Tetraspanins constitute a widely expressed protein family of more than 30 members characterized by four transmembrane regions and two extracellular loops with a conserved CCG motif. Several lines of evidence indicate that tetraspanins are involved in cell adhesion, migration, tumor metastasis and membrane fusion events in mammals. Tetraspanins associate with transmembrane proteins such as integrins and Ig superfamily proteins and also with cellular proteins like PKC. Thus, tetraspanins are thought to play a role in assembling membrane proteins for inter- and intracellular signaling. C. elegans has 20 tetraspanin genes (
tsp-1 ~
tsp-20) and we previously showed that reduction of function of
tsp-15 , one of nematode tetraspanin, resulted in morphological and functional abnormalities in cuticle and hypodermis (1). To explore genetic hierarchy of epidermal integrity regulated by
tsp-15, we have screened 15000 mutagenized haploid genomes for suppressors of epidermal abnormalities (Dpy, Bli, Lvl, and molting defect) elicited by hypomorphic
tsp-15 mutant. Using SNP mapping, one recessive suppressor allele termed as
sts-1 (suppressor of tetraspanin) was mapped in cluster of LG III.
sts-1 was suggested as upstream of
tsp-15 since
sts-1 was unable to suppress larval lethality of
tsp-15 null mutant. Further characterization of
sts-1 gene will be discussed. (1) Moribe, H., Yochem, J., Yamada, H., Tabuse, Y., Fujimoto, T., and Mekada, E. (2004). J. Cell Sci. 117, 5209-5220.