Siwi cooperates with Par-1 kinase to regulate mitochondrial Papi scaffolding Siwi-piRISC biogenesis
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ABSTRACT:
PROVIDER: PRJNA743683 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR15039453.fastq.gz | Fastqsanger.gz | |||
| SRR15039454.fastq.gz | Fastqsanger.gz | |||
| SRR15039455.fastq.gz | Fastqsanger.gz | |||
| SRR15039456.fastq.gz | Fastqsanger.gz | |||
| SRR15117316.fastq.gz | Fastqsanger.gz |
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Project description:Bombyx Papi contains two K-homology (KH) domains and one Tudor domain, and acts as a scaffold for Siwi-piRISC biogenesis on the mitochondrial surface. To initiate this process, Papi binds first to Siwi via the Tudor domain and subsequently to piRNA precursors loaded onto Siwi via the KH domains. This second action depends on phosphorylation of Papi. However, its underlying mechanism remains unknown. Here, we show that Siwi targets Par-1 kinase to mitochondrial Papi to promote its phosphorylation at Ser547 in the auxiliary domain and that this modification enhances the ability of Papi to bind Siwi-bound piRNA precursors via the KH domains. Papi S547A mutant still bound to Siwi, like wild-type (WT) Papi, although it evaded phosphorylation by Par-1: Consequently, Papi lost the ability to bind RNAs, abrogating the generation of Siwi-piRISC. Papi mutant lacking the Tudor and auxiliary domains escaped coordinated regulation by Siwi and Par-1 and lost their bias to bind piRNA precursors. Pseudo-phosphorylation mutants of Papi restored Siwi-piRISC formation in Papi-lacking cells, but their ability to bind RNAs required Siwi, similar to WT Papi. Par-1-dependent, multilayered mechanism by which Siwi regulates the role of Papi in Siwi-piRISC biogenesis was revealed.
2022-01-25 | GSE179432 | GEO
Project description:PIWI-interacting RNAs (piRNAs) are germline-enriched small RNAs that control transposons to maintain genome integrity1,2,3. To achieve this, piRNAs bind PIWI proteins upon being processed from piRNA precursors1,2,3. Bioinformatic studies of piRNA biogenesis in Drosophila showed that the piRNA 5′ end is formed by PIWI-Slicer or Zucchini (Zuc) endonucleolytic cleavage, while the 3′ end is formed by Zuc or Nibbler (Nbr) 3′-to-5′ exonucleolytic activity4,5,6. piRNA 3′-end formation in Bombyx was shown to be mediated by PNLDC1/Trimmer (Trim) 3′-to-5′ exonuclease7, while piRNA intermediates are bound with PIWI anchored onto mitochondrial protein PAPI8. However, the requirement for Zuc and Nbr in piRNA biogenesis in Bombyx has not been elucidated. Here, we applied biochemical approaches to understand their involvement in piRNA biogenesis and revealed that Zuc endonuclease, but not Trim and Nbr exonucleases, plays a crucial role in Bombyx piRNA 3′-end formation. Loss of Zuc had little effect on the levels of Trim and Nbr, but led to the aberrant accumulation of piRNA intermediates within the PAPI complex, which were processed to mature piRNAs by recombinant Zuc. Zuc copurified with PAPI, and PAPI exerted RNA-binding activity only when Siwi coexisted with it and PAPI was phosphorylated, suggesting that complex assembly proceeds via a hierarchical process. Bioinformatic analyses of piRNA intermediates within the PAPI complex revealed that both the 5′ and the 3′ ends showed the hallmark of PIWI-Slicer, yet no phasing pattern was observed in mature piRNAs. These findings strongly support the notion that, in Bombyx piRNA, the 5′ end is formed by PIWI-Slicer, but independently of Zuc, while the 3′ end is formed by Zuc endonuclease. The Bombyx piRNA biogenesis is simpler than that of Drosophila, which is reasonable considering that Bombyx has no transcriptional silencing machinery relying on phased piRNAs.
2018-03-01 | GSE107371 | GEO
Project description:Bombyx Papi acts as a scaffold for Siwi-piRISC biogenesis on the mitochondrial surface. Papi binds first to Siwi via the Tudor domain and subsequently to piRNA precursors loaded onto Siwi via the K-homology (KH) domains. This second action depends on phosphorylation of Papi. However, the underlying mechanism remains unknown. Here, we show that Siwi targets Par-1 kinase to Papi to phosphorylate Ser547 in the auxiliary domain. This modification enhances the ability of Papi to bind Siwi-bound piRNA precursors via the KH domains. The Papi S547A mutant bound to Siwi, but evaded phosphorylation by Par-1, abrogating Siwi-piRISC biogenesis. A Papi mutant that lacked the Tudor and auxiliary domains escaped coordinated regulation by Siwi and Par-1 and bound RNAs autonomously. Another Papi mutant that lacked the auxiliary domain bound Siwi but did not bind piRNA precursors. A sophisticated mechanism by which Siwi cooperates with Par-1 kinase to promote Siwi-piRISC biogenesis was uncovered.
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Project description:Hierarchical roles of mitochondrial PAPI and Zucchini in Bombyx germline piRNA biogenesis
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Project description:Ferroptosis is a unique iron-dependent form of non-apoptotic cell death characterized by devastating lipid peroxidation. Whilst growing evidence suggests that ferroptosis is a type of autophagy-dependent cell death, the underlying molecular mechanisms regulating ferroptosis are largely unknown. In this study, through an unbiased RNA-sequencing screening, we demonstrate the activation of a multi-faceted tumor-suppressor protein Par-4/PAWR during ferroptosis. Functional studies reveal that genetic depletion of Par-4 effectively blocks ferroptosis, whereas Par-4 overexpression sensitizes cells to undergo ferroptosis. More importantly, we have determined that Par-4-triggered ferroptosis is mechanistically driven by the autophagic machinery. Upregulation of Par-4 promotes activation of ferritinophagy (autophagic degradation of ferritin) via the nuclear receptor co-activator 4 (NCOA4), resulting in excessive release of free labile iron and, hence, enhanced lipid peroxidation and ferroptosis. Inhibition of Par-4 dramatically suppresses the NCOA4-mediated ferritinophagy signaling axis. Our results also establish that Par-4 activation positively correlates with reactive oxygen species (ROS) production, which is critical for ferritinophagy-mediated ferroptosis. Furthermore, Par-4 knockdown effectively blocked ferroptosis-mediated tumor suppression in the mouse xenograft models. Collectively, these findings reveal that Par-4 has a crucial role in ferroptosis, which could be further exploited for cancer therapy.
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