Xenopus Kielin: A Dorsalizing Factor Containing Multiple Chordin-Type Repeats Secreted from the Embryonic Midline

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 10; pp. 5291 - 5296
• Main Authors: Matsui, Masaru, Mizuseki, Kenji, Nakatani, Jin, Nakanishi, Shigetada, Sasai, Yoshiki
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 09.05.2000; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Amino Acid Sequence; Animals; Biological Sciences; Biology; Body Patterning; Central nervous system; Chd gene; chordin; Complementary DNA; Ectoderm; Embryo, Nonmammalian - physiology; Embryonic structures; Embryos; gastrulation; Gene Expression Regulation, Developmental; Glycoproteins; Growth Substances - chemistry; Growth Substances - genetics; HNF-3b gene; In situ hybridization; Intercellular Signaling Peptides and Proteins; Kielin; kielin gene; Mesoderm; Mesoderm - physiology; Messenger RNA; Molecular Sequence Data; Molecules; MyoD Protein - genetics; Neural cell adhesion molecules; Organ Culture Techniques; Prenatal development; Proteins - chemistry; Repetitive Sequences, Amino Acid; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Shh gene; Signal Transduction; Tissues; Xenopus; Xenopus - embryology; Xenopus Proteins
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.090020497

The midline tissues are important inductive centers of early vertebrate embryos. By signal peptide selection screening, we isolated a secreted factor, Kielin, which contains multiple cys-rich repeats similar to those in chordin (Chd). Expression of Kielin starts at midgastrula stages in the notochord and is detected in the floor plate of neurula embryos. Kielin is induced in mesoderm and in ectoderm by nodal-related genes. Chd is sufficient to activate Kielin expression in mesoderm whereas Shh or HNF-3β in addition to Chd is required for induction in ectoderm. Kielin has a distinct biological activity from that of Chd. Injection of Kielin mRNA causes dorsalization of ventral marginal zone explants and expansion of MyoD expression in neurula embryos. Unlike Chd, Kielin does not efficiently induce neural differentiation of animal cap ectoderm, suggesting that the activity of Kielin is not simply caused by BMP4 blockade. Kielin is a signaling molecule that mediates inductive activities of the embryonic midline.