Biology subjects

Lanjuin, A.

Publications and source records attributed to Lanjuin, A..

9 recordsLinked to original sources

bioRxiv2025

Nutrient-Responsive Formation of Mitochondrial-Derived Structures in Caenorhabditis elegans

Mitochondrial morphology is dynamically regulated through remodeling processes essential for maintaining mitochondrial function and ensuring cellular and metabolic homeostasis. While classical models of mitochondrial dynamics center on cycles of fragmentation and elongation, emerging evidence highlights additional membrane remodeling mechanisms, including the formation of mitochondrial-derived vesicles (MDVs) and mitochondrial-derived compartments (MDCs). These mitochondrial-derived structures, however, have been predominantly characterized in cultured cells and unicellular organisms, leaving their relevance in multicellular systems largely unexplored. Here, we identify a previously uncharacterized class of mitochondrial-derived structures in Caenorhabditis elegans muscle cells that are induced in response to intermittent fasting. We show that these structures appear specifically during the refeeding phase-- coinciding with mitochondrial elongation --and are absent during fasting. Consistent with MDCs, the structures, approximately 1 {micro}m in size, are enriched in outer mitochondrial membrane markers such as TOMM-20aa1-49 and TOMM-70, but notably lack components of the inner mitochondrial membrane. Their formation requires the microtubule-associated MIRO-1/2 proteins, and their size is modulated by the mitochondrial dynamics machinery. Together, our findings reveal a nutritionally regulated mitochondrial remodeling event in C. elegans muscle that may play a role in mitochondrial quality control and adaptation to metabolic cues.

cell biology↗

bioRxiv2024

Novel Imaging Tools to Study Mitochondrial Dynamics in Caenorhabditis elegans

Mitochondria exhibit a close interplay between their structure and function. Understanding this intricate relationship requires advanced imaging techniques that can capture the dynamic nature of mitochondria and their impact on cellular processes. However, much of the work on mitochondrial dynamics has been done in single celled organisms or in vitro cell culture. Here, we introduce novel genetic tools for live imaging of mitochondrial networks in the nematode Caenorhabditis elegans, addressing a pressing need for advanced techniques in studying organelle dynamics within live intact multicellular organisms. Through a comprehensive analysis, we directly compare our tools with existing methods, demonstrating their advantages for visualizing mitochondrial morphology and contrasting their impact on organismal physiology. We reveal limitations of conventional techniques, while showcasing the utility and versatility of our approaches, including endogenous CRISPR tags and ectopic labeling. By providing a guide for selecting the most suitable tools based on experimental goals, our work advances mitochondrial research in C. elegans and enhances the strategic integration of diverse imaging modalities for a holistic understanding of organelle dynamics in living organisms.

cell biology↗

bioRxiv2022

Ultra-sensitive coupling between organ growth and size by YAP-1 ensures uniform body plan proportions in C. elegans

Imbalance between the growth rate of different organs can amplify to large deviations of their size proportions during development. We show that, for the C. elegans pharynx, such size divergence is prevented by reciprocal coordination of pharyngeal growth with other tissues. Live imaging of hundreds of individuals revealed that small pharynxes grow more rapidly than large pharynxes, catching up in volume during development. Moreover, pharynx-to-body size proportions were robust to even strong tissue-specific inhibition of mTORC1 and insulin signalling. Tissue-specific depletion of these pathways slowed-down the growth of the respective tissue and additionally triggered a systemic growth response that ensured appropriate organ size proportions. By mathematical modelling, we show that the conservation of proportions requires a bi-directional ultra-sensitive coupling of body growth and pharynx size that cannot be explained by a reduction of food uptake alone. Instead, organ growth coordination requires regulation by the mechano-transducing transcriptional co-activator YAP/yap-1. Knock-down of yap-1 makes animals sensitive to tissue-specific inhibition mTORC1 inhibition, causing a disproportionate pharynx and developmental arrest. Our data suggests that mechano-transduction tightly coordinates organ growth during C. elegans development to ensure the uniformity of body plan proportions among individuals.

developmental biology↗

bioRxiv2021

A Single-copy Knock In Translating Ribosome ImmunoPrecipitation (SKI TRIP) tool kit for tissue specific profiling of actively translated mRNAs in C. elegans.

Translating Ribosome Affinity Purification (TRAP) methods have emerged as a powerful approach to profile actively translated transcripts in specific cell and tissue types. Epitope tagged ribosomal subunits are expressed in defined cell populations and used to pull down ribosomes and their associated mRNAs, providing a snapshot of cell type-specific translation occurring in that space and time. Current TRAP toolkits available to the C. elegans community have been built using multi-copy arrays, randomly integrated in the genome. Here we introduce a Single-copy Knock In Translating Ribosome ImmunoPrecipitation (SKI TRIP) tool kit, a collection of C. elegans strains engineered by CRISPR in which tissue specific expression of FLAG tagged ribosomal subunit protein RPL-22 is driven by cassettes present in single copy from defined sites in the genome. In depth characterization of the SKI TRIP strains and methodology shows that 3xFLAG tagged RPL-22 expressed from its endogenous locus or within defined cell types incorporates into actively translating ribosomes and can be used to efficiently and cleanly pull-down cell type specific transcripts without impacting overall mRNA translation or fitness of the animal. We propose SKI TRIP use for the study of processes that are acutely sensitive to changes in translation, such as aging.

genetics↗

bioRxiv2021

Efficacy of longevity interventions in C. elegans is determined by early life activity of RNA splicing factors

Geroscience aims to target the aging process to extend healthspan. However, even isogenic individuals show heterogeneity in natural aging rate and responsiveness to pro-longevity interventions, limiting translational potential. Using in vivo mini gene reporters in isogenic C. elegans, we show that alternative splicing of mRNAs related to lipid metabolism in young animals is coupled to subsequent life expectancy. Further, activity of RNA splicing factors REPO-1 and SFA-1 early in life modulates effectiveness of specific longevity interventions via POD-2/ACC1 and regulation of lipid utilization. In addition, early inhibition of REPO-1 renders animals refractory to late onset suppression of the TORC1 pathway. Together these data suggest that activity of RNA splicing factors and the metabolic landscape early in life can modulate responsiveness to longevity interventions and may explain variance in efficacy between individuals. One Sentence SummaryEfficacy of pro-longevity interventions in C. elegans is determined by the activity of splicing factors and the lipid metabolic landscape early in the life of the individual.

genetics↗

bioRxiv2021

Neuronal mTORC1 inhibition promotes longevity without suppressing anabolic growth and reproduction in C. elegans

One of the most robust and reproducible methods to prolong lifespan in a variety of organisms is inhibition of the mTORC1 (mechanistic target of rapamycin complex 1) pathway. mTORC1 is a metabolic sensor that promotes anabolic growth when nutrients are abundant. Inhibition of mTORC1 extends lifespan, but also frequently has other effects such as stunted growth, slowed development, reduced fertility, and disrupted metabolism. It has long been assumed that suppression of anabolism and resulting phenotypes such as impaired growth and reproduction may be causal to mTORC1 longevity, but this hypothesis has not been directly tested. RAGA-1 is an upstream activator of TORC1. Previous work from our lab using a C. elegans model of mTORC1 longevity, the long-lived raga-1 null mutant, found that the presence of raga-1 only in the neurons suppresses longevity of the null mutant. Here, we use the auxin-inducible degradation (AID) system to test whether neuronal mTORC1 inhibition is sufficient for longevity, and whether any changes in lifespan are also linked to stunted growth or fertility. We find that life-long AID of RAGA-1 either in all somatic tissue or only in the neurons of C. elegans is sufficient to extend lifespan. We also find that AID of RAGA-1 or LET-363/mTOR beginning at day 1 of adulthood extends lifespan to a similar extent. Unlike somatic degradation of RAGA-1, neuronal degradation of RAGA-1 doesnt impair growth, slow development, or decrease the reproductive capacity of the worms. Lastly, while AID of LET-363/mTOR in all somatic cells shortens lifespan, neuronal AID of LET-363/mTOR slows aging. This work demonstrates that targeting mTORC1 specifically in the neurons uncouples longevity from growth and reproductive impairments, challenging previously held ideas about the mechanisms of mTORC1 longevity and elucidating the promise of tissue-specific aging therapeutics.

genetics↗

bioRxiv2019

Neuronal TORC1 modulates longevity via AMPK and cell nonautonomous regulation of mitochondrial dynamics in C. elegans

Target of rapamycin complex 1 (TORC1) and AMP-activated protein kinase (AMPK) antagonistically modulate metabolism and aging. However, how they coordinate to determine longevity and if they act via separable mechanisms is unclear. Here, we show that neuronal AMPK is essential for lifespan extension from TORC1 inhibition, and that TORC1 suppression increases lifespan cell non autonomously via distinct mechanisms from global AMPK activation. Lifespan extension by null mutations in genes encoding raga-1 (RagA) or rsks-1 (S6K) is fully suppressed by neuronal-specific rescues. Loss of RAGA-1 increases lifespan via maintaining mitochondrial fusion. Neuronal RAGA-1 abrogation of raga-1 mutant longevity requires UNC-64/syntaxin, and promotes mitochondrial fission cell nonautonomously. Finally, deleting the mitochondrial fission factor DRP-1 renders the animal refractory to the pro-aging effects of neuronal RAGA-1. Our results highlight a new role for neuronal TORC1 in cell nonautonomous regulation of longevity, and suggest TORC1 in the central nervous system might be targeted to promote healthy aging.

genetics↗

bioRxiv2018

Single-copy Knock-In Loci for Defined Gene Expression in C. elegans

We have generated a single-copy knock-in loci for defined gene expression (SKI LODGE) system to insert any cDNA by CRISPR/Cas9 at defined safe harbors in the Caenorhabditis elegans genome. Utilizing a single crRNA guide, which also acts as a Co-CRISPR enrichment marker, any cDNA sequence can be introduced as a single integrated copy, regulated by different tissue-specific promoters. The SKI LODGE system provides a fast, economical and effective approach for generating single-copy non-silenced transgenes in C. elegans.

genetics↗

bioRxiv2017

Oxytocin Signaling in the Medial Amygdala is required for Sex Discrimination of Social Cues

The neural control of social behaviors in rodents requires the encoding of pheromonal cues by the vomeronasal system. Here we show that the typical preference of male mice for females is eliminated in mutants lacking oxytocin, a neuropeptide modulating social behaviors in many species. Ablation of the oxytocin receptor in aromatase expressing neurons of the medial amygdala (MeA) fully recapitulates the elimination of female preference in males. Further, single unit recording in the MeA uncovered significant changes in the sensory representation of conspecific cues in the absence of oxytocin signaling. Finally, acute manipulation of oxytocin signaling in adults is sufficient to alter social interaction preferences in males as well as responses of MeA neurons to chemosensory cues. These results uncover the critical role of oxytocin signaling in a molecularly defined neuronal population in order to modulate the behavioral and physiological responses of male mice to females on a moment-to-moment basis.

neuroscience↗