Dataset Information

Ubiquilin1 promotes antigen-receptor mediated proliferation by eliminating mislocalized mitochondrial proteins

ABSTRACT: Ubiquilins (Ubqlns) are a family of ubiquitin receptors that promote the delivery of hydrophobic and aggregated ubiquitinated proteins to the proteasome for degradation. We carried out a proteomic analysis of a B cell lymphoma-derived cell line, BJAB, that requires UBQLN1 for survival to identify UBQLN1 client proteins. When UBQLN1 expression was acutely inhibited, 120 mitochondrial proteins were enriched in the cytoplasm, suggesting that the accumulation of mitochondrial client proteins in the absence of UBQLN1 is cytostatic. Using a Ubqln1-/- mouse strain, we found that B cell receptor (BCR) ligation of Ubqln1-/- B cells led to a defect in cell cycle entry. As in BJAB cells, mitochondrial proteins accumulated in BCR-stimulated cells, leading to protein synthesis inhibition and cell cycle block. Thus, UBQLN1 plays an important role in clearing mislocalized mitochondrial proteins upon cell stimulation, and its absence leads to suppression of protein synthesis and cell cycle arrest.

OTHER RELATED OMICS DATASETS IN: PRJNA340282

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): B Cell, Primary Cell, Cell Culture

SUBMITTER: Miguel Prado

LAB HEAD: Daniel J Finley

PROVIDER: PXD007610 | Pride | 2017-09-25

REPOSITORIES: Pride

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Publications

Ubiquilin1 promotes antigen-receptor mediated proliferation by eliminating mislocalized mitochondrial proteins.

Whiteley Alexandra M AM Prado Miguel A MA Peng Ivan I Abbas Alexander R AR Haley Benjamin B Paulo Joao A JA Reichelt Mike M Katakam Anand A Sagolla Meredith M Modrusan Zora Z Lee Dong Yun DY Roose-Girma Merone M Kirkpatrick Donald S DS McKenzie Brent S BS Gygi Steven P SP Finley Daniel D Brown Eric J EJ

eLife 20170921

Ubiquilins (Ubqlns) are a family of ubiquitin receptors that promote the delivery of hydrophobic and aggregated ubiquitinated proteins to the proteasome for degradation. We carried out a proteomic analysis of a B cell lymphoma-derived cell line, BJAB, that requires UBQLN1 for survival to identify UBQLN1 client proteins. When UBQLN1 expression was acutely inhibited, 120 mitochondrial proteins were enriched in the cytoplasm, suggesting that the accumulation of mitochondrial client proteins in the ...[more]

PMID: 28933694

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Project description:During early embryonic cell divisions, the total nuclear volume doubles with each cycle. At a critical volume ratio between the nucleus and cytoplasm, embryos start transcribing their genome in a reproducible and sequential manner. However, the underlying molecular mechanism for these well-timed events remains unclear. Previous studies proposed that titration of a regulatory factor by the exponentially increasing DNA content of the system triggers the onset of the first transcripts. Nevertheless, a systematic investigation of nuclear proteome changes during development is still missing. In this study, we perform this investigation and find that differential nuclear import timing can largely explain the sequential onset of transcription. First, we investigated nuclear proteome changes in early development. We found that nuclear proteins sequentially titrate into the embryonic nuclei. Interestingly, transcription factors and RNA polymerases enter the nucleus at different times, which correspond to the activation of their nuclear functions. Notably, we observed a high correlation between when transcription factors enter the nucleus and the order in which they activate downstream transcription. Time-lapse imaging of protein import into nuclei encapsulated in droplets of cytoplasmic extract validated our discovery of the sequential nuclear import by mass spectrometry. Lastly, we investigated the underlying molecular mechanism responsible for the differential timing of protein entry into embryonic nuclei. To this end, we quantified the relative affinity of substrates to importin and observe that high-affinity substrates tend to enter the nucleus earlier than low-affinity substrates. Notably, we can explain > 36% of the observed time-variation of when proteins enter the nucleus in the embryo with this simple affinity assay. Together, our results suggest that embryos control protein entry into the nucleus by modulating importin affinities, which then determines the timing of essential nuclear processes in early development.

Dataset Information

Ubiquilin1 promotes antigen-receptor mediated proliferation by eliminating mislocalized mitochondrial proteins

Publications

Ubiquilin1 promotes antigen-receptor mediated proliferation by eliminating mislocalized mitochondrial proteins.

Similar Datasets

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