Decapentaplegic is required for arrest in G1 phase during Drosophila eye development

During eye development in Drosophila, cell cycle progression is coordinated with differentiation. Prior to differentiation, cells arrest in G1 phase anterior to and within the morphogenetic furrow. We show that Decapentaplegic (Dpp), a TGF-&bgr; family member, is required to establish this G1 arrest, since Dpp-unresponsive cells located in the anterior half of the morphogenetic furrow show ectopic S phases and ectopic expression of the cell cycle regulators Cyclins A, E and B. Conversely, ubiquitous over-expression of Dpp in the eye imaginal disc transiently inhibits S phase without affecting Cyclin E or Cyclin A abundance. This Dpp-mediated inhibition of S phase occurs independently of the Cyclin A inhibitor Roughex and of the expression of Dacapo, a Cyclin E-Cdk2 inhibitor. Furthermore, Dpp-signaling genes interact genetically with a hypomorphic cyclin E allele. Taken together our results suggest that Dpp acts to induce G1 arrest in the anterior part of the morphogenetic furrow by a novel inhibitory mechanism. In addition, our results provide evidence for a Dpp-independent mechanism that acts in the posterior part of the morphogenetic furrow to maintain G1 arrest

Myc-Dependent Genome Instability and Lifespan in Drosophila

The Myc family of transcription factors are key regulators of cell growth and proliferation that are dysregulated in a large number of human cancers. When overexpressed, Myc family proteins also cause genomic instability, a hallmark of both transformed and aging cells. Using an in vivo lacZ mutation reporter, we show that overexpression of Myc in Drosophila increases the frequency of large genome rearrangements associated with erroneous repair of DNA double-strand breaks (DSBs). In addition, we find that overexpression of Myc shortens adult lifespan and, conversely, that Myc haploinsufficiency reduces mutation load and extends lifespan. Our data provide the first evidence that Myc may act as a pro-aging factor, possibly through its ability to greatly increase genome instability

Essential Functions of the Histone Demethylase Lid

Drosophila Little imaginal discs (Lid) is a recently described member of the JmjC domain class of histone demethylases that specifically targets trimethylated histone H3 lysine 4 (H3K4me3). To understand its biological function, we have utilized a series of Lid deletions and point mutations to assess the role that each domain plays in histone demethylation, in animal viability, and in cell growth mediated by the transcription factor dMyc. Strikingly, we find that lid mutants are rescued to adulthood by either wildtype or enzymatically inactive Lid expressed under the control of its endogenous promoter, demonstrating that Lid's demethylase activity is not essential for development. In contrast, ubiquitous expression of UAS-Lid transgenes lacking its JmjN, C-terminal PHD domain, and C5HC2 zinc finger were unable to rescue lid homozygous mutants, indicating that these domains carry out Lid's essential developmental functions. Although Lid-dependent demethylase activity is not essential, dynamic removal of H3K4me3 may still be an important component of development, as we have observed a genetic interaction between lid and another H3K4me3 demethylase, dKDM2. We also show that Lid's essential C-terminal PHD finger binds specifically to di- and trimethylated H3K4 and that this activity is required for Lid to function in dMyc-induced cell growth. Taken together, our findings highlight the importance of Lid function in the regulated removal and recognition of H3K4me3 during development

Identification of novel G1 to S phase regulators in Drosophila / by Julie Secombe.

Bibliography: p. 143-160.160 p., [66] leaves, [30] leaves of plates : ill. (some col.) ; 30 cm.Focusses on identifying genes involved in the regulation of Cyclin E transcription or function during Drosophila development.Thesis (Ph.D.)--University of Adelaide, Dept. of Chemistry, 199

The Histone Demethylase KDM5 Activates Gene Expression by Recognizing Chromatin Context through Its PHD Reader Motif

KDM5 family proteins are critically important transcriptional regulators whose physiological functions in the context of a whole animal remain largely unknown. Using genome-wide gene expression and binding analyses in Drosophila adults, we demonstrate that KDM5 (Lid) is a direct regulator of genes required for mitochondrial structure and function. Significantly, this occurs independently of KDM5’s well-described JmjC domain-encoded histone demethylase activity. Instead, it requires the PHD motif of KDM5 that binds to histone H3 that is di- or trimethylated on lysine 4 (H3K4me2/3). Genome-wide, KDM5 binding overlaps with the active chromatin mark H3K4me3, and a fly strain specifically lacking H3K4me2/3 binding shows defective KDM5 promoter recruitment and gene activation. KDM5 therefore plays a central role in regulating mitochondrial function by utilizing its ability to recognize specific chromatin contexts. Importantly, KDM5-mediated regulation of mitochondrial activity is likely to be key in human diseases caused by dysfunction of this family of proteins

Myc: a weapon of mass destruction.

Growth and proliferation potentiated by deregulated myc oncogene expression is balanced by myc-induced apoptosis. Abrogation of this apoptotic pathway in Myc overexpressing cells leads to cancer progression. Recent work has shown that cell clones in the Drosophila wing disc with higher dMyc expression levels act as supercompetitors to potentiate the programmed death of surrounding normal cells. Yet another paper identifies dE2F1 as a critical component of pathways that normally restrict the ability of growth perturbing genes like dMyc to cause organ overgrowth

The Trithorax group protein Lid is a trimethyl histone H3K4 demethylase required for dMyc-induced cell growth.

The Myc oncoprotein is a potent inducer of cell growth, cell cycle progression, and apoptosis. While many direct Myc target genes have been identified, the molecular determinants of Myc's transcriptional specificity remain elusive. We have carried out a genetic screen in Drosophila and identified the Trithorax group protein Little imaginal discs (Lid) as a regulator of dMyc-induced cell growth. Lid binds to dMyc and is required for dMyc-induced expression of the growth regulatory gene Nop60B. The mammalian Lid orthologs, Rbp-2 (JARID1A) and Plu-1 (JARID1B), also bind to c-Myc, indicating that Lid-Myc function is conserved. We demonstrate that Lid is a JmjC-dependent trimethyl H3K4 demethylase in vivo and that this enzymatic activity is negatively regulated by dMyc, which binds to Lid's JmjC domain. Because Myc binding is associated with high levels of trimethylated H3K4, we propose that the Lid-dMyc complex facilitates Myc binding to, or maintenance of, this chromatin context

KDM5 Interacts with Foxo to Modulate Cellular Levels of Oxidative Stress

<div><p>Increased cellular levels of oxidative stress are implicated in a large number of human diseases. Here we describe the transcription co-factor KDM5 (also known as Lid) as a new critical regulator of cellular redox state. Moreover, this occurs through a novel KDM5 activity whereby it alters the ability of the transcription factor Foxo to bind to DNA. Our microarray analyses of <i>kdm5</i> mutants revealed a striking enrichment for genes required to regulate cellular levels of oxidative stress. Consistent with this, loss of <i>kdm5</i> results in increased sensitivity to treatment with oxidizers, elevated levels of oxidized proteins, and increased mutation load. KDM5 activates oxidative stress resistance genes by interacting with Foxo to facilitate its recruitment to KDM5-Foxo co-regulated genes. Significantly, this occurs independently of KDM5's well-characterized demethylase activity. Instead, KDM5 interacts with the lysine deacetylase HDAC4 to promote Foxo deacetylation, which affects Foxo DNA binding.</p></div

KDM5 directly regulates oxidative stress resistance genes.

<p>(A) Real-time PCR analyses of <i>4E-BP</i>, <i>l(2)efl</i>, <i>CG5316</i>, <i>spirit</i>, <i>Prx2540-2</i> and <i>CG10211</i> from wildtype (<i>w¹¹¹⁸</i>), <i>kdm5^K6801</i> mutant and <i>foxo²¹</i> mutant 3^rd instar larvae in 5% sucrose or 20 mM paraquat/5% sucrose for six hours (oxidative stress). (B) Schematic of the promoters of <i>4E-BP</i>, <i>l(2)efl</i>, <i>CG5316</i>, <i>spirit</i>, <i>Prx2540-2</i> and <i>CG10211</i> showing the position of the Foxo binding site (FHREs; black boxes). Primers surrounding these sites were used for ChIP analyses shown in parts C and D. (C) ChIP analyses of <i>4E-BP</i>, <i>l(2)efl</i>, <i>CG5316</i>, <i>spirit</i>, <i>Prx2540-2</i> and <i>CG10211</i>. Anti-Foxo ChIP is shown in black bars while control anti-Foxo ChIP from <i>foxo²¹</i> homozygous mutant larvae is shown in grey. Data are shown as % of input DNA. All six genes tested show significant attenuation of anti-Foxo ChIP signal (<i>p</i><<0.01). (D) ChIP analyses of <i>4E-BP</i>, <i>l(2)efl</i>, <i>CG5316</i>, <i>spirit</i>, <i>Prx2540-2</i> and <i>CG10211</i>. Anti-KDM5 ChIP is shown in black bars while control anti-KDM5 ChIP from <i>kdm5^K6801</i> homozygous mutant larvae is shown in grey. Data are shown as % of input DNA. All six genes tested show significant attenuation of anti-KDM5 ChIP signal (<i>p</i><<0.01).</p

DVT: a high-throughput analysis pipeline for locomotion and social behavior in adult Drosophila melanogaster

Abstract Background Drosophila melanogaster is excellent animal model for understanding the molecular basis of human neurological and motor disorders. The experimental conditions and chamber design varied between studies. Moreover, most previously established paradigms focus on fly trace detection algorithm development. A comprehensive understanding on how fly behaves in the chamber is still lacking. Results In this report, we established 74 unique behavior metrics quantifying spatiotemporal characteristics of adult fly locomotion and social behaviors, of which 49 were newly proposed. By the aiding of the developed analysis pipeline, Drosophila video tracking (DVT), we identified siginificantly different patterns of fly behavior confronted with different chamber height, fly density, illumination and experimental time. Meanwhile, three fly strains which are widely used as control lines, Canton-S(CS), w 1118 and Oregon-R (OR), were found to exhibit distinct motion explosiveness and exercise endurance. Conclusions We believe the proposed behavior metrics set and pipeline should help identify subtle spatial and temporal differences of drosophila behavior confronted with different environmental factors or gene variants