A dual-strategy expression screen for candidate connectivity labels in the developing thalamus.

The thalamus or "inner chamber" of the brain is divided into ~30 discrete nuclei, with highly specific patterns of afferent and efferent connectivity. To identify genes that may direct these patterns of connectivity, we used two strategies. First, we used a bioinformatics pipeline to survey the predicted proteomes of nematode, fruitfly, mouse and human for extracellular proteins containing any of a list of motifs found in known guidance or connectivity molecules.

Draxin, a repulsive guidance protein for spinal cord and forebrain commissures.

Axon guidance proteins are critical for the correct wiring of the nervous system during development. Several axon guidance cues and their family members have been well characterized. More unidentified axon guidance cues are assumed to participate in the formation of the extremely complex nervous system.

The extracellular leucine-rich repeat superfamily; a comparative survey and analysis of evolutionary relationships and expression patterns.

Background: Leucine-rich repeats (LRRs) are highly versatile and evolvable protein-ligand interaction motifs found in a large number of proteins with diverse functions, including innate immunity and nervous system development. Here we catalogue all of the extracellular LRR (eLRR) proteins in worms, flies, mice and humans. We use convergent evidence from several transmembrane-prediction and motif-detection programs, including a customised algorithm, LRRscan, to identify eLRR proteins, and a hierarchical clustering method based on TribeMCL to establish their evolutionary relationships.

Tsukushi cooperates with VG1 to induce primitive streak and Hensen's node formation in the chick embryo.

Three classes of signaling molecule, VG1, WNT and BMP, play crucial roles in axis formation in the chick embryo. Although VG1 and WNT signals have a pivotal function in inducing the primitive streak and Hensen's node in the embryo midline, their action is complemented by that of BMP antagonists that protect the prospective axial tissue from the inhibitory influence of BMPs secreted from the periphery. We have previously reported that a secreted factor, chick Tsukushi (TSK), is expressed in the primitive streak and Hensen's node, where it works as a BMP antagonist.

The LRR and Ig domain-containing membrane protein SST273 is expressed on motoneurons.

We performed signal sequence trap cDNA cloning using a cDNA library of enriched chicken embryonic spinal motoneurons and identified a novel transmembrane molecule, SST273 (Signal Sequence Trap clone 273). SST273 has five leucine-rich repeats (LRRs) and one immunoglobulin (Ig) domain in its extracellular domain. The human (KIAA1465) and mouse (BC059068) homologues of SST273 were already cloned, but had not yet been analyzed.

Expression pattern of LINGO-1 in the developing nervous system of the chick embryo.

We isolated a chick homologue of LINGO-1 (cLINGO-1), a novel component of the Nogo-66 receptor (NgR)/p75 neurotrophin receptor (NTR) signaling complex, and examined the expression of cLINGO-1 in the developing brain and spinal cord of the chick embryo by in situ hybridization and immunohistochemistry. cLINGO-1 was expressed broadly in the spinal cord, including the ventral portion of the ventricular zone, and motor neurons. cLINGO-1 was also expressed in the dorsal root ganglion and boundary cap cells at dorsal and ventral roots.

EphA receptor tyrosine kinases interact with co-expressed ephrin-A ligands in cis.

Eph receptor tyrosine kinases have been implicated in various developmental processes, including axonal guidance, angiogenesis and morphogenesis. In general, Eph receptors and their ligands, ephrins, are reciprocally compartmentalized during embryogenesis. However, they are expressed in an overlapping fashion in some developing neural and non-neural tissues.