Biology subjects

Power, K. M.

Publications and source records attributed to Power, K. M..

4 recordsLinked to original sources

bioRxiv2024

NEKL-4 regulates microtubule stability and mitochondrial health in C. elegans ciliated neurons

Ciliopathies are often caused by defects in the ciliary microtubule core. Glutamylation is abundant in cilia, and its dysregulation may contribute to ciliopathies and neurodegeneration. Mutation of the deglutamylase CCP1 causes infantile-onset neurodegeneration. In C. elegans, ccpp-1 loss causes age-related ciliary degradation that is suppressed by mutation in the conserved NEK10 homolog nekl-4. NEKL-4 is absent from cilia, yet negatively regulates ciliary stability via an unknown, glutamylation-independent mechanism. We show that NEKL-4 was mitochondria-associated. nekl-4 mutants had longer mitochondria, a higher baseline mitochondrial oxidation state, and suppressed ccpp-1 mutant lifespan extension in response to oxidative stress. A kinase-dead nekl-4(KD) mutant ectopically localized to ccpp-1 cilia and rescued degenerating microtubule doublet B-tubules. A nondegradable nekl-4(PEST{Delta}) mutant resembled the ccpp-1 mutant with dye filling defects and B-tubule breaks. The nekl-4(PEST{Delta}) Dyf phenotype was suppressed by mutation in the depolymerizing kinesin-8 KLP-13/KIF19A. We conclude that NEKL-4 influences ciliary stability by activating ciliary kinesins and promoting mitochondrial homeostasis. SummaryNeurodegeneration and ciliary degeneration are caused by mutation of the deglutamylase CCP1/CCPP-1 in humans and C. elegans. The conserved NIMA-related kinase NEKL-4/NEK10 can suppress or promote degeneration in an activity-dependent manner that involves cilia-mitochondria communication and that is independent of glutamylation.

cell biology↗

bioRxiv2023

Ciliary intrinsic mechanisms regulate dynamic ciliary extracellular vesicle release from sensory neurons

Cilia-derived extracellular vesicles (EVs) contain signaling proteins and act in intercellular communication. Polycystin-2 (PKD-2), a transient receptor potential channel, is a conserved ciliary EVs cargo. Caenorhabditis elegans serves as a model for studying ciliary EV biogenesis and function. C. elegans males release EVs in a mechanically-induced manner and deposit PKD-2-labeled EVs onto the hermaphrodite vulva during mating, suggesting an active release process. Here, we study the dynamics of ciliary EV release using time-lapse imaging and find that cilia can sustain the release of PKD-2-labeled EVs for a two-hour duration. Intriguingly, this extended release doesnt require neuronal synaptic transmission. Instead, ciliary intrinsic mechanisms regulate PKD-2 ciliary membrane replenishment and dynamic EV release. The ciliary kinesin-3 motor KLP-6 is necessary for both initial and extended ciliary EV release, while the transition zone protein NPHP-4 is required only for sustained EV release. The dihydroceramide desaturase DEGS1/2 ortholog TTM-5 is highly expressed in the EV-releasing sensory neurons, localizes to cilia, and is required for sustained but not initial ciliary EV release, implicating ceramide in ciliary ectocytosis. The study offers a comprehensive portrait of real-time ciliary EV release, and mechanisms supporting cilia as proficient EV release platforms.

cell biology↗

bioRxiv2021

Tracking extracellular vesicle (EV) cargo as a platform for studying EVomics, signaling, and targeting in vivo

Extracellular vesicle (EV)-based signaling is a challenge to study, due to EV small size, heterogeneity, and limited information on cargo content in vivo. We present Caenorhabditis elegans as a discovery platform that allows single EV tracking from source to target tissue in living animals. We enriched ciliary EVs using GFP-tagged PKD-2 cargo followed by mass spectrometry analysis to identify 2,888 cargo candidates. By integrating our dataset with single-cell transcriptomic data, we identified EV cargo produced by individual neurons and other cell and tissue types. A single cilium produces multiple EVs with distinct protein content. Ciliary EVs carry nucleic acid binding proteins. We observed transfer of EV cargo from the male reproductive tract to the hermaphrodite uterus during mating, a direct demonstration of animal-to-animal EV targeting. One-Sentence SummaryHere we present a discovery platform for studying animal extracellular vesicle composition and biogenesis.

cell biology↗

bioRxiv2020

Mutation of NEKL-4/NEK10 and TTLL genes opposes loss of the CCPP-1 deglutamylase and prevents neuronal ciliary degeneration

Ciliary microtubules are subject to post-translational modifications that act as a "Tubulin Code" to regulate motor traffic, binding proteins and stability. In humans, loss of CCP1, a cytosolic carboxypeptidase and tubulin deglutamylating enzyme, causes infantile-onset neurodegeneration. In C. elegans, mutations in ccpp-1, the homolog of CCP1, result in progressive degeneration of neuronal cilia and loss of neuronal function. To identify genes that regulate microtubule glutamylation and ciliary integrity, we performed a forward genetic screen for suppressors of ciliary degeneration in ccpp-1 mutants. We isolated the ttll-5(my38) suppressor, a mutation in the tubulin tyrosine ligase-like glutamylase gene. We show that mutation in ttll-4, ttll-5, or ttll-11 gene suppressed the hyperglutamylation-induced loss of microtubules and kinesin-2 mislocalization in ccpp-1 cilia. We also identified the nekl-4(my31) suppressor, an allele affecting the NIMA (Never in Mitosis A)-related kinase NEKL-4/NEK10. In humans, NEK10 mutation causes bronchiectasis, an airway and mucociliary transport disorder caused by defective motile cilia. C. elegans NEKL-4 does not localize to cilia yet plays a role in regulating axonemal microtubule stability. This work defines a pathway in which glutamylation, a component of the Tubulin Code, is written by TTLL-4, TTLL-5, and TTLL-11; is erased by CCPP-1; is read by ciliary kinesins; and its downstream effects are modulated by NEKL-4 activity. Identification of regulators of microtubule glutamylation in diverse cellular contexts is important to the development of effective therapies for disorders characterized by changes in microtubule glutamylation. By identifying C. elegans genes important for neuronal and ciliary stability, our work may inform research into human ciliopathies and neurodegenerative diseases.

genetics↗