scholarly journals E3 ubiquitin ligase RFWD2 controls lung branching through protein-level regulation of ETV transcription factors

2016 ◽  
Vol 113 (27) ◽  
pp. 7557-7562 ◽  
Author(s):  
Yan Zhang ◽  
Shigetoshi Yokoyama ◽  
John C. Herriges ◽  
Zhen Zhang ◽  
Randee E. Young ◽  
...  

The mammalian lung is an elaborate branching organ, and it forms following a highly stereotypical morphogenesis program. It is well established that precise control at the transcript level is a key genetic underpinning of lung branching. In comparison, little is known about how regulation at the protein level may play a role. Ring finger and WD domain 2 (RFWD2, also termed COP1) is an E3 ubiquitin ligase that modifies specific target proteins, priming their degradation via the ubiquitin proteasome system. RFWD2 is known to function in the adult in pathogenic processes such as tumorigenesis. Here, we show that prenatal inactivation of Rfwd2 gene in the lung epithelium led to a striking halt in branching morphogenesis shortly after secondary branch formation. This defect is accompanied by distalization of the lung epithelium while growth and cellular differentiation still occurred. In the mutant lung, two E26 transformation-specific (ETS) transcription factors essential for normal lung branching, ETS translocation variant 4 (ETV4) and ETV5, were up-regulated at the protein level, but not at the transcript level. Introduction of Etv loss-of-function alleles into the Rfwd2 mutant background attenuated the branching phenotype, suggesting that RFWD2 functions, at least in part, through degrading ETV proteins. Because a number of E3 ligases are known to target factors important for lung development, our findings provide a preview of protein-level regulatory network essential for lung branching morphogenesis.

2019 ◽  
Author(s):  
RA Seaborne ◽  
DC Hughes ◽  
DC Turner ◽  
DJ Owens ◽  
LM Baehr ◽  
...  

AbstractWe aimed to investigate a novel and uncharacterised E3 ubiquitin ligase in skeletal muscle atrophy, recovery from atrophy/injury, anabolism and hypertrophy. We demonstrated an alternate gene expression profile for UBR5 versus well characterised E3-ligases, MuRF1/MAFbx, where after atrophy evoked by continuous-low-frequency electrical-stimulation in rats, MuRF1/MAFbx were both elevated yet UBR5 was unchanged. Furthermore, after recovery of muscle mass post tetrodotoxin (TTX) induced-atrophy in rats, UBR5 was hypomethylated and increased at the gene expression level, while a suppression of MuRF1/MAFbx was observed. At the protein level, we also demonstrated a significant increase in UBR5 after recovery of muscle mass from hindlimb unloading in both adult and aged rats, and after recovery from atrophy evoked by nerve crush injury in mice. During anabolism and hypertrophy, UBR5 gene expression increased following acute loading in three-dimensional bioengineered mouse muscle in-vitro, and after chronic electrical-stimulation-induced hypertrophy in rats in-vivo, without increases in MuRF1/MAFbx. Additionally, UBR5 protein abundance increased following functional overload-induced hypertrophy of the plantaris muscle in mice and during differentiation of primary human muscle cells. Finally, in humans, genetic association studies (>700,000 SNPs) demonstrated that the A alleles of rs10505025 and rs4734621 SNPs in the UBR5 gene were strongly associated with larger cross-sectional area of fast-twitch muscle fibres and favoured strength/power versus endurance/untrained phenotypes. Overall, we suggest that UBR5 is a novel E3 ubiquitin ligase that is inversely regulated to MuRF1/MAFbx, is epigenetically regulated, and is elevated at both the gene expression and protein level during recovery from skeletal muscle atrophy and hypertrophy.Key PointsWe have recently identified that a HECT domain E3 ubiquitin ligase, named UBR5, is altered epigenetically (via DNA methylation) after human skeletal muscle hypertrophy, where its gene expression is positively correlated with increasing lean leg mass after training and retraining.In the present study we extensively investigate this novel and uncharacterised E3 ubiquitin ligase (UBR5) in skeletal muscle atrophy, recovery from atrophy and injury, anabolism and hypertrophy.We demonstrated that UBR5 was epigenetically via altered DNA methylation during recovery from atrophy.We also determined that UBR5 was alternatively regulated versus well characterised E3 ligases, MuRF1/MAFbx, at the gene expression level during atrophy, recovery from atrophy and hypertrophy.UBR5 also increased at the protein level during recovery from atrophy and injury, hypertrophy and during human muscle cell differentiation.Finally, in humans, genetic variations of the UBR5 gene were strongly associated with larger fast-twitch muscle fibres and strength/power performance versus endurance/untrained phenotypes.


2020 ◽  
Vol 21 (22) ◽  
pp. 8719
Author(s):  
Kamini Kaushal ◽  
Sang Hyeon Woo ◽  
Apoorvi Tyagi ◽  
Dong Ha Kim ◽  
Bharathi Suresh ◽  
...  

Fumarylacetoacetate hydrolase (FAH) is the last enzyme in the degradation pathway of the amino acids tyrosine and phenylalanine in mammals that catalyzes the hydrolysis of 4-fumarylacetoacetate into acetoacetate and fumarate. Mutations of the FAH gene are associated with hereditary tyrosinemia type I (HT1), resulting in reduced protein stability, misfolding, accelerated degradation and deficiency in functional proteins. Identifying E3 ligases, which are necessary for FAH protein stability and degradation, is essential. In this study, we demonstrated that the FAH protein level is elevated in liver cancer tissues compared to that in normal tissues. Further, we showed that the FAH protein undergoes 26S proteasomal degradation and its protein turnover is regulated by the anaphase-promoting complex/cyclosome-Cdh1 (APC/C)Cdh1 E3 ubiquitin ligase complex. APC/CCdh1 acts as a negative stabilizer of FAH protein by promoting FAH polyubiquitination and decreases the half-life of FAH protein. Thus, we envision that Cdh1 might be a key factor in the maintenance of FAH protein level to regulate FAH-mediated physiological functions.


Author(s):  
Ota Fuchs

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.


2021 ◽  
Vol 22 (11) ◽  
pp. 5712
Author(s):  
Michał Tracz ◽  
Ireneusz Górniak ◽  
Andrzej Szczepaniak ◽  
Wojciech Białek

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.


2021 ◽  
Author(s):  
◽  
Carla Coppola

In this study, I focused on a new family of receptors, called RMRs (Receptor-like Membrane RING-H2) and I tried to investigate their role in the moss Physcomitrium patens Mitten (previously Physcomitrella patens). There is some evidence that in Angiosperms, RMRs are vacuolar receptors for the neutral/storage vacuole that is a compartment where storage proteins and metabolites are accumulated during seeds development or in somatic tissues. It is distinguished from lytic vacuole which has the same functions as animal lysosomes. The five PpRMR genes have been knocked-out, yielding viable material without visible phenotype (Ayachi, 2012). A trafficking phenotype was described by Fahr (2017) who generated the construct Citrine-Cardosin (Ci-Card) composed of the fluorescent protein Citrine fused to the C-terminal vacuolar sorting determinant (ctVSD) from cardosin A (cardosin is addressed to the vacuole in higher plants —Pereira et al., 2013). The fusion protein was delivered to the central vacuole of PpWT but mistargeted in PpRMR-KO lines, indicating that the targeting of this protein to the vacuole depends on PpRMRs. The introduction of this thesis presents the plant endomembrane system, with particular attention to vacuolar transport and ubiquitylation. In the second chapter, I show the techniques used to attempt to detect PpRMRs by Western Blot: our failure may be due to a rapid degradation of these proteins, which could prevent their detection. In the third chapter, I focused on PpRMR2 involvement in ubiquitylation. We hypothesize that PpRMRs are E3 ligases because they are members of the PA-TM-RING protein family. Most of these proteins have an E3 ubiquitin ligase activity in animals (Seroogy et al., 2004; Borchers et al., 2002), for this reason, we think that plant PpRMRs could have this function as well, which could contribute to vacuolar targeting. Indeed, I could confirm that PpRMR2 has an E3 ubiquitin ligase activity. PpRMRs substrates are still unknown in moss thus we have analysed putative candidates supposing that they could be ubiquitylated by PpRMRs. We have tested this hypothesis through in vitro ubiquitylation assays, obtaining ambiguous results. In the fourth chapter, I show preliminary results about the visible phenotype of PpRMR-KO mutants: PpWT and PpRMR-KO lines displayed phenotypic differences in leafy gametophores, which were accentuated upon salt stress exposure. Lastly, I transformed the transgenic lines PpWT/Ci-Card and Pp5KO/Ci-Card with mutated versions of PpRMR2 and analysed their effect on vacuolar transport by confocal microscopy. For most of the constructions tested, the trafficking was perturbed in both lines. Only PpWT/Ci-Card expressing PpRMR2ΔSer (lacking the Serine-Rich motif) displayed a typical vacuolar pattern.


Open Biology ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 200041 ◽  
Author(s):  
Zhuoyao Chen ◽  
Gregory A. Wasney ◽  
Sarah Picaud ◽  
Panagis Filippakopoulos ◽  
Masoud Vedadi ◽  
...  

Wnt signalling is dependent on dishevelled proteins (DVL1-3), which assemble an intracellular Wnt signalosome at the plasma membrane. The levels of DVL1-3 are regulated by multiple Cullin-RING E3 ligases that mediate their ubiquitination and degradation. The BTB-Kelch protein KLHL12 was the first E3 ubiquitin ligase to be identified for DVL1-3, but the molecular mechanisms determining its substrate interactions have remained unknown. Here, we mapped the interaction of DVL1-3 to a ‘PGXPP' motif that is conserved in other known partners and substrates of KLHL12, including PLEKHA4, PEF1, SEC31 and DRD4. To determine the binding mechanism, we solved a 2.4 Å crystal structure of the Kelch domain of KLHL12 in complex with a DVL1 peptide that bound with low micromolar affinity. The DVL1 substrate adopted a U-shaped turn conformation that enabled hydrophobic interactions with all six blades of the Kelch domain β-propeller. In cells, the mutation or deletion of this motif reduced the binding and ubiquitination of DVL1 and increased its stability confirming this sequence as a degron motif for KLHL12 recruitment. These results define the molecular mechanisms determining DVL regulation by KLHL12 and establish the KLHL12 Kelch domain as a new protein interaction module for a novel proline-rich motif.


2021 ◽  
Vol 12 ◽  
Author(s):  
Shuang Liu ◽  
Meixuezi Tong ◽  
Lifang Zhao ◽  
Xin Li ◽  
Ljerka Kunst

The outer epidermal cell walls of plant shoots are covered with a cuticle, a continuous lipid structure that provides protection from desiccation, UV light, pathogens, and insects. The cuticle is mostly composed of cutin and cuticular wax. Cuticular wax synthesis is synchronized with surface area expansion during plant development and is associated with plant responses to biotic and abiotic stresses. Cuticular wax deposition is tightly regulated by well-established transcriptional and post-transcriptional regulatory mechanisms, as well as post-translationally via the ubiquitin-26S proteasome system (UPS). The UPS is highly conserved in eukaryotes and involves the covalent attachment of polyubiquitin chains to the target protein by an E3 ligase, followed by the degradation of the modified protein by the 26S proteasome. A large number of E3 ligases are encoded in the Arabidopsis genome, but only a few have been implicated in the regulation of cuticular wax deposition. In this study, we have conducted an E3 ligase reverse genetic screen and identified a novel RING-type E3 ubiquitin ligase, AtARRE, which negatively regulates wax biosynthesis in Arabidopsis. Arabidopsis plants overexpressing AtARRE exhibit glossy stems and siliques, reduced fertility and fusion between aerial organs. Wax load and wax compositional analyses of AtARRE overexpressors showed that the alkane-forming branch of the wax biosynthetic pathway is affected. Co-expression of AtARRE and candidate target proteins involved in alkane formation in both Nicotiana benthamiana and stable Arabidopsis transgenic lines demonstrated that AtARRE controls the levels of wax biosynthetic enzymes ECERIFERUM1 (CER1) and ECERIFERUM3 (CER3). CER1 has also been confirmed to be a ubiquitination substrate of the AtARRE E3 ligase by an in vivo ubiquitination assay using a reconstituted Escherichia coli system. The AtARRE gene is expressed throughout the plant, with the highest expression detected in fully expanded rosette leaves and oldest stem internodes. AtARRE gene expression can also be induced by exposure to pathogens. These findings reveal that wax biosynthesis in mature plant tissues and in response to pathogen infection is controlled post-translationally.


2007 ◽  
Vol 87 (1) ◽  
pp. 219-244 ◽  
Author(s):  
Yutaka Maeda ◽  
Vrushank Davé ◽  
Jeffrey A. Whitsett

The vertebrate lung consists of multiple cell types that are derived primarily from endodermal and mesodermal compartments of the early embryo. The process of pulmonary organogenesis requires the generation of precise signaling centers that are linked to transcriptional programs that, in turn, regulate cell numbers, differentiation, and behavior, as branching morphogenesis and alveolarization proceed. This review summarizes knowledge regarding the expression and proposed roles of transcription factors influencing lung formation and function with particular focus on knowledge derived from the study of the mouse. A group of transcription factors active in the endodermally derived cells of the developing lung tubules, including thyroid transcription factor-1 (TTF-1), β-catenin, Forkhead orthologs (FOX), GATA, SOX, and ETS family members are required for normal lung morphogenesis and function. In contrast, a group of distinct proteins, including FOXF1, POD1, GLI, and HOX family members, play important roles in the developing lung mesenchyme, from which pulmonary vessels and bronchial smooth muscle develop. Lung formation is dependent on reciprocal signaling among cells of both endodermal and mesenchymal compartments that instruct transcriptional processes mediating lung formation and adaptation to breathing after birth.


2010 ◽  
Vol 19 (11) ◽  
pp. 2251-2267 ◽  
Author(s):  
Laura L. Yates ◽  
Carsten Schnatwinkel ◽  
Jennifer N. Murdoch ◽  
Debora Bogani ◽  
Caroline J. Formstone ◽  
...  

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