End of the line? Tramtrack and cell fate determination in <i>Drosophila</i>

Badenhorst, Paul; Harrison, S.C.; Travers, Andrew

doi:10.1111/j.1365-2443.1996.tb00011.x

Cited by 10 publications

(4 citation statements)

References 65 publications

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“…Antibody staining of polytene chromosomes revealed that Ttk69 bound to a large number of euchromatic sites (Fig. 8A), an observation consistent with the pleiotropic nature of Ttk overexpression and loss-of-function phenotypes as well as with the developmentally complex Ttk expression profile (2,4,15,18). Similarly, many euchromatic sites were stained with antibody against dSmt3 (Fig.…”

Section: Fig 4 Dsmt3-protein Conjugates In Drosophila and Human Celmentioning

confidence: 55%

Covalent Modification of the Transcriptional Repressor Tramtrack by the Ubiquitin-Related Protein Smt3 in Drosophila Flies

Lehembre

Badenhorst

Müller

et al. 2000

Molecular and Cellular Biology

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The ubiquitin-related SUMO-1 modifier can be covalently attached to a variety of proteins. To date, four substrates have been characterized in mammalian cells: RanGAP1, IB␣, and the two nuclear body-associated PML and Sp100 proteins. SUMO-1 modification has been shown to be involved in protein localization and/or stabilization and to require the activity of specialized E1-activating and E2 Ubc9-conjugating enzymes. SUMO-1 homologues have been identified in various species and belong to the so-called Smt3 family of proteins. Here we have characterized the Drosophila homologues of mammalian SUMO-1 and Ubc9 (termed dSmt3 and dUbc9, respectively). We show that dUbc9 is the conjugating enzyme for dSmt3 and that dSmt3 can covalently modify a number of proteins in Drosophila cells in addition to the human PML substrate. The dSmt3 transcript and protein are maternally deposited in embryos, where the protein accumulates predominantly in nuclei. Similar to its human counterpart, dSmt3 protein is observed in a punctate nuclear pattern. We demonstrate that Tramtrack 69 (Ttk69), a repressor of neuronal differentiation, is a bona fide in vivo substrate for dSmt3 conjugation. Finally, we show that both the modified and unmodified forms of Ttk69 can bind to a Ttk69 binding site in vitro. Moreover, dSmt3 and Ttk69 proteins colocalize on polytene chromosomes, indicating that the dSmt3-conjugated Ttk69 species can bind at sites of Ttk69 action in vivo. Altogether, these data indicate a high conservation of the Smt3 conjugation pathway and further suggest that this mechanism may play a role in the transcriptional regulation of cell differentiation in Drosophila flies.Ubiquitination is a well-known process of posttranslational modification of proteins. The covalent conjugation of the small protein ubiquitin can regulate the function and the stability of its target proteins (for a review, see reference 7). The reaction involves the formation of an isopeptide bond between the carboxyl-terminal glycine residue of ubiquitin and the ε-amino group of a lysine residue of an acceptor protein. This covalent attachment is carried out by a multistep pathway. Initially, ubiquitin is activated by the ATP-dependent formation of a high-energy thioester intermediate between the ubiquitin-activating enzyme (E1) and the C terminus of ubiquitin. Next, ubiquitin is transferred from the E1 to a cysteine residue of a ubiquitin-conjugating enzyme (E2) through transacetylation.

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Section: Fig 4 Dsmt3-protein Conjugates In Drosophila and Human Celmentioning

confidence: 55%

Covalent Modification of the Transcriptional Repressor Tramtrack by the Ubiquitin-Related Protein Smt3 in Drosophila Flies

Lehembre

Badenhorst

Müller

et al. 2000

Molecular and Cellular Biology

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“…Such a function would be consistent with the developmental expression pattern of Ttk69. High levels of Ttk69 expression are detected towards the end of embryogenesis, when most cell types have already been specified and the chosen fate needs to be stabilized (Badenhorst et al ., 1996; Badenhorst, 2001). Our results imply in particular that dMi‐2 is involved in ttk ‐mediated neuronal repression.…”

Section: Discussionmentioning

confidence: 99%

Tramtrack69 interacts with the dMi‐2 subunit of the Drosophila NuRD chromatin remodelling complex

et al. 2001

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dMi-2, the ATPase subunit of the Drosophila nucleosome remodelling and histone deacetylation (dNuRD) complex, was identified in a two-hybrid screen as an interacting partner of the transcriptional repressor, Tramtrack69 (Ttk69). A short region of Ttk69 is sufficient to mediate this interaction. Ttk69, but not the Ttk88 isoform, co-purifies with the dNuRD complex isolated from embryo extracts. dMi-2 and Ttk69 coimmunoprecipitate from embryonic extracts, indicating that they can associate in vivo. Both dMi-2 and Ttk69 co-localize at a number of discrete sites on polytene chromosomes, showing that they bind common target loci. We also demonstrate that dMi-2 and Ttk interact genetically, indicating a functional interaction in vivo. We propose that Ttk69 represses some target genes by remodelling chromatin structure through the recruitment of the dNuRD complex.

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“…Indeed, eff is thought to play essential roles in telomere function (Cenci et al 2005). Eff biochemically interacts with the zinc-finger transcriptional repressor encoded by the tramtrack gene (ttk) (Badenhorst et al 1996;Tang et al 1997), whose mutations also suppress ISWI-EGUF eye phenotypes ( Figures 3A and 4A). Another gene that suppresses the ISWI-EGUF eye is multiprotein bridging factor 1 (mbf1) (Figures 3A and 4A).…”

Section: K159rmentioning

confidence: 99%

The Nucleosome Remodeling Factor ISWI Functionally Interacts With an Evolutionarily Conserved Network of Cellular Factors

et al. 2010

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ISWI is an evolutionarily conserved ATP-dependent chromatin remodeling factor playing central roles in DNA replication, RNA transcription, and chromosome organization. The variety of biological functions dependent on ISWI suggests that its activity could be highly regulated. Our group has previously isolated and characterized new cellular activities that positively regulate ISWI in Drosophila melanogaster. To identify factors that antagonize ISWI activity we developed a novel in vivo eye-based assay to screen for genetic suppressors of ISWI. Our screen revealed that ISWI interacts with an evolutionarily conserved network of cellular and nuclear factors that escaped previous genetic and biochemical analyses.

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End of the line? Tramtrack and cell fate determination in Drosophila

Cited by 10 publications

References 65 publications

Covalent Modification of the Transcriptional Repressor Tramtrack by the Ubiquitin-Related Protein Smt3 in Drosophila Flies

Covalent Modification of the Transcriptional Repressor Tramtrack by the Ubiquitin-Related Protein Smt3 in Drosophila Flies

Tramtrack69 interacts with the dMi‐2 subunit of the Drosophila NuRD chromatin remodelling complex

The Nucleosome Remodeling Factor ISWI Functionally Interacts With an Evolutionarily Conserved Network of Cellular Factors

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