FIGURE 9:

SPV-1 regulates spermathecal contractility via calcium and Rho-ROCK signaling. (A) Summary table of findings. SPV-1 regulates both the Rho-ROCK and calcium signaling pathways, which together are required for activation of myosin and tissue contractility. Increasing RHO-1 activity leads to faster transits (decreased dwell times) similar to decreased SPV-1, but does not alter calcium signaling. Increasing active CDC-42 does not alter dwell times but does alter calcium signaling similar to decreased SPV-1. Increasing SPV-1 increases dwell times, often resulting in transit failures and embryo trapping, and decreases calcium signaling activity and magnitude. Decreasing CDC-42 using RNAi does not alter dwell time or calcium signaling. (B) Proposed model of the network regulating actomyosin contractility in the spermatheca. Gray lines along the outside display previously known interactions. Orange lines display interactions investigated in this study. Solid lines indicate direct interactions, dotted lines indicate resultant interactions with known intermediates not shown, and dashed lines indicate unknown intermediates. SPV-1, CDC-42, and/or an unknown effector symbolized by the question mark could interact with any of the upstream members of the calcium signaling pathway; those arrows were omitted for clarity.