In X. laevis embryos high levels of the anti-apoptotic factor p27BBP/eIF6 are stage-dependently found in BrdU and TUNEL-reactive territories.
p27BBP/eIF6 (β4 binding protein/eukaryotic initiation factor 6) is a highly conserved protein necessary for cell life. In adult eIF6 mice, a 50% decrease in the protein levels in all tissues is accompanied by a reduction in cell proliferation only in the liver, fat cells and cultured fibroblasts. During X. laevis embryogenesis expression of p27BBP/eIF6 is abundant in high proliferative territories. However, in Xenopus cell proliferation appears unaffected following p27BBP/eIF6 over-expression or down-regulation. Indeed, p27BBP/eIF6 is an anti-apoptotic factor acting upstream of Bcl2 that reduces endogenous apoptosis. We studied p27BBP/eIF6 protein localization in wild type embryos and compared it to proliferation and apoptosis. At the beginning of embryogenesis, high levels of p27BBP/eIF6, proliferation and apoptosis overlap. In later development stages high proliferation levels are present in the same regions where higher p27BBP/eIF6 expression is observed, while apoptosis does not appear specifically concentrated in the same sites. The higher presence of p27BBP/eIF6 would appear related to an increased need of apoptosis control in the regions where cell death is essential for normal development.
De Marco
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Department of Structural and Functional Biology, University of Naples Federico II, Naples, Italy. nademarc@unina.it
Campanella
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Carotenuto
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R
D000818:Animals; D017209:Apoptosis; D001973:Bromodeoxyuridine / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D016923:Cell Death; D049109:Cell Proliferation; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D047108:Embryonic Development; D039642:Eukaryotic Initiation Factors; D005455:Fluorescent Antibody Technique; D020287:In Situ Nick-End Labeling; D007381:Intermediate Filament Proteins / Q000032:analysis / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000032:analysis / Q000378:metabolism*; D029867:Xenopus Proteins / Q000032:analysis / Q000378:metabolism*; D014982:Xenopus laevis
D002352:Carrier Proteins; D039642:Eukaryotic Initiation Factors; D007381:Intermediate Filament Proteins; D010448:Peptide Initiation Factors; D029867:Xenopus Proteins; C021019:eIF-6; C504182:eIF6 protein, Xenopus; D001973:Bromodeoxyuridine