The nuclear receptor homologue Ftz-F1 and the homeodomain protein Ftz are mutually dependent cofactors

Abstract

Nuclear hormone receptors and homeodomain proteins are two classes of transcription factor that regulate major developmental processes. Both depend on interactions with other proteins for specificity and activity. The Drosophila gene fushi tarazu (ftz), which encodes a homeodomain protein (Ftz), is required zygotically for the formation of alternate segments in the developing embryo. Here we show that the orphan nuclear receptor alphaFtz-F1 (ref. 3), which is deposited in the egg during oogenesis, is an obligatory cofactor for Ftz. The two proteins interact specifically and directly, both in vitro and in vivo, through a conserved domain in the Ftz polypeptide. This interaction suggests that other nuclear receptor/homeodomain protein interactions maybe important and common in developing organisms.

A comparison of invivo and invitro DNA-binding specificities suggests a new model for homeoprotein DNA binding in Drosophila embryos

“…Instead, these cofactors probably act in alternative ways. For example, our data indicate that conditions in the embryo modify the DNA-binding preferences of Eve and Ftz in essentially the same way ( Figure 7B); yet a cofactor important for Ftz activity in vivo, Ftz-F1, has no affect on eve function (Guichet et al, 1997;Yu et al, 1997). If the in vivo distribution of Eve and Ftz was determined primarily by cooperative DNA binding with cofactors, then another cofactor with the same DNA-binding specificity as Ftz-F1 would be required to position Eve in the same manner as Ftz.…”

Directionality of nucleocytoplasmic transport of the retroviral gag protein depends on sequential binding of karyopherins and viral RNA

“…For far Western blot analysis, KH3-importin.11 was immunoprecipitated from transfected QT6 cells using anti-HA antibody and detected by Western blotting. The blot was stripped and incubated with 0-6 M guanidinium-HCl (60,61). Purified protein H6.MA, H6.Gag.3h, or H6.NLS-GFP was used as a probe, incubated with appropriate antibodies, detected via Western blotting, and quantified using densitometry and ImageJ software.…”

Nuclear receptor BgFTZ‐F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica

“…In D. melanogaster, the ftz-f1 gene generates two isoforms differing only in their N-terminal part. The ␣FTZ-F1 isoform, from maternal origin, is only present during early embryonic development, where it regulates early segmentation through the interaction with the homeotic gene ftz (Guichet et al, 1997;Yu et al, 1997). The other isoform, ␤FTZ-F1, is detected during late embryogenesis and throughout the postembryonic development (Ueda et al, 1990;Sullivan and Thummel, 2003).…”