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Induction of cytoplasmic factors that bind to the 3' AU‐rich region of human Interferon β mRNA during early development of Xenopus laevis
Author(s) -
Grafi Gideon,
Galili Gad
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80846-m
Subject(s) - xenopus , blastula , messenger rna , biology , heterologous , cytoplasm , microbiology and biotechnology , embryogenesis , human fertilization , embryo , protein biosynthesis , gene , gastrulation , biochemistry , genetics
Certain endogenous Xenopus mRNAs, carrying a destabilizing 3' AU‐rich sequence, are unusually very stable in oocytes and become unstable only after fertilization. In addition, heterologous short lived mRNA, containing 3' AU‐rich sequences, appear to be very stable when injected into Xenopus oocytes. In the present study, a human interferon β (hu‐IFNβ) mRNA, carrying the destabilizing 3' AU‐rich element, was used as a probe to identify Xenopus proteins that specifically bind to the 3' AU‐rich element as well as to study their relative levels during early embryonic development. While three major proteins that specifically bind to the 3' AU‐rich element were detected in human SV80 cells, that naturally express hu‐IFNβ (proteins termed AU‐F1, F2 and F3), only two proteins, migrating similarly to the SV80 AU‐F1 and AU‐F3, were detected in cytoplasmic extracts from Xenopus oocytes or eggs. Following fertilization, the intensity of the Xenopus AU‐F1 and AU‐F3 proteins increased considerably and a new protein, corresponding to SV80 AU‐F2, was also detected. Cyclohexamide applied either at the morula or at the early blastula stages reduced the intensity of the AU‐binding factors, while actinomycin D did not, indicating that the levels of these factors during these stages are regulated posttranscriptionally. In contrast, application of each of these metabolic inhibitors at the late blastula stage increased the intensity of the AU‐binding proteins. The possible function of these AU‐binding factors in regulating the expression and half life of AU‐rich mRNAs is discussed.