Figure 4. TTM-5 facilitates the dynamic release of PKD-2 ciliary EVs.
(A) Schematic cartoon of TTM-5 action site. TTM-5 is the ortholog of DEGS1/2 (delta-4-desaturase, sphingolipid 1/2), an enzyme that converts dihydroceramides to ceramides. The unsaturated fatty acid chain creates a kink in the chain, making the cone shape of mature ceramides to support the high curvature membrane of cilia and EV.
(B) A CRISPR reporter of TTM-5::GFP is expressed in male-specific EV-releasing neurons, including four cephalic male (CEM) neurons and 17 neurons in the tail (soma of R8B and R9B are shown, for the full tail images, see Figure S3C). In the tail EV-releasing neurons, TTM-5 primarily localizes to the soma, ciliary base, and cilium and is not detectable in EVs.
(C) Representative images of PKD-2::GFP ciliary EV release in male tail sensory neurons at 0 and 1 hour in wild-type and ttm-5 mutant males. Blue lines indicate the outline of the male tail. Orange lines indicate the outline of the EV clouds released by the tail.
(D) Quantification of EV counts at 0 and 1 hour of wild-type and ttm-5 mutant males. The scatter plot with lines indicates the mean ± SEM. Each data point represents the total EV count released by an individual C. elegans male. n = 12. Statistical analysis was performed using one-way ANOVA with Bonferroni correction. ns denotes not significant (p ≥ 0.05), and * denotes p < 0.05.