NRSF/REST is required for gastrulation and neurogenesis during zebrafish development

Repressor element 1-silencing transcription factor (REST) was recognized as a transcription suppressor regulating nervous system differentiation. However, the role of REST during early development has not been clarified. We cloned the zebrafish homolog of human REST. Real-time polymerase chain reaction results showed that zebrafish REST mRNA was both maternal and zygotic with the higher expression level from blastula to the late segmentation period. Whole-mount in situ hybridization showed that REST was strongly expressed in the blastoderm since dome stage and dynamically expressed mainly in developing brain, especially in the border of the brain subdivisions in early segmentation period. Knockdown of REST using translation blocking morpholino (MO-tra) technique resulted in gastrulation delay or even blockage, and subsequently led to embryo lethality by early segmentation period with deficient neurogenesis. However, splicing blocking morpholino for REST did not show obviously abnormal phenotype until 48 hpf (hours post-fertilization), indicating that maternal REST was an important regulator for gastrulation. Further study revealed that the abnormal development in MO-tra morphants was at least partly due to the dysfunction of protein transportation from the yolk to the blastoderm. Our results showed that REST (especially maternal supplied REST) was required for gastrulation and neurogenesis during zebrafish early embryogenesis.