Light and the E3 ubiquitin ligase COP1/SPA control the protein stability of the MYB transcription factors PAP1 and PAP2 involved in anthocyanin accumulation in Arabidopsis

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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Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

Cardiovascular & Haematological Disorders - Drug Targets ◽

10.2174/1871529x18666180522073855 ◽

2019 ◽

Vol 19 (1) ◽

pp. 51-78 ◽

Cited By ~ 3

Author(s):

Ota Fuchs

Keyword(s):

Clinical Trials ◽

Transcription Factors ◽

Ubiquitin Ligase ◽

Mononuclear Cells ◽

E3 Ubiquitin Ligase ◽

Lymphocytic Leukemia ◽

Monocarboxylate Transporter ◽

Immunomodulatory Drugs ◽

Monocarboxylate Transporter 1 ◽

Argonaute 2

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

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An Angelman syndrome substitution in the HECT E3 ubiquitin ligase C-terminal Lobe of E6AP affects protein stability and activity

PLoS ONE ◽

10.1371/journal.pone.0235925 ◽

2020 ◽

Vol 15 (7) ◽

pp. e0235925

Author(s):

Steven A. Beasley ◽

Chloe E. Kellum ◽

Rachel J. Orlomoski ◽

Feston Idrizi ◽

Donald E. Spratt

Keyword(s):

Protein Stability ◽

Ubiquitin Ligase ◽

Angelman Syndrome ◽

E3 Ubiquitin Ligase

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Direct regulation of Chk1 protein stability by E3 ubiquitin ligase HUWE1

FEBS Journal ◽

10.1111/febs.15132 ◽

2019 ◽

Vol 287 (10) ◽

pp. 1985-1999 ◽

Cited By ~ 6

Author(s):

Katelyn B. Cassidy ◽

Scott Bang ◽

Manabu Kurokawa ◽

Scott A. Gerber

Keyword(s):

Protein Stability ◽

Ubiquitin Ligase ◽

E3 Ubiquitin Ligase ◽

Direct Regulation

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OP0119 The CRL4 Cereblon E3 Ubiquitin Ligase Modulator CC-220 Induces Degradation of the Transcription Factors Aiolos and Ikaros: Immunomodulation in Healthy Volunteers and Relevance to Systemic Lupus Erythematosus

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2015-eular.3498 ◽

2015 ◽

Vol 74 (Suppl 2) ◽

pp. 113.2-113 ◽

Cited By ~ 2

Author(s):

P. Schafer ◽

Y. Ye ◽

L. Wu ◽

J. Kosek ◽

Z. Yang ◽

...

Keyword(s):

Systemic Lupus Erythematosus ◽

Transcription Factors ◽

Healthy Volunteers ◽

Ubiquitin Ligase ◽

Lupus Erythematosus ◽

E3 Ubiquitin Ligase ◽

Systemic Lupus

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A Novel Degron-mediated Degradation of the RTG Pathway Regulator, Mks1p, by SCFGrr1

Molecular Biology of the Cell ◽

10.1091/mbc.e05-06-0516 ◽

2005 ◽

Vol 16 (10) ◽

pp. 4893-4904 ◽

Cited By ~ 25

Author(s):

Zhengchang Liu ◽

Mário Spírek ◽

Janet Thornton ◽

Ronald A. Butow

Keyword(s):

Transcription Factors ◽

Ubiquitin Ligase ◽

Positive Charge ◽

E3 Ubiquitin Ligase ◽

Retrograde Signaling ◽

Yeast Cells ◽

Leucine Rich Repeat ◽

Negative Regulators ◽

Acidic Domain ◽

Lrr Domain

Yeast cells respond to mitochondrial dysfunction by altering the expression of a subset of nuclear genes, a process known as retrograde signaling (RS). RS terminates with two transcription factors, Rtg1p and Rtg3p. One positive regulator, Rtg2p, and four negative regulators, Lst8p, Mks1p, and the redundant 14-3-3 proteins, Bmh1p and Bmh2p, control RS upstream of Rtg1/3p. Mks1p is negatively regulated by binding to Rtg2p and positively regulated when bound to Bmh1/2p. Here we report that Grr1p, a component of the SCFGrr1 E3 ubiquitin ligase, modulates RS by affecting Mks1p levels. Grr1p polyubiquitinates Mks1p not bound to either Rtg2p or to Bmh1/2p, targeting it for degradation. An acidic domain region of Mks1p constitutes the portable Mks1p degron sequence. We have isolated dominant mutations in Grr1p leading to increased Mks1p degradation. These mutations result in a gain of positive charge on the concave surface of the leucine rich repeat (LRR) domain of Grr1p, the proposed substrate binding site. We propose that Mks1p is a central player of RS and is acted upon by multiple regulators of the pathway.

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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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Functions of COP1/SPA E3 Ubiquitin Ligase Mediated by MpCRY in the Liverwort Marchantia Polymorpha under Blue Light

International Journal of Molecular Sciences ◽

10.3390/ijms23010158 ◽

2021 ◽

Vol 23 (1) ◽

pp. 158

Author(s):

Li Zhang ◽

Tianhong Li ◽

Shengzhong Su ◽

Hao Peng ◽

Sudi Li ◽

...

Keyword(s):

Transcription Factors ◽

Blue Light ◽

Ubiquitin Ligase ◽

E3 Ubiquitin Ligase ◽

Land Plants ◽

Marchantia Polymorpha ◽

Regulatory Pathway ◽

Knock Out

COP1/SPA1 complex in Arabidopsis inhibits photomorphogenesis through the ubiquitination of multiple photo-responsive transcription factors in darkness, but such inhibiting function of COP1/SPA1 complex would be suppressed by cryptochromes in blue light. Extensive studies have been conducted on these mechanisms in Arabidopsis whereas little attention has been focused on whether another branch of land plants bryophyte utilizes this blue-light regulatory pathway. To study this problem, we conducted a study in the liverwort Marchantia polymorpha and obtained a MpSPA knock-out mutant, in which Mpspa exhibits the phenotype of an increased percentage of individuals with asymmetrical thallus growth, similar to MpCRY knock-out mutant. We also verified interactions of MpSPA with MpCRY (in a blue light-independent way) and with MpCOP1. Concomitantly, both MpSPA and MpCOP1 could interact with MpHY5, and MpSPA can promote MpCOP1 to ubiquitinate MpHY5 but MpCRY does not regulate the ubiquitination of MpHY5 by MpCOP1/MpSPA complex. These data suggest that COP1/SPA ubiquitinating HY5 is conserved in Marchantia polymorpha, but dissimilar to CRY in Arabidopsis, MpCRY is not an inhibitor of this process under blue light.

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