pVHL regulates protein stability of TCF/LEF transcription factor family via ubiquitin-independent proteasomal degradation

The Wnt/β-catenin signaling pathway plays key roles in development and adult tissue homeostasis by controlling cell proliferation and cell fate decisions. In this pathway, transcription factors TCF/LEFs are the key components to repress target gene expression by recruiting co-repressors or to activate target gene expression by recruiting β-catenin when the Wnt signals are absent or present, respectively. While progress has been made in our understanding of Wnt signaling regulation, the underlying mechanism that regulates the protein stability of the TCF/LEF family is far less clear. Here, we show that von Hippel-Lindau protein (pVHL), which is the substrate recognition component in an E3 ubiquitin ligase complex, controls TCF/LEF protein stability. Unexpectedly, pVHL directly binds to TCF/LEFs and promotes their proteasomal degradation independent of E3 ubiquitin ligase activity. Knockout of vhl in zebrafish embryos leads to a reduction of dorsal habenular neurons and this effect is upstream of dorsal habenular neurons phenotype in tcf7l2-null mutants. Our study uncovers a previously unknown mechanism for the protein stability regulation of the TCF/LEF transcription factors and demonstrates that pVHL contains a 26S proteasome binding domain that drives ubiquitin-independent proteasomal degradation. These findings provide new insights into the ubiquitin-independent actions of pVHL and uncover novel mechanistical regulation of Wnt/β-catenin signaling.

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Trip12, a HECT domain E3 ubiquitin ligase, targets Sox6 for proteasomal degradation and affects fiber type-specific gene expression in muscle cells

Skeletal Muscle ◽

10.1186/2044-5040-3-11 ◽

2013 ◽

Vol 3 (1) ◽

pp. 11 ◽

Cited By ~ 16

Author(s):

Chung-Il An ◽

Edward Ganio ◽

Nobuko Hagiwara

Keyword(s):

Gene Expression ◽

Ubiquitin Ligase ◽

Fiber Type ◽

E3 Ubiquitin Ligase ◽

Muscle Cells ◽

Proteasomal Degradation ◽

Specific Gene ◽

Hect Domain ◽

Specific Gene Expression

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Neuroblastoma and pre-B lymphoma cells share expression of key transcription factors but display tissue restricted target gene expression

BMC Cancer ◽

10.1186/1471-2407-4-80 ◽

2004 ◽

Vol 4 (1) ◽

Cited By ~ 9

Author(s):

Anna Lagergren ◽

Christina Manetopoulos ◽

Håkan Axelson ◽

Mikael Sigvardsson

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Target Gene ◽

Lymphoma Cells ◽

B Lymphoma ◽

Target Gene Expression ◽

B Lymphoma Cells

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FLT3ITD Target Enhancers Are Primed but Inaccessible in Fetal Hematopoietic Progenitors

Blood ◽

10.1182/blood-2019-126201 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1228-1228

Author(s):

Yanan Li ◽

Riddhi M Patel ◽

Emily Casey ◽

Jeffrey A. Magee

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Target Gene ◽

Target Genes ◽

Conflicts Of Interest ◽

Gene Activation ◽

Chromatin Accessibility ◽

Luciferase Reporter ◽

Enhancer Activity ◽

Target Gene Expression

The FLT3 Internal Tandem Duplication (FLT3ITD) is common somatic mutation in acute myeloid leukemia (AML). We have previously shown that FLT3ITD fails to induce changes in HSC self-renewal, myelopoiesis and leukemogenesis during fetal stages of life. FLT3ITD signal transduction pathways are hyperactivated in fetal progenitors, but FLT3ITD target genes are not. This suggests that postnatal-specific transcription factors may be required to help induce FLT3ITD target gene expression. Alternatively, repressive histone modifications may impose a barrier to FLT3ITD target gene activation in fetal HPCs that is relaxed during postnatal development. To resolve these possibilities, we used ATAC-seq, as well as H3K4me1, H3K27ac and H3K27me3 ChIP-seq, to identify cis-elements that putatively control FLT3ITD target gene expression in fetal and adult hematopoietic progenitor cells (HPCs). We identified many enhancer elements (ATAC-seq peaks with H3K4me1 and H3K27ac) that exhibited increased chromatin accessibility and activity in FLT3ITD adult HPCs relative to wild type adult HPCs. These elements were enriched near FLT3ITD target genes. HOMER analysis showed enrichment for STAT5, ETS, RUNX1 and IRF binding motifs within the FLT3ITD target enhancers, but motifs for temporally dynamic transcription factors were not identified. We cloned a subset of the enhancers and confirmed that they could synergize with their promoter to activate a luciferase reporter. For representative enhancers, STAT5 binding sites were required to activate the enhancer - as anticipated - and RUNX1 repressed enhancer activity. We tested whether accessibility or priming changed between fetal and adult stages of HPC development. FLT3ITD-dependent changes in chromatin accessibility were not observed in fetal HPCs, though the enhancers were primed early in development as evidenced by the presence of H3K4me1. Repressive H3K27me3 were not present at FLT3ITD target enhancers in either or adult HPCs. The data show that FLT3ITD target enhancers are demarcated early in hematopoietic development, long before they become responsive to FLT3ITD signaling. Repressive marks do not appear to create an epigenetic barrier to enhancer activation in the fetal stage. Instead, age-specific transcription factors are likely required to pioneer enhancer elements so that they can respond to STAT5 and other FLT3ITD effectors. Disclosures No relevant conflicts of interest to declare.

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The ubiquitin ligase RNF181 stabilizes ERα and modulates breast cancer progression

Oncogene ◽

10.1038/s41388-020-01464-z ◽

2020 ◽

Vol 39 (44) ◽

pp. 6776-6788

Author(s):

Jian Zhu ◽

Xin Li ◽

Peng Su ◽

Min Xue ◽

Yifeng Zang ◽

...

Keyword(s):

Breast Cancer ◽

Gene Expression ◽

Cancer Progression ◽

Ubiquitin Ligase ◽

Target Gene ◽

Endocrine Resistance ◽

Breast Cancer Progression ◽

Sequencing Analysis ◽

Target Gene Expression ◽

Positive Breast Cancer

Abstract ERα positive breast cancer accounts for 70% of breast malignancies. Compared with ERα negative types, ERα positive breast cancer could be effective controlled by endocrine therapy. However, more than half of the patients will develop endocrine resistance, making it an important clinical issue for breast cancer therapy. Endocrine resistance might be caused by multiple alternations, including the components of ERα signaling, during tumor progression. Thus, it is urgent and necessary to uncover the molecular mechanisms that controls ERα expression and stability to improve breast cancer therapeutics. In our current study, we identifies that the ubiquitin ligase RNF181 stabilizes ERα and facilitates breast cancer progression. The expression of RNF181 is correlated with ERα level in human breast tumors and relates to poor survival in endocrine-treated patients. RNF181 depletion inhibits breast cancer progression in vivo and in vitro, reduces ERα protein level and its target gene expression, such as PS2 and GREB1. Unbiased RNA sequencing analysis indicates RNF181 is necessary for ERα signature gene expression in whole genomic level. Immuno-precipitation assays indicate that RNF181 associates with ERα and promotes its stability possibly via inducing ERα K63-linked poly-ubiquitination. In conclusion, our data implicate a non-genomic mechanism by RNF181 via stabilizing ERα protein controls ERα target gene expression linked to breast cancer progression.

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Gene regulation through chromatin remodelling by members of the nuclear receptor superfamily

Biochemical Society Transactions ◽

10.1042/bst0280369 ◽

2000 ◽

Vol 28 (4) ◽

pp. 369-373 ◽

Cited By ~ 15

Author(s):

I. J. McEwan

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Transcription Factors ◽

Thyroid Hormones ◽

Target Gene ◽

Protein Complexes ◽

Nuclear Receptor Superfamily ◽

Target Gene Expression ◽

Dna Elements ◽

Introductory Review

The intracellular receptors for steroid hormones, thyroid hormones, retinoids and vitamin D3 are known to bind to specific DNA elements and thus regulate target gene expression. This introductory review and the following papers address some of the mechanisms underlying this action. In particular, the ability of this family of transcription factors to recruit multi-protein complexes that have the capacity to remodel chromatin structure in order to silence or activate target gene expression is discussed.

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The Human Adenovirus Type 5 E4orf6/E1B55K E3 Ubiquitin Ligase Complex Can Mimic E1A Effects on E2F

mSphere ◽

10.1128/msphere.00014-15 ◽

2015 ◽

Vol 1 (1) ◽

Cited By ~ 1

Author(s):

Frédéric Dallaire ◽

Sabrina Schreiner ◽

G. Eric Blair ◽

Thomas Dobner ◽

Philip E. Branton ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Dna Synthesis ◽

Ubiquitin Ligase ◽

E3 Ubiquitin Ligase ◽

Viral Gene Expression ◽

Adenovirus Vector ◽

Human Adenovirus ◽

Viral Gene ◽

E2f Transcription Factors

ABSTRACT During the course of work on the adenovirus E3 ubiquitin ligase formed by the viral E4orf6 and E1B55K proteins, we found, very surprisingly, that expression of these species was sufficient to permit low levels of replication of an adenovirus vector lacking E1A, the central regulator of infection. E1A products uncouple E2F transcription factors from Rb repression complexes, thus stimulating viral gene expression and cell and viral DNA synthesis. We found that the E4orf6/E1B55K ligase mimics these functions. This finding is of significance because it represents an entirely new function for the ligase in regulating adenovirus replication. The human adenovirus E4orf6/E1B55K E3 ubiquitin ligase is well known to promote viral replication by degrading an increasing number of cellular proteins that inhibit the efficient production of viral progeny. We report here a new function of the adenovirus 5 (Ad5) viral ligase complex that, although at lower levels, mimics effects of E1A products on E2F transcription factors. When expressed in the absence of E1A, the E4orf6 protein in complex with E1B55K binds E2F, disrupts E2F/retinoblastoma protein (Rb) complexes, and induces hyperphosphorylation of Rb, leading to induction of viral and cellular DNA synthesis as well as stimulation of early and late viral gene expression and production of viral progeny of E1/E3-defective adenovirus vectors. These new and previously undescribed functions of the E4orf6/E1B55K E3 ubiquitin ligase could play an important role in promoting the replication of wild-type viruses. IMPORTANCE During the course of work on the adenovirus E3 ubiquitin ligase formed by the viral E4orf6 and E1B55K proteins, we found, very surprisingly, that expression of these species was sufficient to permit low levels of replication of an adenovirus vector lacking E1A, the central regulator of infection. E1A products uncouple E2F transcription factors from Rb repression complexes, thus stimulating viral gene expression and cell and viral DNA synthesis. We found that the E4orf6/E1B55K ligase mimics these functions. This finding is of significance because it represents an entirely new function for the ligase in regulating adenovirus replication.

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