Dbnl and β-catenin promote pro-N-cadherin processing to maintain apico-basal polarity.

The neural tube forms when neural stem cells arrange into a pseudostratified, single-cell-layered epithelium, with a marked apico-basal polarity, and in which adherens junctions (AJs) concentrate in the subapical domain. We previously reported that sustained β-catenin expression promotes the formation of enlarged apical complexes (ACs), enhancing apico-basal polarity, although the mechanism through which this occurs remained unclear. Here, we show that β-catenin interacts with phosphorylated pro-N-cadherin early in its transit through the Golgi apparatus, promoting propeptide excision and the final maturation of N-cadherin.

PI3K regulates intraepithelial cell positioning through Rho GTP-ases in the developing neural tube.

Phosphatidylinositol 3-kinases (PI3Ks) are signal transducers of many biological processes. Class 1 A PI3Ks are hetero dimers formed by a regulatory and a catalytic subunit. We have used the developing chicken neural tube (NT) to study the roles played by PI3K during the process of cell proliferation and differentiation.

Chemical speciation of MeHg and Hg in aqueous solution and HEK cells nuclei by means of DNA interacting fluorogenic probes.

Selected new fluorogenic probes that interact in different ways with Hg and MeHg have been prepared and used for the chemical speciation of both cations in aqueous solution as well as in HEK293 cells. The best selective speciation of Hg and MeHg has been achieved by approaches based on fluorogenic probes supported in cultured cells, due to the particular sensitivity of the HEK293 cells to permeation by Hg, MeHg and the fluorogenic probes. In particular, MeHg was selectively detected in cell nuclei by probe JG45.

Ciliary adenylyl cyclases control the Hedgehog pathway.

Protein kinase A (PKA) accumulates at the base of the cilium where it negatively regulates the Hedgehog (Hh) pathway. Although PKA activity is essentially controlled by the cAMP produced by adenylyl cyclases, the influence of these enzymes on the Hh pathway remains unclear. Here, we show that adenylyl cyclase 5 and adenylyl cyclase 6 (AC5 and AC6, also known as ADCY5 and ADCY6, respectively) are the two isoforms most strongly expressed in cerebellar granular neuron precursors (CGNPs).

MicroRNA 22 regulates cell cycle length in cerebellar granular neuron precursors.

During cerebellum development, Sonic hedgehog (Shh)-induced proliferation of cerebellar granular neuronal precursors (CGNPs) is potently inhibited by bone morphogenetic proteins (BMPs). We have previously reported the upregulation of TIEG-1 and Mash1, two antimitotic factors that modulate MYCN transcription and N-Myc activity, in response to BMP2. To gain further insight into the BMP antimitotic mechanism, we used microRNA (miRNA) arrays to compare the miRNAs of CGNPs proliferating in response to Shh with those of CGNPs treated with Shh plus BMP2.