Slitrk6 expression profile in the mouse embryo and its relationship to that of Nlrr3.

Slitrk6 is a member of the Slitrk family of proteins, which are integral membrane proteins possessing two leucine-rich repeat (LRR) domains and a carboxy-terminal domain partially similar to that in the trk neurotrophin receptor proteins. Here, I show that Slitrk6 is uniquely expressed in various organs, different from other Slitrk genes which are predominantly expressed in neural tissues. In the developing mouse embryo, Slitrk6 expression was detected in the otic cyst, lateral trunk epidermis and its underlying mesenchymal tissue, limb bud, maxillary process, pharyngeal arches, cochlea, retina, tongue, tooth primordium, central nervous system (CNS), and the visceral organ primordia including of the lung, gastrointestinal tract (particularly in the enteric neurons) and pancreas. The expression in these organs occurred in a spatially restricted manner. In the CNS, the expression was highly compartmentalized in the dorsal thalamus, cerebellum and medulla. The expression compartment in the thalamus in which Slitrk6 was expressed was closely related to the Gbx2-expressing prosomere 2. Interestingly, the Slitrk6 expression in the CNS, cochlea, tongue, tooth primordial, and other organs was partially complementary to the expression of Nlrr3, which belongs to another family of neuronal LRR-containing transmembrane proteins. The complementary expression of the two proteins in the dorsal thalamus persisted from E13.5 to the adult stage.