Saturday, January 27, 2018

Preprint describes contribution of Drosophila double-knockdown assay to understanding 16p11.2 deletion syndrome

Pervasive epistasis in cell proliferation pathways modulates neurodevelopmental defects of autism-associated 16p11.2 deletion

Janani Iyer, Mayanglambam Dhruba Singh, Matthew Jensen, Payal Patel, Lucilla Pizzo, Emily Huber, Haley Koerselman, Alexis T. Weiner, Paola Lepanto, Komal Vadodaria, Alexis Kubina, Qingyu Wang, Abigail Talbert, Sneha Yennawar, Jose Badano, J. Robert Manak, Melissa M. Rolls, Arjun Krishnan, Santhosh Girirajan

From the abstract: "We used RNA interference in Drosophila melanogaster to evaluate the phenotype, function, and interactions of conserved 16p11.2 homologs ... Leveraging the Drosophila eye for studying gene interactions, we performed 561 pairwise knockdowns of gene expression, and identified 24 interactions between 16p11.2 homologs ... and 62 interactions with other neurodevelopmental genes ... Overall, these results point towards a new model for pathogenicity of rare CNVs, where CNV genes interact with each other in conserved pathways to modulate expression of the neurodevelopmental phenotype."

Tuesday, January 23, 2018

Methods report--using the fly eye to study Tau toxicity

Dourlen P. Identification of Tau Toxicity Modifiers in the Drosophila Eye. Methods Mol Biol. 2017;1523:375-389 PMID: 27975266.

The abstract: "Drosophila is a powerful model to study human diseases thanks to its genetic tools and ease of screening. Human genes can be expressed in targeted organs and their toxicity assessed on easily scorable external phenotypes that can be used as readout to perform genetic screen of toxicity modifiers. In this chapter, I describe how to express human Tau protein in the Drosophila eye, assess protein expression by western blot, assess Tau toxicity by quantifying the size of the Tau-induced rough eye, and perform a genetic screen of modifiers of Tau toxicity in the Drosophila eye."

Drosophila contributes to platform for identification of "tumor calibrated inhibitors"

Sonoshita M, Scopton AP, Ung PMU, Murray MA, Silber L, Maldonado AY, Real A, Schlessinger A, Cagan RL, Dar AC. A whole-animal platform to advance a clinical kinase inhibitor into new disease space. Nat Chem Biol. 2018 Jan 22. PMID: 29355849.

From the abstract: "Synthetic tailoring of approved drugs for new indications is often difficult ... Here, we report a multidisciplinary approach for accessing novel target and chemical space starting from an FDA-approved kinase inhibitor. By combining chemical and genetic modifier screening with computational modeling, we identify distinct kinases that strongly enhance ('pro-targets') or limit ('anti-targets') whole-animal activity of the clinical kinase inhibitor sorafenib in a Drosophila medullary thyroid carcinoma (MTC) model. ... Through progressive synthetic refinement, we report a new class of 'tumor calibrated inhibitors' with unique polypharmacology and strongly improved therapeutic index in fly and human MTC xenograft models. This platform provides a rational approach to creating new high-efficacy and low-toxicity drugs."

Wednesday, January 3, 2018

Drosophila model points to involvement of potassium channel in aging hearts

Klassen MP, Peters CJ, Zhou S, Williams HH, Jan LY, Jan YN. Age-dependent diastolic heart failure in an in vivo Drosophila model. Elife. 2017 Mar 22;6. pii: e20851. PMID: 28328397; PMCID: PMC5362267.

The abstract: "While the signals and complexes that coordinate the heartbeat are well established, how the heart maintains its electromechanical rhythm over a lifetime remains an open question with significant implications to human health. Reasoning that this homeostatic challenge confronts all pulsatile organs, we developed a high resolution imaging and analysis toolset for measuring cardiac function in intact, unanesthetized Drosophila melanogaster. We demonstrate that, as in humans, normal aging primarily manifests as defects in relaxation (diastole) while preserving contractile performance. Using this approach, we discovered that a pair of two-pore potassium channel (K2P) subunits, largely dispensable early in life, are necessary for terminating contraction (systole) in aged animals, where their loss culminates in fibrillatory cardiac arrest. As the pumping function of its heart is acutely dispensable for survival, Drosophila represents a uniquely accessible model for understanding the signaling networks maintaining cardiac performance during normal aging."

Drosophila gut as model for uncovering mechanisms of antimicrobial activity

Liu X, Hodgson JJ, Buchon N. Drosophila as a model for homeostatic,antibacterial, and antiviral mechanisms in the gut. PLoS Pathog. 2017 May 4;13(5):e1006277. PMID: 28472194; PMCID: PMC5417715.

This review article includes an illustrated comparison of fly and mammalian guts and their interactions with microbes such as bacteria and viruses.

Tuesday, January 2, 2018

Protocol for testing of candidate heart-disease genes in Drosophila

Zhu JY, Fu Y, Richman A, Han Z. Validating Candidate Congenital Heart Disease Genes in Drosophila. Bio Protoc. 2017 Jun 20;7(12). pii: e2350. PMID: 29276722; PMCID: PMC5739056.

From the abstract: "... A high throughput in vivo model system to validate candidate gene association with pathology is ... useful. We present such a system employing Drosophila to validate candidate congenital heart disease (CHD) genes. The protocols exploit comprehensive libraries of UAS-GeneX-RNAi fly strains ... These protocols were recently used to evaluate more than 100 candidate CHD genes implicated by patient whole-exome sequencing (Zhu et al., 2017)."

Protocol for infection of Drosophila with a parasite for research studies related to leishmaniasis

Okuda K, Silverman N. Drosophila Model of Leishmania amazonensis Infection. Bio Protoc. 2017 Dec 5;7(23). pii: e2640. PMID: 29276726; PMCID: PMC5738924.

The abstract: "This protocol describes how to generate and harvest antibody-free L. amazonensis amastigotes, and how to infect adult Drosophila melanogaster with these parasites. This model recapitulates key aspects of the interactions between Leishmania amastigotes and animal phagocytes."

Drosophila model of polycystic kidney disease leads to mechanistic insights

Gamberi C, Hipfner DR, Trudel M, Lubell WD. Bicaudal C mutation causes myc and TOR pathway up-regulation and polycystic kidney disease-like phenotypes in Drosophila. PLoS Genet. 2017 Apr 13;13(4):e1006694. PMID: 28406902; PMCID: PMC5390980.

The abstract: "Progressive cystic kidney degeneration underlies diverse renal diseases, including the most common cause of kidney failure, autosomal dominant Polycystic Kidney Disease (PKD). Genetic analyses of patients and animal models have identified several key drivers of this disease. The precise molecular and cellular changes underlying cystogenesis remain, however, elusive. Drosophila mutants lacking the translational regulator Bicaudal C (BicC, the fly ortholog of vertebrate BICC1 implicated in renal cystogenesis) exhibited progressive cystic degeneration of the renal tubules (so called "Malpighian" tubules) and reduced renal function. The BicC protein was shown to bind to Drosophila (d-) myc mRNA in tubules. Elevation of d-Myc protein levels was a cause of tubular degeneration in BicC mutants. Activation of the Target of Rapamycin (TOR) kinase pathway, another common feature of PKD, was found in BicC mutant flies. Rapamycin administration substantially reduced the cystic phenotype in flies. We present new mechanistic insight on BicC function and propose that Drosophila may serve as a genetically tractable model for dissecting the evolutionarily-conserved molecular mechanisms of renal cystogenesis."