Biology subjects

Touroutine, D.

Publications and source records attributed to Touroutine, D..

3 recordsLinked to original sources

bioRxiv2021

Kinesin-II motors differentially impact biogenesis of distinct extracellular vesicle subpopulations shed from C. elegans sensory cilia

Extracellular vesicles (EVs) are bioactive lipid-bilayer enclosed particles released from nearly all cells. One specialized site for EV shedding is the primary cilium, a conserved signaling organelle. The mechanisms underlying cargo enrichment and biogenesis of heterogeneous EVs shed from cilia are unclear. Here we discover the conserved ion channel CLHM-1 as a new ciliary EV cargo. Using super-resolution microscopy, we imaged EVs released into the environment from sensory neuron cilia of C. elegans expressing fluorescently-tagged CLHM-1 and TRP polycystin-2 channel PKD-2 EV cargoes at endogenous levels. We find that these proteins are enriched in distinct EV subpopulations that are differentially shed in response to availability of hermaphrodite mating partners. Both CLHM-1 and PKD-2 localize to the ciliary base and middle segment of the cilium proper, but PKD-2 alone is present in the cilium distal tip and EVs shed from this site. CLHM-1 EVs released into the environment bud from a secondary site, the periciliary membrane compartment at the ciliary base. We show that individual heterotrimeric and homomeric kinesin-II motors have discrete impacts on the colocalization of PKD-2 and CLHM-1 in both cilia and EVs. Total loss of kinesin-II activity significantly decreases shedding of PKD-2 but not CLHM-1 EVs. Our data demonstrate that anterograde kinesin-II-dependent intraflagellar transport is required for selective enrichment of specific protein cargoes into heterogeneous EVs with different signaling potentials.

cell biology↗

bioRxiv2020

A conserved neuropeptide system links head and body motor circuits to enable adaptive behavior

Neuromodulators promote adaptive behaviors that are often complex and involve concerted activity changes across circuits that are often not physically connected. It is not well understood how neuromodulatory systems accomplish these tasks. Here we show that the C. elegans NLP-12 neuropeptide system shapes responses to food availability by modulating the activity of head and body wall motor neurons through alternate G-protein coupled receptor (GPCR) targets, CKR-1 and CKR-2. We show ckr-2 deletion reduces body bend depth during movement under basal conditions. We demonstrate CKR-1 is a functional NLP-12 receptor and define its expression in the nervous system. In contrast to basal locomotion, biased CKR-1 GPCR stimulation of head motor neurons promotes turning during local searching. Deletion of ckr-1 reduces head neuron activity and diminishes turning while specific ckr-1 overexpression or head neuron activation promote turning. Thus, our studies suggest locomotor responses to changing food availability are regulated through conditional NLP-12 stimulation of head or body wall motor circuits. Impact statementInvestigation of neuromodulatory control of ethologically conserved area-restricted food search behavior shows that NLP-12 stimulation of the head motor circuit promotes food searching through the previously uncharacterized CKR-1 GPCR.

neuroscience↗

bioRxiv2020

A rapid, super-selective method for detection of single nucleotide variants in C. elegans

With the widespread use of single nucleotide variants generated through mutagenesis screens, the million mutation project, and genome editing technologies, there is pressing need for an efficient and low-cost strategy to genotype single nucleotide substitutions. We have developed a rapid and inexpensive method for detection of point mutants through optimization of SuperSelective (SS) primers for end point PCR in Caenorhabditis elegans. Each SS primer consists of a 5 "anchor" that hybridizes to the template, followed by a non-complementary "bridge," and a "foot" corresponding to the target allele. The foot sequence is short, such that a single mismatch at the terminal 3 nucleotide destabilizes primer binding and prevents extension, enabling discrimination of different alleles. We explored how length, stability, and sequence composition of each SS primer segment affected selectivity and efficiency in order to develop simple rules for primer design that allow for distinction between any mismatches in various genetic contexts over a broad range of annealing temperatures. Manipulating bridge length affects amplification efficiency, while modifying the foot sequence can increase discriminatory power. Flexibility in the positioning of the anchor enables SS primers to be used for genotyping in regions with sequences that are challenging for standard primer design. In summary, we have demonstrated flexibility in design of SS primers and their utility for genotyping in C. elegans. Since SS primers reliably detect single nucleotide variants, we propose that this method could have broad application for SNP mapping, screening of CRISPR mutants, and colony PCR to identify successful site-directed mutagenesis constructs.

genetics↗