Differential Regulation of Germline mRNAs in Soma and Germ Cells by Zebrafish miR-430

SummaryEarly in development, primordial germ cells (PGCs) are set aside from somatic cells and acquire a unique gene-expression program [1]. The mechanisms underlying germline-specific gene expression are largely unknown. Nanos expression is required during germline development 2, 3, 4 and 5 and is posttranscriptionally restricted to PGCs 4, 6, 7 and 8. Here we report that the microRNA miR-430 targets the 3′ untranslated region (UTR) of nanos1 during zebrafish embryogenesis. A miR-430 target site within the nanos1 3′ UTR reduces poly(A) tail length, mRNA stability, and translation. Repression is disrupted in maternal-zygotic dicer mutants (MZdicer), which lack mature miRNAs [9], and is restored by injection of processed miR-430. Although miR-430 represses other genes equally in germline and soma, specific regions in the nanos1 3′ UTR compensate for microRNA-mediated repression in PGCs and allow germline-specific expression. We show that the 3′ UTR of an additional PGC-specific gene, TDRD7, is also targeted by miR-430. These results indicate that miR-430 targets the 3′ UTRs of germline genes and suggest that differential susceptibility to microRNAs contributes to tissue-specific gene expression.