Circular RNA CircSLC22A23 Promotes Gastric Cancer Progression by Activating HNRNPU Expression.

BACKGROUND: Circular RNAs (CircRNAs) play essential roles in cancer occurrence as regulatory RNAs. However, circRNA-mediated regulation of gastric cancer (GC) remains poorly understood. AIM: The purpose of this study was to investigate the molecular mechanism of circSLC22A23 (hsa_circ_0075504) underlying GC occurrence. METHODS: CircSLC22A23 levels were first quantified by quantitative real-time reverse transcription-polymerase chain reaction in GC cell lines, 80 paired GC tissues and adjacent normal tissues, and 27 pairs of plasma samples from preoperative and postoperative patients with GC. Then circSLC22A23 was knocked-down with short hairpin RNA to analyze its oncogenic effects on the proliferation, migration, and invasion of GC cells. Finally, circRNA-binding proteins and their downstream target genes were identified by RNA pulldown, mass spectrometry, RNA immunoprecipitation, quantitative real-time reverse transcription-polymerase chain reaction, and Western blot assays. RESULTS: CircSLC22A23 was found to be highly expressed in GC cells, GC tissues, and plasma from GC patients. Knockdown of circSLC22A23 inhibited GC cell proliferation, migration and invasion. RNA pulldown and RNA immunoprecipitation assays verified the interaction between circSLC22A23 and heterogeneous nuclear ribonucleoprotein U (HNRNPU). Knockdown of circSLC22A23 decreased HNRNPU protein levels. Moreover, rescue assays showed that the tumor suppressive effect of circSLC22A23 knockdown was reversed by HNRNPU overexpression. Finally, epidermal growth factor receptor (EGFR) was found to be one of the downstream target genes of HNRNPU that was up regulated by circSLC22A23. CONCLUSION: CircSLC22A23 regulated the transcription of EGFR through activation of HNRNPU in GC cells, suggesting that circSLC22A23 may serve as a potential therapeutic target for the treatment of GC.

CircIRAK3 exerts negative feedback regulation on inflammation by binding to HNRNP U and destabilizing proinflammatory cytokine mRNA in osteoarthritis and chondrogenesis.

Osteoarthritis (OA) is the most prevalent age-related and degenerative joint disease with limited treatment options. Previous studies have identified the therapeutic effects of mesenchymal stem cells (MSCs) therapy. Nevertheless, chronic inflammation impedes MSCs therapeutic effect. There have been reports suggesting that circular RNAs (circRNAs) are involved in OA and chondrogenesis. The combination of MSCs and circRNAs in therapies appears to be a promising option. In this study, we identified circIRAK3 as a significant regulator in cartilage degeneration and chondrogenesis through high-throughput sequencing analyses. We observed increased circIRAK3 in OA cartilage and during MSCs chondrogenesis. Knockdown of circIRAK3 resulted in excessive apoptosis, inhibited proliferation, and degradation of chondrocytes, along with the inhibition of MSCs chondrogenesis. Mechanistically, circIRAK3 bound to HNRNP U and competitively prevented its binding to IL-1ß, TNFα, and IL6 mRNA, thereby promoting mRNA degradation. Notably, circIRAK3 expression in plasma increased with higher OARSI scores. Intra-articular injection of adeno-associated virus-circIRAK3 delayed cartilage degeneration and reduced inflammation in DMM mouse model. Our study highlights a compensatory regulation network of circIRAK3 in chondrocytes in response to inflammation. CircIRAK3 has the potential to serve as a new therapeutic target for OA. Furthermore, therapies targeting circIRAK3 combined with MSCs hold promise.

Alternative Splicing Factor Heterogeneous Nuclear Ribonucleoprotein U as a Promising Biomarker for Gastric Cancer Risk and Prognosis with Tumor-Promoting Properties.

Gastric cancer (GC) is a major global health concern with poor outcomes. Heterogeneous nuclear ribonucleoprotein U (HNRNPU) is a multifunctional protein that participates in pre-mRNA packaging, alternative splicing regulation, and chromatin remodeling. Its potential role in GC remains unclear. In this study, the expression characteristics of HNRNPU were analyzed by The Cancer Genome Atlas data, Gene Expression Omnibus data, and then further identified by real-time quantitative PCR and immunohistochemistry using tissue specimens. From superficial gastritis, atrophic gastritis, and hyperplasia to GC, the in situ expression of HNRNPU protein gradually increased, and the areas under the curve for diagnosis of GC and its precancerous lesions were 0.911 and 0.847, respectively. A nomogram integrating HNRNPU expression, lymph node metastasis, and other prognostic indicators exhibited an area under the curve of 0.785 for predicting survival risk. Knockdown of HNRNPU significantly inhibited GC cell proliferation, migration, and invasion and promoted apoptosis in vitro. In addition, RNA-sequencing analysis showed that HNRNPU could affect alternative splicing events in GC cells, with functional enrichment analysis revealing that HNRNPU may exert malignant biological function in GC progression through alternative splicing regulation. In summary, the increased expression of HNRNPU was significantly associated with the development of GC, with a good performance in diagnosing and predicting the prognostic risk of GC. Functionally, HNRNPU may play an oncogenic role in GC by regulating alternative splicing.

RNA-binding protein hnRNPU regulates multiple myeloma resistance to selinexor.

Multiple myeloma (MM) is an incurable haematological cancer. Selinexor is the first-in-class selective inhibitor of nuclear export (SINE) and was newly approved for the treatment of MM. Until now, very few studies have investigated selinexor resistance in MM. Heterogeneous nuclear ribonucleoprotein U (hnRNPU) is an RNA-binding protein and a component of hnRNP complexes. Here we found that hnRNPU regulates MM sensitivity to selinexor. Cell apoptosis assays were performed to compare selinexor-induced cell death in control knockdown (CTR-KD) and hnRNPU knockdown (hnR-KD) MM cells. HnRNPU knockdown-induced nuclear protein retention was examined by proteomics array. HnRNPU-conferred mRNA translation regulation was evaluated by sucrose gradient assay, RNA electrophoresis mobility shift assay, and RNA pull-down assay. We found that hnR-KD MM cells were more sensitive to selinexor-induced cell death in vitro and in mouse model. MM patients who responded to selinexor had relatively low hnRNPU expression. In brief, hnRNPU comprehensively regulated MM sensitivity to selinexor by affecting the localization of LTV1 and NMD3, and mRNA translation of MDM2 and RAN, which were involved in XPO1-mediated nuclear export of ribosome subunits and tumor suppressors. Our discoveries indicate that hnRNPU might be a possible marker to categorize MM patients for the use of Selinexor.

Deficiency of the Heterogeneous Nuclear Ribonucleoprotein U locus leads to delayed hindbrain neurogenesis.

Genetic variants affecting Heterogeneous Nuclear Ribonucleoprotein U (HNRNPU) have been identified in several neurodevelopmental disorders (NDDs). HNRNPU is widely expressed in the human brain and shows the highest postnatal expression in the cerebellum. Recent studies have investigated the role of HNRNPU in cerebral cortical development, but the effects of HNRNPU deficiency on cerebellar development remain unknown. Here, we describe the molecular and cellular outcomes of HNRNPU locus deficiency during in vitro neural differentiation of patient-derived and isogenic neuroepithelial stem cells with a hindbrain profile. We demonstrate that HNRNPU deficiency leads to chromatin remodeling of A/B compartments, and transcriptional rewiring, partly by impacting exon inclusion during mRNA processing. Genomic regions affected by the chromatin restructuring and host genes of exon usage differences show a strong enrichment for genes implicated in epilepsies, intellectual disability, and autism. Lastly, we show that at the cellular level HNRNPU downregulation leads to an increased fraction of neural progenitors in the maturing neuronal population. We conclude that the HNRNPU locus is involved in delayed commitment of neural progenitors to differentiate in cell types with hindbrain profile.

Selective DNA-binding of SP120 (rat ortholog of human hnRNP U) is mediated by arginine-glycine rich domain and modulated by RNA.

A human protein heterogeneous ribonucleoprotein U (hnRNP U) also known as Scaffold attachment factor A (SAF-A) and its orthologous rat protein SP120 are abundant and multifunctional nuclear protein that directly binds to both DNA and RNA. The C-terminal region of hnRNP U enriched with arginine and glycine is essential for the interaction with RNA and the N-terminal region of SAF-A termed SAP domain has been ascribed to the DNA binding. We have reported that rat hnRNP U specifically and cooperatively binds to AT-rich DNA called nuclear scaffold/matrix-associated region (S/MAR) although its detailed mechanism remained unclear. In the present study analysis of hnRNP U deletion mutants revealed for the first time that a C-terminal domain enriched with Arg-Gly (defined here as 'RG domain') is predominantly important for the S/MAR-selective DNA binding activities. RG domain alone directly bound to S/MAR and coexistence with the SAP domain exerted a synergistic effect. The binding was inhibited by netropsin, a minor groove binder with preference to AT pairs that are enriched in S/MAR, suggesting that RG domain interacts with minor groove of S/MAR DNA. Interestingly, excess amounts of RNA attenuated the RG domain-dependent S/MAR-binding of hnRNP U. Taken together, hnRNP U may be the key element for the RNA-regulated recognition of S/MAR DNA and thus contributing to the dynamic structural changes of chromatin compartments.

Hepatocyte-secreted FAM3D ameliorates hepatic steatosis by activating FPR1-hnRNP U-GR-SCAD pathway to enhance lipid oxidation.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide; however, the underlying mechanisms remain poorly understood. FAM3D is a member of the FAM3 family; however, its role in hepatic glycolipid metabolism remains unknown. Serum FAM3D levels are positively correlated with fasting blood glucose levels in patients with diabetes. Hepatocytes express and secrete FAM3D, and its expression is increased in steatotic human and mouse livers. Hepatic FAM3D overexpression ameliorated hyperglycemia and steatosis in obese mice, whereas FAM3D-deficient mice exhibited exaggerated hyperglycemia and steatosis after high-fat diet (HFD)-feeding. In cultured hepatocytes, FAM3D overexpression or recombinant FAM3D protein (rFAM3D) treatment reduced gluconeogenesis and lipid deposition, which were blocked by anti-FAM3D antibodies or inhibition of its receptor, formyl peptide receptor 1 (FPR1). FPR1 overexpression suppressed gluconeogenesis and reduced lipid deposition in wild hepatocytes but not in FAM3D-deficient hepatocytes. The addition of rFAM3D restored FPR1's inhibitory effects on gluconeogenesis and lipid deposition in FAM3D-deficient hepatocytes. Hepatic FPR1 overexpression ameliorated hyperglycemia and steatosis in obese mice. RNA sequencing and DNA pull-down revealed that the FAM3D-FPR1 axis upregulated the expression of heterogeneous nuclear ribonucleoprotein U (hnRNP U), which recruits the glucocorticoid receptor (GR) to the promoter region of the short-chain acyl-CoA dehydrogenase (SCAD) gene, promoting its transcription to enhance lipid oxidation. Moreover, FAM3D-FPR1 axis also activates calmodulin-Akt pathway to suppress gluconeogenesis in hepatocytes. In conclusion, hepatocyte-secreted FAM3D activated the FPR1-hnRNP U-GR-SCAD pathway to enhance lipid oxidation in hepatocytes. Under obesity conditions, increased hepatic FAM3D expression is a compensatory mechanism against dysregulated glucose and lipid metabolism.

HNRNPU's multi-tasking is essential for proper cortical development.

Heterogeneous nuclear ribonucleoprotein U (HNRNPU) is a nuclear protein that plays a crucial role in various biological functions, such as RNA splicing and chromatin organization. HNRNPU/scaffold attachment factor A (SAF-A) activities are essential for regulating gene expression, DNA replication, genome integrity, and mitotic fidelity. These functions are critical to ensure the robustness of developmental processes, particularly those involved in shaping the human brain. As a result, HNRNPU is associated with various neurodevelopmental disorders (HNRNPU-related neurodevelopmental disorder, HNRNPU-NDD) characterized by developmental delay and intellectual disability. Our research demonstrates that the loss of HNRNPU function results in the death of both neural progenitor cells and post-mitotic neurons, with a higher sensitivity observed in the former. We reported that HNRNPU truncation leads to the dysregulation of gene expression and alternative splicing of genes that converge on several signaling pathways, some of which are likely to be involved in the pathology of HNRNPU-related NDD.

HNRNPU facilitates antibody class-switch recombination through C-NHEJ promotion and R-loop suppression.

B cells generate functionally different classes of antibodies through class-switch recombination (CSR), which requires classical non-homologous end joining (C-NHEJ) to join the DNA breaks at the donor and acceptor switch (S) regions. We show that the RNA-binding protein HNRNPU promotes C-NHEJ-mediated S-S joining through the 53BP1-shieldin DNA-repair complex. Notably, HNRNPU binds to the S region RNA/DNA G-quadruplexes, contributing to regulating R-loop and single-stranded DNA (ssDNA) accumulation. HNRNPU is an intrinsically disordered protein that interacts with both C-NHEJ and R-loop complexes in an RNA-dependent manner. Strikingly, recruitment of HNRNPU and the C-NHEJ factors is highly sensitive to liquid-liquid phase separation inhibitors, suggestive of DNA-repair condensate formation. We propose that HNRNPU facilitates CSR by forming and stabilizing the C-NHEJ ribonucleoprotein complex and preventing excessive R-loop accumulation, which otherwise would cause persistent DNA breaks and aberrant DNA repair, leading to genomic instability.

Malat1 deficiency prevents neonatal heart regeneration by inducing cardiomyocyte binucleation.

The adult mammalian heart has limited regenerative capacity, while the neonatal heart fully regenerates during the first week of life. Postnatal regeneration is mainly driven by proliferation of preexisting cardiomyocytes and supported by proregenerative macrophages and angiogenesis. Although the process of regeneration has been well studied in the neonatal mouse, the molecular mechanisms that define the switch between regenerative and nonregenerative cardiomyocytes are not well understood. Here, using in vivo and in vitro approaches, we identified the lncRNA Malat1 as a key player in postnatal cardiac regeneration. Malat1 deletion prevented heart regeneration in mice after myocardial infarction on postnatal day 3 associated with a decline in cardiomyocyte proliferation and reparative angiogenesis. Interestingly, Malat1 deficiency increased cardiomyocyte binucleation even in the absence of cardiac injury. Cardiomyocyte-specific deletion of Malat1 was sufficient to block regeneration, supporting a critical role of Malat1 in regulating cardiomyocyte proliferation and binucleation, a landmark of mature nonregenerative cardiomyocytes. In vitro, Malat1 deficiency induced binucleation and the expression of a maturation gene program. Finally, the loss of hnRNP U, an interaction partner of Malat1, induced similar features in vitro, suggesting that Malat1 regulates cardiomyocyte proliferation and binucleation by hnRNP U to control the regenerative window in the heart.

LncRNA HEM2ATM improves obesity-associated adipose tissues meta-inflammation and insulin resistance by interacting with heterogeneous nuclear ribonucleoprotein U.

Obesity is a complicated metabolic disease characterized by meta-inflammation in adipose tissues. In this study, we explored the roles of a new long non-coding RNA (lncRNA), HEM2ATM, which is highly expressed in adipose tissue M2 macrophages, in modulating obesity-associated meta-inflammation and insulin resistance. HEM2ATM expression decreased significantly in adipose tissue macrophages (ATMs) obtained from epididymal adipose tissues of high-fat diet (HFD)-induced obese mice. Overexpression of macrophage HEM2ATM improved meta-inflammation and insulin resistance in the adipose tissues of HFD-fed mice. Functionally, HEM2ATM negatively regulated the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in macrophages. Mechanistically, HEM2ATM bound to heterogeneous nuclear ribonucleoprotein U (hnRNP U), suppressed hnRNP U translocation from the nucleus to the cytoplasm, hindered the function of cytoplasmic hnRNP U on TNF-α and IL-6 mRNA stabilization, and decreased the secretion of TNF-α and IL-6. Collectively, HEM2ATM is a novel suppressor of obesity-associated meta-inflammation and insulin resistance.

HNRNPU promotes the progression of triple-negative breast cancer via RNA transcription and alternative splicing mechanisms.

Triple-negative breast cancer (TNBC) is a great detriment to women's health due to the lack of effective therapeutic targets. In this study, we employed an integrated genetic screen to identify a pivotal oncogenic factor, heterogeneous nuclear ribonucleoprotein U (HNRNPU), which is required for the progression of TNBC. We elucidated the pro-oncogenic role of HNRNPU, which can induce the proliferation and migration of TNBC cells via its association with DEAD box helicase 5 (DDX5) protein. Elevated levels of the HNRNPU-DDX5 complex prohibited the intron retention of minichromosome maintenance protein 10 (MCM10) pre-mRNA, decreased nonsense-mediated mRNA decay, and activated Wnt/ß-catenin signalling; on the other hand, HNRNPU-DDX5 is located in the transcriptional start sites (TSS) of LIM domain only protein 4 (LMO4) and its upregulation promoted the transcription of LMO4, consequently activating PI3K-Akt-mTOR signalling. Our data highlight the synergetic effects of HNRNPU in RNA transcription and splicing in regulating cancer progression and suggest that HNRNPU may act as a potential molecular target in the treatment of TNBC.

FBXO34 promotes latent HIV-1 activation by post-transcriptional modulation.

ABSTRACTAcquired immunodeficiency syndrome (AIDS) cannot be completely cured, mainly due to the existence of a latent HIV-1 reservoir. However, our current understanding of the molecular mechanisms underlying the establishment and maintenance of HIV-1 latent reservoir is not comprehensive. Here, using a genome-wide CRISPR-Cas9 activation library screening, we identified E3 ubiquitin ligase F-box protein 34 (FBXO34) and the substrate of FBXO34, heterogeneous nuclear ribonucleoprotein U (hnRNP U) was identified by affinity purification mass spectrometry, as new host factors related to HIV-1 latent maintenance. Overexpression of FBXO34 or knockout of hnRNP U can activate latent HIV-1 in multiple latent cell lines. FBXO34 mainly promotes hnRNP U ubiquitination, which leads to hnRNP U degradation and abolishment of the interaction between hnRNP U and HIV-1 mRNA. In a latently infected cell line, hnRNP U interacts with the ReV region of HIV-1 mRNA through amino acids 1-339 to hinder HIV-1 translation, thereby, promoting HIV-1 latency. Importantly, we confirmed the role of the FBXO34/hnRNP U axis in the primary CD4+ T lymphocyte model, and detected differences in hnRNP U expression levels in samples from patients treated with antiretroviral therapy (ART) and healthy people, which further suggests that the FBXO34/hnRNP U axis is a new pathway involved in HIV-1 latency. These results provide mechanistic insights into the critical role of ubiquitination and hnRNP U in HIV-1 latency. This novel FBXO34/hnRNP U axis in HIV transcription may be directly targeted to control HIV reservoirs in patients in the future.

Modulation of pre-mRNA structure by hnRNP proteins regulates alternative splicing of MALT1.

Alternative splicing plays key roles for cell type-specific regulation of protein function. It is controlled by cis-regulatory RNA elements that are recognized by RNA binding proteins (RBPs). The MALT1 paracaspase is a key factor of signaling pathways that mediate innate and adaptive immune responses. Alternative splicing of MALT1 is critical for controlling optimal T cell activation. We demonstrate that MALT1 splicing depends on RNA structural elements that sequester the splice sites of the alternatively spliced exon7. The RBPs hnRNP U and hnRNP L bind competitively to stem-loop RNA structures that involve the 5' and 3' splice sites flanking exon7. While hnRNP U stabilizes RNA stem-loop conformations that maintain exon7 skipping, hnRNP L disrupts these RNA elements to facilitate recruitment of the essential splicing factor U2AF2, thereby promoting exon7 inclusion. Our data represent a paradigm for the control of splice site selection by differential RBP binding and modulation of pre-mRNA structure.

Heterogeneous nuclear ribonucleoprotein U (HNRNPU) safeguards the developing mouse cortex.

HNRNPU encodes the heterogeneous nuclear ribonucleoprotein U, which participates in RNA splicing and chromatin organization. Microdeletions in the 1q44 locus encompassing HNRNPU and other genes and point mutations in HNRNPU cause brain disorders, including early-onset seizures and severe intellectual disability. We aimed to understand HNRNPU's roles in the developing brain. Our work revealed that HNRNPU loss of function leads to rapid cell death of both postmitotic neurons and neural progenitors, with an apparent higher sensitivity of the latter. Further, expression and alternative splicing of multiple genes involved in cell survival, cell motility, and synapse formation are affected following Hnrnpu's conditional truncation. Finally, we identified pharmaceutical and genetic agents that can partially reverse the loss of cortical structures in Hnrnpu mutated embryonic brains, ameliorate radial neuronal migration defects and rescue cultured neural progenitors' cell death.

Long Noncoding RNA lncRHL Regulates Hepatic VLDL Secretion by Modulating hnRNPU/BMAL1/MTTP Axis.

Dysregulation of hepatic VLDL secretion contributes to the pathogenesis of metabolic diseases, such as nonalcoholic fatty liver disease (NAFLD) and hyperlipidemia. Accumulating evidence has suggested that long noncoding RNAs (lncRNAs) had malfunctioning roles in the pathogenesis of NAFLD. However, the function of lncRNAs in controlling hepatic VLDL secretion remains largely unillustrated. Here, we identified a novel lncRNA, lncRNA regulator of hyperlipidemia (lncRHL), which was liver-enriched, downregulated on high-fat diet feeding, and inhibited by oleic acid treatment in primary hepatocytes. With genetic manipulation in mice and primary hepatocytes, depletion of lncRHL induces hepatic VLDL secretion accompanied by decreased hepatic lipid contents. Conversely, lncRHL restoration reduces VLDL secretion with increased lipid deposition in hepatocytes. Mechanistic analyses indicate that lncRHL binds directly to heterogeneous nuclear ribonuclear protein U (hnRNPU), and thereby enhances its stability, and that hnRNPU can transcriptional activate Bmal1, leading to inhibition of VLDL secretion in hepatocytes. lncRHL deficiency accelerates the protein degradation of hnRNPU and suppresses the transcription of Bmal1, which in turn activates VLDL secretion in hepatocytes. With results taken together, we conclude that lncRHL is a novel suppressor of hepatic VLDL secretion. Activating the lncRHL/hnRNPU/BMAL1/MTTP axis represents a potential strategy for the maintenance of intrahepatic and plasma lipid homeostasis.

Heterogeneous nuclear ribonucleoprotein U-actin complex derived from extracellular vesicles facilitates proliferation and migration of human coronary artery endothelial cells by promoting RNA polymerase II transcription.

Coronary artery disease (CAD) represents a fatal public threat. The involvement of extracellular vesicles (EVs) in CAD has been documented. This study explored the regulation of embryonic stem cells (ESCs)-derived EVs-hnRNPU-actin complex in human coronary artery endothelial cell (HCAEC) growth. Firstly, in vitro HCAEC hypoxia models were established. EVs were extracted from ESCs by ultracentrifugation. HCAECs were treated with EVs and si-VEGF for 24 h under hypoxia, followed by assessment of cell proliferation, apoptosis, migration, and tube formation. Uptake of EVs by HCAECs was testified. Additionally, hnRNPU, VEGF, and RNA Pol II levels were determined using Western blotting and CHIP assays. Interaction between hnRNPU and actin was evaluated by Co-immunoprecipitation assay. HCAEC viability and proliferation were lowered, apoptosis was enhanced, wound fusion was decreased, and the number of tubular capillary structures was reduced under hypoxia, whereas ESC-EVs treatment counteracted these effects. Moreover, EVs transferred hnRNPU into HCAECs. EVs-hnRNPU-actin complex increased RNA Pol II level on the VEGF gene promoter and promoted VEGF expression in HCAECs. Inhibition of hnRNPU or VEGF both annulled the promotion of EVs on HCAEC growth. Collectively, ESC-EVs-hnRNPU-actin increased RNA Pol II phosphorylation and VEGF expression, thus promoting HCAEC growth.

Expanding the phenotype of HNRNPU-related neurodevelopmental disorder with emphasis on seizure phenotype and review of literature.

Pathogenic variants in heterogeneous nuclear ribonucleoprotein U (HNRNPU) results in a novel neurodevelopmental disorder recently delineated. Here, we report on 17 previously unpublished patients carrying HNRNPU pathogenic variants. All patients were found to harbor de novo loss-of-function variants except for one individual where the inheritance could not be determined, as a parent was unavailable for testing. All patients had seizures which started in early childhood, global developmental delay, intellectual disability, and dysmorphic features. In addition, hypotonia, behavioral abnormalities (such as autistic features, aggression, anxiety, and obsessive-compulsive behaviors), and cardiac (septal defects) and/or brain abnormalities (ventriculomegaly and corpus callosum thinning/agenesis) were frequently observed. We have noted four recurrent variants in the literature (c.1089G>A p.(Trp363*), c.706_707del p.(Glu236Thrfs*6), c.847_857del p.(Phe283Serfs*5), and c.1681dels p.(Gln561Serfs*45)).

Targeting HNRNPU to overcome cisplatin resistance in bladder cancer.

PURPOSE: The overall response of cisplatin-based chemotherapy in bladder urothelial carcinoma (BUC) remains unsatisfactory due to the complex pathological subtypes, genomic difference, and drug resistance. The genes that associated with cisplatin resistance remain unclear. Herein, we aimed to identify the cisplatin resistance associated genes in BUC. EXPERIMENTAL DESIGN: The cytotoxicity of cisplatin was evaluated in six bladder cancer cell lines to compare their responses to cisplatin. The T24 cancer cells exhibited the lowest sensitivity to cisplatin and was therefore selected to explore the mechanisms of drug resistance. We performed genome-wide CRISPR screening in T24 cancer cells in vitro, and identified that the gene heterogeneous nuclear ribonucleoprotein U (HNRNPU) was the top candidate gene related to cisplatin resistance. Epigenetic and transcriptional profiles of HNRNPU-depleted cells after cisplatin treatment were analyzed to investigate the relationship between HNRNPU and cisplatin resistance. In vivo experiments were also performed to demonstrate the function of HNRNPU depletion in cisplatin sensitivity. RESULTS: Significant correlation was found between HNRNPU expression level and sensitivity to cisplatin in bladder cancer cell lines. In the high HNRNPU expressing T24 cancer cells, knockout of HNRNPU inhibited cell proliferation, invasion, and migration. In addition, loss of HNRNPU promoted apoptosis and S-phase arrest in the T24 cells treated with cisplatin. Data from The Cancer Genome Atlas (TCGA) demonstrated that HNRNPU expression was significantly higher in tumor tissues than in normal tissues. High HNRNPU level was negatively correlated with patient survival. Transcriptomic profiling analysis showed that knockout of HNRNPU enhanced cisplatin sensitivity by regulating DNA damage repair genes. Furthermore, it was found that HNRNPU regulates chemosensitivity by affecting the expression of neurofibromin 1 (NF1). CONCLUSIONS: Our study demonstrated that HNRNPU expression is associated with cisplatin sensitivity in bladder urothelial carcinoma cells. Inhibition of HNRNPU could be a potential therapy for cisplatin-resistant bladder cancer.

hnRNPub inhibits LPS-induced NF-κB pathway by targeting TRAF6 for K48-linked ubiquitination in miiuy croaker (Miichthys miiuy).

As an important adaptor protein in innate immunity, TRAF6 is not only responsible for the transduction of signal pathways, but its E3 ligase activity to transfer ubiquitination has also been widely studied. Under LPS stimulation, TRAF6 transfers the K63-linked ubiquitination chain to TAK1, which in turn activates the transcription factor NF-κB and cell signaling factors downstream of the signaling pathway. However, how TRAF6 expression is regulated remains largely unknown, especially in teleost. In this study, we identified hnRNPub as a suppressor of TRAF6 expression. The mRNA level of hnRNPub significantly increased under LPS stimulation, and hnRNPub inhibited NF-κB signaling pathway by targeting TRAF6. Knockdown of hnRNPub potentiated inflammatory cytokines, such as TNFα,IL-1ß,IL-8. Mechanistically, hnRNPub inhibited NF-κB signaling pathway through mediating K48-linked ubiquitination and proteasomal degradation of TRAF6. Thus, our findings reveal that hnRNPub limits LPS-induced innate activation by promoting K48-linked polyubiquitination and proteasomal degradation of TRAF6.