Molecular cloning and early expression of chick embryo SCO-spondin.
SCO-spondin is a multidomain glycoprotein secreted by the subcommissural organ (SCO). It belongs to the thrombospondin type 1 repeat superfamily and has been identified in several vertebrate species. We report the cloning of the chick SCO-spondin ortholog and examine its temporal and spatial expression during early embryogenesis from Hamburger and Hamilton (HH) stage 12 to HH stage 21. Chick SCO-spondin cDNA contains a long open reading frame encoding a predicted protein of 5255 amino acids. Northern blot analysis has revealed SCO-spondin mRNA as a band of about 15 kb. Many conserved domains have been identified, including 27 thrombospondin type 1 repeats, 13 low-density lipoprotein receptor type A domains, one EMI domain (a cysteine-rich domain of extracellular proteins), three von Willebrand factor type D domains, and one cystine knot C-terminal domain. Whole-mount in situ hybridization enabled the first signal of mRNA expression to be detected at HH stage 17, exclusively in a thin area of the prosencephalon roof plate. During the following stages of development, SCO-spondin expression remained restricted to this region. The multidomain structure of SCO-spondin and its early expression suggest that it plays a role in developmental processes in the central nervous system.
Didier
Robert
R
INSERM U384, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France.
Meiniel
Olivier
O
Meiniel
Annie
A
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics* / Q000378:metabolism*; D002642:Chick Embryo / Q000196:embryology / Q000378:metabolism*; D003001:Cloning, Molecular / Q000379:methods*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D013351:Subcommissural Organ / Q000196:embryology / Q000378:metabolism
D015816:Cell Adhesion Molecules, Neuronal; D012333:RNA, Messenger; C108402:SCO-spondin