Shiraki, Riona et al. (2021) International Worm Meeting "The C. elegans spermiogenesis-inducing compound DDI-4 can trigger the acrosome reaction in mouse spermatozoa"

Yamanaka, MIkiko, Nishimura, Hitoshi, Shiraki, Riona, Shimada, Yoshihiro, Hashimoto, Masaharu, Kaneko, Mayumi, Ohkura, Kouhei, Omote, Masaaki, Hashiba, Youki, Karuo, Yukiko

[International Worm Meeting, 2021]

In Caenorhabditis elegans, spermiogenesis undergoes two pivotal events; sperm formation and activation. Pseudopods extend from round spermatids to form motile spermatozoa, whereas membranous organelles (MOs) in spermatids fuse with the plasma membrane (PM) to activate spermatozoa. During the latter process, MOs release their contents extracellularly, and some proteins that are essential for fertilization relocate from the MO membrane onto the sperm surface, resulting in the acquisition of sperm fertility. These cytological features of MO fusion are similar to those of the acrosome reaction in mouse spermatozoa, representing one event for sperm activation. Thus, we hypothesized that C. elegans and the mouse might share a common mechanism for sperm activation. To explore this, we first screened a chemical library to obtain compounds that trigger C. elegans spermiogenesis. Of 480 entries contained in the library, we got several compounds as C. elegans spermiogenesis activators and chose one of the positive agents, named DDI-4, for further analyses. Intriguingly, 100 microM DDI-4 could induce the acrosome reaction in ~85% of mouse cauda epididymal spermatozoa, while ~70% became acrosome-reacted with 10 microM the calcium ionophore A23187. Moreover, DDI-4 promoted tyrosine phosphorylation of mouse sperm proteins, a typical capacitation signature, at least in vitro. These results indicate that DDI-4 can activate both C. elegans and mouse spermatozoa in vitro. In other words, these two species presumably possess targets of DDI-4 that function in sperm activation. To obtain clues regarding the DDI-4 targets or DDI-4-related factors, we screened mutants whose spermatids were resistant to DDI-4 in ethyl methanesulfonate-treated worms. Since two mutant strains were eventually isolated, we are currently investigating those strains by next-generation sequencing to identify mutated genes by which spermatids will become incapable of being activated with DDI-4. Information of such genes might contribute to elucidating the common mechanism for sperm activation in C. elegans and the mouse.

Vidal Iglesias, Berta et al. (2013) International Worm Meeting "Role of sox-2 in postembryonic lineage progression."

Vidal Iglesias, Berta, Hobert, Oliver

[International Worm Meeting, 2013]

sox-2 is a highly conserved transcription factor that is well known to be a stem cell master regulator and is one of the Yamanaka factors required for the generation of induced pluripotent stem cells. sox-2 has also been extensively associated to neurogenesis and plays an important role in the maintenance of neural stem cells. Using a fosmid-based reporter gene we have seen that sox-2 is expressed broadly during C. elegans embryogenesis, being expressed in several neuronal progenitors, although not exclusively neither in all of them. The sox-2 null mutant is L1 lethal and has the pharynx unattached; however, quantification of a panneuronal reporter does not show any neuronal specification defects, indicating that sox-2 is dispesable for C. elegans embryonic neurogenesis. Interestingly, at the L1 stage, sox-2 is also expressed in several postembryonic blast cells, which have to keep dividing during larval development to give rise to different postembryonic lineages that generate neurons among other cell types. Being sox-2 an important pluripotency factor, we hypothesized that it might be required in the L1 blast cells to retain their developmental potential. Using mosaic analysis strategies to overcome the L1 lethality of the sox-2 null allele, we have so far identified defects in three different postembryonic lineages in the absence of sox-2: the V5 lineage, which originates the postdeirid, the K lineage that gives rise to the DVB neuron and the B lineage, which generates the spicules in males. These results support the idea that postembryonic blast cell competence is compromised in the absence of sox-2. The extent of sox-2 functions in different postembryonic lineages and its mechanism of action to control lineage progression are currently being investigated.

Tomoko Yamada-Inagawa et al. (2003) International Worm Meeting "AAA family proteins related to human genetic diseases in C. elegans - II"

Kunitoshi Yamanaka, Toshinobu Suzaki, Teru Ogura, Tomoko Yamada-Inagawa

[International Worm Meeting, 2003]

We have studied Escherichia coli FtsH, which is a membrane-bound, oligomeric ATP-dependent metalloprotease belonging to the AAA (ATPases associated with diverse cellular activities. For details of AAA, see the poster presented by K. Yamanaka et al.) family. C. elegans has three FtsH homologues (Y47G6A.10, Y38F2AR.para and M03C11.5). Their expression and roles are yet unknown. Y47G6A.10 and Y38F2AR.para are highly homologous with human paraplegin, which is a nuclear-encoded mitochondrial protein and whose mutation is responsible for a human genetic disease, hereditary spastic paraplegia (HSP). Progressive weakness and spasticity of the lower limbs due to degeneration of corticospinal axons are the clinical hallmarks of HSP. The marked genetic heterogeneity in HSP, with 20 loci chromosomally mapped and eight genes so far identified, suggests that a number of defective cellular processes may result in the disease. However, little is known about pathogenesis of HSP. Furthermore, no specific treatment is currently available to prevent, cure, or delay progression of symptoms of HSP. In order to establish a model system for HSP, we initiated to analyze paraplegin homologues in C. elegans.The analysis of GFP fusion constructs of Y47G6A.10 and Y38F2AR.para showed that their expression pattern was not identical. In addition, effects of RNAi were also different; mixed phenotype (embryonic lethal, larval lethal or slow growth) for Y47G6A.10, but no obvious effect for Y38F2AR.para. Progressively retarded motility was also observed for Y47G6A.10. Succinate dehydrogenase assay and electron microscopic observation of Y47G6A.10 (RNAi) indicated mitochondrial defects. These are in good agreement with the previous reports of the clinical characteristic of HSP patients and the analyses of muscle biopsy from patients, suggesting that Y47G6A.10 is a functional homologue of paraplegin.C24B5.2 and/or F32D1.1 are homologous with another AAA protein, spastin, which is also related to HSP. Results on these proteins are also discussed.