title: Complex functions of Mef2 splice variants in the differentiation of endoderm and of a neuronal cell type in a sea anemone.
abstract: In triploblastic animals, mesoderm gives rise to many tissues and organs, including muscle. By contrast, the representatives of the diploblastic phylum Cnidaria (corals, sea anemones, jellyfish and hydroids) lack mesoderm but possess muscle. In vertebrates and insects, the transcription factor Mef2 plays a pivotal role in muscle differentiation; however, it is also an important regulator of neuron differentiation and survival. In the sea anemone Nematostella vectensis, an organism that lacks mesoderm but has muscles and neurons, Mef2 (Nvmef2) has been reported in single ectodermal cells of likely neural origin. To our surprise, we found that Nvmef2 is alternatively spliced, forming differentially expressed variants. Using morpholino-mediated knockdown and mRNA injection, we demonstrate that specific splice variants of Nvmef2 are required for the proliferation and differentiation of endodermal cells and for the development of ectodermal nematocytes, a neuronal cell type. Moreover, we identified a small conserved motif in the transactivation domain that is crucially involved in the endodermal function of Nvmef2. The identification of a crucial and conserved motif in the transactivation domain predicts a similarly important role in vertebrate Mef2 function. This is the first functional study of a determinant of several mesodermal derivatives in a diploblastic animal. Our data suggest that the involvement of alternative splice variants of Mef2 in endomesoderm and neuron differentiation predates the cnidarian-bilaterian split.
authors: Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria.
authors: Grigory
authors: G
authors: Genikhovich
authors: Ulrich
authors: U
authors: Technau
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D019070:Cell Lineage / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D004625:Embryo, Nonmammalian; D004707:Endoderm / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D064326:MEF2 Transcription Factors; D008954:Models, Biological; D060172:Morpholinos / Q000494:pharmacology; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D020033:Protein Isoforms / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012615:Sea Anemones / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
chemical_list: D064326:MEF2 Transcription Factors; D060172:Morpholinos; D018006:Myogenic Regulatory Factors; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms