Fertilization regulates apoptosis of Ciona intestinalis extra-embryonic cells through thyroxine (T4)-dependent NF-kappaB pathway activation during early embryonic development.
In Ciona intestinalis, the elimination of extra-embryonic test cells during early stage of development is delayed by a fertilization signal. Test cells undergo a caspase-dependent apoptosis event repressed by thyroxine (T4)-activated NF-kappaB. When apoptosis was experimentally blocked, the hatching stage was delayed. The incubation of unfertilized eggs with a 1-h-fertilized egg extract or purified T4 restored apoptosis in test cells at a similar timing than found in fertilized eggs. Ciona expresses specific genes forming a functional IkappaB/NF-kappaB pathway. One, Ci-p65, was transiently induced upon fertilization via T4 and found to exert its anti-apoptotic role in test cells nuclei as well as in a reconstituted cell system. Blocking NF-kappaB activity by dexamethasone-induced overexpression of Ci-IkappaB abrogated the repression of apoptosis in test cells. Overall, the data are consistent for defining a central coupling role of both T4 and NF-kappaB during early embryo development.
Maury
Benoît
B
UMR 5539, Centre National de la Recherche Scientifique, Dynamique Moléculaire des Interactions Membranaires, Case courrier no. 107-Université Montpellier 2, France.
Martinand-Mari
Camille
C
Chambon
Jean-Philippe
JP
Soulé
Jonathan
J
Degols
Geneviève
G
Sahuquet
Alain
A
Weill
Mylène
M
Berthomieu
Arnaud
A
Fort
Philippe
P
Mangeat
Paul
P
Baghdiguian
Stephen
S
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002457:Cell Extracts / Q000494:pharmacology; D002467:Cell Nucleus / Q000737:chemistry; D002938:Ciona intestinalis / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D047108:Embryonic Development; D005306:Fertilization; D015870:Gene Expression; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D010063:Ovum / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction; D013974:Thyroxine / Q000378:metabolism* / Q000494:pharmacology; D015053:Zygote / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*
D061945:Caspase Inhibitors; D002457:Cell Extracts; D016328:NF-kappa B; D003907:Dexamethasone; D020169:Caspases; D013974:Thyroxine