Abstract
microRNAs are evolutionarily conserved non-coding RNAs that direct post-transcriptional regulation of target transcripts. We use the sea urchin embryo to achieve a comprehensive understanding of miR-1’s function in a developing embryo. Results indicate that miR-1 regulates gut contractions, specification, and positioning of serotonergic neurons, as well as mesodermally-derived muscles, pigment cells, and skeletogenic cells. Gain-of-function of miR-1 generally leads to more severe developmental defects than its loss-of-function. We identified that miR-1 directly suppresses Ets1/2, Tbr, and VegfR7 of the skeletogenic gene regulatory network, and Notch, Nodal, and Wnt1 signaling components. We found that miR-1’s direct suppression of Nodal may indirectly regulate FoxQ2 to impact serotonergic neurons. Excess miR-1 may lead to decreased Nodal and Notch that result in decreased circumpharnygeal muscle fibers and the number of pigment cells. The striking ectopic skeletal branching induced by miR-1 mimic injections may be explained by miR-1’s direct suppression of Nodal that leads to expression changes of Vegf3, and Fgfa that mediate skeletogenesis. This work demonstrates that miR-1 plays a diverse regulatory role that impacts tissues derived from all germ layers.
Summary statement This study identifies wide-ranging regulatory roles and regulatory mechanisms of miR-1 that impact structures derived from all three germ layers during embryonic development.
Competing Interest Statement
The authors have declared no competing interest.
Abbreviations
- ALP
- alkaline phosphatase
- ALR
- anterolateral rod
- BC
- blastocoelar cells
- BR
- body rod
- BE-DVM
- border ectoderm-dorsal ventral margin
- cWnt
- canonical Wnt
- DE
- dorsal ectoderm
- Dpf
- days post fertilization
- DVC
- dorsoventral connecting rod
- EMT
- epithelial to mesenchymal transition
- GRN
- gene regulatory network
- PC
- pigment cells
- Hpf
- hours post fertilization
- PC
- pigment cell
- PMCs
- primary mesenchyme cells
- POR
- postoral rod
- TF
- transcription factor
- VE
- ventral ectoderm
- Vegf
- vascular endothelial growth factor