Genetic studies in eukaryotes have implicated spliceosome components in Argonaute-mediated silencing. Little is known however about how this occurs and whether or not it involves direct participation in small RNA biogenesis and downstream silencing, or more indirect effects for example on the expression of Argonaute pathway proteins. Here, we show that the C. elegans germline KH protein TOFU-7, previously reported as a piRNA-related factor, interacts by yeast 2 hybrid with SFTB-2, CDC5L and M03F8.3., components of the PRP-19 splicing complex. TOFU-7 also interacts with HSP-90, a chaperone required for loading piRNA guides onto PIWI. These factors are all required for piRNA-mediated establishment of silencing, yet their genetic behavior suggest they may function at different steps of the piRNA pathway. In
tofu-7 mutants PRG-1 and mature piRNAs are completely absent. In contrast, depletion of HSP-90 or CDC5L using an auxin-inducible system results in rapid disappearance of TOFU-7 protein and a mobility in shift in PRG-1. The
tofu-7 phenotype is epistatic to the degron depletion of HSP-90 or CDC5L resulting in absent rather than mobility shifted PRG-1. Our findings support a model in which TOFU-7 engages HSP-90 and PRP-19 components to enable PRG-1 loading and stability. Future studies will also explore the possibility that PRP19 complex recruits the spliceosome to promote piRNA biogenesis.