Biology subjects

Wagner, O. I.

Publications and source records attributed to Wagner, O. I..

4 recordsLinked to original sources

bioRxiv2025

Phosphatidylinositol Transfer Protein-1 Integrates Insulin/IGF-1 and TOR Signaling to Negatively Regulate Lifespan and Healthspan in Caenorhabditis elegans

BackgroundPhosphatidylinositol transfer protein-1 (pitp-1) is involved in phosphoinositide turnover. The role of pitp-1 in promoting healthy longevity remains unknown. Our previous work showed that the phosphoinositide turnover genes dagl-1 and dgk-5 regulates lifespan, as overexpression of dagl-1 or knockdown of dgk-5 prolongs lifespan and enhances oxidative stress resistance through TOR signaling. As pitp-1 is a key component of this pathway, we investigated its role in lifespan regulation and the underlying mechanisms, aiming to clarify whether it represents a critical regulator of healthy longevity and how it coordinates conserved signaling pathways to regulate aging. MethodsC. elegans mutants, RNAi-mediated knockdown, and transgenic overexpression were applied to assess lifespan, motility, stress resistance. Temporal and tissue-specific RNAi were applied to identify the critical time window and tissue for pitp-1-mediated lifespan regulation. TOR signaling was measured by phosphorylated S6 kinase and puromycin incorporation, and transcriptomic analysis identified affected pathways. Resultspitp-1 negatively regulates lifespan and healthspan in Caenorhabditis elegans. Genetic deletion or RNAi-mediated knockdown of pitp-1 extends lifespan, attenuates age-related motility decline, and increases oxidative stress resistance. Temporal and spatial analyses reveal that suppression of pitp-1 in neurons during early adulthood is sufficient to promote healthy longevity. Mechanistically, these beneficial effects upon pitp-1 reduction are mediated by suppressing TOR signaling. Conversely, pitp-1 overexpression shortens lifespan and impairs healthspan via TOR activation. Moreover, pitp-1 is transcriptionally repressed by DAF-16 downstream of insulin/IGF-1 signaling (IIS), and contributes to IIS-mediated lifespan extension. ConclusionThese findings identify pitp-1 as a novel regulator of healthy aging that integrates IIS and TOR pathways, providing new insights into conserved mechanisms for promoting healthy longevity.

genetics↗

bioRxiv2025

Crosstalk between tubulin glutamylation and tyrosination regulates kine-sin-3-mediated axonal transport

Tubulin post-translational modifications (PTM) are critical regulators of microtubule function and diversity in neurons. In Caenorhabditis elegans, we investigated how tubulin deglutamylases (CCPP-1 and CCPP-6) and polyglutamylases (TTLL-5 and TTLL-9) affect kinesin-3 KIF1A/UNC-104-mediated axonal transport. Loss of CCPP-1 not only facilitates tubulin polyglutamylation as expected, but it also leads to increased tyrosination in Western blots. Vice versa, loss of TTLL-5 reduces tubulin polyglutamylation as expected, but also leads to reduced tyrosination signals. This crosstalk in tubulin PTM appears to be a critical feature as no tyrosination or detyrosination enzymes are known in C. elegans. Notably, acetylation and detyrosination remain unaffected in the deglutamylation and polyglutamylation mutants. Functionally, reduced glutamylation and tyrosination improved UNC-104 motility. Conversely, increased glutamylation and tyrosination negatively affected the movement of both the UNC-104 motor and its cargo RAB-3. UNC-104 motors visibly accumulate in neuronal cell bodies of ccpp-1 mutants while being significantly reduced in ttll-5 mutants. In ttll-5 mutants, motors tend to cluster along distal axonal regions and these clusters are reduced in ccpp-1 mutants revealing a role of tubulin PTM in axonal motor scaffolding. Employing promoter fusions, we confirmed that all investigated PTM enzymes express in neurons and colocalize with UNC-104. Moreover, co-immunoprecipitation assays revealed that hyperglutamylated tubulin appears in a physical complex with UNC-104, while hypoglutamylated tubulin binds less effectively to the motor. In our model, highly negatively charged polyglutamylated tubulin traps UNC-104 onto microtubules via increased charge-interactions. Tubulin "stickiness" is reduced in polyglutamylase mutants leading to increased motor speeds. Reduced synaptic vesicle transport in ccpp-1 mutants has a negative impact on the nematodes touch sensing, highlighting C. elegans as a valuable model for investigating tubulin PTM-related neurological disorders.

cell biology↗

bioRxiv2024

A mutation in vesicular acetylcholine transporter increases tubulin acetylation compromising axonal transport

Kinesin-3 UNC-104(KIF1A) is the major anterograde axonal transporter of synaptic vesicles and is expressed pan-neuronally. Genetic defects in this molecular motor are linked to KIF1A-associated neurological disorders (KAND) encompassing Charcot-Marie-Tooth (CMT) disease and hereditary spastic paraplegia (HSP). From a candidate screen for genes causing neurotransmission defects in C. elegans and simultaneously affecting post-translational modification of tubulin, we identified allele unc-17(e245) significantly elevating tubulin acetylation in vitro and in vivo. UNC-17 encodes for a VAChT (vesicle acetylcholine transporter) and its human ortholog SLC18A3 is implicated in Alzheimers and Huntingtons disease. To exclude secondary effects of the unc-17 mutation, we tracked UNC-104 and RAB-3 motility in the non-cholinergic ALM neuron. With upregulated tubulin acetylation in ALM (anterior lateral microtubule) neurons in unc-17(e245) strains (visualized by immunostaining), motility of both, motor and its cargo, is significantly compromised. However, motility of UNC-104 improves when knocking down alpha-tubulin acetyltransferase MEC-17(ATAT1) in unc-17(e245) strains and, conversely, is negatively affected when overexpressing MEC-17 in wild type animals. UNC-17 and UNC-104 are co-expressed and colocalize in cholinergic head neurons, suggesting a functional motor-cargo relationship. Strikingly, mec-17 knockdown significantly enhances their colocalization, while unc-17 knockdown reduces UNC-104/MEC-17 colocalization in ALM neurons. Direct interactions were confirmed by bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP): MEC-17 depletion strengthens UNC-104/UNC-17 association and stabilizes the motor-cargo complex, whereas unc-17 knockdown attenuates UNC-104/MEC-17 interactions, as evidenced by diminished Co-IP signals. We propose that unc-17 knock-down releases MEC-17 from the transport complex, thereby enhancing its tubulin acetyltransferase activity. This elevated acetylation may disrupt motor motility, ultimately impairing synaptic vesicle trafficking. This dynamic interplay, modulated by tubulin acetylation, highlights a regulatory axis involving UNC-104, UNC-17, and MEC-17 across cholinergic and glutamatergic neurons, offering new insights into axonal transport defects relevant to KIF1A-associated neurological disorder (KAND).

cell biology↗

bioRxiv2019

Depletion of intermediate filament IFB-1 negatively affects mobility and physiological function of mitochondria in C. elegans sensory neurons

Mitochondria and intermediate filament (IF) accumulations often occur during imbalanced axonal transport leading to various types of neurological diseases. It is still poorly understood whether a link between neuronal IFs and mitochondrial mobility exist. In C. elegans, among the 11 cytoplasmic IF family proteins, IFB-1 is of particular interest as it is expressed in a subset of sensory neurons. Depletion of IFB-1 leads to mild dye-filling and significant chemotaxis defects as well as reduced life span. Sensory neuron development is affected and mitochondria transport is slowed down leading to reduced densities of these organelles. Mitochondria tend to cluster in neurons of IFB-1 mutants likely dependent on fission but independent of fusion events. Oxygen consumption and mitochondrial membrane potential is measurably reduced in worms carrying mutations in the ifb-1 gene. Membrane potential also seems to play a role in transport such as FCCP treatment led to increased directional switching of mitochondria. Mitochondria colocalize with IFB-1 in worm neurons and appear in a complex with IFB-1 in pull-down assays. In summary, we propose a model in which neuronal intermediate filaments may serve as critical (transient) anchor points for mitochondria during their long-range transport in neurons for steady and balanced transport. Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/723205v3_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1c6fc73org.highwire.dtl.DTLVardef@e7fd9aorg.highwire.dtl.DTLVardef@ba9742org.highwire.dtl.DTLVardef@20a9ed_HPS_FORMAT_FIGEXP M_FIG C_FIG SynopsisVarious neurological diseases are both associated with abnormal accumulations of neuronal intermediate filaments as well as mitochondria. Here, we report a link between these two phenomena employing the model organisms C. elegans. Depletion of neuronal intermediate filament IFB-1 impairs the transport of mitochondria in sensory neurons leading to clustered and accumulated mitochondria affecting neuronal growth and oxygen consumption in nematodes.

cell biology↗