scholarly journals Mutations in LZTR1 drive human disease by dysregulating RAS ubiquitination

Science ◽  
2018 ◽  
Vol 362 (6419) ◽  
pp. 1177-1182 ◽  
Author(s):  
M. Steklov ◽  
S. Pandolfi ◽  
M. F. Baietti ◽  
A. Batiuk ◽  
P. Carai ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Human Disease ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
Ras Signaling ◽  
Ras Proteins ◽  
Ubiquitin Ligase Complex ◽  
Cullin 3 ◽  
Guanosine Triphosphatase

The leucine zipper–like transcriptional regulator 1 (LZTR1) protein, an adaptor for cullin 3 (CUL3) ubiquitin ligase complex, is implicated in human disease, yet its mechanism of action remains unknown. We found that Lztr1 haploinsufficiency in mice recapitulates Noonan syndrome phenotypes, whereas LZTR1 loss in Schwann cells drives dedifferentiation and proliferation. By trapping LZTR1 complexes from intact mammalian cells, we identified the guanosine triphosphatase RAS as a substrate for the LZTR1-CUL3 complex. Ubiquitome analysis showed that loss of Lztr1 abrogated Ras ubiquitination at lysine-170. LZTR1-mediated ubiquitination inhibited RAS signaling by attenuating its association with the membrane. Disease-associated LZTR1 mutations disrupted either LZTR1-CUL3 complex formation or its interaction with RAS proteins. RAS regulation by LZTR1-mediated ubiquitination provides an explanation for the role of LZTR1 in human disease.

scholarly journals A synthetic lethal screen identifies HDAC4 as a potential target in MELK overexpressing cancers

2021 ◽  
Author(s):  
Floris Foijer ◽  
Lin Zhou ◽  
Fernando R Rosas Bringas ◽  
Bjorn Bakker ◽  
Judith E Simon ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
Chemotherapy Resistance ◽  
Synthetic Lethal ◽  
Ubiquitin Ligase Complex ◽  
Synthetic Lethal Interactions ◽  
A Subunit ◽  
Scf Ubiquitin Ligase

Maternal embryonic leucine zipper kinase (MELK) is frequently overexpressed in cancer, but the role of MELK in cancer is still poorly understood. MELK was shown to have roles in many cancer-associated processes including tumor growth, chemotherapy resistance, and tumor recurrence. To determine whether the frequent overexpression of MELK can be exploited in therapy, we performed a high-throughput screen using a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential when MELK is overexpressed. We identified two such genes: LAG2 and HDA3. LAG2 encodes an inhibitor of the SCF ubiquitin-ligase complex, while HDA3 encodes a subunit of the HDA1 histone deacetylase complex. We find that one of these synthetic lethal interactions is conserved in mammalian cells, as inhibition of a human homolog of HDA3 (HDAC4) is synthetically toxic in MELK overexpression cells. Altogether, our work might provide a new angle of how to exploit MELK overexpression in cancers and might thus lead to novel intervention strategies.

scholarly journals A synthetic lethal screen identifies HDAC4 as a potential target in MELK overexpressing cancers

2021 ◽  
Author(s):  
Lin Zhou ◽  
Siqi Zheng ◽  
Fernando R Rosas Bringas ◽  
Bjorn Bakker ◽  
Judith E Simon ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
Chemotherapy Resistance ◽  
Synthetic Lethal ◽  
Ubiquitin Ligase Complex ◽  
Synthetic Lethal Interactions ◽  
Histone Deacetylase 4 ◽  
A Subunit

Abstract Maternal embryonic leucine zipper kinase (MELK) is frequently overexpressed in cancer, but the role of MELK in cancer is still poorly understood. MELK was shown to have roles in many cancer-associated processes including tumor growth, chemotherapy resistance, and tumor recurrence. To determine whether the frequent overexpression of MELK can be exploited in therapy, we performed a high-throughput screen using a library of Saccharomyces cerevisiae mutants to identify genes whose functions become essential when MELK is overexpressed. We identified two such genes: LAG2 and HDA3. LAG2 encodes an inhibitor of the Skp, Cullin, F-box containing (SCF) ubiquitin-ligase complex, while HDA3 encodes a subunit of the HDA1 histone deacetylase complex. We find that one of these synthetic lethal interactions is conserved in mammalian cells, as inhibition of a human homolog of HDA3 (Histone Deacetylase 4, HDAC4) is synthetically toxic in MELK overexpression cells. Altogether, our work identified a novel potential drug target for tumors that overexpress MELK.

scholarly journals A SPOPL/Cullin-3 ubiquitin ligase complex regulates endocytic trafficking by targeting EPS15 at endosomes

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Michaela Gschweitl ◽  
Anna Ulbricht ◽  
Christopher A Barnes ◽  
Radoslav I Enchev ◽  
Ingrid Stoffel-Studer ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Influenza A ◽  
Endocytic Trafficking ◽  
Dependent Manner ◽  
Ubiquitin Ligase Complex ◽  
Cullin 3 ◽  
Host Cell Entry ◽  
Endosome Maturation

Cullin-3 (CUL3)-based ubiquitin ligases regulate endosome maturation and trafficking of endocytic cargo to lysosomes in mammalian cells. Here, we report that these functions depend on SPOPL, a substrate-specific CUL3 adaptor. We find that SPOPL associates with endosomes and is required for both the formation of multivesicular bodies (MVBs) and the endocytic host cell entry of influenza A virus. In SPOPL-depleted cells, endosomes are enlarged and fail to acquire intraluminal vesicles (ILVs). We identify a critical substrate ubiquitinated by CUL3-SPOPL as EPS15, an endocytic adaptor that also associates with the ESCRT-0 complex members HRS and STAM on endosomes. Indeed, EPS15 is ubiquitinated in a SPOPL-dependent manner, and accumulates with HRS in cells lacking SPOPL. Together, our data indicates that a CUL3-SPOPL E3 ubiquitin ligase complex regulates endocytic trafficking and MVB formation by ubiquitinating and degrading EPS15 at endosomes, thereby influencing influenza A virus infection as well as degradation of EGFR and other EPS15 targets.

scholarly journals Hydrogen Peroxide Toxicity Induces Ras Signaling in Human Neuroblastoma SH-SY5Y Cultured Cells

2010 ◽  
Vol 2010 ◽  
pp. 1-4 ◽  
Author(s):  
Jirapa Chetsawang ◽  
Piyarat Govitrapong ◽  
Banthit Chetsawang
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Viability ◽  
Cultured Cells ◽  
Neuronal Cells ◽  
Competitive Inhibitor ◽  
Ras Signaling ◽  
Ras Proteins ◽  
Human Neuroblastoma ◽  
Dependent Signaling Pathway

It has been reported that overproduction of reactive oxygen species occurs after brain injury and mediates neuronal cells degeneration. In the present study, we examined the role of Ras signaling on hydrogen peroxide-induced neuronal cells degeneration in dopaminergic neuroblastoma SH-SY5Y cells. Hydrogen peroxide significantly reduced cell viability in SH-SY5Y cultured cells. An inhibitor of the enzyme that catalyzes the farnesylation of Ras proteins, FTI-277, and a competitive inhibitor of GTP-binding proteins, GDP-beta-S significantly decreased hydrogen peroxide-induced reduction in cell viability in SH-SY5Y cultured cells. The results of this study might indicate that a Ras-dependent signaling pathway plays a role in hydrogen peroxide-induced toxicity in neuronal cells.

scholarly journals The role of SCF ubiquitin-ligase complex at the beginning of life

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Jiayan Xie ◽  
Yimei Jin ◽  
Guang Wang
Keyword(s):  
Cell Cycle ◽  
Ubiquitin Ligase ◽  
Cellular Proteins ◽  
Cell Cycle Regulators ◽  
Signal Transducers ◽  
E3 Ligases ◽  
Cellular Processes ◽  
Ubiquitin Ligase Complex ◽  
Scf Ubiquitin Ligase

AbstractAs the largest family of E3 ligases, the Skp1-cullin 1-F-box (SCF) E3 ligase complex is comprised of Cullins, Skp1 and F-box proteins. And the SCF E3 ubiquitin ligases play an important role in regulating critical cellular processes, which promote degradation of many cellular proteins, including signal transducers, cell cycle regulators, and transcription factors. We review the biological roles of the SCF ubiquitin-ligase complex in gametogenesis, oocyte-to-embryo transition, embryo development and the regulation for estrogen and progestin. We find that researches about the SCF ubiquitin-ligase complex at the beginning of life are not comprehensive, thus more in-depth researches will promote its eventual clinical application.

scholarly journals p97 Negatively Regulates NRF2 by Extracting Ubiquitylated NRF2 from the KEAP1-CUL3 E3 Complex

2017 ◽  
Vol 37 (8) ◽  
Author(s):  
Shasha Tao ◽  
Pengfei Liu ◽  
Gang Luo ◽  
Montserrat Rojo de la Vega ◽  
Heping Chen ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Protein Complexes ◽  
E3 Ubiquitin Ligase ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Ubiquitin Ligase Complex ◽  
Ubiquitin Proteasome ◽  
Client Proteins

ABSTRACT Activation of the stress-responsive transcription factor NRF2 is the major line of defense to combat oxidative or electrophilic insults. Under basal conditions, NRF2 is continuously ubiquitylated by the KEAP1-CUL3-RBX1 E3 ubiquitin ligase complex and is targeted to the proteasome for degradation (the canonical mechanism). However, the path from the CUL3 complex to ultimate proteasomal degradation was previously unknown. p97 is a ubiquitin-targeted ATP-dependent segregase that extracts ubiquitylated client proteins from membranes, protein complexes, or chromatin and has an essential role in autophagy and the ubiquitin proteasome system (UPS). In this study, we show that p97 negatively regulates NRF2 through the canonical pathway by extracting ubiquitylated NRF2 from the KEAP1-CUL3 E3 complex, with the aid of the heterodimeric cofactor UFD1/NPL4 and the UBA-UBX-containing protein UBXN7, for efficient proteasomal degradation. Given the role of NRF2 in chemoresistance and the surging interest in p97 inhibitors to treat cancers, our results indicate that dual p97/NRF2 inhibitors may offer a more potent and long-term avenue of p97-targeted treatment.

scholarly journals Phyllopod Acts as an Adaptor Protein To Link the Sina Ubiquitin Ligase to the Substrate Protein Tramtrack

2002 ◽  
Vol 22 (19) ◽  
pp. 6854-6865 ◽  
Author(s):  
Songhui Li ◽  
Chunyan Xu ◽  
Richard W. Carthew
Keyword(s):  
Ubiquitin Ligase ◽  
Neuronal Development ◽  
Adaptor Protein ◽  
Ras Signaling ◽  
Binding Domains ◽  
Substrate Protein ◽  
Ras Activation ◽  
Ubiquitin Ligase Complex ◽  
Acid Domain ◽  
F Box Protein

ABSTRACT The RING domain protein Sina, together with Phyllopod and the F-box protein Ebi, forms a Ras-regulated E3 ubiquitin ligase complex that activates photoreceptor cell differentiation in the eye of Drosophila melanogaster. The expression of Phyllopod is induced upon Ras activation, allowing the complex to degrade the transcription repressor Tramtrack and removing its block of neuronal development in photoreceptor precursors. We show that Phyllopod functions as an adaptor in the complex, physically linking Sina with Tramtrack via separate binding domains. One 19-amino-acid domain in Phyllopod interacts with a region of Sina's SBD domain. Another domain in Phyllopod interacts with a C-terminal helix in the POZ domain of Tramtrack. This interaction is specific to the Tramtrack POZ domain and not to other POZ domain proteins present in photoreceptor precursors. Degradation of Tramtrack is dependent upon association of Sina with its cognate binding site in Phyllopod. These results illustrate how Ras signaling can modulate an E3 ligase activity not by the phosphorylation of substrate proteins but by regulating the expression of specific E3 adaptors.

scholarly journals Revisiting the NaCl cotransporter regulation by with-no-lysine kinases

2015 ◽  
Vol 308 (10) ◽  
pp. C779-C791 ◽  
Author(s):  
Silvana Bazúa-Valenti ◽  
Gerardo Gamba
Keyword(s):  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Type Ii ◽  
Complex Issue ◽  
Dark Ages ◽  
Ubiquitin Ligase Complex ◽  
Pseudohypoaldosteronism Type Ii ◽  
Cullin 3 ◽  
Increased Activity ◽  
Pseudohypoaldosteronism Type

The renal thiazide-sensitive Na+-Cl− cotransporter (NCC) is the salt transporter in the distal convoluted tubule. Its activity is fundamental for defining blood pressure levels. Decreased NCC activity is associated with salt-remediable arterial hypotension with hypokalemia (Gitelman disease), while increased activity results in salt-sensitive arterial hypertension with hyperkalemia (pseudohypoaldosteronism type II; PHAII). The discovery of four different genes causing PHAII revealed a complex multiprotein system that regulates the activity of NCC. Two genes encode for with-no-lysine (K) kinases WNK1 and WNK4, while two encode for kelch-like 3 (KLHL3) and cullin 3 (CUL3) proteins that form a RING type E3 ubiquitin ligase complex. Extensive research has shown that WNK1 and WNK4 are the targets for the KLHL3-CUL3 complex and that WNKs modulate the activity of NCC by means of intermediary Ste20-type kinases known as SPAK or OSR1. The understanding of the effect of WNKs on NCC is a complex issue, but recent evidence discussed in this review suggests that we could be reaching the end of the dark ages regarding this matter.

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