Zygotic LvBMP5-8 is required for skeletal patterning and for left-right but not dorsal-ventral specification in the sea urchin embryo

作者：Piacentino Michael L; Chung Oliver; Ramachandran Janani; Zuch Daniel T; Yu Jia; Conaway Evan A; Reyna Arlene E; Bradham Cynthia A^*

来源：Developmental Biology, 2016, 412(1): 44-56.

DOI：10.1016/j.ydbio.2016.02.015

• Sea urchin
• BMP5-8
• Skeletal patterning
• Left-right
• Dorsal-ventral
• Neurogenesis

Skeletal patterning in the sea urchin embryo requires coordinated signaling between the pattern-dictating ectoderm and the skeletogenic primary mesenchyme cells (PMCs); recent studies have begun to uncover the molecular basis for this process. Using an unbiased RNA-Seq-based screen, we have previously identified the TGF-ss superfamily ligand, LvBMP5-8, as a skeletal patterning gene in Lytechinus variegatus embryos. This result is surprising, since both BMP5-8 and BMP2/4 ligands have been implicated in sea urchin dorsal ventral (DV) and left right (LR) axis specification. Here, we demonstrate that zygotic LvBMP5-8 is required for normal skeletal patterning on the left side, as well as for normal PMC positioning during gastrulation. Zygotic LvBMP5-8 is required for expression of the left-side marker soxE, suggesting that LvBMP5-8 is required for left-side specification. Interestingly, we also find that LvBMP5-8 knockdown suppresses serotonergic neurogenesis on the left side. While LvBMP5-8 over expression is sufficient to dorsalize embryos, we find that zygotic LvBMP5-8 is not required for normal DV specification or development. In addition, ectopic LvBMP5-8 does not dorsalize LvBMP2/4 morphant embryos, indicating that, in the absence of BMP2/4, BMP5-8 is insufficient to specify dorsal. Taken together, our data demonstrate that zygotic LvBMP5-8 signaling is essential for left-side specification, and for normal left-side skeletal and neural patterning, but not for DV specification. Thus, while both BMP2/4 and BMP5-8 regulate LR axis specification, BMP2/4 but not zygotic BMP5-8 regulates DV axis specification in sea urchin embryos.

• 出版日期2016-4-1