Research Nodes Seminar]

Host: Ferran Azorin 

Organizer: Cell Pathophysiology Node

Date: Wednesday 24 March 2021, 12.00h

ABSTRACT:

The maternal to zygotic transition (MZT) is a universal process that occurs in all animals and involves the activation of the silent zygotic genome that sequentially initiates the clearance of the maternal oocyte program to ultimately adopt embryonic pluripotency. Thus, MZT is an in vivo cellular reprogramming event, in which the old maternal program is erased, and new zygotic instructions are implemented. While some maternal factors such as some transcriptional factors or chromatin modifiers have been uncovered as required for zygotic genome activation (ZGA), there are hundreds of highly deposited RNAs whose role during MZT is unknown. Therefore, to better understand this fundamental process in biology a systematic analysis of the maternal contribution is required. In our lab, we have recently demonstrated that CRISPR-RfxCas13d, a novel CRISPR-Cas system targeting RNA, is an effective and precise system to deplete specific mRNA transcripts in zebrafish and other animal embryos such as medaka, killifish or mouse. Notably, we have showed that maternally-provided transcripts are efficiently targeted, resulting in a 76% average decrease in transcript levels and the recapitulation of well-known embryonic phenotypes. Now, we are using ribosome-profiling and RNA-seq data to select a subset of maternally-provided mRNA candidates with an expression pattern that suggest a potential role in ZGA. We are currently performing a CRISPR-Cas13d functional screening targeting these maternal RNAs to uncover new factors involved in MZT and ZGA. Altogether, our results will contribute to better understand the molecular factors driving not only ZGA but also cell reprogramming and pluripotency in vivo during early vertebrate development.