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SpMyb functions as an intramodular repressor to regulate spatial expression of CyIIIa in sea urchin embryos

Coffman, James A. and Kirchhamer, Carmen V. and Harrington, Michael G. and Davidson, Eric H. (1997) SpMyb functions as an intramodular repressor to regulate spatial expression of CyIIIa in sea urchin embryos. Development, 124 (23). pp. 4717-4727. ISSN 0950-1991.

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The CyIIIa actin gene of Strongylocentrotus purpuratus is transcribed exclusively in the embryonic aboral ectoderm, under the control of 2.3 kb cis-regulatory domain that contains a proximal module that controls expression in early embryogenesis, and a middle module that controls expression in later embryogenesis. Previous studies demonstrated that the SpRunt-1 target site within the middle module is required for the sharp increase in CyIIIa transcription which accompanies differentiation of the aboral ectoderm, and that a negative regulatory region near the SpRunt-1 target site is required to prevent ectopic transcription in the oral ectoderm and skeletogenic mesenchyme. This negative regulatory region contains a consensus binding site for the myb family of transcription factors. In vitro DNA-binding experiments reveal that a protein in blastula-stage nuclei interacts specifically with the myb target site. Gene transfer experiments utilizing CyIIIa reporter constructs containing oligonucleotide substitutions indicate that this site is both necessary and sufficient to prevent ectopic expression of CyIIIa. Synthetic oligonucleotides containing the myb target site were used to purify a protein from sea urchin embryo nuclear extracts by affinity chromatography. This protein is immunoprecipitated by antibodies specific to the evolutionarily conserved myb domain, and amino acid sequences obtained from the purified protein were found to be identical to sequences within the myb domain. Sequence information was used to obtain cDNA clones of SpMyb, the S. purpuratus member of the myb family of transcription factors. Through interactions within the middle module, SpMyb functions to repress activation of CyIIIa in the oral ectoderm and skeletogenic mesenchyme.

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Harrington, Michael G.0000-0002-7923-8032
Additional Information:© 1997 The Company of Biologists Limited. Accepted 5 September 1997. The authors are indebted to Dr Joseph Lipsick (Stanford University Medical Center) for the kind gift of BP-2 antiserum. We thank Nicolette Halloran and Jina Yun for technical assistance, and Drs Ellen Rothenberg, Maria Arnone, and Leonard Bogarad for critical reviews of the manuscript. This work was supported by the Stowers Institute for Medical Research, by a grant from the NICHHD (HD-05753), and from NSF subcontract (STC DIR 8809719).
Funding AgencyGrant Number
Stowers Institute for Medical ResearchUNSPECIFIED
National Institute of Child Health and Human Development (NICHD)HD-05753
NSFSTC DIR 8809719
Subject Keywords:Strongylocentrotus purpuratus; myb; CyIIIa; transcriptional regulation; embryogenesis
Issue or Number:23
Record Number:CaltechAUTHORS:20120118-111148067
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Official Citation:SpMyb functions as an intramodular repressor to regulate spatial expression of CyIIIa in sea urchin embryos J.A. Coffman, C.V. Kirchhamer, M.G. Harrington, E.H. Davidson Development 1997 124: 4717-4727
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28829
Deposited By: Tony Diaz
Deposited On:19 Jan 2012 21:08
Last Modified:03 Oct 2019 03:35

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