Reactivation of developmental programs: the cAMP-response element-binding protein pathway is involved in hydra head regeneration.
Hydra regenerate throughout their life. We previously described early modulations in cAMP-response element-binding protein (CREB) DNA-binding activity during regeneration. We now show that the Ser-67 residue located in the P-box is a target for post-translational regulation. The antihydra CREB antiserum detected CREB-positive nuclei distributed in endoderm and ectoderm, whereas the phosphoSer133-CREB antibody detected phospho-CREB-positive nuclei exclusively in endodermal cells. During early regeneration, we observed a dramatic increase in the number of phospho-CREB-positive nuclei in head-regenerating tips, exceeding 80% of the endodermal cells. We identified among CREB-binding kinases the p80 kinase, which showed an enhanced activity and a hyperphosphorylated status during head but not foot regeneration. According to biochemical and immunological evidence, this p80 kinase belongs to the Ribosomal protein S6 kinase family. Exposure to the U0126 mitogen-activated protein kinase kinase inhibitor inhibited head but not foot regeneration, abolished CREB phosphorylation and activation of the early gene HyBra1 in head-regenerating tips. These data support a role for the mitogen-activated protein kinase/ribosomal protein S6 kinase/CREB pathway in hydra head organizer activity.
Department of Zoology and Animal Biology, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
Kostas
K
Kaloulis
Simona
S
Chera
Monika
M
Hassel
Dominique
D
Gauchat
Brigitte
B
Galliot
D000595:Amino Acid Sequence; D000818:Animals; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006257:Head; D006829:Hydra / Q000254:growth & development / Q000502:physiology*; D007700:Kinetics; D016350:Leucine Zippers / Q000235:genetics; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D012038:Regeneration / Q000502:physiology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D017362:Cyclic AMP Response Element-Binding Protein; D010750:Phosphoproteins