Working model for dynamic activities of Hnrnpa1 during zebrafish MZT. Before ZGA, cytoplasmically localized Hnrnpa1 selectively binds to 3′ UTRs of maternal mRNAs that undergo ZGA-dependent (ZD) decay and positively regulates poly(A) tail length and translation via an unknown mechanism (either by inhibiting active deadenylation or by promoting polyadenylation). Following ZGA, Hnrnpa1 dissociates from maternal transcripts and translocates to the nucleus, where it binds noncoding RNAs derived from zebrafish Chromosome 4, including pri-mir-430. Nuclear Hnrnpa1 promotes pri-mir-430 processing, thereby indirectly contributes to consequential CCR4-NOT-mediated deadenylation and clearance of ZD decay mRNAs.
