Cited by 207Ubiquitin and proteasome pathwaysCellular transport and secretionAutophagy in Disease and Therapy

The DOI matches its Crossref record; 57 of the 57 references it cites were found in a registry or an index; 5 of the 26 sources its claims cite were checked for support.

Essential Role of Ubiquitin-Specific Protease 8 for Receptor Tyrosine Kinase Stability and Endocytic Trafficking In Vivo

Open access

Abstract

Posttranslational modification by ubiquitin controls multiple cellular functions and is counteracted by the activities of deubiquitinating enzymes. UBPy (USP8) is a growth-regulated ubiquitin isopeptidase that interacts with the HRS-STAM complex. Using Cre-loxP-mediated gene targeting in mice, we show that lack of UBPy results in embryonic lethality, whereas its conditional inactivation in adults causes fatal liver failure. The defect is accompanied by a strong reduction or absence of several growth factor receptor tyrosine kinases (RTKs), like epidermal growth factor receptor, hepatocyte growth factor receptor (c-met), and ERBB3. UBPy-deficient cells exhibit aberrantly enlarged early endosomes colocalizing with enhanced ubiquitination and have reduced levels of HRS and STAM2. Congruently immortalized cells gradually stop proliferation upon induced deletion of UBPy. These results unveil a central and nonredundant role of UBPy in growth regulation, endosomal sorting, and the control of RTKs in vivo.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

UBPy (USP8) is essential in vivo: constitutive deletion causes embryonic lethality, while induced deletion in adult mice causes fatal liver failure. UBPy maintains receptor tyrosine kinase protein levels and endocytic trafficking, at least in part by counteracting ubiquitination and stabilizing the HRS-STAM complex.

Key findings

  • Heterozygote intercrosses yielded 13 UBPy+/+ (27.7%) and 34 UBPy+/− (72.3%) animals but no UBPy−/− mice; E9.5 mutant embryos were growth retarded and disorganized. Adult induced deletion caused death 4 to 6 days after poly(I:C), with severe liver failure, hyperbilirubinemia, and elevated liver enzymes.
  • Immortalized UBPy-deficient MEFs stopped growing 6 to 8 days after tamoxifen-induced deletion, with severely reduced BrdU incorporation but no enhanced apoptosis/TUNEL in MEFs; in contrast, hepatocytes showed apoptosis.
  • Loss of UBPy strongly reduced or eliminated RTKs: EGFR, c-met, and ERBB3 were decreased/absent in liver extracts, and EGFR was strongly reduced in cells; EGFR mRNA did not differ significantly, and EGF-induced Erk1/2 phosphorylation was impaired, while STAT1 phosphorylation was unaffected.
  • UBPy-deficient cells showed enlarged EEA1-positive early endosomes, accumulated multivesicular bodies, reduced/absent HRS and STAM2, and enhanced ubiquitinated substrates colocalizing with enlarged endosomes; proteasomal activity was not impaired and free ubiquitin levels were unchanged, while ALIX and TSG101 were unaffected.

Methods

  • Conditional Cre-loxP UBPy mice were generated by flanking exon IV with loxP sites; germline deletion used EIIa-Cre, and adult inducible deletion used MX-Cre with poly(I:C). Embryos were from heterozygous matings.
  • Immortalized UBPy fl/fl MEFs expressing Cre-ERT2 were used for tamoxifen-inducible deletion; analyses included immunoblotting, Southern/Northern blotting, immunofluorescence, electron microscopy, BrdU incorporation, TUNEL, liver plasma analysis, and proteasome activity assays.
  • EGF stimulation was performed after serum starvation with 100 ng/ml EGF; data are means ± standard errors of the mean, with statistical differences determined by Student’s t test.

Limitations

  • The paper states that because of the severe liver phenotype and early death, cell-type-specific inactivation will be necessary to define the physiological relevance in other organs or cell types, and that detailed mechanisms leading to RTK reduction need to be defined.
  • The paper notes that MX-Cre-mediated deletion is generally fastest and most efficient in the liver, which most likely explains why the phenotype manifests there although UBPy is also expressed in other cell types.
  • Evident from the text: constitutive UBPy loss is embryonic lethal, limiting analysis of adult constitutive deletion; much mechanistic work relies on an immortalized MEF line and induced deletion, and the proposal that UBPy has two independent functions in RTK degradation is presented as a model.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1128/mcb.01566-06

Cites

57 of 57 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

5 of 26 cited sources checked · 3 supported · 0 flagged · accuracy not yet measured

Show all 64 claims

  • Probably not a substantial claim. 9
  • The quote only partly states this claim. 1
  • It may state two separate claims as one. 15
22 of 22
  • The paper relies on this without support.

    Poly(I:C) administration alone does not cause the lethal liver failure observed in ΔUBPy mice.

    “Mutant mice with the induced deletion of UBPy (⌬UBPy mice) died 4 to 6 days after the administration of poly(I ⅐ C)”
  • The paper relies on this without support.

    UBPy functions as a deubiquitinating enzyme (DUB).

    “Consistent with the function of UBPy as a DUB”
  • The paper relies on this without support.

    UBPy is expressed in other cell types.

    “although UBPy is also expressed in other cell types.”
  • The paper relies on this without support.

    MVB maturation is a prerequisite of RTK degradation via the lysosomal pathway.

    “a prerequisite of RTK degradation via the lysosomal pathway.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Mutant mice reported dead before day-7 sampling

    Major

    The results state that mice with induced UBPy deletion died 4 to 6 days after poly(I 1⁄7 C) administration, but the Figure 2 caption says plasma was collected from 12 such mice seven days after induction.

1 of 1

Citations

Cites

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Show all 56 references

Research works printed but not linked: 4

  1. Feil R., 1997, Naunyn-Schmiedebergs Arch. Pharmacol., 355, 41
  2. Huang T. T., 2006, Nat. Cell Biol., 8, 3309
  3. Schumann G., 2002, Clin. Chem. Lab. Med., 40, 725
  4. Williams D. A., 2000, Blood, 96, 1646

Cited by

Sorted by citations

Items 101–200 of 207

Metadata

Authors
Niendorf, S., Oksche, A., Kisser, A., Löhler, J., Prinz, M., Schorle, H., Feller, S., Lewitzky, M., Horak, I., & Knobeloch, K.-P.
Affiliations
  • Leibniz-Forschungsinstitut für Molekulare Pharmakologie (DE)
  • Charité – Universitätsmedizin Berlin (DE)
  • Leibniz Institute of Virology (LIV) (DE)
  • University of Göttingen (DE)
  • University of Bonn (DE)
  • Cancer Research UK (GB)
Venue
Molecular and Cellular Biology
Published
2007-07-01
Volume
27
Issue
13
Pages
5029-5039
ISSN
  • 0270-7306 (ISSN-L)
  • 1098-5549
OpenAlex
W2069862324
Cited by
207
References
56
Citations by year
2026: 8 · 2025: 9 · 2024: 13 · 2023: 9 · 2022: 7 · 2021: 9 · 2020: 9 · 2019: 10 · 2018: 15 · 2017: 9 · 2016: 9 · 2015: 17 · 2014: 9 · 2013: 14 · 2012: 10
FWCI
4.13
Type
journal article
Language
en
Open access
Locations
  • Molecular and Cellular Biology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Informationszentrum Lebenswissenschaften (ZB MED) (submittedVersion)
  • GRO (submittedVersion)
Funders
Deutsche Forschungsgemeinschaft
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ubiquitin and proteasome pathways
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Autophagy in Disease and Therapy
Keywords
USP8, receptor tyrosine kinase, receptor stability, endosomal trafficking, STAM2, early endosomes, ubiquitination, epidermal growth factor receptor, c-Met, HER3, liver failure, embryonic lethality, growth regulation, cell proliferation
MeSH terms
Animals, Cell Line, Transformed, Death, Embryo, Mammalian, Endocytosis, Enzyme Stability, Fibroblasts, Humans, Liver, Endopeptidases, Endosomes, Mutagenesis, Gene Deletion, Gene Targeting, Proto-Oncogene Proteins c-met, Receptor Protein-Tyrosine Kinases, Receptor, ErbB-3, Ubiquitin, Ubiquitin Thiolesterase, Multiprotein Complexes, Cell Proliferation, Mice, Endosomal Sorting Complexes Required for Transport, ErbB Receptors

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