Cloning, characterization and expression of two Xenopus bcl-2-like cell-survival genes.
We describe two cloned cDNAs, termed xR1 and xR11, isolated from a Xenopus laevis stage 28-30 embryonic head cDNA library. Comparison of amino acid (aa) sequences derived from nucleotide (nt) sequences of xR1 and xR11 cDNAs revealed substantial homology with bcl-2-related genes, especially with bcl-xL. In particular, there was a marked conservation of the BH1 and BH2 domains considered to be important for the anti-cell death and heterodimerisation properties of bcl-2. Constitutive expression of xR11 in cultured rat fibroblast (Rat-1) cells conferred a strong protection against cell death induced by the cytotoxic agents staurosporine and cycloheximide, by serum deprivation and specific deregulation of c-myc. Measurement of xR1 and xR11 mRNAs by RNase protection assay revealed similar widespread expression in Xenopus embryos and tadpoles. Except for an abrupt increase in the accumulation of xR1 and xR11 mRNAs in brains of mid-metamorphic and post-metamorphic tadpoles and adults, there was insignificant modulation of their expression in tissues undergoing total regression (tail) or morphogenesis (limb) during natural or thyroid hormone-induced metamorphosis. These findings raise the possibility of continuing expression of cell survival genes in tissues undergoing total regression during post-embryonic development.
Cruz-Reyes
J
J
Division of Developmental Biochemistry, National Institute for Medical Research, Mill Hill, London, UK.
Tata
J R
JR
D000470:Alkaloids / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D016895:Culture Media, Serum-Free; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology; D005809:Genes, Regulator / Q000235:genetics; D008969:Molecular Sequence Data; D009024:Morphogenesis; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics*; D011519:Proto-Oncogenes / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D019311:Staurosporine; D014018:Tissue Distribution; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics*; D051020:bcl-X Protein
D000470:Alkaloids; C494809:BCL2L1 protein, Xenopus; C489429:BCL2L2 protein, Xenopus; D016895:Culture Media, Serum-Free; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016271:Proto-Oncogene Proteins c-myc; D011994:Recombinant Proteins; D029867:Xenopus Proteins; D051020:bcl-X Protein; C069483:c-Myc1 protein, Xenopus; C069482:c-myc II protein, Xenopus; D003513:Cycloheximide; D019311:Staurosporine