Biology subjects

AlOkda, A.

Publications and source records attributed to AlOkda, A..

5 recordsLinked to original sources

bioRxiv2025

Cyrene: A Novel Geroprotective Compound that Extends Lifespan and Healthspan in C. elegans and Drosophila

As aging is the primary risk factor for many chronic diseases, geroscience aims to target aging to delay age-related decline. Here, we identify Cyrene (dihydrolevoglucosenone), a sustainable, biocompatible solvent, as a novel geroprotective compound. Cyrene extends lifespan and healthspan in C. elegans, improving locomotor function and resistance to oxidative, thermal, osmotic, genotoxic, and proteotoxic stress. It also confers protection in neurodegenerative models of Alzheimers, Parkinsons, and Huntingtons disease. Cyrene is effective when delivered during development or early adulthood and requires administration before day 8 to extend longevity. Its benefits are independent of bacterial metabolism and partially independent of the FOXO transcription factor DAF-16. Importantly, Cyrene also extends lifespan and enhances oxidative stress resistance in Drosophila melanogaster, demonstrating cross-species efficacy. These findings identify Cyrene as a novel geroprotective compound that promotes longevity, resilience, and neuroprotection. Conservation across species supports future work to dissect molecular mechanisms and test its potential in mammals.

developmental biology↗

bioRxiv2025

Elevated mitochondrial superoxide promotes longevity through a mitochondria-to-nucleus kinase signaling pathway

The reactive oxygen species superoxide is generated by mitochondria during the process of producing energy. While superoxide can cause oxidative damage to the cell, we and others have shown that a mild increase in mitochondrial superoxide extends longevity in multiple model organisms. To elucidate the molecular mechanisms involved, we identified transcriptional changes in mitochondrial superoxide dismutase deletion mutants (sod-2 worms) using RNA sequencing. sod-2 mutants exhibit a number of changes in nuclear gene expression resulting from elevated mitochondrial superoxide suggesting that mitochondria-to-nucleus signaling is contributing to their longevity. Gene ontology enrichment analysis demonstrated that genes involved in innate immunity and cuticle formation are significantly upregulated in sod-2 worms. To identify kinases involved in this lifespan-extending pathway, we completed a targeted RNA interference screen to examine the contribution of 61 selected kinases to sod-2 longevity. From this screen, we found 25 kinases which are required for the long lifespan of sod-2 mutants including mak-2, which has an established role in a kinase signaling pathway involved in axon regeneration. Disruption of mak-2 specifically reduces sod-2 lifespan but not wild-type longevity and also decreases resistance to multiple exogenous stressors. In examining other genes that act with mak-2 in pathways controlling axon regeneration, we identified a SEK-3/PMK-3/MAK-2/CEBP-1 signaling pathway that is specifically required for sod-2 longevity but not wild-type lifespan. Combined these results suggest a novel role for kinases with established roles in axon regeneration in promoting longevity through a mitochondria-to-nucleus signaling pathway.

genetics↗

bioRxiv2024

Mild activation of the mitochondrial unfolded protein response increases lifespan without increasing resistance to stress

The mitochondrial unfolded protein response (mitoUPR) is a stress response pathway that responds to mitochondrial insults by altering gene expression to recover mitochondrial homeostasis. The mitoUPR is mediated by the stress-activated transcription factor ATFS-1. Constitutive activation of ATFS-1 increases resistance to exogenous stressors but paradoxically decreases lifespan. In this work, we determined the optimal levels of expression of activated ATFS-1 with respect to lifespan and resistance to stress by treating constitutively-active atfs-1(et17) worms with different concentrations of RNA interference (RNAi) bacteria targeting atfs-1. We observed the maximum lifespan of atfs-1(et17) worms at full-strength atfs-1 RNAi, which was significantly longer than wild-type lifespan. Under the conditions of maximum lifespan, atfs-1(et17) worms did not show enhanced resistance to stress, suggesting a trade-off between stress resistance and longevity. The maximum resistance to stress in atfs-1(et17) worms occurred on empty vector (0% atfs-1 knockdown). Under these conditions, atfs-1(et17) worms are short-lived. This indicates that constitutive activation of ATFS-1 can increase lifespan or enhance resistance to stress but not both, at the same time. Finally, we determined the timing requirements for ATFS-1 to affect lifespan. We found that knocking down atfs-1 expression only during development is sufficient to extend atfs-1(et17) lifespan, while adult-only knockdown has no effect. Overall, these results demonstrate that constitutively active ATFS-1 can extend lifespan when expressed at low levels and that this lifespan extension is not dependent on the ability of ATFS-1 to enhance resistance to stress.

developmental biology↗

bioRxiv2023

Endosomal trafficking protein TBC-2 isrequired for the longevity of long-livedmitochondrial mutants

Mutations that result in a mild impairment of mitochondrial function can extend longevity. Previous studies have shown that the increase in lifespan is dependent on stress responsive transcription factors, including DAF-16/FOXO, which exhibits increased nuclear localization in long-lived mitochondrial mutants. We recently found that the localization of DAF-16 within the cell is dependent on the endosomal trafficking protein TBC-2. Based on the important role of DAF-16 in both longevity and resistance to stress, we examined the effect of disrupting tbc-2 on lifespan and stress resistance in the long-lived mitochondrial mutants nuo-6 and isp-1 in C. elegans. Loss of tbc-2 markedly reduced the long lifespans of both mitochondrial mutants. Disruption of tbc-2 also decreased resistance to specific exogenous stressors in nuo-6 and isp-1 mutants. In contrast, tbc-2 inhibition had no effect on oxidative stress resistance or lifespan in isp-1 worms when DAF-16 is absent suggesting that the effect of tbc-2 on mitochondrial mutant lifespan may be mediated by mislocalization of DAF-16. However, this result is complicated by the fact that deletion of daf-16 markedly decreases both phenotypes in isp-1 worms. Surprisingly, disruption of tbc-2 did not prevent the upregulation of DAF-16 target genes in the long-lived mitochondrial mutants, suggesting the possibility that the effect of tbc-2 on lifespan and stress resistance in the long-lived mitochondrial mutants is at least partially independent of its effects on DAF-16 localization. Overall, this work demonstrates the importance of endosomal trafficking for the extended longevity and enhanced stress resistance resulting from mild impairment of mitochondrial function.

genetics↗

bioRxiv2020

Monitoring alpha-synuclein oligomerization and inclusion formation using bimolecular fluorescence complementation assays: What you see is not always what you get.

Bimolecular fluorescence complementation (BiFC) was introduced a decade ago as a method to monitor alpha-synuclein (-syn) oligomerization in intact cells. Since then, several -syn BiFC cellular assays and animal models have been developed based on the assumption that an increase in the fluorescent signal correlates with increased -syn oligomerization or aggregation. Despite the increasing use of these assays and models in mechanistic studies, target validation and drug screening, there have been no reports that 1) validate the extent to which the BiFC fluorescent signal correlates with -syn oligomerization at the biochemical level; 2) provide a structural characterization of the oligomers and aggregates formed by the BiFC fragments; or 3) investigate the extent to which the oligomers of the fluorescent complex resemble oligomers formed on the pathway to -syn fibrillization. To address this knowledge gap, we first analysed the expression level and oligomerization properties of the individual constituents of -syn-Venus, one of the most commonly used BiFC systems, in HEK-293 & SH-SY5Y cells from three different laboratories using multiple approaches, including size exclusion chromatography, semiquantitative Western blot analysis, in-cell crosslinking, immunocytochemistry and sedimentation assays. Next, we investigated the biochemical and aggregation properties of -syn upon co-expression of both BiFC fragments. Our results show that 1) the C-terminal-Venus fused to -syn (-syn-Vc) is present in much lower abundance than its counterpart with N-terminal-Venus fused to -syn (Vn--syn) ; 2) Vn--syn exhibits a high propensity to form oligomers and higher-order aggregates; and 3) the expression of either or both fragments does not result in the formation of -syn fibrils or cellular inclusions. Furthermore, our results suggest that only a small fraction of Vn--syn is involved in the formation of the fluorescent BiFC complex and that some of the fluorescent signal may arise from the association or entrapment of -syn-Vc in Vn--syn aggregates. The fact that the N-terminal fragment exists predominantly in an aggregated state also indicates that one must exercise caution when using this system to investigate -syn oligomerization in cells or in vivo. Altogether, our results suggest that cellular and animal models of oligomerization, aggregation and cell-to-cell transmission that are based on the -syn BiFC systems should be thoroughly characterized at the biochemical level to ensure that they reproduce the process of interest and measure what they are intended to measure. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/074161v3_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@fe4896org.highwire.dtl.DTLVardef@4f912forg.highwire.dtl.DTLVardef@1c4e157org.highwire.dtl.DTLVardef@a648e6_HPS_FORMAT_FIGEXP M_FIG C_FIG Bimolecular fluorescence complementation (BiFC) was introduced a decade ago to monitor alpha-synuclein oligomerization in intact cells, based on the assumption that an increase in the fluorescent signal correlates with -synuclein oligomerization and aggregation. Herein, we used several biochemical and cellular assays to characterize commonly used -synuclein Venus BiFC assays. Our results show that one of the BiFC fragments (Vn--synuclein) exhibits higher expression levels and aggregation propensity than its counterpart (-synuclein-Vc), thus complicating the interpretation of the molecular interactions that give rise to the fluorescence signal and raise concerns about their application to investigate -syn oligomerization in cells or in vivo.

biochemistry↗