Fly model leads to new model for cellular mechanisms underlying diseases associated with disruption of Valosin-Containing Proteins

Nat Commun. 2021 Jan 21;12(1):513. doi: 10.1038/s41467-020-20796-8.

SVIP is a molecular determinant of lysosomal dynamic stability, neurodegeneration and lifespan.

Johnson AE, Orr BO, Fetter RD, Moughamian AJ, Primeaux LA,
Geier EG, Yokoyama JS, Miller BL, Davis GW
 

From the abstract:

Missense mutations in Valosin-Containing Protein (VCP) are linked to diverse degenerative diseases including IBMPFD, amyotrophic lateral sclerosis (ALS), muscular dystrophy and Parkinson's disease. Here, we characterize a VCP-binding co-factor (SVIP) that specifically recruits VCP to lysosomes. ... We also establish multiple links between SVIP and VCP-dependent disease in our Drosophila model system. ... Finally, we identify a human SVIP mutation and confirm the pathogenicity of this mutation in our Drosophila model. We propose a model for VCP disease based on the differential, co-factor-dependent recruitment of VCP to intracellular organelles.

DOI: 10.1038/s41467-020-20796-8
PMID: 33479240

Wondering what's IBMPFD? Answer: Inclusion body myopathy with early-onset Paget disease and frontotemporal dementia.

Study of the fly embryo as a route to understanding cellular mechanisms of cancer

Mol Biol Cell. 2021 Jan 21:mbcE20100625. doi: 10.1091/mbc.E20-10-0625.
Molecular mechanisms underlying cellular effects of human MEK1 mutations.

Marmion RA(1), Yang L(1), Goyal Y(1)(2)(3), Jindal GA(1)(2)(4), Wetzel JL(1)(5),
Singh M(1)(5), Schüpbach T(6), Shvartsman SY(1)(2)(6)(7).

Abstract:

Terminal regions of Drosophila embryos are patterned by signaling through ERK, which is genetically deregulated in multiple human diseases. Quantitative studies of terminal patterning have been recently used to investigate gain-of-function variants of human MEK1, encoding the MEK kinase that directly activates ERK by dual phosphorylation. Unexpectedly, several mutations reduced ERK activation by extracellular signals, possibly through a negative feedback triggered by signal-independent activity of the mutant variants. Here we present experimental evidence supporting this model. Using a MEK variant that combines a mutation within the negative regulatory region with alanine substitutions in the activation loop, we prove that pathogenic variants indeed acquire signal-independent kinase activity. We also demonstrate that signal-dependent activation of these variants is independent of KSR, a conserved adaptor that is indispensable for activation of normal MEK. Finally, we show that attenuation of ERK activation by extracellular signals stems from transcriptional induction of Mkp3, a dual specificity phosphatase that deactivates ERK by dephosphorylation. These findings in the Drosophila embryo highlight its power for investigating diverse effects of human disease mutations.

DOI: 10.1091/mbc.E20-10-0625
PMID: 33476180

Study of Drosophila orthologs of human Cyotsolic 5'-Nucleotidase II genes, which have been implicated in neuropsychiatric disorders

Transl Psychiatry. 2021 Jan 18;11(1):55. doi: 10.1038/s41398-020-01149-x.

Investigating cytosolic 5'-nucleotidase II family genes as candidates for neuropsychiatric disorders in Drosophila

Singgih EL, van der Voet M, Schimmel-Naber M, Brinkmann EL, Schenck
A, Franke B

Abstract:
Cytosolic 5'-nucleotidases II (cNT5-II) are an evolutionary conserved family of 5'-nucleotidases that catalyze the intracellular hydrolysis of nucleotides. In humans, the family is encoded by five genes, namely NT5C2, NT5DC1, NT5DC2, NT5DC3, and NT5DC4. While very little is known about the role of these genes in the nervous system, several of them have been associated with neuropsychiatric disorders. Here, we tested whether manipulating neuronal expression of cNT5-II orthologues affects neuropsychiatric disorders-related phenotypes in the model organism Drosophila melanogaster. We investigated the brain expression of Drosophila orthologues of cNT5-II family (dNT5A-CG2277, dNT5B-CG32549, and dNT5C-CG1814) using quantitative real-time polymerase chain reaction (qRT-PCR). Using the UAS/Gal4 system, we also manipulated the expression of these genes specifically in neurons. The knockdown was subjected to neuropsychiatric disorder-relevant behavioral assays, namely light-off jump reflex habituation and locomotor activity, and sleep was measured. In addition, neuromuscular
junction synaptic morphology was assessed. We found that dNT5A, dNT5B, and dNT5C were all expressed in the brain. dNT5C was particularly enriched in the brain, especially at pharate and adult stages. Pan-neuronal knockdown of dNT5A and dNT5C showed impaired habituation learning. Knockdown of each of the genes also consistently led to mildly reduced activity and/or increased sleep. None of the knockdown models displayed significant alterations in synaptic morphology. In conclusion, in addition to genetic associations with psychiatric disorders in humans, altered expression of cNT5-II genes in the Drosophila nervous system plays a role in disease-relevant behaviors.

DOI: 10.1038/s41398-020-01149-x
PMID: 33462198

Genetic screen in flies aims to identify new targets for cancer treatment

Cancers (Basel). 2021 Jan 14;13(2):E293. doi: 10.3390/cancers13020293.

Genetic Screening for Potential New Targets in Chronic Myeloid Leukemia Based on
Drosophila Transgenic for Human BCR-ABL1.

Lo Iacono M(1), Signorino E(1), Petiti J(1), Pradotto M(1), Calabrese C(1),
Panuzzo C(1), Caciolli F(1), Pergolizzi B(1), De Gobbi M(1), Rege-Cambrin G(1),
Fava C(1), Giachino C(1), Bracco E(2), Saglio G(1), Frassoni F(1), Cilloni D(1).

Author information:
(1)Department of Clinical and Biological Sciences, University of Turin, 10043
Turin, Italy.
(2)Department of Oncology, University of Turin, 10043 Turin, Italy.

Chronic myeloid leukemia is a myeloproliferative neoplasm characterized by the presence of the Philadelphia chromosome that originates from the reciprocal translocation t(9;22)(q34;q11.2) and encodes for the constitutively active tyrosine kinase protein BCR-ABL1 from the Breakpoint Cluster Region (BCR) sequence and the Abelson (ABL1) gene. Despite BCR-ABL1 being one of the most studied oncogenic proteins, some molecular mechanisms remain enigmatic, and several of the proteins, acting either as positive or negative BCR-ABL1 regulators, are still unknown. The Drosophila melanogaster represents a powerful tool for genetic investigations and a promising model to study the BCR-ABL1 signaling pathway. To identify new components involved in BCR-ABL1 transforming activity, we conducted an extensive genetic screening using different Drosophila mutant strains carrying specific small deletions within the chromosomes 2 and 3 and the gmrGal4,UAS-BCR-ABL1 4M/TM3 transgenic Drosophila as the background. From the screening, we identified several putative candidate genes that may be involved either in sustaining chronic myeloid leukemia (CML) or in its progression. We also identified, for the first time, a tight connection between the BCR-ABL1 protein and Rab family members, and this correlation was also validated in CML patients. In conclusion, our data identified many genes that, by interacting with BCR-ABL1, regulate several important biological pathways and could promote disease onset and progression.

DOI: 10.3390/cancers13020293
PMID: 33466839

Preprint: ORF3a protein from the virus that causes COVID-19 is pathogenic in Drosophila

SARS-CoV-2 protein ORF3a is pathogenic in Drosophila and causes phenotypes associated with COVID-19 post-viral syndrome

Shuo Yang, Meijie Tian, Aaron N. Johnson 

Summary: The Coronavirus Disease 2019 (COVID-19) pandemic has caused millions of deaths and will continue to exact incalculable tolls worldwide. While great strides have been made toward understanding and combating the mechanisms of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection, relatively little is known about the individual SARS-CoV-2 proteins that contribute to pathogenicity during infection and that cause neurological sequela after viral clearance. We used Drosophila to develop an in vivo model that characterizes mechanisms of SARS-CoV-2 pathogenicity, and found ORF3a adversely affects longevity and motor function by inducing apoptosis and inflammation in the nervous system. Chloroquine alleviated ORF3a induced phenotypes in the CNS, arguing our Drosophila model is amenable to high throughput drug screening. Our work provides novel insights into the pathogenic nature of SARS-CoV-2 in the nervous system that can be used to develop new treatment strategies for post-viral syndrome.

https://www.biorxiv.org/content/10.1101/2020.12.20.423533v1

Preprint: Results of a Drosophila study of ASD-associated gene variants impacts understanding of neurological diseases

Drosophila functional screening of de novo variants in autism uncovers deleterious variants and facilitates discovery of rare neurodevelopmental diseases

Marcogliese et al.

BioRxiv pre-print:
https://www.biorxiv.org/content/10.1101/2020.12.30.424813v1

Abstract: Individuals with autism spectrum disorders (ASD) exhibit an increased burden of de novo variants in a broadening range of genes. We functionally tested the effects of ASD missense variants using Drosophila through ‘humanization’ rescue and overexpression-based strategies. We studied 79 ASD variants in 74 genes identified in the Simons Simplex Collection and found 38% of them caused functional alterations. Moreover, we identified GLRA2 as the cause of a spectrum of neurodevelopmental phenotypes beyond ASD in eight previously undiagnosed subjects. Functional characterization of variants in ASD candidate genes point to conserved neurobiological mechanisms and facilitates gene discovery for rare neurodevelopmental diseases.