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Developmental Cell Oct 2023The Hippo pathway is an evolutionarily conserved regulator of tissue growth that integrates inputs from both polarity and actomyosin networks. An upstream activator of...
The Hippo pathway is an evolutionarily conserved regulator of tissue growth that integrates inputs from both polarity and actomyosin networks. An upstream activator of the Hippo pathway, Kibra, localizes at the junctional and medial regions of the apical cortex in epithelial cells, and medial accumulation promotes Kibra activity. Here, we demonstrate that cortical Kibra distribution is controlled by a tug-of-war between apical polarity and actomyosin dynamics. We show that while the apical polarity network, in part via atypical protein kinase C (aPKC), tethers Kibra at the junctional cortex to silence its activity, medial actomyosin flows promote Kibra-mediated Hippo complex formation at the medial cortex, thereby activating the Hippo pathway. This study provides a mechanistic understanding of the relationship between the Hippo pathway, polarity, and actomyosin cytoskeleton, and it offers novel insights into how fundamental features of epithelial tissue architecture can serve as inputs into signaling cascades that control tissue growth, patterning, and morphogenesis.
Topics: Animals; Actomyosin; Cell Polarity; Drosophila; Drosophila Proteins; Hippo Signaling Pathway; Protein Serine-Threonine Kinases; Signal Transduction
PubMed: 37729921
DOI: 10.1016/j.devcel.2023.08.029 -
Science (New York, N.Y.) Jul 2023Gene expression is controlled by the precise activation and repression of transcription. Repression is mediated by specialized transcription factors (TFs) that recruit...
Gene expression is controlled by the precise activation and repression of transcription. Repression is mediated by specialized transcription factors (TFs) that recruit co-repressors (CoRs) to silence transcription, even in the presence of activating cues. However, whether CoRs can dominantly silence all enhancers or display distinct specificities is unclear. In this work, we report that most enhancers in can be repressed by only a subset of CoRs, and enhancers classified by CoR sensitivity show distinct chromatin features, function, TF motifs, and binding. Distinct TF motifs render enhancers more resistant or sensitive to specific CoRs, as we demonstrate by motif mutagenesis and addition. These CoR-enhancer compatibilities constitute an additional layer of regulatory specificity that allows differential regulation at close genomic distances and is indicative of distinct mechanisms of transcriptional repression.
Topics: Animals; Chromatin; Drosophila melanogaster; Drosophila Proteins; Enhancer Elements, Genetic; Gene Expression Regulation, Developmental; Repressor Proteins; Amino Acid Motifs
PubMed: 37440660
DOI: 10.1126/science.adf6149 -
Proteomics May 2024Drosophila melanogaster is a popular model organism to elucidate the molecular mechanisms that underlie the structure and function of the eye as well as the causes of...
Drosophila melanogaster is a popular model organism to elucidate the molecular mechanisms that underlie the structure and function of the eye as well as the causes of retinopathies, aging, light-induced damage, or dietary deficiencies. Large-scale screens have isolated genes whose mutation causes morphological and functional ocular defects, which led to the discovery of key components of the phototransduction cascade. However, the proteome of the Drosophila eye is poorly characterized. Here, we used GeLC-MS/MS to quantify 3516 proteins, including the absolute (molar) quantities of 43 proteins in the eye of adult male Drosophila reared on standard laboratory food. This work provides a generic and expandable resource for further genetic, pharmacological, and dietary studies.
Topics: Animals; Drosophila melanogaster; Proteome; Male; Drosophila Proteins; Tandem Mass Spectrometry; Eye; Eye Proteins; Proteomics
PubMed: 37963819
DOI: 10.1002/pmic.202300330 -
Nature Communications Aug 2023Binding of transcription factors (TFs) promotes the subsequent recruitment of coactivators and preinitiation complexes to initiate eukaryotic transcription, but this...
Binding of transcription factors (TFs) promotes the subsequent recruitment of coactivators and preinitiation complexes to initiate eukaryotic transcription, but this time course is usually not visualized. It is commonly assumed that recruited factors eventually co-reside in a higher-order structure, allowing distantly bound TFs to activate transcription at core promoters. We use live imaging of endogenously tagged proteins, including the pioneer TF Zelda, the coactivator dBrd4, and RNA polymerase II (RNAPII), to define a cascade of events upstream of transcriptional initiation in early Drosophila embryos. These factors are sequentially and transiently recruited to discrete clusters during activation of non-histone genes. Zelda and the acetyltransferase dCBP nucleate dBrd4 clusters, which then trigger pre-transcriptional clustering of RNAPII. Subsequent transcriptional elongation disperses clusters of dBrd4 and RNAPII. Our results suggest that activation of transcription by eukaryotic TFs involves a succession of distinct biomolecular condensates that culminates in a self-limiting burst of transcription.
Topics: Animals; Transcription Factors; Drosophila; Drosophila Proteins; RNA Polymerase II; Promoter Regions, Genetic; Transcription, Genetic; Transcriptional Activation
PubMed: 37563108
DOI: 10.1038/s41467-023-40485-6 -
ELife May 2024is a powerful model to study how lipids affect spermatogenesis. Yet, the contribution of neutral lipids, a major lipid group which resides in organelles called lipid...
is a powerful model to study how lipids affect spermatogenesis. Yet, the contribution of neutral lipids, a major lipid group which resides in organelles called lipid droplets (LD), to sperm development is largely unknown. Emerging evidence suggests LD are present in the testis and that loss of neutral lipid- and LD-associated genes causes subfertility; however, key regulators of testis neutral lipids and LD remain unclear. Here, we show LD are present in early-stage somatic and germline cells within the testis. We identified a role for triglyceride lipase () in regulating testis LD, and found that whole-body loss of leads to defects in sperm development. Importantly, these represent cell-autonomous roles for in regulating testis LD and spermatogenesis. Because lipidomic analysis of mutants revealed excess triglyceride accumulation, and spermatogenic defects in mutants were rescued by genetically blocking triglyceride synthesis, our data suggest that -mediated regulation of triglyceride influences sperm development. This identifies triglyceride as an important neutral lipid that contributes to sperm development, and reveals a key role for in regulating testis triglyceride levels during spermatogenesis.
Topics: Spermatogenesis; Animals; Male; Triglycerides; Drosophila Proteins; Testis; Drosophila melanogaster; Lipase; Lipid Droplets; Spermatozoa
PubMed: 38805376
DOI: 10.7554/eLife.87523 -
Cell Reports Jul 2023The ability to feed on a sugar-containing diet depends on a gene regulatory network controlled by the intracellular sugar sensor Mondo/ChREBP-Mlx, which remains...
The ability to feed on a sugar-containing diet depends on a gene regulatory network controlled by the intracellular sugar sensor Mondo/ChREBP-Mlx, which remains insufficiently characterized. Here, we present a genome-wide temporal clustering of sugar-responsive gene expression in Drosophila larvae. We identify gene expression programs responding to sugar feeding, including downregulation of ribosome biogenesis genes, known targets of Myc. Clockwork orange (CWO), a component of the circadian clock, is found to be a mediator of this repressive response and to be necessary for survival on a high-sugar diet. CWO expression is directly activated by Mondo-Mlx, and it counteracts Myc through repression of its gene expression and through binding to overlapping genomic regions. CWO mouse ortholog BHLHE41 has a conserved role in repressing ribosome biogenesis genes in primary hepatocytes. Collectively, our data uncover a cross-talk between conserved gene regulatory circuits balancing the activities of anabolic pathways to maintain homeostasis during sugar feeding.
Topics: Animals; Mice; Drosophila; Drosophila Proteins; Ribosomes; Sugars; Transcription Factors; Repressor Proteins
PubMed: 37405919
DOI: 10.1016/j.celrep.2023.112739 -
ELife Mar 2024A complete map of the external sense organs shows how fruit fly larvae detect different aspects of their environment.
A complete map of the external sense organs shows how fruit fly larvae detect different aspects of their environment.
Topics: Animals; Larva; Drosophila; Drosophila Proteins; Sense Organs; Emotions; Drosophila melanogaster
PubMed: 38456840
DOI: 10.7554/eLife.96708 -
EMBO Reports Jul 2023We report that preexisting (old) and newly synthesized (new) histones H3 and H4 are asymmetrically partitioned during the division of Drosophila intestinal stem cells...
We report that preexisting (old) and newly synthesized (new) histones H3 and H4 are asymmetrically partitioned during the division of Drosophila intestinal stem cells (ISCs). Furthermore, the inheritance patterns of old and new H3 and H4 in postmitotic cell pairs correlate with distinct expression patterns of Delta, an important cell fate gene. To understand the biological significance of this phenomenon, we expressed a mutant H3T3A to compromise asymmetric histone inheritance. Under this condition, we observe an increase in Delta-symmetric cell pairs and overpopulated ISC-like, Delta-positive cells. Single-cell RNA-seq assays further indicate that H3T3A expression compromises ISC differentiation. Together, our results indicate that asymmetric histone inheritance potentially contributes to establishing distinct cell identities in a somatic stem cell lineage, consistent with previous findings in Drosophila male germline stem cells.
Topics: Animals; Drosophila; Histones; Intestines; Cell Differentiation; Drosophila Proteins; Cell Division
PubMed: 37255015
DOI: 10.15252/embr.202256404 -
Proceedings of the National Academy of... Jul 2023Circadian behavioral rhythms in are regulated by about 75 pairs of brain neurons. They all express the core clock genes but have distinct functions and gene expression...
Circadian behavioral rhythms in are regulated by about 75 pairs of brain neurons. They all express the core clock genes but have distinct functions and gene expression profiles. To understand the importance of these distinct molecular programs, neuron-specific gene manipulations are essential. Although RNAi based methods are standard to manipulate gene expression in a cell-specific manner, they are often ineffective, especially in assays involving smaller numbers of neurons or weaker Gal4 drivers. We and others recently exploited a neuron-specific CRISPR-based method to mutagenize genes within circadian neurons. Here, we further explore this approach to mutagenize three well-studied clock genes: the transcription factor gene the photoreceptor gene (), and the neuropeptide gene (pigment dispersing factor). The CRISPR-based strategy not only reproduced their known phenotypes but also assigned function for different light-mediated phenotypes to discrete, different subsets of clock neurons. We further tested two recently published methods for temporal regulation in adult neurons, inducible Cas9 and the auxin-inducible gene expression system. The results were not identical, but both approaches successfully showed that the adult-specific knockout of the neuropeptide reproduces the canonical loss-of-function mutant phenotypes. In summary, a CRISPR-based strategy is a highly effective, reliable, and general method to temporally manipulate gene function in specific adult neurons.
Topics: Animals; Drosophila melanogaster; Drosophila Proteins; Circadian Rhythm; Neuropeptides; Cryptochromes; Neurons; Circadian Clocks
PubMed: 37428902
DOI: 10.1073/pnas.2303779120 -
Autophagy May 2024The selective clearance of unwanted, damaged or dangerous components by macroautophagy/autophagy is critical for maintaining cellular homeostasis in organisms from yeast...
The selective clearance of unwanted, damaged or dangerous components by macroautophagy/autophagy is critical for maintaining cellular homeostasis in organisms from yeast to humans. In recent years, significant progress has been made in understanding how phagophores selectively sequester specific cargo. Nevertheless, a fundamental question remains: Can distinct selective autophagy programs simultaneously operate within the same cell? A recent study from the Baehrecke lab has unveiled a developmentally programmed Pink1-dependent reticulophagy process in the Drosophila intestine. Furthermore, this study demonstrated that autophagy differentially clears mitochondria and ER in the same cell under the regulation of Pink1 through different E3 ubiquitin ligases, highlighting the need for further exploration in understanding the complexity of autophagic substrate selection and crosstalk between diverse autophagy programs.
Topics: Ubiquitin-Protein Ligases; Mitophagy; Animals; Humans; Drosophila Proteins; Autophagy; Protein Serine-Threonine Kinases; Mitochondria; Drosophila melanogaster
PubMed: 38456640
DOI: 10.1080/15548627.2024.2323294