Monday, November 4, 2019

Experiments in Drosophila contribute to study of human gene variants associated with an early onset epileptic encephalopathy

Suzuki H, Yoshida T, Morisada N, Uehara T, Kosaki K, Sato K, Matsubara K, Takano-Shimizu T, Takenouchi T. De novo NSF mutations cause early infantile epileptic encephalopathy. Ann Clin Transl Neurol. 2019 Nov 1. doi: 10.1002/acn3.50917. PubMed PMID: 31675180.

Abstract: "N-ethylmaleimide-sensitive factor (NSF) plays a critical role in intracellular vesicle transport, which is essential for neurotransmitter release. Herein, we, for the first time, document human monogenic disease phenotype of de novo pathogenic variants in NSF, that is, epileptic encephalopathy of early infantile onset. When expressed in the developing eye of Drosophila, the mutant NSF severely affected eye development, while the wild-type allele had no detectable effect under the same conditions. Our findings suggest that the two pathogenic variants exert a dominant negative effect. De novo heterozygous mutations in the NSF gene cause early infantile epileptic encephalopathy."

Wednesday, October 30, 2019

Fly study related to distal hereditary motor neuropathy

Kang KH, Han JE, Hong YB, Nam SH, Choi BO, Koh H. Human HSPB1 mutation recapitulates features of distal hereditary motor neuropathy (dHMN) in Drosophila. Biochem Biophys Res Commun. 2019 Oct 17. pii: S0006-291X(19)32012-1. PubMed PMID: 31630804.

Abstract: "Distal hereditary motor neuropathies (dHMN) are a group of inherited peripheral nerve disorders characterized by length-dependent motor neuron weakness and subsequent muscle atrophy. Missense mutations in the gene encoding small heat shock protein HSPB1 (HSP27) have been associated with hereditary neuropathies including dHMN. HSPB1 is a member of the small heat shock protein (sHSP) family characterized by a highly conserved α-crystallin domain that is critical to their chaperone activity. In this study, we modeled HSPB1 mutant-induced neuropathies in Drosophila using a human HSPB1S135F mutant that has a missense mutation in its α-crystallin domain. Overexpression of the HSPB1 mutant produced no significant defect in the Drosophila development, however, a partial reduction in the life span was observed. Further, the HSPB1 mutant gene induced an obvious loss of motor activity when expressed in Drosophila neurons. Moreover, suppression of histone deacetylase 6 (HDAC6) expression, which has critical roles in HSPB1 mutant-induced axonal defects, successfully rescued the motor defects in the HSPB1 mutant Drosophila model."

Friday, October 11, 2019

Drosophila studies help identify and understand role of the CSDE1 gene in an autism-related syndrome

Guo H, Li Y, Shen L, Wang T, Jia X, Liu L, Xu T, Ou M, Hoekzema K, Wu H, et al. Disruptive variants of CSDE1 associate with autism and interfere with neuronal development and synaptic transmission. Sci Adv. 2019 Sep 25;5(9):eaax2166. PubMed PMID: 31579823; PubMed Central PMCID: PMC6760934.

Abstract: "RNA binding proteins are key players in posttranscriptional regulation and have been implicated in neurodevelopmental and neuropsychiatric disorders. Here, we report a significant burden of heterozygous, likely gene-disrupting variants in CSDE1 (encoding a highly constrained RNA binding protein) among patients with autism and related neurodevelopmental disabilities. Analysis of 17 patients identifies common phenotypes including autism, intellectual disability, language and motor delay, seizures, macrocephaly, and variable ocular abnormalities. HITS-CLIP revealed that Csde1-binding targets are enriched in autism-associated gene sets, especially FMRP targets, and in neuronal development and synaptic plasticity-related pathways. Csde1 knockdown in primary mouse cortical neurons leads to an overgrowth of the neurites and abnormal dendritic spine morphology/synapse formation and impaired synaptic transmission, whereas mutant and knockdown experiments in Drosophila result in defects in synapse growth and synaptic transmission. Our study defines a new autism-related syndrome and highlights the functional role of CSDE1 in synapse development and synaptic transmission."

Monday, October 7, 2019

New drug target for renal cancer identified based on fly and human studies--work from the lab of 2019 Nobel prize winner W. Kaelin

Nicholson HE, Tariq Z, Housden BE, Jennings RB, Stransky LA, Perrimon N, Signoretti S, Kaelin WG Jr. HIF-independent synthetic lethality between CDK4/6 inhibition and VHL loss across species. Sci Signal. 2019 Oct 1;12(601). PubMed PMID: 31575731.

Abstract: "Inactivation of the VHL tumor suppressor gene is the signature initiating event in clear cell renal cell carcinoma (ccRCC), the most common form of kidney cancer, and causes the accumulation of hypoxia-inducible factor 2α (HIF-2α). HIF-2α inhibitors are effective in some ccRCC cases, but both de novo and acquired resistance have been observed in the laboratory and in the clinic. Here, we identified synthetic lethality between decreased activity of cyclin-dependent kinases 4 and 6 (CDK4/6) and VHL inactivation in two species (human and Drosophila) and across diverse human ccRCC cell lines in culture and xenografts. Although HIF-2α transcriptionally induced the CDK4/6 partner cyclin D1, HIF-2α was not required for the increased CDK4/6 requirement of VHL-/- ccRCC cells. Accordingly, the antiproliferative effects of CDK4/6 inhibition were synergistic with HIF-2α inhibition in HIF-2α-dependent VHL-/- ccRCC cells and not antagonistic with HIF-2α inhibition in HIF-2α-independent cells. These findings support testing CDK4/6 inhibitors as treatments for ccRCC, alone and in combination with HIF-2α inhibitors."

Review: "Insights from Drosophila melanogaster model of Alzheimer's disease"

Tue NT, Dat TQ, Ly LL, Anh VD, Yoshida H. Insights from Drosophila melanogaster model of Alzheimer's disease. Front Biosci (Landmark Ed). 2020 Jan 1;25:134-146. PubMed PMID: 31585881.

Abstract: "Alzheimer's disease (AD) is a common chronic neurodegenerative disease that mainly affects the medial temporal lobe and associated neocortical structures. The disease process involves two abnormal structures, plaques and tangles, which damage and destroy nerve cells. Tangles are twisted fibers of tau protein that build up inside cells. Plaques are deposits of a protein fragment called amyloid-beta (Aβ) that accumulate in the spaces between nerve cells. Aβ derives from the amyloid precursor protein and is the main component of amyloid plaques in the AD brain. Although AD has been extensively examined, its pathogenetic mechanisms remain unclear and there are currently no effective drugs for this disorder. Many AD model systems have recently been established using Drosophila melanogaster by expressing the proteins involved in AD in the brain. These systems successfully reflect some of the symptoms associated with AD such as the onset of learning defects, age-dependent short-term memory impairment, increase of wakefulness and consolidated sleep disruption by expressing human Aβ42 or human APP/BACE in Drosophila central nervous system. We herein discuss these Drosophila AD models."

Tuesday, October 1, 2019

Study related to kidney disease uses flies as in vivo test model for follow-up of genes identified in a human cell-based screen

Cina DP, Ketela T, Brown KR, Chandrashekhar M, Mero P, Li C, Onay T, Fu Y, Han Z, Saleem MA, Moffat J, Quaggin SE. Forward genetic screen in human podocytes identifies diphthamide biosynthesis genes as regulators of adhesion. Am J Physiol Renal Physiol. 2019 Sep 30. doi: 10.1152/ajprenal.00195.2019. PubMed PMID: 31566424.

From the abstract: "... To identify novel genes that are important for podocyte function, we designed an in vitro genetic screen based on podocyte adhesion to plates coated with either fibronectin or soluble FLT1/Fc. .. A genome-scale pooled RNA interference screen on immortalized human podocytes identified 77 genes that increased adhesion to fibronectin, 101 genes that increased adhesion to sFLT1/Fc, and 44 genes that increased adhesion to both substrates when knocked down. Multiple shRNAs against each of DPH1, DPH2, DPH3, and DPH4 were top hits ... We then used CRISPR-Cas9 to generate podocyte knockout cells for DPH1, DPH2, or DPH3 which also displayed increased adhesion ... as well as a spreading defect. Last, we showed that Drosophila nephrocyte-specific knock-down of Dph1, Dph2, and Dph4 results in altered nephrocyte function. ... Given the central role of podocyte adhesion as a marker of podocyte health, these data are a rich source of candidate regulators of glomerular disease."

'Multilayered' approach to study of Huntington Disease includes testing in fly HD models

Al-Ramahi I, Lu B, Di Paola S, Pang K, de Haro M, Peluso I, Gallego-Flores T, Malik NT, Erikson K, Bleiberg BA, Avalos M, Fan G, Rivers LE, Laitman AM, Diaz-García JR, Hild M, Palacino J, Liu Z, Medina DL, Botas J. High-Throughput Functional Analysis Distinguishes Pathogenic, Nonpathogenic, and Compensatory Transcriptional Changes in Neurodegeneration. Cell Syst. 2018 Jul 25;7(1):28-40.e4. PubMed PMID: 29936182; PubMed Central PMCID: PMC6082401.

Abstract: "Discriminating transcriptional changes that drive disease pathogenesis from nonpathogenic and compensatory responses is a daunting challenge. This is particularly true for neurodegenerative diseases, which affect the expression of thousands of genes in different brain regions at different disease stages. Here we integrate functional testing and network approaches to analyze previously reported transcriptional alterations in the brains of Huntington disease (HD) patients. We selected 312 genes whose expression is dysregulated both in HD patients and in HD mice and then replicated and/or antagonized each alteration in a Drosophila HD model. High-throughput behavioral testing in this model and controls revealed that transcriptional changes in synaptic biology and calcium signaling are compensatory, whereas alterations involving the actin cytoskeleton and inflammation drive disease. Knockdown of disease-driving genes in HD patient-derived cells lowered mutant Huntingtin levels and activated macroautophagy, suggesting a mechanism for mitigating pathogenesis. Our multilayered approach can thus untangle the wealth of information generated by transcriptomics and identify early therapeutic intervention points."