Filamin and Phospholipase C-ε Are Required for Calcium Signaling in the Caenorhabditis elegans Spermatheca

The caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter,are fertilized,and exit into the uterus. fln-1/filamin,a stretch-sensitive structural and signaling scaffold,and plc-1/phospholipase c-ε,an enzyme that generates the second messenger ip3,are required for embryos to exit normally after fertilization. using gcamp,a genetically encoded calcium indicator,we show that entry of an oocyte into the spermatheca initiates a distinctive series of ip3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. plc-1 is required for the calcium release mechanism triggered by oocyte entry,and fln-1 is required for timely initiation of the calcium oscillations. inx-12,a gap junction subunit,coordinates propagation of the calcium transients across the spermatheca. gain-of-function mutations in itr-1/ip3r,an ip3-dependent calcium channel,and loss-of-function mutations in lfe-2,a negative regulator of ip3signaling,increase calcium release and suppress the exit defect in filamin-deficient animals. we further demonstrate that a regulatory cassette consisting of mel-11/myosin phosphatase and nmy-1/non-muscle myosin is required for coordinated contraction of the spermatheca. in summary,this study answers long-standing questions concerning calcium signaling dynamics in the c. elegans spermatheca and suggests fln-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue. © 2013 kovacevic et al.