Dataset Information

Unanchored Ubiquitin Chains Do Not Lead to Marked Genetic Alterations in Drosophila melanogaster

ABSTRACT: Post-translational control by ubiquitin regulates various aspects of cellular biology. This chemical modification on proteins presents itself in numerous iterations, from a single mono-ubiquitination event to chains of poly-ubiquitin. Among the various types of poly-ubiquitin constructed are untethered species that comprise a series of ubiquitin moieties linked to one another, but free from another protein. The current notion is that these unanchored poly-ubiquitin species are deleterious to the cell and are rapidly deconstructed. We recently examined the toxicity and utilization of untethered poly-ubiquitin in an intact organism by using the fruit fly, Drosophila melanogaster. We found that these ubiquitin species are largely innocuous to flies and that free poly-Ub can be controlled by being degraded by the proteasome or being conjugated onto another protein as a single unit. However, whether the fly is mounting an organismal defense against untethered chains was not explored in detail. Here, we conducted RNA-seq analyses to examine at the transcriptome level the impact of unanchored poly-Ub in the fly. We found ~90 transcripts whose expression is altered in the presence of different types of unanchored poly-ubiquitin. The set of genes identified was mostly devoid of ubiquitin-, proteasome- or autophagy-related components. The largest gene ontology category identified, housing ~15 of the altered genes, was proteolysis. The seeming absence of a large and multipronged response to unanchored ubiquitin chains in the fly supports the conclusion that these species need not be toxic in vivo and underscores the need to reexamine the role of free ubiquitin chains in the cell. We designed two types of poly-Ub chains with six Ub molecules in tandem. They cannot be cleaved by DUBs (there are no "GG" motifs linking the Ub molecules). Ub6-GG can be conjugated in toto onto other proteins; Ub6-Stop cannot. We drove ubiquitous expression using sqh-Gal4, and then performed RNA-Seq on adult flies to determine any cellular response to the presence of our unanchored Ub chains.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE125090 | GEO | 2019/05/01

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:The COP9 signalosome (CSN) is a conserved protein complex occurring in all eukaryotes. The mammalian CSN consists of eight subunits (CSN1 – CSN8) and possesses an intrinsic metalloprotease JAMM motif localised to CSN5. In addition, it is associated with kinases such as protein kinase CK2 and D and the ubiquitin (Ub) specific protease 15. It regulates cullin-RING Ub ligases (CRLs) that label proteins for proteolysis with poly-Ub chains in the Ub proteasome system (UPS). CRLs contain one of the scaffolding cullins 1 – 7, a RING domain protein e. g. Rbx1, and one of hundreds of substrate binding units such as F-box or BTB proteins that specifically target proteins for ubiquitination. The CSN forms functional supercomplexes with CRLs. It removes the Ub-like protein Nedd8 from cullins by its metalloprotease activity and thereby inactivates CRLs. On the other hand, it is essential for CRL function by protecting components and allowing reassembly of the complexes. As a regulator of the UPS the CSN is involved in cell cycle10, DNA repair and development. Overexpression of CSN subunits has been reported in tumour cells. Up to date nothing is known about CSN biogenesis and its regulation. Ten years ago we have observed that overexpression of selected CSN subunits caused a coordinated increase of all CSN subunits and a de novo biosynthesis of the entire complex. Here we show that overexpression of CSN1 mediates an increase of c-Myc which coordinates CSN subunit expression via microRNAs (miRNAs). miRNAs are evolutionarily conserved, endogenous, small, noncoding RNA molecules of about 22 nucleotides that function as posttranscriptional gene regulators. We found that inhibitors of let-7 family miRNAs or upregulation of c-Myc, which represses let-7 miRNAs, resulted in a coordinated increase of CSN subunits and de novo CSN biogenesis. Keywords: Gene expression analysis of human RNA samples using topic-defined PIQOR™ Ubiquitin-PS Microarrays. Two different platforms were used (these are two different microarray batches which are identical in terms of the spotted cDNAs, but differ in the position of some cDNAs) Gene expression analysis of Hela cells overexpressing either CSN2 or CSN1 was performed to study CSN biogenesis and its regulation. Curcumin, Nr. 8 (Curcumin analogon) and Piceatannol were used for the treatment of Hela cells since they inhibit the CSN associated kinases. The aim was to investigate the effect on the signalosome. For each treatment 50 µM Curcumin, Nr. 8 and Piceatannol were used.

Dataset Information

Unanchored Ubiquitin Chains Do Not Lead to Marked Genetic Alterations in Drosophila melanogaster

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets