Mutations in LZTR1 drive human disease by dysregulating RAS ubiquitination.
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ABSTRACT:
SUBMITTER: Steklov M
PROVIDER: S-EPMC8058620 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Mutations in LZTR1, a substrate adaptor for cullin 3 (CUL3) ubiquitin ligase complexes1, have been recently associated with Noonan syndrome2,3 and familial Schwannomatosis4-6. Concordantly, we found that Lztr1+/- mice showed craniofacial abnormalities, cardio defects, and premature ageing; whereas loss of LZTR1 in Schwann cells drives their dedifferentiation into proliferating, pro-myelinating cells. We screened for LZTR1 substrates by trapping LZTR1 complexes from intact mammalian cells. In parallel, we analysed changes in the ubiquitin landscape induced by LZTR1 loss of function. RAS proteins emerged as substrates of the LZTR1/CUL3 complex, which inhibits the RAS pathway by ubiquitinating RAS at K170 and triggering its dissociation from the membrane. Disease-associated LZTR1 mutations affect either the LZTR1/CUL3 complex formation, or the interaction with RAS proteins. These results position LZTR1 as a key node in the RAS pathway, loss-of-function of which leads to a human disease.
2018-11-04 | PXD007049 | Pride
Project description:Mutations in LZTR1, a substrate adaptor for cullin 3 (CUL3) ubiquitin ligase complexes, have been recently associated with Noonan syndrome and familial Schwannomatosis. Concordantly, we found that Lztr1+/- mice showed craniofacial abnormalities, cardio defects, and premature ageing; whereas loss of LZTR1 in Schwann cells drives their dedifferentiation into proliferating, pro-myelinating cells. In the present dataset we screened for changes in the ubiquitin landscape induced by LZTR1 loss of function by mass spectrometry-based proteomics and identified RAS proteins as substrates of the LZTR1/CUL3 complex. In follow-up experiments we showed that LZTR1/CUL3 inhibits the RAS pathway by ubiquitinating RAS at K170 and triggering its dissociation from the membrane. Disease-associated LZTR1 mutations affect either the LZTR1/CUL3 complex formation, or the interaction with RAS proteins. Together, our results position LZTR1 as a key node in the RAS pathway, loss-of-function of which leads to human disease.
2018-11-07 | PXD007035 | Pride
Project description:In genetic screens aimed at understanding drug resistance mechanisms in chronic myeloid leukemia cells, inactivation of the cullin 3 adapter protein-encoding leucine zipper-like transcription regulator 1 (LZTR1) gene led to enhanced mitogen-activated protein kinase (MAPK) pathway activity and reduced sensitivity to tyrosine kinase inhibitors. Knockdown of the Drosophila LZTR1 ortholog CG3711 resulted in a Ras-dependent gain-of-function phenotype. Endogenous human LZTR1 associates with the main RAS isoforms. Inactivation of LZTR1 led to decreased ubiquitination and enhanced plasma membrane localization of endogenous KRAS (V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog). We propose that LZTR1 acts as a conserved regulator of RAS ubiquitination and MAPK pathway activation. Because LZTR1 disease mutations failed to revert loss-of-function phenotypes, our findings provide a molecular rationale for LZTR1 involvement in a variety of inherited and acquired human disorders.
| S-EPMC6794158 | biostudies-literature
Project description:Mosaic mutations present in the germline have important implications for reproductive risk and disease transmission. We previously demonstrated a phenomenon occurring in the male germline, whereby specific mutations arising spontaneously in stem cells (spermatogonia) lead to clonal expansion, resulting in elevated mutation levels in sperm over time. This process, termed "selfish spermatogonial selection," explains the high spontaneous birth prevalence and strong paternal age-effect of disorders such as achondroplasia and Apert, Noonan and Costello syndromes, with direct experimental evidence currently available for specific positions of six genes (FGFR2, FGFR3, RET, PTPN11, HRAS, and KRAS). We present a discovery screen to identify novel mutations and genes showing evidence of positive selection in the male germline, by performing massively parallel simplex PCR using RainDance technology to interrogate mutational hotspots in 67 genes (51.5 kb in total) in 276 biopsies of testes from five men (median age, 83 yr). Following ultradeep sequencing (about 16,000×), development of a low-frequency variant prioritization strategy, and targeted validation, we identified 61 distinct variants present at frequencies as low as 0.06%, including 54 variants not previously directly associated with selfish selection. The majority (80%) of variants identified have previously been implicated in developmental disorders and/or oncogenesis and include mutations in six newly associated genes (BRAF, CBL, MAP2K1, MAP2K2, RAF1, and SOS1), all of which encode components of the RAS-MAPK pathway and activate signaling. Our findings extend the link between mutations dysregulating the RAS-MAPK pathway and selfish selection, and show that the aging male germline is a repository for such deleterious mutations.
| S-EPMC6280762 | biostudies-literature
Project description:Meningiomas are the most common primary brain tumors, where complete surgical resection is often challenging giving rise to recurrence. Mutations of the E3 ubiquitin ligase TRAF7 are found in one-fourth of meningioma patients and typically co-occur with mutations in either KLF4, AKT1, or PI3KCA. By creating an in vitro meningioma model derived from primary meningeal cells, we elucidated the cooperative interactions that conspire meningioma development. A multi-omics framework on meningeal cells revealed TRAF7-mediated rewiring of the proteome with the majority of protein expression being post‐transcriptionally‐regulated. Integrating TRAF7-driven ubiquitinome and proteome alterations and TRAF7 interactome highlight the role of TRAF7 in posttranslational regulation of the cytoskeleton organization. TRAF7 controls actin dynamics by acting as a proteostatic regulator of the RAS-related small GTPases. TRAF7 loss-of-function diminishes ubiquitination of RAS and CDC42, leading to the activation of the PAK and MAPK signaling pathways. Up-regulation of CDC42 signaling promotes anchorage-independent growth of meningeal cells. On the other hand, the RAS/MAPK pathway triggers the tumor suppressive activity of KLF4 that inhibits meningeal cell growth due to the activation of the Semaphorin pathway. Simultaneous loss of KLF4 and TRAF7 function enhances tumorigenic transformation of meningeal cells, functionally confirming their roles in meningioma development.
2024-06-19 | PXD021188 | Pride
Project description:Leucine zipper-like transcriptional regulator 1 (LZTR1) encodes a member of the BTB-Kelch superfamily, which interacts with the Cullin3 (CUL3)-based E3 ubiquitin ligase complex. Mutations in LZTR1 have been identified in glioblastoma, schwannomatosis, and Noonan syndrome. However, the functional role of LZTR1 in carcinogenesis or human development is not fully understood. Here, we demonstrate that LZTR1 facilitates the polyubiquitination and degradation of RAS via the ubiquitin-proteasome pathway, leading to the inhibition of the RAS/MAPK signaling. The polyubiquitination and degradation of RAS was also observed in cells expressing MRAS, HRAS, NRAS, and KRAS as well as oncogenic RAS mutants and inhibited the activation of ERK1/2 and cell growth. In vivo ubiquitination assays showed that MRAS-K127 and HRAS-K170 were ubiquitinated by LZTR1 and that the polyubiquitinated-chains contained mainly Ub-K48, K63, and K33-linked chains, suggesting its possible involvement in autophagy. Immunoprecipitation analyses showed the interaction of LZTR1 and RAS-GTPases with autophagy-related proteins, including LC3B and SQSTM1/p62. Co-expression of LZTR1 and RAS increased the expression of lipidated form of LC3B. However, long-term treatment with chloroquine had little effect on RAS protein levels, suggesting that the contribution of autophagy to LZTR1-mediated RAS degradation is minimal. Taken together, these results show that LZTR1 functions as a "RAS killer protein" mainly via the ubiquitin-proteasome pathway regardless of the type of RAS GTPase, controlling downstream signal transduction. Our results also suggest a possible association of LZTR1 and RAS-GTPases with the autophagy. These findings provide clues for the elucidation of the mechanisms of RAS degradation and regulation of the RAS/MAPK signaling cascade.
| S-EPMC7206011 | biostudies-literature
Project description:The transcription factor SOX9 is frequently amplified in diverse advanced-stage human tumors. Its stability has been shown to be tightly controlled by ubiquitination-dependent proteasome degradation. However, the exact underlying molecular mechanisms remain unclear. This work reports that SOX9 protein abundance is regulated by the Cullin 3-based ubiquitin ligase KEAP1 via proteasome-mediated degradation. Loss-of-function mutations in KEAP1 compromise polyubiquitination-mediated SOX9 degradation, leading to increased protein levels, which facilitate tumorigenesis. Moreover, the loss of critical ubiquitination residues in SOX9, by either a SOX9 (ΔK2) truncation or K249R mutation, leads to elevated protein stability. Furthermore, it is shown that the KEAP1/SOX9 interaction is modulated by CKIγ-mediated phosphorylation. Importantly, it is demonstrated that DNA damage drugs, topoisomerase inhibitors, can trigger CKI activation to restore the KEAP1/SOX9 interaction and its consequent degradation. Collectively, herein the findings uncover a novel molecular mechanism through which SOX9 protein stability is negatively regulated by KEAP1 to control tumorigenesis. Thus, these results suggest that mitigating SOX9 resistance to KEAP1-mediated degradation can represent a novel therapeutic strategy for cancers with KEAP1 mutations.
| S-EPMC7610265 | biostudies-literature
Project description:Proliferative chronic myelomonocytic leukemia (pCMML), an aggressive CMML subtype, is associated with dismal outcomes. RAS pathway mutations, mainly NRASG12D, define the pCMML phenotype as demonstrated by our exome sequencing, progenitor colony assays and a Vav-Cre-NrasG12D mouse model. Further, these mutations promote CMML transformation to acute myeloid leukemia. Using a multiomics platform and biochemical and molecular studies we show that in pCMML RAS pathway mutations are associated with a unique gene expression profile enriched in mitotic kinases such as polo-like kinase 1 (PLK1). PLK1 transcript levels are shown to be regulated by an unmutated lysine methyl-transferase (KMT2A) resulting in increased promoter monomethylation of lysine 4 of histone 3. Pharmacologic inhibition of PLK1 in RAS mutant patient-derived xenografts, demonstrates the utility of personalized biomarker-driven therapeutics in pCMML.
| S-EPMC8131698 | biostudies-literature
Project description:ObjectivesWe aimed to determine the proportion of individuals in our schwannomatosis cohort whose disease is associated with an LZTR1 mutation.MethodsWe used exome sequencing, Sanger sequencing, and copy number analysis to screen 65 unrelated individuals with schwannomatosis who were negative for a germline NF2 or SMARCB1 mutation. We also screened samples from 39 patients with a unilateral vestibular schwannoma (UVS), plus at least one other schwannoma, but who did not have an identifiable germline or mosaic NF2 mutation.ResultsWe identified germline LZTR1 mutations in 6 of 16 patients (37.5%) with schwannomatosis who had at least one affected relative, 11 of 49 (22%) sporadic patients, and 2 of 39 patients with UVS in our cohort. Three germline mutation-positive patients in total had developed a UVS. Mosaicism was excluded in 3 patients without germline mutation in NF2, SMARCB1, or LZTR1 by mutation screening in 2 tumors from each.ConclusionsOur data confirm the relationship between mutations in LZTR1 and schwannomatosis. They indicate that germline mutations in LZTR1 confer an increased risk of vestibular schwannoma, providing further overlap with NF2, and that further causative genes for schwannomatosis remain to be identified.
| S-EPMC4336087 | biostudies-literature
Project description:Expansion mutations in polyalanine stretches are associated with a growing number of diseases sharing a high degree of genotypic and phenotypic commonality. These similarities prompted us to query the normal function of physiological polyalanine stretches and to investigate whether a common molecular mechanism is involved in these diseases. Here, we show that UBA6, an E1 ubiquitin-activating enzyme, recognizes a polyalanine stretch within its cognate E2 ubiquitin-conjugating enzyme USE1. Aberrations in this polyalanine stretch reduce ubiquitin transfer to USE1 and, subsequently, polyubiquitination and degradation of its target, the ubiquitin ligase E6AP. Furthermore, we identify competition for the UBA6-USE1 interaction by various proteins with polyalanine expansion mutations in the disease state. The deleterious interactions of expanded polyalanine tract proteins with UBA6 in mouse primary neurons alter the levels and ubiquitination-dependent degradation of E6AP, which in turn affects the levels of the synaptic protein Arc. These effects are also observed in induced pluripotent stem cell-derived autonomic neurons from patients with polyalanine expansion mutations, where UBA6 overexpression increases neuronal resilience to cell death. Our results suggest a shared mechanism for such mutations that may contribute to the congenital malformations seen in polyalanine tract diseases.
| S-EPMC10897158 | biostudies-literature