RESUMO
The piRNA pathway protects germline genomes from selfish genetic elements (e.g. transposons) through their transcript cleavage in the cytoplasm and/or their transcriptional silencing in the nucleus. Here, we describe a mechanism by which the nuclear and cytoplasmic arms of the piRNA pathway are linked. We find that during mitosis of Drosophila spermatogonia, nuclear Piwi interacts with nuage, the compartment that mediates the cytoplasmic arm of the piRNA pathway. At the end of mitosis, Piwi leaves nuage to return to the nucleus. Dissociation of Piwi from nuage occurs at the depolymerizing microtubules of the central spindle, mediated by a microtubule-depolymerizing kinesin, Klp10A. Depletion of klp10A delays the return of Piwi to the nucleus and affects piRNA production, suggesting the role of nuclear-cytoplasmic communication in piRNA biogenesis. We propose that cell cycle-dependent communication between the nuclear and cytoplasmic arms of the piRNA pathway may play a previously unappreciated role in piRNA regulation.
Assuntos
Proteínas Argonautas/metabolismo , Proteínas de Drosophila/metabolismo , Cinesinas/metabolismo , RNA Interferente Pequeno/genética , Animais , Proteínas Argonautas/genética , Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Divisão Celular/fisiologia , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Elementos de DNA Transponíveis , Proteínas de Drosophila/genética , Drosophila melanogaster , Feminino , Inativação Gênica , Células Germinativas , Cinesinas/genética , Masculino , Ovário/metabolismo , RNA Interferente Pequeno/metabolismoRESUMO
In this study, we developed an efficient co-conversion marker, using the conserved dpy-10 gene, to facilitate creation and detection of CRISPR/Cas9-mediated targeted genomic changes in an emerging male/female nematode model system, Caenorhabditis nigoni .
RESUMO
In animals, PIWI-interacting RNAs (piRNAs) direct PIWI proteins to silence complementary targets such as transposons. In Drosophila and other species with a maternally specified germline, piRNAs deposited in the egg initiate piRNA biogenesis in the progeny. However, Y chromosome loci cannot participate in such a chain of intergenerational inheritance. How then can the biogenesis of Y-linked piRNAs be initiated? Here, using Suppressor of Stellate (Su(Ste)), a Y-linked Drosophila melanogaster piRNA locus as a model, we show that Su(Ste) piRNAs are made in the early male germline via 5'-to-3' phased piRNA biogenesis initiated by maternally deposited 1360/Hoppel transposon piRNAs. Notably, deposition of Su(Ste) piRNAs from XXY mothers obviates the need for phased piRNA biogenesis in sons. Together, our study uncovers a developmentally programmed, intergenerational mechanism that allows fly mothers to protect their sons using a Y-linked piRNA locus.
Assuntos
Proteínas de Drosophila , Drosophila , Animais , Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , RNA de Interação com Piwi , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas Argonautas/genéticaRESUMO
Piwi-interacting RNAs (piRNAs) play essential roles in silencing repetitive elements to promote fertility in metazoans. Studies in worms, flies, and mammals reveal that piRNAs are expressed in a sex-specific manner. However, the mechanisms underlying this sex-specific regulation are unknown. Here we identify SNPC-1.3, a male germline-enriched variant of a conserved subunit of the small nuclear RNA-activating protein complex, as a male-specific piRNA transcription factor in Caenorhabditis elegans. SNPC-1.3 colocalizes with the core piRNA transcription factor, SNPC-4, in nuclear foci of the male germline. Binding of SNPC-1.3 at male piRNA loci drives spermatogenic piRNA transcription and requires SNPC-4. Loss of snpc-1.3 leads to depletion of male piRNAs and defects in male-dependent fertility. Furthermore, TRA-1, a master regulator of sex determination, binds to the snpc-1.3 promoter and represses its expression during oogenesis. Loss of TRA-1 targeting causes ectopic expression of snpc-1.3 and male piRNAs during oogenesis. Thus, sexually dimorphic regulation of snpc-1.3 expression coordinates male and female piRNA expression during germline development.