Temporal regulation of the muscle gene cascade by Macho1 and Tbx6 transcription factors in Ciona intestinalis.
For over a century, muscle formation in the ascidian embryo has been representative of 'mosaic' development. The molecular basis of muscle-fate predetermination has been partly elucidated with the discovery of Macho1, a maternal zinc-finger transcription factor necessary and sufficient for primary muscle development, and of its transcriptional intermediaries Tbx6b and Tbx6c. However, the molecular mechanisms by which the maternal information is decoded by cis-regulatory modules (CRMs) associated with muscle transcription factor and structural genes, and the ways by which a seamless transition from maternal to zygotic transcription is ensured, are still mostly unclear. By combining misexpression assays with CRM analyses, we have identified the mechanisms through which Ciona Macho1 (Ci-Macho1) initiates expression of Ci-Tbx6b and Ci-Tbx6c, and we have unveiled the cross-regulatory interactions between the latter transcription factors. Knowledge acquired from the analysis of the Ci-Tbx6b CRM facilitated both the identification of a related CRM in the Ci-Tbx6c locus and the characterization of two CRMs associated with the structural muscle gene fibrillar collagen 1 (CiFCol1). We use these representative examples to reconstruct how compact CRMs orchestrate the muscle developmental program from pre-localized ooplasmic determinants to differentiated larval muscle in ascidian embryos.
Kugler
Jamie E
JE
Department of Cell and Developmental Biology, Weill Medical College of Cornell University, 1300 York Avenue, Box 60, New York, NY 10065, USA.
Gazdoiu
Stefan
S
Oda-Ishii
Izumi
I
Passamaneck
Yale J
YJ
Erives
Albert J
AJ
Di Gregorio
Anna
A
D000818:Animals; D002938:Ciona intestinalis / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004527:Egg Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D047108:Embryonic Development / Q000235:genetics; D024022:Fibrillar Collagens / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D024510:Muscle Development / Q000235:genetics; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D019076:Transgenes / Q000235:genetics
D004527:Egg Proteins; D024022:Fibrillar Collagens; D014157:Transcription Factors