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Drosophila HP1a IP-MS - The composition and organization of Drosophila heterochromatin are heterogeneous and dynamic

ABSTRACT: Heterochromatin is enriched for characteristic epigenetic factors, including Heterochromatin Protein 1a (HP1a) and is essential for many organismal functions. However, how this nuclear domain is organized and functions is unclear. We extensively investigated heterochromatin protein compostion by biochemically purifying Drosophila melanogaster HP1a interactors.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Drosophila Melanogaster (fruit Fly)

TISSUE(S): Cell Culture

SUBMITTER: Joel Swenson

LAB HEAD: Gary H Karpen

PROVIDER: PXD003780 | Pride | 2016-08-18

REPOSITORIES: Pride

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			Action	DRS
	5475 (F009629).mzid_5475_(F009629).pride.mgf.gz	Mzid
	5475.mgf	Mgf
	5475F009629.mzid.gz	Mzid
	5475F009629.mzid_5475_F009629.MGF	Mzid
	5476.mgf	Mgf

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Publications

The composition and organization of Drosophila heterochromatin are heterogeneous and dynamic.

Swenson Joel M JM Colmenares Serafin U SU Strom Amy R AR Costes Sylvain V SV Karpen Gary H GH

eLife 20160811

Heterochromatin is enriched for specific epigenetic factors including Heterochromatin Protein 1a (HP1a), and is essential for many organismal functions. To elucidate heterochromatin organization and regulation, we purified Drosophila melanogaster HP1a interactors, and performed a genome-wide RNAi screen to identify genes that impact HP1a levels or localization. The majority of the over four hundred putative HP1a interactors and regulators identified were previously unknown. We found that 13 of 1 ...[more]

PMID: 27514026

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Project description:Small RNA silencing pathways protect genome integrity in part through establishing heterochromatin at transposon loci. In animals, this process requires piRNA-guided targeting of nuclear PIWI proteins to nascent transcripts. The molecular events contributing to heterochromatin formation upon PIWI binding to nascent RNA, a transient molecule at chromatin, are unknown. Here, we identify SFINX, a protein complex that is required for Piwi-mediated co-transcriptional silencing in Drosophila. It consists of Nxf2—a variant of the nuclear RNA export factor Nxf1/Tap, the mRNA export co-factor Nxt1/p15, and the Piwi-associated protein Panoramix. In the absence of Nxf2, Panoramix is targeted for degradation and piRNA-loaded Piwi is unable to establish heterochromatin. Consequently, nxf2 mutants exhibit severe transposon de-repression and are sterile. We show that within SFINX, Panoramix connects to the heterochromatin machinery while Nxf2 enables target silencing via nascent RNA. Thus, the Nxf2-Nxt1 heterodimer—despite having originated from core mRNA export machinery—has been repurposed for heterochromatin formation. Our data establish an unexpected link between nuclear small RNA biology and NXF-variants, which are widespread in animal lineages, but mostly lack ascribed functions.

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