kdm4aa knockout disturbs early embryonic development in Zebrafish via downregulating rbm46

Area of Science:

• Developmental Biology
• Epigenetics
• Zebrafish Model Organisms

Background:

• Histone lysine-specific demethylase 4A (KDM4A) is vital for mammalian embryonic development.
• Zebrafish (Danio rerio) possess two kdm4a paralogs, kdm4aa and kdm4ab, complicating functional studies.
• The specific role of KDM4A in zebrafish embryogenesis is largely unknown.

Purpose of the Study:

• To investigate the function of KDM4A, specifically the kdm4aa paralog, in zebrafish embryogenesis.
• To elucidate the molecular mechanisms by which kdm4aa influences embryonic development.
• To determine the relationship between kdm4aa, RBM46, and cellular energy homeostasis.

Main Methods:

• Kdm4aa knockout zebrafish model generation.
• Quantitative reverse transcription PCR (RT-qPCR) to assess gene expression.
• CUT&Tag-qPCR to analyze histone modifications at target gene promoters.
• Measurement of reactive oxygen species (ROS) and adenosine triphosphate (ATP) levels.
• Rescue experiments using RBM46 mRNA injection.

Main Results:

• Kdm4aa knockout resulted in significantly increased embryonic mortality during gastrulation.
• Downregulation of RNA-binding motif protein 46 (RBM46) was observed post-kdm4aa knockout.
• KDM4A knockout altered histone methylation patterns (decreased H3K4me3, increased H3K9me3 and H3K36me3) at the RBM46 promoter.
• Kdm4aa deficiency led to elevated ROS and reduced ATP levels in embryos.
• RBM46 mRNA injection rescued the lethal phenotype by alleviating ROS and restoring ATP levels.

Conclusions:

• KDM4A (specifically kdm4aa) plays an essential role in zebrafish embryogenesis.
• Kdm4aa knockout disrupts embryonic development primarily by suppressing RBM46 expression.
• The observed developmental defects are linked to metabolic dysregulation, including ROS accumulation and ATP depletion.