کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2173097 | 1093694 | 2013 | 11 صفحه PDF | دانلود رایگان |
Ci-MRF is the sole myogenic regulatory factor (MRF) of the ascidian Ciona intestinalis, an invertebrate chordate. In order to investigate its properties we developed a simple in vivo assay based on misexpressing Ci-MRF in the notochord of Ciona embryos. We used this assay to examine the roles of three structural motifs that are conserved among MRFs: an alanine–threonine (Ala–Thr) dipeptide of the basic domain that is known in vertebrates as the myogenic code, a cysteine/histidine-rich (C/H) domain found just N-terminal to the basic domain, and a carboxy-terminal amphipathic α-helix referred to as Helix III. We show that the Ala–Thr dipeptide is necessary for normal Ci-MRF function, and that while eliminating the C/H domain or Helix III individually has no demonstrable effect on Ci-MRF, simultaneous loss of both motifs significantly reduces its activity. Our studies also indicate that direct interaction between CiMRF and an essential E-box of Ciona Troponin I is required for the expression of this muscle-specific gene and that multiple classes of MRF-regulated genes exist in Ciona. These findings are consistent with substantial conservation of MRF-directed myogenesis in chordates and demonstrate for the first time that the Ala/Thr dipeptide of the basic domain of an invertebrate MRF behaves as a myogenic code.
► A simple, functional assay for studying CiMRF-the Ciona myogenic regulatory factor.
► The C/H domain and the C-terminal Helix III of CiMRF have partly redundant roles.
► As in vertebrate MRFs the myogenic code dipeptide is crucial for CiMRF activity.
► As in vertebrates multiple classes of MRF-regulated genes exist in Ciona.
► MRF-directed myogenesis is complex and highly conserved in the chordates.
Journal: Developmental Biology - Volume 376, Issue 2, 15 April 2013, Pages 213–223