SpRunt-1, a new member of the runt domain family of transcription factors, is a positive regulator of the aboral ectoderm-specific CyIIIA gene in sea urchin embryos.
In this paper we present a structural and functional characterization of a new sea urchin embryo transcription factor, SpRunt-1. This factor was isolated by means of its specific interaction with a cis-regulatory target site of the CyIIIa gene. Here we show that this target site, the P7I site, is required for normal embryonic activation of CyIIIa x CAT reporter gene constructs. An oligonucleotide affinity column bearing the P7I target site purifies a 21-kDa polypeptide from blastula-stage nuclear extracts, and the amino acid sequence obtained from this polypeptide was used to generate a nucleic acid probe with which the corresponding cDNA was cloned. The cDNA encodes an approximately 60-kDa protein, SpRunt-1, which includes a "runt domain" that is closely homologous to those of Drosophila and mammalian runt domain transcription factors. RNA and genomic blots show that SpRunt-1 is represented by a single embryonic transcript, encoded by one of possibly two runt-domain-containing genes. By RNA probe protection we found that transcripts of SpRunt-1 increase in concentration dramatically after the blastula stage of development, suggesting that the up-regulation of CyIIIa that occurs after blastula stage is a function of zygotically transcribed SpRunt-1. These results are discussed with reference to known features of the runt domain family of transcription factors.
Coffman
J A
JA
Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125, USA.
Kirchhamer
C V
CV
Harrington
M G
MG
Davidson
E H
EH
D000199:Actins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000737:chemistry; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012617:Sea Urchins / Q000196:embryology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*; D014158:Transcription, Genetic
D000199:Actins; D004268:DNA-Binding Proteins; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; C098677:SpRunt-1 protein, Strongylocentrotus purpuratus; D014157:Transcription Factors