Gene regulatory network for neurogenesis in a sea star embryo connects broad neural specification and localized patterning.

A great challenge in development biology is to understand how interacting networks of regulatory genes can direct the often highly complex patterning of cells in a 3D embryo. Here, we detail the gene regulatory network that describes the distribution of ciliary band-associated neurons in the bipinnaria larva of the sea star. This larva, typically for the ancestral deuterostome dipleurula larval type that it represents, forms two loops of ciliary bands that extend across much of the anterior-posterior and dorsal-ventral ectoderm.

Destruction complex function in the Wnt signaling pathway of Drosophila requires multiple interactions between Adenomatous polyposis coli 2 and Armadillo.

The tumor suppressor Adenomatous polyposis coli (APC) negatively regulates Wnt signaling through its activity in the destruction complex. APC binds directly to the main effector of the pathway, β-catenin (βcat, Drosophila Armadillo), and helps to target it for degradation. In vitro studies demonstrated that a nonphosphorylated 20-amino-acid repeat (20R) of APC binds to βcat through the N-terminal extended region of a 20R.

Transcription elongation factor ELL2 directs immunoglobulin secretion in plasma cells by stimulating altered RNA processing.

Immunoglobulin secretion is modulated by competition between the use of a weak promoter-proximal poly(A) site and a nonconsensus splice site in the final secretory-specific exon of the heavy chain pre-mRNA. The RNA polymerase II transcription elongation factor ELL2, which is induced in plasma cells, enhanced both polyadenylation and exon skipping with the gene encoding the immunoglobulin heavy-chain complex (Igh) and reporter constructs. Lowering ELL2 expression by transfection of heterogenous ribonucleoprotein F (hnRNP F) or small interfering RNA resulted in lower abundance of secretory-specific forms of immunoglobulin heavy-chain mRNA.