Worm Breeder's Gazette 17(2): 30 (April 1, 2002)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

C. elegans SEK-1 MAPKK regulates locomotion by functioning downstream of UNC-43 CaMKII

Miho Tanaka-Hino, Naoki Hisamoto, Kunihiro Matsumoto

Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, JAPAN

C. elegans UNC-43, the type II Ca²⁺ and calmodulin-dependent protein kinase (CaMKII), acts upstream of the NSY-1 MAPKKK-SEK-1 MAPKK-MAPK pathway to establish asymmetric cell fate decision in olfactory AWC neuron (Sagasti et al., 2001; Tanaka-Hino et al., 2002). UNC-43 also regulates several other neuronal functions including locomotion. In fact, the unc-43(gf) gain-of-function causes severe Unc phenotype. Although the GOA-1/EGL-30 heterotrimeric G protein network is involved in UNC-43-mediated regulation of locomotion, other components acting downstream of UNC-43 in the pathway are still unknown. We have determined whether the SEK-1 MAPKK is also involved in the UNC-43 locomotory function. In contrast to unc-43(gf) single mutants, unc-43(gf);sek-1(lf) double mutant animals exhibited almostly normal movement pattern. Thus, the sek-1 loss-of-function mutation can suppress the movement defect of unc-43(gf). Next, we examined the effect of the activated sek-1 mutation (sek-1-STDD; Tanaka-Hino et al., 2002) on the locomotion. When sek-1-STDD was expressed by the jkk-1 promoter (Kawasaki et al., 1999) in N2 wild-type animals, they showed severe Unc phenotype similar to unc-43(gf). This Unc phenotype was suppressed by the goa-1(lf) mutation. These results suggest that SEK-1 functions downstream of UNC-43 and upstream of GOA-1 to regulate proper movement.

Kawasaki M., Hisamoto N., Iino Y., Yamamoto M., Ninomiya-Tsuji, J., Matsumoto, K. A Caenorhabditis elegans JNK signal transduction pathway regulates coordinated movement via type-D GABAergic motor neurons. EMBO J., 18: 3604-3615 (1999).

Sagasti, A., Hisamoto, N., Hyodo, J., Tanaka-Hino, M., Matsumoto, K., Bargmann, C. I. The CaMKII UNC43 activates the MAPKKK NSY-1 to execute a lateral signaling decision required for asymmetric olfactory neuron fates. Cell, 105: 221-232 (2001).

Tanaka-Hino, M., Sagasti, A., Hisamoto, N., Kawasaki, M., Nakano, S., Ninomiya-Tsuji, J., Bargamnn, C. I., Matsumoto, K. SEK-1 MAPKK mediates Ca²⁺ signaling to determine neuronal asymmetric development in C. elegans. EMBO Rep., 3: 56-62 (2002).