Molecular diversity of diencephalic astrocytes reveals adult astrogenesis regulated by Smad4.

Astrocytes regulate brain-wide functions and also show region-specific differences, but little is known about how general and region-specific functions are aligned at the single-cell level. To explore this, we isolated adult mouse diencephalic astrocytes by ACSA-2-mediated magnetic-activated cell sorting (MACS). Single-cell RNA-seq revealed 7 gene expression clusters of astrocytes, with 4 forming a supercluster.

Proteolytic processing of palmitoylated Hedgehog peptides specifies the 3-4 intervein region of the wing.

Cell fate determination during development often requires morphogen transport from producing to distant responding cells. Hedgehog (Hh) morphogens present a challenge to this concept, as all Hhs are synthesized as terminally lipidated molecules that form insoluble clusters at the surface of producing cells. While several proposed Hh transport modes tie directly into these unusual properties, the crucial step of Hh relay from producing cells to receptors on remote responding cells remains unresolved.

Anti-ACSA-2 defines a novel monoclonal antibody for prospective isolation of living neonatal and adult astrocytes.

Astrocytes are the most abundant cell type of the central nervous system and cover a broad range of functionalities. We report here the generation of a novel monoclonal antibody, anti-astrocyte cell surface antigen-2 (Anti-ACSA-2). Flow cytometry, immunohistochemistry and immunocytochemistry revealed that Anti-ACSA-2 reacted specifically with a not yet identified glycosylated surface molecule of murine astrocytes at all developmental stages.

Sonic hedgehog processing and release are regulated by glypican heparan sulfate proteoglycans.

All Hedgehog morphogens are released from producing cells, despite being synthesized as N- and C-terminally lipidated molecules, a modification that firmly tethers them to the cell membrane. We have previously shown that proteolytic removal of both lipidated peptides, called shedding, releases bioactive Sonic hedgehog (Shh) morphogens from the surface of transfected Bosc23 cells. Using in vivo knockdown together with in vitro cell culture studies, we now show that glypican heparan sulfate proteoglycans regulate this process, through their heparan sulfate chains, in a cell autonomous manner.

Heparan sulfate expression in the neural crest is essential for mouse cardiogenesis.

Impaired heparan sulfate (HS) synthesis in vertebrate development causes complex malformations due to the functional disruption of multiple HS-binding growth factors and morphogens. Here, we report developmental heart defects in mice bearing a targeted disruption of the HS-generating enzyme GlcNAc N-deacetylase/GlcN N-sulfotransferase 1 (NDST1), including ventricular septal defects (VSD), persistent truncus arteriosus (PTA), double outlet right ventricle (DORV), and retroesophageal right subclavian artery (RERSC). These defects closely resemble cardiac anomalies observed in mice made deficient in the cardiogenic regulator fibroblast growth factor 8 (FGF8).

An emerging role of Sonic hedgehog shedding as a modulator of heparan sulfate interactions.

Major developmental morphogens of the Hedgehog (Hh) family act at short range and long range to direct cell fate decisions in vertebrate and invertebrate tissues. To this end, Hhs are released from local sources and act at a distance on target cells that express the Hh receptor Patched. However, morphogen secretion and spreading are not passive processes because all Hhs are synthesized as dually (N- and C-terminal) lipidated proteins that firmly tether to the surface of producing cells.

Sonic hedgehog shedding results in functional activation of the solubilized protein.

All Hedgehog (Hh) proteins are released from producing cells despite being synthesized as N- and C-terminally lipidated, membrane-tethered molecules. Thus, a cellular mechanism is needed for Hh solubilization. We previously suggested that a disintegrin and metalloprotease (ADAM)-mediated shedding of Sonic hedgehog (ShhNp) from its lipidated N and C termini results in protein solubilization.

Dual roles of the Cardin-Weintraub motif in multimeric Sonic hedgehog.

The fly morphogen Hedgehog (Hh) and its mammalian orthologs, Sonic, Indian, and Desert hedgehog, are secreted signaling molecules that mediate tissue patterning during embryogenesis and function in tissue homeostasis and regeneration in the adult. The function of all Hh family members is regulated at the levels of morphogen multimerization on the surface of producing cells, multimer release, multimer diffusion to target cells, and signal reception. These mechanisms are all known to depend on interactions of positively charged Hh amino acids (the Cardin-Weintraub (CW) motif) with negatively charged heparan sulfate (HS) glycosaminoglycan chains.