Thursday, October 14, 2021

Drosophila assays of movement and mitochondria included in study of an autosomal dominant spastic paraplegia and dystonia

Mov Disord. 2021 Oct 11. doi: 10.1002/mds.28821

A Novel Variant of ATP5MC3 Associated with Both Dystonia and Spastic Paraplegia

Neilson DE, Zech M, Hufnagel RB, Slone J, Wang X, Homan S, Gutzwiller LM, Leslie EJ, Leslie ND, Xiao J, Hedera P, LeDoux MS, Gebelein B, Wilbert F, Eckenweiler M, Winkelmann J, Gilbert DL, Huang T


BACKGROUND: In a large pedigree with an unusual phenotype of spastic paraplegia or dystonia and autosomal dominant inheritance, linkage analysis previously mapped the disease to chromosome 2q24-2q31.

OBJECTIVE: The aim of this study is to identify the genetic cause and molecular basis of an unusual autosomal dominant spastic paraplegia and dystonia.

METHODS: Whole exome sequencing following linkage analysis was used to identify the genetic cause in a large family. Cosegregation analysis was also performed. An additional 384 individuals with spastic paraplegia or dystonia were screened for pathogenic sequence variants in the adenosine triphosphate (ATP) synthase membrane subunit C locus 3 gene (ATP5MC3). The identified variant was submitted to the "GeneMatcher" program for recruitment of additional subjects. Mitochondrial functions were analyzed in patient-derived fibroblast cell lines. Transgenic Drosophila carrying mutants were studied for movement behavior and mitochondrial function.

RESULTS: Exome analysis revealed a variant (c.318C > G; p.Asn106Lys) (NM_001689.4) in ATP5MC3 in a large family with autosomal dominant spastic paraplegia and dystonia that cosegregated with affected individuals. No variants were identified in an additional 384 individuals with spastic paraplegia or dystonia. GeneMatcher identified an individual with the same genetic change, acquired de novo, who manifested upper-limb dystonia. Patient fibroblast studies showed impaired complex V activity, ATP generation, and oxygen consumption. Drosophila carrying orthologous mutations also exhibited impaired mitochondrial function and displayed reduced mobility.

CONCLUSION: A unique form of familial spastic paraplegia and dystonia is associated with a heterozygous ATP5MC3 variant that also reduces mitochondrial complex V activity.

DOI: 10.1002/mds.28821
PMID: 34636445

Tumors sap nutrients from surrounding cells -- Drosophila study related to cancer

Dev Biol. 2021 Aug;476:294-307. doi: 10.1016/j.ydbio.2021.04.008

Autophagy induction in tumor surrounding cells promotes tumor growth in adult Drosophila intestines

Zhao H, Shi L, Kong R, Li Z, Liu F, Zhao H, Li Z


During tumorigenesis, tumor cells interact intimately with their surrounding cells (microenvironment) for their growth and progression. However, the roles of tumor microenvironment in tumor development and progression are not fully understood. Here, using an established benign tumor model in adult Drosophila intestines, we find that non-cell autonomous autophagy (NAA) is induced in tumor surrounding neighbor cells. Tumor growth can be significantly suppressed by genetic ablation of autophagy induction in tumor neighboring cells, indicating that tumor neighboring cells act as tumor microenvironment to promote tumor growth. Autophagy in tumor neighboring cells is induced downstream of elevated ROS and activated JNK signaling in tumor cells. Interestingly, we find that active transport of nutrients, such as amino acids, from tumor neighboring cells sustains tumor growth, and increasing nutrient availability could significantly restore tumor growth. Together, these data demonstrate that tumor cells take advantage of their surrounding normal neighbor cells as nutrient sources through NAA to meet their high metabolic demand for growth and progression. Thus we provide insights into our understanding of the mechanisms underlying the interaction between tumor cells and their microenvironment in tumor development.

DOI: 10.1016/j.ydbio.2021.04.008
PMID: 33940033

Wednesday, October 6, 2021

Drosophila used in study related to fragile X-associated primary ovariant insufficiency

Fertil Steril. 2021 Sep;116(3):843-854. doi: 10.1016/j.fertnstert.2021.04.021 

Identifying susceptibility genes for primary ovarian insufficiency on the high-risk genetic background of a fragile X premutation. 

Trevino CE, Rounds JC, Charen K, Shubeck L, Hipp HS, Spencer JB, Johnston HR, Cutler DJ, Zwick ME, Epstein MP, Murray A, Macpherson JN, Mila M, Rodriguez-Revenga L, Berry-Kravis E, Hall DA, Leehey MA, Liu Y, Welt C, Warren ST, Sherman SL. Jin P, Allen EG


OBJECTIVE: To identify modifying genes that explains the risk of fragile X-associated primary ovarian insufficiency (FXPOI).

DESIGN: Gene-based, case/control association study, followed by a functional screen of highly ranked genes using a Drosophila model.

SETTING: Participants were recruited from academic and clinical settings.

PATIENT(S): Women with a premutation (PM) who experienced FXPOI at the age of 35 years or younger (n = 63) and women with a PM who experienced menopause at the age of 50 years or older (n = 51) provided clinical information and a deoxyribonucleic acid sample for whole genome sequencing. The functional screen was on the basis of Drosophila TRiP lines.

INTERVENTION(S): Clinical information and a DNA sample were collected for whole genome sequencing.

MAIN OUTCOME MEASURES: A polygenic risk score derived from common variants associated with natural age at menopause was calculated and associated with the risk of FXPOI. Genes associated with the risk of FXPOI were identified on the basis of the P-value from gene-based association test and an altered level of fecundity when knocked down in the Drosophila PM model.

RESULTS: The polygenic risk score on the basis of common variants associated with natural age at menopause explained approximately 8% of the variance in the risk of FXPOI. Further, SUMO1 and KRR1 were identified as possible modifying genes associated with the risk of FXPOI on the basis of an untargeted gene analysis of rare variants.

CONCLUSIONS: In addition to the large genetic effect of a PM on ovarian function, the additive effects of common variants associated with natural age at menopause and the effect of rare modifying variants appear to play a role in FXPOI risk.

DOI: 10.1016/j.fertnstert.2021.04.021
PMID: 34016428

Tuesday, October 5, 2021

Review: Fly Models of Liver Diseases

Front Physiol. 2021 Sep 16;12:728407

Drosophila melanogaster: A Powerful Tiny Animal Model for the Study of Metabolic Hepatic Diseases

Moraes KCM, Montagne J

Animal experimentation is limited by unethical procedures, time-consuming protocols, and high cost. Thus, the development of innovative approaches for disease treatment based on alternative models in a fast, safe, and economic manner is an important, yet challenging goal. In this paradigm, the fruit-fly Drosophila melanogaster has become a powerful model for biomedical research, considering its short life cycle and low-cost maintenance. In addition, biological processes are conserved and homologs of ∼75% of human disease-related genes are found in the fruit-fly. Therefore, this model has been used in innovative approaches to evaluate and validate the functional activities of candidate molecules identified via in vitro large-scale analyses, as putative agents to treat or reverse pathological conditions. In this context, Drosophila offers a powerful alternative to investigate the molecular aspects of liver diseases, since no effective therapies are available for those pathologies. Non-alcoholic fatty liver disease is the most common form of chronic hepatic dysfunctions, which may progress to the development of chronic hepatitis and ultimately to cirrhosis, thereby increasing the risk for hepatocellular carcinoma (HCC). This deleterious situation reinforces the use of the Drosophila model to accelerate functional research aimed at deciphering the mechanisms that sustain the disease. In this short review, we illustrate the relevance of using the fruit-fly to address aspects of liver pathologies to contribute to the biomedical area.

DOI: 10.3389/fphys.2021.728407
PMCID: PMC8481879
PMID: 34603083

Friday, October 1, 2021

Drosophila study related to aging and age-related disorders

Proc Natl Acad Sci U S A. 2021 Oct 5;118(40):e2110387118.

A genetic model of methionine restriction extends Drosophila health- and

Parkhitko AA, Wang L, Filine E, Jouandin P, Leshchiner D, Binari R, Asara JM, Rabinowitz JD, Perrimon N

Loss of metabolic homeostasis is a hallmark of aging and is characterized by dramatic metabolic reprogramming. To analyze how the fate of labeled methionine is altered during aging, we applied 13C5-Methionine labeling to Drosophila and demonstrated significant changes in the activity of different branches of the methionine metabolism as flies age. We further tested whether targeted degradation of methionine metabolism components would "reset" methionine metabolism flux and extend the fly lifespan. Specifically, we created transgenic flies with inducible expression of Methioninase, a bacterial enzyme capable of degrading methionine and revealed methionine requirements for normal maintenance of lifespan. We also demonstrated that microbiota-derived methionine is an alternative and important source in addition to food-derived methionine. In this genetic model of methionine restriction (MetR), we also demonstrate that either whole-body or tissue-specific Methioninase expression can dramatically extend Drosophila health- and lifespan and exerts physiological effects associated with MetR. Interestingly, while previous dietary MetR extended lifespan in flies only in low amino acid conditions, MetR from Methioninase expression extends lifespan independently of amino acid levels in the food. Finally, because impairment of the methionine metabolism has been previously associated with the development of Alzheimer's disease, we compared methionine metabolism reprogramming between aging flies and a Drosophila model relevant to Alzheimer's disease, and found that overexpression of human Tau caused methionine metabolism flux reprogramming similar to the changes found in aged flies. Altogether, our study highlights Methioninase as a potential agent for health- and lifespan extension.

DOI: 10.1073/pnas.2110387118
PMID: 34588310

Drosophila assay developed to test variants of human PTEN, a gene associate with cancers and ASD

A scalable Drosophila assay for clinical interpretation of human PTEN variants in suppression of PI3K/AKT induced cellular proliferation

Payel Ganguly, Landiso Madonsela, Jesse T. Chao, Christopher J. R. Loewen, Timothy P. O’Connor, Esther M. Verheyen, Douglas W. Allan

Abstract: "Gene variant discovery is becoming routine, but it remains difficult to usefully interpret the functional consequence or disease relevance of most variants. ... Drosophila melanogaster offers great potential as an assay platform, but was untested for high numbers of human variants adherent to these guidelines. Here, we wished to test the utility of Drosophila as a platform for scalable well-established assays. We took a genetic interaction approach to test the function of ~100 human PTEN variants in cancer-relevant suppression of PI3K/AKT signaling in cellular growth and proliferation. We validated the assay using biochemically characterized PTEN mutants as well as 23 total known pathogenic and benign PTEN variants, all of which the assay correctly assigned into predicted functional categories. ... Overall, we demonstrate that Drosophila offers a powerful assay platform for clinical variant interpretation, that can be used in conjunction with other well-established assays, to increase confidence in the accurate assessment of variant function and pathogenicity."

Access a Science in Vancouver feature on this article here.

Wednesday, September 29, 2021

Genetic and drug screens applied to a Drosophila model of acute myeloid leukemia reveal potential link to hypoxia signaling

Dis Model Mech. 2021 Sep 28:dmm.048953. doi: 10.1242/dmm.048953.  

Pharmacological or genetic inhibition of hypoxia signaling attenuates oncogenic
RAS-induced cancer phenotypes.

Zhu JY, Huang X, Fu Y, Wang Y, Zheng P, Liu Y, Han Z

Author information:
(1)Center for Precision Disease Modeling, Department of Medicine, University of
Maryland School of Medicine, Baltimore, MD 21201, USA.
(2)Division of Endocrinology, Diabetes and Nutrition, Department of Medicine,
University of Maryland School of Medicine, Baltimore, MD 21201, USA.
(3)Division of Immunotherapy, University of Maryland School of Medicine,
Baltimore, MD 21201, USA.

Abstract: "Oncogenic Ras mutations are highly prevalent in hematopoietic malignancies. However, it is difficult to directly target oncogenic RAS proteins for therapeutic intervention. We have developed a Drosophila Acute Myeloid Leukemia (AML) model induced by human KRASG12V, which exhibits a dramatic increase in myeloid-like leukemia cells. We performed both genetic and drug screens using this model. The genetic screen identified 24 candidate genes able to attenuate the oncogenic RAS-induced phenotype, including two key hypoxia pathway genes HIF1A and ARNT (HIF1B). The drug screen revealed echinomycin, an inhibitor of HIF1A, could effectively attenuate the leukemia phenotype caused by KRASG12V. Furthermore, we showed that echinomycin treatment could effectively suppress oncogenic RAS-driven leukemia cell proliferation using both human leukemia cell lines and a mouse xenograft model. These data suggest that inhibiting the hypoxia pathway could be an effective treatment approach for oncogenic RAS-induced cancer phenotype, and that echinomycin is a promising targeted drug to attenuate oncogenic RAS-induced cancer phenotypes."

DOI: 10.1242/dmm.048953
PMID: 34580712