title: Specific expression of a TRIM-containing factor in ectoderm cells affects the skeletal morphogenetic program of the sea urchin embryo.
abstract: In the indirect developing sea urchin embryo, the primary mesenchyme cells (PMCs) acquire most of the positional and temporal information from the overlying ectoderm for skeletal initiation and growth. In this study, we characterize the function of the novel gene strim1, which encodes a tripartite motif-containing (TRIM) protein, that adds to the list of genes constituting the epithelial-mesenchymal signaling network. We report that strim1 is expressed in ectoderm regions adjacent to the bilateral clusters of PMCs and that its misexpression leads to severe skeletal abnormalities. Reciprocally, knock down of strim1 function abrogates PMC positioning and blocks skeletogenesis. Blastomere transplantation experiments establish that the defects in PMC patterning, number and skeletal growth depend upon strim1 misexpression in ectoderm cells. Furthermore, clonal expression of strim1 into knocked down embryos locally restores skeletogenesis. We also provide evidence that the Otp and Pax2/5/8 regulators, as well as FGFA, but not VEGF, ligand act downstream to strim1 in ectoderm cells, and that strim1 triggers the expression of the PMC marker sm30, an ectoderm-signaling dependent gene. We conclude that the strim1 function elicits specific gene expression both in ectoderm cells and PMCs to guide the skeletal biomineralization during morphogenesis.
authors: Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari STEMBIO, Università di Palermo, Viale delle Scienze Edificio 16, 90128 Palermo, Italy. vincenzo.cavalieri@unipa.it
authors: Vincenzo
authors: V
authors: Cavalieri
authors: Rosa
authors: R
authors: Guarcello
authors: Giovanni
authors: G
authors: Spinelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001757:Blastomeres / Q000166:cytology; D001846:Bone Development; D001842:Bone and Bones / Q000196:embryology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002465:Cell Movement; D018076:DNA, Complementary / Q000378:metabolism; D004475:Ectoderm / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008024:Ligands; D008648:Mesoderm / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012617:Sea Urchins; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D008024:Ligands