PEZO-1 and TRP-4 mechanosensors are involved in mating behavior in Caenorhabditis elegans.

Male mating in Caenorhabditis elegans is a complex behavior with a strong mechanosensory component. C. elegans has several characterized mechanotransducer proteins, but few have been shown to contribute to mating. Here, we investigated the roles of PEZO-1, a piezo channel, and TRP-4, a mechanotransducing TRPN channel, in male mating behavior. We show that pezo-1 is expressed in several male-specific neurons with known roles in mating. We show that, among other neurons, trp-4 is expressed in the Post-Cloacal sensilla neuron type A (PCA) sensory neuron, which monitors relative sliding between the male and the hermaphrodite and inhibits neurons involved in vulva detection. Mutations in both genes compromise many steps of mating, including initial response to the hermaphrodite, scanning, turning, and vulva detection. We performed pan-neuronal imaging during mating between freely moving mutant males and hermaphrodites. Both pezo-1 and trp-4 mutants showed spurious activation of the sensory neurons involved in vulva detection. In trp-4 mutants, this spurious activation might be caused by PCA failure to inhibit vulva-detecting neurons during scanning. Indeed, we show that without functional TRP-4, PCA fails to detect the relative sliding between the male and hermaphrodite. Cell-specific TRP-4 expression restores PCA's mechanosensory function. Our results demonstrate new roles for both PEZO-1 and TRP-4 mechanotransducers in C. elegans mating behavior.

Conserved missense variant in ALDH1A3 ortholog impairs fecundity in C. elegans.

Accumulating evidence demonstrates that mutations in ALDH1A3 (the aldehyde dehydrogenase 1 family, member A3) are associated with developmental defects. The ALDH1A3 enzyme catalyzes retinoic acid biosynthesis and is essential to patterning and neuronal differentiation in the development of embryonic nervous system. Several missense mutations in ALDH1A3 have been identified in family studies of autosomal recessive microphthalmia, autism spectrum disorder, and other neurological disorders. However, there has been no evidence from animal models that verify the functional consequence of missense mutations in ALDH1A3. Here, we introduced the equivalent of the ALDH1A3 C174Y variant into the Caenorhabditis elegans ortholog, alh-1, at the corresponding locus. Mutant animals with this missense mutation exhibited decreased fecundity by 50% compared to wild-type animals, indicating disrupted protein function. To our knowledge, this is the first ALDH1A3 C174Y missense model, which might be used to elucidate the effects of ALDH1A3 C174Y missense mutation in the retinoic acid signaling pathway during development.

Caenorhabditis elegans PIEZO channel coordinates multiple reproductive tissues to govern ovulation.

PIEZO1 and PIEZO2 are newly identified mechanosensitive ion channels that exhibit a preference for calcium in response to mechanical stimuli. In this study, we discovered the vital roles of pezo-1, the sole PIEZO ortholog in Caenorhabditiselegans, in regulating reproduction. A number of deletion alleles, as well as a putative gain-of-function mutant, of PEZO-1 caused a severe reduction in brood size. In vivo observations showed that oocytes undergo a variety of transit defects as they enter and exit the spermatheca during ovulation. Post-ovulation oocytes were frequently damaged during spermathecal contraction. However, the calcium signaling was not dramatically changed in the pezo-1 mutants during ovulation. Loss of PEZO-1 also led to an inability of self-sperm to navigate back to the spermatheca properly after being pushed out of the spermatheca during ovulation. These findings suggest that PEZO-1 acts in different reproductive tissues to promote proper ovulation and fertilization in C. elegans.

Autism-associated missense genetic variants impact locomotion and neurodevelopment in Caenorhabditis elegans.

Autism spectrum disorder (ASD) involves thousands of alleles in over 850 genes, but the current functional inference tools are not sufficient to predict phenotypic changes. As a result, the causal relationship of most of these genetic variants in the pathogenesis of ASD has not yet been demonstrated and an experimental method prioritizing missense alleles for further intensive analysis is crucial. For this purpose, we have designed a pipeline that uses Caenorhabditis elegans as a genetic model to screen for phenotype-changing missense alleles inferred from human ASD studies. We identified highly conserved human ASD-associated missense variants in their C. elegans orthologs, used a CRISPR/Cas9-mediated homology-directed knock-in strategy to generate missense mutants and analyzed their impact on behaviors and development via several broad-spectrum assays. All tested missense alleles were predicted to perturb protein function, but we found only 70% of them showed detectable phenotypic changes in morphology, locomotion or fecundity. Our findings indicate that certain missense variants in the C. elegans orthologs of human CACNA1D, CHD7, CHD8, CUL3, DLG4, GLRA2, NAA15, PTEN, SYNGAP1 and TPH2 impact neurodevelopment and movement functions, elevating these genes as candidates for future study into ASD. Our approach will help prioritize functionally important missense variants for detailed studies in vertebrate models and human cells.

Snail as a novel marker for regional metastasis in head and neck squamous cell carcinoma.

OBJECTIVE: Previous studies have shown Snail expression integral to the epithelial-mesenchymal transition during tumor progression. However, its behavior in clinical head and neck squamous cell carcinomas (HNSCCs) is yet undefined. We therefore sought to (1) investigate clinical and histopathologic characteristics of Snail-positive HNSCC and (2) understand the link between Snail and other commonly used HNSCC tumor markers. STUDY DESIGN: A retrospective case-control study was conducted. SETTING: This study was conducted in a large-scale academic center. STUDY SUBJECTS: Of 51 consecutive HNSCC, 42 surgical resections were included. METHODS: Two separate pathologists performed standard histopathologic reviews along with immunohistochemistries (Snail, E-cadherin, p16, epidermal growth factor receptor [EGFR]) and in situ hybridization (human papilloma virus [HPV]). Medical review for all cases was performed. RESULTS: Twenty-two (52%) of 42 cases stained 4+ Snail (>75% staining). The remaining 20 cases were considered negative. Snail was strongly inversely related to E-cadherin expression (ρ = -0.69, P < .001), but statistically independent from HPV, p16, or EGFR expression. Snail(+) tumors were equally represented from each anatomic subsite. Snail(+) tumors were strongly associated with poor differentiation (P < .001) and basaloid classification (P = .004). Snail(+) tumors were also strongly associated with lymphovascular invasion (P = .02), but not perineural invasion. Ultimately, 11 (50%) of 22 of Snail(+) tumors demonstrated positive nodal metastasis and 11 (79%) of 14 node-positive cases were Snail(+) (P = .02). CONCLUSION: This pilot study provides promising evidence of Snail' role as a molecular prognostic marker for HNSCC. Snail positivity is significantly predictive of poorly differentiated, lymphovascular invasive, as well as regionally metastatic tumors. Because Snail positivity appears independent of HPV, p16, and EGFR expression, Snail may prove to improve upon these markers' predictive limitations.