Molecular Signatures of CB-6644 Inhibition of the RUVBL1/2 Complex in Multiple Myeloma.

Multiple myeloma is the second most hematological cancer. RUVBL1 and RUVBL2 form a subcomplex of many chromatin remodeling complexes implicated in cancer progression. As an inhibitor specific to the RUVBL1/2 complex, CB-6644 exhibits remarkable anti-tumor activity in xenograft models of Burkitt's lymphoma and multiple myeloma (MM). In this work, we defined transcriptional signatures corresponding to CB-6644 treatment in MM cells and determined underlying epigenetic changes in terms of chromatin accessibility. CB-6644 upregulated biological processes related to interferon response and downregulated those linked to cell proliferation in MM cells. Transcriptional regulator inference identified E2Fs as regulators for downregulated genes and MED1 and MYC as regulators for upregulated genes. CB-6644-induced changes in chromatin accessibility occurred mostly in non-promoter regions. Footprinting analysis identified transcription factors implied in modulating chromatin accessibility in response to CB-6644 treatment, including ATF4/CEBP and IRF4. Lastly, integrative analysis of transcription responses to various chemical compounds of the molecular signature genes from public gene expression data identified CB-5083, a p97 inhibitor, as a synergistic candidate with CB-6644 in MM cells, but experimental validation refuted this hypothesis.

Maturation and Assembly of mTOR Complexes by the HSP90-R2TP-TTT Chaperone System: Molecular Insights and Mechanisms.

The mechanistic target of rapamycin (mTOR) is a master regulator of cell growth and metabolism, integrating environmental signals to regulate anabolic and catabolic processes, regulating lipid synthesis, growth factor-induced cell proliferation, cell survival, and migration. These activities are performed as part of two distinct complexes, mTORC1 and mTORC2, each with specific roles. mTORC1 and mTORC2 are elaborated dimeric structures formed by the interaction of mTOR with specific partners. mTOR functions only as part of these large complexes, but their assembly and activation require a dedicated and sophisticated chaperone system. mTOR folding and assembly are temporarily separated with the TELO2-TTI1-TTI2 (TTT) complex assisting the cotranslational folding of mTOR into a native conformation. Matured mTOR is then transferred to the R2TP complex for assembly of active mTORC1 and mTORC2 complexes. R2TP works in concert with the HSP90 chaperone to promote the incorporation of additional subunits to mTOR and dimerization. This review summarizes our current knowledge on how the HSP90-R2TP-TTT chaperone system facilitates the maturation and assembly of active mTORC1 and mTORC2 complexes, discussing interactions, structures, and mechanisms.

Molecular insights into type I interferon suppression and enhanced pathogenicity by species B human adenoviruses B7 and B14.

Human adenoviruses (HAdVs) are small DNA viruses that generally cause mild disease. Certain strains, particularly those belonging to species B HAdVs, can cause severe pneumonia and have a relatively high mortality rate. Little is known about the molecular aspects of how these highly pathogenic species affect the infected cell and how they suppress innate immunity. The present study provides molecular insights into how species B adenoviruses suppress the interferon signaling pathway. Our study shows that these viruses, unlike HAdV-C2, are resistant to type I interferon. This resistance likely arises due to the highly efficient suppression of interferon-stimulated gene expression. Unlike in HAdV-C2, HAdV-B7 and B14 sequester STAT2 and RNA polymerase II from interferon-stimulated gene promoters in infected cells. This results in suppressed interferon- stimulated gene activation. In addition, we show that RuvBL1 and RuvBL2, cofactors important for RNA polymerase II recruitment to promoters and interferon-stimulated gene activation, are redirected to the cytoplasm forming high molecular weight complexes that, likely, are unable to associate with chromatin. Proteomic analysis also identified key differences in the way these viruses affect the host cell, providing insights into species B-associated high pathogenicity. Curiously, we observed that at the level of protein expression changes to the infected cell, HAdV-C2 and B7 were more similar than those of the same species, B7 and B14. Collectively, our study represents the first such study of innate immune suppression by the highly pathogenic HAdV-B7 and B14, laying an important foundation for future investigations.IMPORTANCEHuman adenoviruses form a large family of double-stranded DNA viruses known for a variety of usually mild diseases. Certain strains of human adenovirus cause severe pneumonia leading to much higher mortality and morbidity than most other strains. The reasons for this enhanced pathogenicity are unknown. Our study provides a molecular investigation of how these highly pathogenic strains might inactivate the interferon signaling pathway, highlighting the lack of sensitivity of these viruses to type I interferon in general while providing a global picture of how viral changes in cellular proteins drive worse disease outcomes.

RUVBL1 in Clear-Cell Renal Cell Carcinoma: Unraveling Prognostic Significance and Correlation with HIF1A.

This study investigates the roles of RUVBL1 and HIF1A in ccRCC development and explores their clinical significance as prognostic biomarkers. mRNA and protein expressions were analyzed using TCGA data and an institutional tissue cohort, respectively. Correlations with clinicopathological parameters and patient outcomes were assessed. TCGA data revealed significantly elevated RUVBL1 mRNA expression in ccRCC tissues, associated with advanced histological grade, T stage, lymph node metastasis, and clinical stage. High RUVBL1 mRNA expression correlated with inferior overall survival and served as an adverse prognostic factor. Similarly, HIF1A mRNA expression was significantly higher in ccRCC tissues, correlating with worse overall survival and acting as an adverse prognostic factor for treatment outcomes. Simultaneous evaluation of RUVBL1 and HIF1A mRNA expression demonstrated enhanced prognostic capacity, surpassing the predictive power of individual markers. Immunohistochemical staining confirmed substantial upregulation of both RUVBL1 and HIF-1α proteins in ccRCC tissues. Furthermore, high expression of both RUVBL1 and HIF-1α proteins was significantly associated with shorter patient survival time. Our findings underscore the significance of RUVBL1 and HIF-1α as potential prognostic markers in ccRCC, paving the way for further research to translate these insights into clinically relevant applications.

IRX2 regulates endometrial carcinoma oncogenesis by transcriptional repressing RUVBL1.

Endometrial carcinoma (EC) is a rising concern among gynecological malignancies. Iroquois Homeobox 2 (IRX2), a member of the Iroquois homeobox gene family, demonstrates variable effects in different cancer types, emphasizing the need for extensive exploration of its involvement in EC progression. Utilizing TCGA and GEO databases, as well as performing immunohistochemistry (IHC) analysis on clinical samples, we assessed the expression levels of IRX2 and its promoter methylation in EC. To understand the functional roles of IRX2, we conducted various assays including in vitro CCK-8 assays, colony formation assays, cell invasion assays, and cell apoptosis assays. Moreover, we utilized in vivo subcutaneous xenograft mouse models. Additionally, we performed KEGG pathway and gene set enrichment analyses to gain insights into the underlying mechanisms. To validate the regulatory relationship between IRX2 and RUVBL1, we employed chromatin immunoprecipitation and luciferase reporter assays. Our results indicate significantly reduced levels of IRX2 expression in EC, correlating with higher histological grades, advanced clinical stages, and diminished overall survival. We observed that DNA methylation of the IRX2 promoter suppresses its expression in EC, with cg26333652 and cg11793269 playing critical roles as methylated sites. In contrast, ectopic overexpression of IRX2 substantially inhibits cell proliferation and invasion, and promotes cell apoptosis. Additionally, we discovered that IRX2 exerts negative regulation on the expression of RUVBL1, which is upregulated in EC and associated with a poorer prognosis. In conclusion, our findings indicate that decreased expression of IRX2 facilitates EC cell growth through the regulation of RUVBL1 expression, thereby contributing to the development of EC. Hence, targeting the IRX2-RUVBL1 axis holds promise as a potential therapeutic strategy for EC treatment.

Ruvbl1 is Essential for Ciliary Beating during Xenopus laevis Embryogenesis.

The Ruvb-like AAA ATPase1 (Ruvbl1; also known as Pontin) is an evolutionary conserved protein belonging to the adenosine triphosphates associated with diverse cellular activities (AAA+) superfamily of ATPases. Ruvbl1 is a component of various protein supercomplexes and is involved in a variety of cellular activities, including chromatin remodeling, DNA damage repair, and mitotic spindle assembly however, the developmental significance of this protein is unknown and needs detailed investigation. We investigated the developmental significance of Ruvbl1 in multiciliated cells of the Xenopus laevis epidermis since ruvbl1 is expressed in the multiciliated cells and pronephros during X. laevis embryogenesis. The knockdown of ruvbl1 significantly impaired cilia-driven fluid flow and basal body polarity in the X. laevis epidermis compared to control embryos, but did not affect cilia morphology. Our results suggest that Ruvbl1 plays a significant role in embryonic development by regulating ciliary beating; however, further investigation is needed to determine the mechanisms involved.

Generation and application of endogenously floxed alleles for cell-specific knockout in zebrafish.

The zebrafish is amenable to a variety of genetic approaches. However, lack of conditional deletion alleles limits stage- or cell-specific gene knockout. Here, we applied an existing protocol to establish a floxed allele for gata2a but failed to do so due to off-target integration and incomplete knockin. To address these problems, we applied simultaneous co-targeting with Cas12a to insert loxP sites in cis, together with transgenic counterscreening and comprehensive molecular analysis, to identify off-target insertions and confirm targeted knockins. We subsequently used our approach to establish endogenously floxed alleles of foxc1a, rasa1a, and ruvbl1, each in a single generation. We demonstrate the utility of these alleles by verifying Cre-dependent deletion, which yielded expected phenotypes in each case. Finally, we used the floxed gata2a allele to demonstrate an endothelial autonomous requirement in lymphatic valve development. Together, our results provide a framework for routine generation and application of endogenously floxed alleles in zebrafish.

Combined CRISPRi and proteomics screening reveal a cohesin-CTCF-bound allele contributing to increased expression of RUVBL1 and prostate cancer progression.

Genome-wide association studies along with expression quantitative trait locus (eQTL) mapping have identified hundreds of single-nucleotide polymorphisms (SNPs) and their target genes in prostate cancer (PCa), yet functional characterization of these risk loci remains challenging. To screen for potential regulatory SNPs, we designed a CRISPRi library containing 9,133 guide RNAs (gRNAs) to cover 2,166 candidate SNP loci implicated in PCa and identified 117 SNPs that could regulate 90 genes for PCa cell growth advantage. Among these, rs60464856 was covered by multiple gRNAs significantly depleted in screening (FDR < 0.05). Pooled SNP association analysis in the PRACTICAL and FinnGen cohorts showed significantly higher PCa risk for the rs60464856 G allele (p value = 1.2 × 10-16 and 3.2 × 10-7, respectively). Subsequent eQTL analysis revealed that the G allele is associated with increased RUVBL1 expression in multiple datasets. Further CRISPRi and xCas9 base editing confirmed that the rs60464856 G allele leads to elevated RUVBL1 expression. Furthermore, SILAC-based proteomic analysis demonstrated allelic binding of cohesin subunits at the rs60464856 region, where the HiC dataset showed consistent chromatin interactions in prostate cell lines. RUVBL1 depletion inhibited PCa cell proliferation and tumor growth in a xenograft mouse model. Gene-set enrichment analysis suggested an association of RUVBL1 expression with cell-cycle-related pathways. Increased expression of RUVBL1 and activation of cell-cycle pathways were correlated with poor PCa survival in TCGA datasets. Our CRISPRi screening prioritized about one hundred regulatory SNPs essential for prostate cell proliferation. In combination with proteomics and functional studies, we characterized the mechanistic role of rs60464856 and RUVBL1 in PCa progression.

OsRuvBL1a DNA helicase boost salinity and drought tolerance in transgenic indica rice raised by in planta transformation.

RuvBL, is a member of SF6 superfamily of helicases and is conserved among the various model systems. Recently, rice (Oryza sativa L.) homolog of RuvBL has been biochemically characterized for its ATPase and DNA helicase activities; however its involvement in stress has not been studied so far. Present investigation reports the detailed functional characterization of OsRuvBL under abiotic stresses through genetic engineering. An efficient Agrobacterium-mediated in planta transformation protocol was developed in indica rice to generate the transgenic lines and study was focused on optimization of factors to achieve maximum transformation efficiency. Overexpressing OsRuvBL1a transgenic lines showed enhanced tolerance under in vivo salinity stress as compared to WT plants. The physiological and biochemical analysis of the OsRuvBL1a transgenic lines showed better performance under salinity and drought stresses. Several stress responsive interacting partners of OsRuvBL1a were identified using Y2H system revealed to its role in stress tolerance. Functional mechanism for boosting stress tolerance by OsRuvBL1a has been proposed in this study. This integration of OsRuvBL1a gene in rice genome using in planta transformation method helped to achieve the abiotic stress resilient smart crop. This study is the first direct evidence to show the novel function of RuvBL in boosting abiotic stress tolerance in plants.

Downregulation of AHNAK2 inhibits cell cycle of lung adenocarcinoma cells by interacting with RUVBL1.

BACKGROUND: Lung adenocarcinoma (LUAD) is the leading cause of death among cancer diseases. The tumorigenic functions of AHNAK2 in LUAD have attracted more attention in recent years, while there are few studies which have reported its high molecular weight. METHODS: The mRNA-seq data of AHNAK2 and corresponding clinical data from UCSC Xena and GEO was analyzed. LUAD cell lines were transfected with sh-NC and sh-AHNAK2, and cell proliferation, migration and invasion were then detected by in vitro experiments. We performed RNA sequencing and mass spectrometry analysis to explore the downstream mechanism and interacting proteins of AHNAK2. Finally, western blot, cell cycle analysis and CO-IP were used to confirm our assumptions regarding previous experiments. RESULTS: Our study revealed that AHNAK2 expression was significantly higher in tumors than in normal lung tissues and higher AHNAK2 expression led to a poor prognosis, especially in patients with advanced tumors. AHNAK2 suppression via shRNA reduced the LUAD cell lines proliferation, migration and invasion and induced significant changes in DNA replication, NF-kappa B signaling pathway and cell cycle. AHNAK2 knockdown also caused G1/S phase cell cycle arrest, which could be attributed to the interaction of AHNAK2 and RUVBL1. In addition, the results from gene set enrichment analysis (GSEA) and RNA sequencing suggested that AHNAK2 probably plays a part in the mitotic cell cycle. CONCLUSION: AHNAK2 promotes proliferation, migration and invasion in LUAD and regulates the cell cycle via the interaction with RUVBL1. More studies of AHNAK2 are still needed to reveal its upstream mechanism.

Epigenetic Control of Translation Checkpoint and Tumor Progression via RUVBL1-EEF1A1 Axis.

Epigenetic dysregulation is reported in multiple cancers including Ewing sarcoma (EwS). However, the epigenetic networks underlying the maintenance of oncogenic signaling and therapeutic response remain unclear. Using a series of epigenetics- and complex-focused CRISPR screens, RUVBL1, the ATPase component of NuA4 histone acetyltransferase complex, is identified to be essential for EwS tumor progression. Suppression of RUVBL1 leads to attenuated tumor growth, loss of histone H4 acetylation, and ablated MYC signaling. Mechanistically, RUVBL1 controls MYC chromatin binding and modulates the MYC-driven EEF1A1 expression and thus protein synthesis. High-density CRISPR gene body scan pinpoints the critical MYC interacting residue in RUVBL1. Finally, this study reveals the synergism between RUVBL1 suppression and pharmacological inhibition of MYC in EwS xenografts and patient-derived samples. These results indicate that the dynamic interplay between chromatin remodelers, oncogenic transcription factors, and protein translation machinery can provide novel opportunities for combination cancer therapy.

Anti-RuvBL1/2 Autoantibodies Detection in a Patient with Overlap Systemic Sclerosis and Polymyositis.

Anti-RuvBL1/2 autoantibodies have recently been detected in patients with systemic sclerosis (SSc) and scleromyositis overlap syndromes. These autoantibodies exhibit a distinct speckled pattern in an indirect immunofluorescent assay on Hep-2 cells. We report the case of a 48 year old man with facial changes, Raynaud's phenomenon, puffy fingers, and muscle pain. A speckled pattern on Hep-2 cells was identified, but the conventional antibody testing was negative. Based on the clinical suspicion and the ANA pattern, further testing was sought demonstrating anti-RuvBL1/2 autoantibodies. Hence, a review of the English literature was performed to define this newly emerging clinical-serological syndrome. With the one here reported, a total of 52 cases have been described to date (December 2022). Anti-RuvBL1/2 autoantibodies are highly specific for SSc and are associated with SSc/PM overlaps. Apart from myopathy, gastrointestinal and pulmonary involvement are frequently observed in these patients (94% and 88%, respectively).

EIF3D promotes resistance to 5-fluorouracil in colorectal cancer through upregulating RUVBL1.

BACKGROUND: As EIF3D is oncogenic in colorectal cancer (CRC) and is associated with multidrug resistance, this study aims to investigate whether and how EIF3D regulates resistance to 5-fluorouracil (5-Fu) in CRC. METHODS: EIF3D-associated genes in CRC were predicted using bioinformatics tools. CRC cells and nude mice received 5-Fu treatment. Then, the impacts of EIF3D and the interaction between EIF3D and RUVBL1 on cell viability, colony formation, apoptosis, and DNA damage were detected through MTT, colony formation, flow cytometry, and immunofluorescence assays, and those on in vivo tumorigenesis through murine xenograft assay. IC50 value of 5-Fu for CRC cells was determined by probit regression analysis. Expressions of EIF3D, eIF4E, EIF3D-associated genes, γH2AX, Bcl-2, Bax, and Cleaved Caspase-3/Caspase-3 in CRC tissues, cells, and/or xenograft tumors were analyzed by qRT-PCR and/or Western blot. RESULTS: EIF3D and RUVBL1 were highly expressed and positively correlated with CRC tissues/cells. In CRC cells, except for eIF4E, both EIF3D and RUVBL1 levels were upregulated by 5-Fu treatment; in addition to that, RUVBL1 level was downregulated by EIF3D silencing rather than eIF4E. Meanwhile, EIF3D silencing diminished IC50 value of 5-Fu and potentiated 5-Fu-induced viability decrease, colony formation inhibition, apoptosis promotion, Bcl-2 downregulation, and γH2AX, Bax, and Cleaved Caspase-3/Caspase-3 upregulation but reversed 5-Fu-triggered RUVBL1 upregulation. RUVBL1 overexpression offsets EIF3D silencing-induced viability decrease and apoptosis promotion of 5-Fu-treated CRC cells, and tumorigenesis suppression and apoptosis promotion in 5-Fu-treated mice. CONCLUSION: EIF3D promotes resistance to 5-Fu in CRC through upregulating RUVBL1 level.

Identification of a Novel Interaction between Theileria Prohibitin (TaPHB-1) and Bovine RuvB-Like AAA ATPase 1.

Theileriosis is a tick-borne disease caused by Theileria annulata, an intracellular parasite that belongs to the phylum Apicomplexa. The infective forms of the parasite to cattle are sporozoites that are introduced into the host when the infected ticks take a blood meal. The sporozoites selectively invade bovine B cells, macrophages, or monocytes, leading to their cellular transformation. The parasite factors involved in the host cell transformation are not well explored. In pursuit of this, we revisited the probable secretome of the parasite and, following a stringent downscaling criterion, have identified Theileria prohibitin (TaPHB-1) as one of factors secreted into the host cells. Interestingly, in infected cells, TaPHB-1 localized both on the parasite surface and in the host cytoplasm, and independent approaches such as coimmunoprecipitation, yeast two-hybrid screening (Y2H), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed RuvB-like AAA ATPase 1 (RUVBL-1) as one of its interacting partners. Further, the T. annulata infection does not affect the localization of bovine prohibitin. Mitigating the expression of bovine RUVBL-1 precluded the translocation of TaPHB-1 in the host cell cytoplasm without affecting the host cell viability. Taken together, we report for the first time a unique interaction of TaPHB-1 with bovine RUVBL-1 that is likely needed to cause cancer-like hallmarks during theileriosis. IMPORTANCE Theileria annulata is an apicomplexan parasite that causes tropical theileriosis in cattle. It is the only eukaryotic pathogen able to cause cellular transformation of host cells yielding a cancer-like phenotype. The parasite factors responsible for the transformation of the host cell are largely unknown. This study demonstrates for the first time the partial role of Theileria prohibitin (TaPHB-1) in maintaining the transformed state of the host cell and its interaction with RuvB-like AAA ATPase 1 (RUVBL-1) in a T. annulata-infected bovine cell line. Interestingly, the knockdown of bovine RUVBL-1 rendered the parasites metabolically inactive, implying that the identified interaction is critical for parasite survival. This study contributes to our understanding the Theileria-host interactions and offers scope for novel therapeutic interventions to control theileriosis.

Identification of a novel target of SETD1A histone methyltransferase and the clinical significance in pancreatic cancer.

Although histone H3K4 methyltransferase SETD1A is overexpressed in various cancer types, the molecular mechanism underlying its overexpression and its target genes in pancreatic ductal adenocarcinoma (PDAC) remain unclarified. We conducted immunohistochemical staining for SETD1A in 105 human PDAC specimens to assess the relationship between SETD1A overexpression and clinicopathological features. The function and target genes of SETD1A were investigated using human pancreatic cancer cell lines. SETD1A expression was upregulated in 51.4% of patients with PDAC and was an independent prognostic factor associated with shorter disease-free survival after resection (p < 0.05). Knockdown and overexpression of SETD1A showed that SETD1A plays a crucial role in increasing the proliferation and motility of PDAC cells. SETD1A overexpression increased tumorigenicity. RNA sequencing of SETD1A-knockdown cells revealed downregulation of RUVBL1, an oncogenic protein ATP-dependent DNA helicase gene. ChIP analysis revealed that SETD1A binds to the RUVBL1 promoter region, resulting in increased H3K4me3 levels. Knockdown of RUVBL1 showed inhibition of cell proliferation, migration, and invasion of PDAC cells, which are similar biological effects to SETD1A knockdown. High expression of both SETD1A and RUVBL1 was an independent prognostic factor not only for disease-free survival but also for overall survival (p < 0.05). In conclusion, we identified RUVBL1 as a novel downstream target gene of the SETD1A-H3K4me3 pathway. Co-expression of SETD1A and RUVBL1 is an important factor for predicting the prognosis of patients with PDAC.

The multi-faceted roles of R2TP complex span across regulation of gene expression, translation, and protein functional assembly.

Macromolecular complexes play essential roles in various cellular processes. The assembly of macromolecular assemblies within the cell must overcome barriers imposed by a crowded cellular environment which is characterized by an estimated concentration of biological macromolecules amounting to 100-450 g/L that take up approximately 5-40% of the cytoplasmic volume. The formation of the macromolecular assemblies is facilitated by molecular chaperones in cooperation with their co-chaperones. The R2TP protein complex has emerged as a co-chaperone of Hsp90 that plays an important role in macromolecular assembly. The R2TP complex is composed of a heterodimer of RPAP3:P1H1DI that is in turn complexed to members of the ATPase associated with diverse cellular activities (AAA +), RUVBL1 and RUVBL2 (R1 and R2) families. What makes the R2TP co-chaperone complex particularly important is that it is involved in a wide variety of cellular processes including gene expression, translation, co-translational complex assembly, and posttranslational protein complex formation. The functional versatility of the R2TP co-chaperone complex makes it central to cellular development; hence, it is implicated in various human diseases. In addition, their roles in the development of infectious disease agents has become of interest. In the current review, we discuss the roles of these proteins as co-chaperones regulating Hsp90 and its partnership with Hsp70. Furthermore, we highlight the structure-function features of the individual proteins within the R2TP complex and describe their roles in various cellular processes.

Hippocalcin-Like 1 blunts liver lipid metabolism to suppress tumorigenesis via directly targeting RUVBL1-mTOR signaling.

Rationale: Hepatocellular carcinoma (HCC) is one of the most severe cancers worldwide, with few effective targeted therapies for HCC. Lipid metabolic reprogramming is emerged as a hallmark of cancer metabolism that guides response to antitumoral therapies. Such lipid metabolic alteration in cancers is critically regulated by the mammalian target of rapamycin mTOR, which is considered as a promising therapeutic target. Despite efforts, mTOR inhibitors (mTORi) have produced limited response clinically, partly due to incomplete knowledge of mTORC1 addiction in cancers. Methods: CRISPR-Cas9 system was used to establish Hpcal1 null mice. The liver cancer model in mice was generated using Hpcal1-deficient mice with diethylnitrosamine (DEN) /CCL4 or MYC/Trp53-/- via hydrodynamic tail-vein injection. RNA-sequencing (RNA-seq) was used to identify potential signaling pathways. The expression of HPCAL1 and mTOR signaling were determined using quantitative polymerase chain reaction (qPCR), western blot and immunohistochemistry. The role of Hpcal1 in liver tumorigenesis and its response to mTORi was assessed by CCK-8 measurements, colony formation assay and in mouse model. Results: In this study, we identified hippocalcin-like protein 1 (HPCAL1) as an important negative regulator of de novo lipid biosynthesis and mTOR signaling activation, limiting liver tumorigenesis and establishing a metabolic vulnerability of HCC in mice. Genetic loss of HPCAL1 rendered HCC mTORC1-addicted and sensitive to mTORi AZD-8055 in vitro and in vivo. Importantly, HPCAL1 expression was inversely correlated with the levels of mTOR phosphorylation and several critical lipid biosynthesis enzymes in human specimens. Mechanistically, HPCAL1 directly bound to RuvB Like AAA ATPase 1 (RUVBL1), inhibiting the assembly of TEL2-TTI1-TTI2 (TTT)-RUVBL complex and subsequent leading the mTOR signaling suppression. Conclusion: We uncover a metabolic vulnerability and mTOR addiction in HCC with HPCAL1 loss that provides a selective therapeutic window for HCC with mTORC1 hyperactivation using mTORi.

High expression of RUVBL1 and HNRNPU is associated with poor overall survival in stage I and II non-small cell lung cancer patients.

The present study aimed to investigate expression levels and prognostic significance of RUVBL1 and HNRNPU in stage I and II non-small-cell lung cancer (NSCLC) patients. Therefore, we evaluated immunohistochemical staining of RUVBL1 and HNRNPU, as well as RNA-seq data from public sources, and the results were evaluated concerning overall survival (OS) and clinicopathological features. We found that RUVBL1 and HNRNPU proteins and mRNA levels were higher in tumor tissues as compared to adjacent/normal tissues. RUVBL1 (p = 0.013) and HNRNPU (p = 0.021) high protein levels were independent prognostic factors for poor OS. Also, the multivariate analysis in the TCGA dataset revealed that high RUVBL1 (p = 0.064) and HNRNPU (p = 0.181) mRNA levels were not significantly associated with prognosis. However, the co-expression status of these markers (R + H +) was independently associated with poor OS both in the TCGA dataset (p = 0.027) and in our cohort (p = 0.001). In conclusion, combined and individual expression of RUVBL1 and HNRNPU proteins, as well as R + H + mRNA status, may serve as potential prognostic biomarkers for NSCLC. This study adds to the previous observations that RUVBL1 and HNRNPU might be novel and promising therapeutic targets and markers for prognostic evaluation.

Deciphering cellular and molecular determinants of human DPCD protein in complex with RUVBL1/RUVBL2 AAA-ATPases.

DPCD is a protein that may play a role in cilia formation and whose absence leads to primary ciliary dyskinesia (PCD), a rare disease caused by impairment of ciliated cells. Except for high-throughput studies that identified DPCD as a possible RUVBL1 (R1) and RUVBL2 (R2) partner, no in-depth cellular, biochemical, and structural investigation involving DPCD have been reported so far. R1 and R2 proteins are ubiquitous highly conserved AAA + family ATPases that assemble and mature a plethora of macromolecular complexes and are pivotal in numerous cellular processes, especially by guaranteeing a co-chaperoning function within R2TP or R2TP-like machineries. In the present study, we identified DPCD as a new R1R2 partner in vivo. We show that DPCD interacts directly with R1 and R2 in vitro and in cells. We characterized the physico-chemical properties of DPCD in solution and built a 3D model of DPCD. In addition, we used a variety of orthogonal biophysical techniques including small-angle X-ray scattering, structural mass spectrometry and electron microscopy to assess the molecular determinants of DPCD interaction with R1R2. Interestingly, DPCD disrupts the dodecameric state of R1R2 complex upon binding and this interaction occurs mainly via the DII domains of R1R2.

Discovery of small-molecule inhibitors of RUVBL1/2 ATPase.

RUVBL1 and RUVBL2 are highly conserved AAA ATPases (ATPases Associated with various cellular Activities) and highly relevant to the progression of cancer, which makes them attractive targets for novel therapeutic anticancer drugs. In this work, docking-based virtual screening was performed to identify compounds with activity against the RUVBL1/2 complex. Seven compounds showed inhibitory activity against the complex in both enzymatic and cellular assays. A series of pyrazolo[1,5-a]pyrimidine-3-carboxamide analogs were synthesized based on the scaffold of compound 15 with inhibitory activity and good potential for structural manipulation. Analysis of the structure-activity relationship identified the benzyl group on R2 and aromatic ring-substituted piperazinyl on R4 as essential for inhibitory activity against the RUVBL1/2 complex. Of these, compound 18, which has IC50 values of 6.0 ± 0.6 µM and 7.7 ± 0.9 µM against RUVBL1/2 complex and RUVBL1 respectively, showed the most potent inhibition in cell lines A549, H1795, HCT116, and MDA-MB-231 with IC50 values of 15 ± 1.2 µM, 15 ± 1.8 µM, 11 ± 1.0 µM, and 8.9 ± 0.9 µM respectively. A docking study of the compound was performed to predict the binding mode of pyrazolo[1,5-a]pyrimidine-3-carboxamides. Furthermore, mass spectrometry-based proteomic analysis was employed to explore cellular proteins dysregulated by treatment with compounds 16, 18, and 19. Together, the data from these analyses suggest that that compound 18 could serve as a starting point for structural modifications in order to improve potency, selectivity, and pharmacokinetic parameters of potential therapeutic molecules.