As the founding member of the microRNA (miRNA) gene family, insights into
lin-4 regulation and function have laid a conceptual foundation for countless miRNA-related studies that followed. We previously showed that a transcriptional
lin-4 reporter in C. elegans was positively regulated by a
lin-4-complementary element (LCE), and by
lin-4 itself. In this study, we sought to (1) identify additional factors required for
lin-4 reporter expression, and (2) validate the endogenous relevance of a potential positive autoregulatory mechanism of
lin-4 expression. We report that all four core nuclear RNAi factors (
nrde-1,
nrde-2,
nrde-3 and
nrde-4), positively regulate
lin-4 reporter expression. In contrast, endogenous
lin-4 levels were largely unaffected in
nrde-2;
nrde-3 mutants. Further, an endogenous LCE deletion generated by CRISPR-Cas9 revealed that the LCE was also not necessary for the activity of the endogenous
lin-4 promoter. Finally, mutations in mature
lin-4 did not reduce primary
lin-4 transcript levels. Taken together, these data indicate that under growth conditions that reveal effects at the transgenic locus, a direct, positive autoregulatory mechanism of
lin-4 expression does not occur in the context of the endogenous
lin-4 locus.