1. The Ciona myogenic regulatory factor functions as a typical MRF but possesses a novel N-terminus that is essential for activity.
- Author
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Ratcliffe LE, Asiedu EK, Pickett CJ, Warburton MA, Izzi SA, and Meedel TH
- Subjects
- Amino Acid Sequence, Animals, Conserved Sequence, Endoderm embryology, Endoderm metabolism, Gene Expression Regulation, Developmental, Green Fluorescent Proteins metabolism, MicroRNAs genetics, MicroRNAs metabolism, Muscle Development genetics, Muscles metabolism, Notochord embryology, Notochord metabolism, Promoter Regions, Genetic genetics, Protein Domains, Structure-Activity Relationship, Ciona intestinalis genetics, Myogenic Regulatory Factors chemistry, Myogenic Regulatory Factors metabolism
- Abstract
Electroporation-based assays were used to test whether the myogenic regulatory factor (MRF) of Ciona intestinalis (CiMRF) interferes with endogenous developmental programs, and to evaluate the importance of its unusual N-terminus for muscle development. We found that CiMRF suppresses both notochord and endoderm development when it is expressed in these tissues by a mechanism that may involve activation of muscle-specific microRNAs. Because these results add to a large body of evidence demonstrating the exceptionally high degree of functional conservation among MRFs, we were surprised to discover that non-ascidian MRFs were not myogenic in Ciona unless they formed part of a chimeric protein containing the CiMRF N-terminus. Equally surprising, we found that despite their widely differing primary sequences, the N-termini of MRFs of other ascidian species could form chimeric MRFs that were also myogenic in Ciona. This domain did not rescue the activity of a Brachyury protein whose transcriptional activation domain had been deleted, and so does not appear to constitute such a domain. Our results indicate that ascidians have previously unrecognized and potentially novel requirements for MRF-directed myogenesis. Moreover, they provide the first example of a domain that is essential to the core function of an important family of gene regulatory proteins, one that, to date, has been found in only a single branch of the family., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2019
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