Skeletogenesis by transfated secondary mesenchyme cells is dependent on extracellular matrix-ectoderm interactions in Paracentrotus lividus sea urchin embryos.
In the sea urchin embryo, primary mesenchyme cells (PMCs) are committed early in development to direct skeletogenesis, provided that a permissive signal is conveyed from adjacent ectoderm cells. We showed that inhibition of extracellular matrix (ECM)-ectoderm cells interaction, by monoclonal antibodies (mAb) to Pl-nectin, causes an impairment of skeletogenesis and reduced expression of Pl-SM30, a spicule-specific matrix protein. When PMCs are experimentally removed, some secondary mesenchyme cells (SMCs) switch to skeletogenic fate. Here, for the first time we studied SMC transfating in PMC-less embryos of Paracentrotus lividus. We observed the appearance of skeletogenic cells within 10 h of PMCs removal, as shown by binding of wheat germ agglutinin (WGA) to cell surface molecules unique to PMCs. Interestingly, the number of WGA-positive cells, expressing also msp130, another PMC-specific marker, doubled with respect to that of PMCs present in normal embryos, though the number of SM30-expressing cells remained constant. In addition, we investigated the ability of SMCs to direct skeletogenesis in embryos exposed to mAbs to Pl-nectin after removal of PMCs. We found that, although phenotypic SMC transfating occurred, spicule development, as well as Pl-SM30-expression was strongly inhibited. These results demonstrate that ectoderm inductive signals are necessary for transfated SMCs to express genes needed for skeletogenesis.
Kiyomoto
Masato
M
Tateyama Marine Laboratory, Marine and Coastal Research Center, Ochanomizu University, Kou-yatsu 11, Tateyama, Chiba 294-0301, Japan. kiyomoto@cc.ocha.ac.jp
Zito
Francesca
F
Costa
Caterina
C
Poma
Veronica
V
Sciarrino
Serafina
S
Matranga
Valeria
V
D000818:Animals; D002356:Cartilage / Q000196:embryology* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D038081:Organogenesis; D047328:Paracentrotus / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D003598:Cytoskeletal Proteins