Sutherland, David Jon (1995) An investigation of the role of rel family members in the early development of Xenopus laevis. PhD thesis, University of Warwick.

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Abstract

XrelA is a maternally expressed Xenopus member of the rel family of transcription factors which includes the Drosophila dorsal-ventral patterning gene dorsal. During the blastula stages XrelA becomes differentially localised to the nuclei of the animal hemisphere and marginal zone. Another rel family member, known as Xrel.2, which is also expressed maternally has been cloned recently, and is a likely endogenous heterodimerisation partner for XrelA. Various attempts have been made · previously to investigate the developmental role of XrelA. Over-expression of XrelA in embryos has dramatic phenotypic effects, but these are probably largely due to transcriptional squelching. The effects of over-expressing a dominant inhibitory variant ofXrelA lacking the transactivation domain, which acts by saturating DNA binding sites for XrelA homodimers, have also been characterised. However, the DNA binding specificity of XrelA present in XrelA!Xrel.2 heterodimers is likely to differ from this.

To avoid this problem, dominant inhibitory variants deficient in DNA binding activity, which act by sequestering wild-type protein into inactive complexes, were constructed from XrelA (XrelAΔSP) and human NFKB 1 (p50ΔiSP). Both clones are capable of inhibiting DNA binding and transactivation by exogenous XrelA and do not possess the squelching activity of wild-type XrelA. Three 1eB binding complexes have been detected in embryos, none of which contains XrelA. The activity of one of these complexes is inhibited by p50ΔiSP, but not by XrelAΔSP. Expression of XrelAΔiSP in embryos has dramatic phenotypic effects. This phenotype has been analysed in detail and exhibits some similarities to that caused by the dominant negative FGF receptor. The fact that expression of p50ΔiSP, or of a deletion of XrelAΔSP (XrelAΔ SP222), which lacks the transactivation domain, have no phenotypic effects suggests that the phenotype probably arises by some mechanism other than inhibition of XrelA, and that the transactivation domain is necessary to this mechanism. Future work might concentrate on the identification of factors interacting with this domain.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QL Zoology Q Science > QP Physiology
Library of Congress Subject Headings (LCSH):	Xenopus laevis, NF-kappa B (DNA-binding protein), DNA-binding proteins
Official Date:	September 1995
Dates:	Date Event September 1995 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Woodland, Hugh R.
Format of File:	pdf
Extent:	xiv, 188 pages : illustrations
Language:	eng

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