Transactivation Domain of Human c-Myc Is Essential to Alleviate Poly(Q)-Mediated Neurotoxicity in Drosophila Disease Models

Myc functions downstream of InR and their concurrent upregulation additively restricts pathogenesis of human poly(Q) disorders in Drosophila disease models

Human polyglutamine [poly(Q)] disorders are caused by abnormal expansion of CAG repeats in one gene (disease specific), yet a plethora of cellular pathways are found to be involved in their pathogenesis and progression. Despite the tremendous effort, all pursuits for the development of intervention therapy against these disorders seem futile. Recent reports suggest combination therapy as a potential strategy to combat the complex pathogenesis of such neurodegenerative disorders. The present study attempted to identify a combinatorial intervention strategy against human poly(Q) disorders in Drosophila disease models. Due to its immense potential to be stimulated by drugs, the evolutionarily conserved insulin signalling cascade which is well-established modifier of human poly(Q) pathogenesis was selected for the study. Genetic screening studies identified Drosophila Myc as a potential partner of insulin receptor (InR) that conferred additive rescue against poly(Q) induced neurodegeneration. Comprehensive analyses demonstrated InR and Myc to confer additive rescue against several events of pathogenesis, including aggregation of expanded poly(Q) containing proteins, transcriptional dysregulation, upsurge of cell death cascades, etc. Also, the synergistic rescue efficiency of InR and Myc was equally efficient in mitigating poly(Q) induced structural and functional deficits. The study also demonstrates that Myc functions downstream of InR signalling cascade to deliver rescue against human poly(Q) mediated toxicity in Drosophila disease models. In conclusion, the present study suggests that InR and Myc have the potential to be developed as a combinatorial therapeutic approach against human poly(Q) diseases.

Normal aging hyperactivates innate immunity and reduces the medical efficacy of minocycline in brain injury

Symptoms of many neurodegenerative diseases appear later in human life. However, young animal models for penetrating traumatic brain injury (pTBI) have been used to study neurodegenerative diseases and evaluate the efficacy of neuroprotective medicines. Possibly because of this discordance, effective neuroprotective drugs have still not been developed. For patients suffering from pTBI, aging is known to be a significant prognostic factor of mortality. In this study, we aimed to establish a model of aged pTBI animals using Drosophila melanogaster. We successfully generated aged pTBI flies as a new pTBI model showing increased neurodegeneration and higher mortality. To elucidate the mechanism of increased vulnerability in aged pTBI animals, we analyzed the GenBank-deposited transcriptome data of young and aged flies, demonstrating the importance of innate immunity genes for higher mortality in aged pTBI models. We found that in the context of pTBI, normal aging strongly activated the expression of antimicrobial peptide genes and upregulated the nuclear factor-κB gene in the immune deficiency pathway, but not the Toll pathway. Moreover, we found that minocycline increased the survival of young pTBI flies, but not aged pTBI flies. These results suggested that immune system activation under neurodegenerative conditions was involved in normal aging, thereby inhibiting the medicinal efficacy of neuroprotective drugs effective for young flies in aged flies.

The Tiny Drosophila Melanogaster for the Biggest Answers in Huntington's Disease

The average life expectancy for humans has increased over the last years. However, the quality of the later stages of life is low and is considered a public health issue of global importance. Late adulthood and the transition into the later stage of life occasionally leads to neurodegenerative diseases that selectively affect different types of neurons and brain regions, producing motor dysfunctions, cognitive impairment, and psychiatric disorders that are progressive, irreversible, without remission periods, and incurable. Huntington's disease (HD) is a common neurodegenerative disorder. In the 25 years since the mutation of the huntingtin (HTT) gene was identified as the molecule responsible for this neural disorder, a variety of animal models, including the fruit fly, have been used to study the disease. Here, we review recent research that used Drosophila as an experimental tool for improving knowledge about the molecular and cellular mechanisms underpinning HD.