Isthmin is a novel secreted protein expressed as part of the Fgf-8 synexpression group in the Xenopus midbrain-hindbrain organizer.
Mech Dev
; 116(1-2): 169-72, 2002 Aug.
Article
in En
| MEDLINE
| ID: mdl-12128218
Patterning of the central nervous system is regulated by a signaling center located at the midbrain-hindbrain boundary (MHB), or isthmus organizer. Fibroblast growth factors secreted from the MHB are required and sufficient to direct the ordered growth and regionalization of the midbrain and anterior hindbrain. In an unbiased secretion cloning screen of Xenopus gastrula embryos we identified a novel gene, which we designated as Isthmin (xIsm) due to its prominent expression at the MHB. xIsm encodes a secreted protein of 449 amino acids containing one copy of the thrombospondin type 1 repeat (TSR). We also found orthologous Isthmin genes in human (hIsm) and mouse (mIsm), as well as a gene encoding an Isthmin-like human unknown protein (hIsm-l). The conservation of a unique carboxy-terminal region between hIsm and hIsm-l suggests that Isthmin is the founding member of a new family of secreted proteins. xIsm was strongly expressed maternally in the Xenopus egg and showed zygotic expression in the ventral blastopore lip, notochord, and MHB. Additional expression domains were detected in neural crest, ear vesicle, and developing blood islands. Interestingly, xIsm was co-expressed with Fibroblast growth factor-8 (xFgf-8) at multiple sites including the MHB, indicating that these two genes are part of a synexpression group which also includes sprouty and sef homologs.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Xenopus
/
Rhombencephalon
/
Mesencephalon
/
Fibroblast Growth Factors
/
Nerve Tissue Proteins
Type of study:
Prognostic_studies
Limits:
Animals
/
Humans
Language:
En
Journal:
Mech Dev
Journal subject:
EMBRIOLOGIA
Year:
2002
Document type:
Article
Affiliation country:
Country of publication: