dTrmt10A impacts Hsp70 chaperone m6A levels and the stress response in the Drosophila brain.

Chronic cellular stress has a profound impact on the brain, leading to degeneration and accelerated aging. Recent work has revealed the vital role of RNA modifications, and the proteins responsible for regulating them, in the stress response. In our study, we defined the role of CG14618/dTrmt10A, the Drosophila counterpart of human TRMT10A a N1-methylguanosine methyltransferase, on m6A regulation and heat stress resilience in the Drosophila brain. By m6A-IP RNA sequencing on Drosophila head tissue, we demonstrated that manipulating dTrmt10A levels indirectly regulates m6A levels on polyA + RNA. dTrmt10A exerted its influence on m6A levels on transcripts enriched for neuronal signaling and heat stress pathways, similar to the m6A methyltransferase Mettl3. Intriguingly, its impact primarily targeted 3' UTR m6A, setting it apart from the majority of Drosophila m6A-modified transcripts which display 5' UTR enrichment. Upregulation of dTrmt10A led to increased resilience to acute heat stress, decreased m6A modification on heat shock chaperones, and coincided with decreased decay of chaperone transcripts and increased translation of chaperone proteins. Overall, these findings establish a potential mechanism by which dTrmt10A regulates the acute brain stress response through m6A modification.

Transformative Network Modeling of Multi-omics Data Reveals Detailed Circuits, Key Regulators, and Potential Therapeutics for Alzheimer's Disease.

To identify the molecular mechanisms and novel therapeutic targets of late-onset Alzheimer's Disease (LOAD), we performed an integrative network analysis of multi-omics profiling of four cortical areas across 364 donors with varying cognitive and neuropathological phenotypes. Our analyses revealed thousands of molecular changes and uncovered neuronal gene subnetworks as the most dysregulated in LOAD. ATP6V1A was identified as a key regulator of a top-ranked neuronal subnetwork, and its role in disease-related processes was evaluated through CRISPR-based manipulation in human induced pluripotent stem cell-derived neurons and RNAi-based knockdown in Drosophila models. Neuronal impairment and neurodegeneration caused by ATP6V1A deficit were improved by a repositioned compound, NCH-51. This study provides not only a global landscape but also detailed signaling circuits of complex molecular interactions in key brain regions affected by LOAD, and the resulting network models will serve as a blueprint for developing next-generation therapeutic agents against LOAD.

Integrated biology approach reveals molecular and pathological interactions among Alzheimer's Aß42, Tau, TREM2, and TYROBP in Drosophila models.

BACKGROUND: Cerebral amyloidosis, neuroinflammation, and tauopathy are key features of Alzheimer's disease (AD), but interactions among these features remain poorly understood. Our previous multiscale molecular network models of AD revealed TYROBP as a key driver of an immune- and microglia-specific network that was robustly associated with AD pathophysiology. Recent genetic studies of AD further identified pathogenic mutations in both TREM2 and TYROBP. METHODS: In this study, we systematically examined molecular and pathological interactions among Aß, tau, TREM2, and TYROBP by integrating signatures from transgenic Drosophila models of AD and transcriptome-wide gene co-expression networks from two human AD cohorts. RESULTS: Glial expression of TREM2/TYROBP exacerbated tau-mediated neurodegeneration and synergistically affected pathways underlying late-onset AD pathology, while neuronal Aß42 and glial TREM2/TYROBP synergistically altered expression of the genes in synaptic function and immune modules in AD. CONCLUSIONS: The comprehensive pathological and molecular data generated through this study strongly validate the causal role of TREM2/TYROBP in driving molecular networks in AD and AD-related phenotypes in flies.

Knockdown of wfs1, a fly homolog of Wolfram syndrome 1, in the nervous system increases susceptibility to age- and stress-induced neuronal dysfunction and degeneration in Drosophila.

Wolfram syndrome (WS), caused by loss-of-function mutations in the Wolfram syndrome 1 gene (WFS1), is characterized by juvenile-onset diabetes mellitus, bilateral optic atrophy, and a wide spectrum of neurological and psychiatric manifestations. WFS1 encodes an endoplasmic reticulum (ER)-resident transmembrane protein, and mutations in this gene lead to pancreatic ß-cell death induced by high levels of ER stress. However, the mechanisms underlying neurodegeneration caused by WFS1 deficiency remain elusive. Here, we investigated the role of WFS1 in the maintenance of neuronal integrity in vivo by knocking down the expression of wfs1, the Drosophila homolog of WFS1, in the central nervous system. Neuronal knockdown of wfs1 caused age-dependent behavioral deficits and neurodegeneration in the fly brain. Knockdown of wfs1 in neurons and glial cells resulted in premature death and significantly exacerbated behavioral deficits in flies, suggesting that wfs1 has important functions in both cell types. Although wfs1 knockdown alone did not promote ER stress, it increased the susceptibility to oxidative stress-, excitotoxicity- or tauopathy-induced behavioral deficits, and neurodegeneration. The glutamate release inhibitor riluzole significantly suppressed premature death phenotypes induced by neuronal and glial knockdown of wfs1. This study highlights the protective role of wfs1 against age-associated neurodegeneration and furthers our understanding of potential disease-modifying factors that determine susceptibility and resilience to age-associated neurodegenerative diseases.

Deficiency of succinyl-CoA synthetase α subunit delays development, impairs locomotor activity and reduces survival under starvation in Drosophila.

Succinyl-CoA synthetase/ligase (SCS) is a mitochondrial enzyme that catalyzes the reversible process from succinyl-CoA to succinate and free coenzyme A in TCA cycle. SCS deficiencies are implicated in mitochondrial hepatoencephalomyopathy in humans. To investigate the impact of SCS deficiencies in Drosophila, we generated a null mutation in Scs alpha subunit (Scsα) using the CRISPR/Cas9 system, and characterized their phenotype. We found that the Drosophila SCS deficiency, designated ScsαKO, contained a high level of succinyl-CoA, a substrate for the enzyme, and altered levels of various metabolites in TCA cycle and glycolysis, indicating that the energy metabolism was impaired. Unlike SCSα deficiencies in humans, there was no reduction in lifespan, indicating that Scsα is not critical for viability in Drosophila. However, they showed developmental delays, locomotor activity defects, and reduced survival under starvation. We also found that glycogen breakdown occurred during development, suggesting that the mutant flies were unable to produce sufficient energy to promote normal growth. These results suggested that SCSα is essential for proper energy metabolism in Drosophila. The ScsαKO flies should be useful as a model to understand the physiological role of SCSα as well as the pathophysiology of SCSα deficiency.