Loss of full-length hnRNP R isoform impairs DNA damage response in motoneurons by inhibiting Yb1 recruitment to chromatin

HNRNPA2B1 and HNRNPR stabilize ASCL1 in an m6A-dependent manner to promote neuroblastoma progression

HNRNPA2B1 and HNRNPR stabilize ASCL1 mRNA in neuroblastoma, but whether their regulatory effects depend on m6A modification and whether their function involves ASCL1 remain unknown. This study investigated the m6A-dependent binding of HNRNPA2B1 and HNRNPR to ASCL1 and subsequent regulation, as well as the expression, clinical significance, and function of HNRNPA2B1 and HNRNPR in neuroblastoma. We revealed that METTL14 mediated ASCL1 m6A modification to stabilize ASCL1. HNRNPA2B1 and HNRNPR significantly enriched ASCL1 mRNA by binding to the 5' and 3' untranslated regions, respectively, and METTL14 knockdown reduced this enrichment. Mutations in m6A sites in the untranslated regions of ASCL1 mRNA considerably decreased probe capacity to engage HNRNPA2B1 and HNRNPR. HNRNPR interacts with IGF2BP1, and knocking down either impaired binding to ASCL1 mRNA. HNRNPA2B1 and HNRNPR knockdown suppressed neuroblastoma cell growth and invasion, while ASCL1 overexpression restored these effects. The high HNRNPA2B1 and HNRNPR expression in neuroblastoma correlated with ASCL1 expression. Thus, HNRNPA2B1 and HNRNPR bind and stabilize ASCL1 mRNA in an m6A-dependent manner to promote neuroblastoma progression. This study not only discovered a new mechanism underlying the high ASCL1 expression in neuroblastoma but also identified the HNRNPA2B1/HNRNPR/ASCL1 axis as a promising target for inhibiting neuroblastoma progression.

HnRNPR strongly represses splicing of a critical exon associated with spinal muscular atrophy through binding to an exonic AU-rich element

BACKGROUND

Spinal muscular atrophy (SMA) is a motor neuron disease caused by mutations of survival of motor neuron 1 (SMN1) gene, which encodes the SMN protein. SMN2, a nearly identical copy of SMN1, with several single-nucleotide substitutions leading to predominant skipping of its exon 7, is insufficient to compensate for loss of SMN1. Heterogeneous nuclear ribonucleoprotein R (hnRNPR) has been previously shown to interact with SMN in the 7SK complex in motoneuron axons and is implicated in the pathogenesis of SMA. Here, we show that hnRNPR also interacts with SMN1/2 pre-mRNAs and potently inhibits exon 7 inclusion.

METHODS

In this study, to examine the mechanism that hnRNPR regulates SMN1/2 splicing, deletion analysis in an SMN2 minigene system, RNA-affinity chromatography, co-overexpression analysis and tethering assay were performed. We screened antisense oligonucleotides (ASOs) in a minigene system and identified a few that markedly promoted SMN2 exon 7 splicing.

RESULTS

We pinpointed an AU-rich element located towards the 3' end of the exon that mediates splicing repression by hnRNPR. We uncovered that both hnRNPR and Sam68 bind to the element in a competitive manner, and the inhibitory effect of hnRNPR is much stronger than Sam68. Moreover, we found that, among the four hnRNPR splicing isoforms, the exon 5-skipped one has the minimal inhibitory effect, and ASOs inducing hnRNPR exon 5 skipping also promote SMN2 exon 7 inclusion.

CONCLUSION

We identified a novel mechanism that contributes to mis-splicing of SMN2 exon 7.

Upregulation of LINC00501 by H3K27 acetylation facilitates gastric cancer metastasis through activating epithelial-mesenchymal transition and angiogenesis

BACKGROUND

The molecular mechanism of the significant role of long noncoding RNAs (lncRNAs) in the progression and metastasis of gastric cancer (GC) remains largely elusive. Our objective is to detect overexpressed lncRNA in GC and investigate its role in promoting epithelial-mesenchymal transition and tumour microenvironment remodel.

METHODS

LncRNA differential expression profile in GC was analysed using RNA microarrays. The level of LINC00501 was evaluated in both GC patient tissues and GC cell lines by quantitative reverse transcription PCR and large-scale (n = 304) tissue microarray. To explore the biological role and regulatory driver of LINC00501 in GC, various experimental techniques including Chromatin isolation by RNA purification (ChIRP), RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) assay, dual luciferase assays were performed.

RESULTS

Clinically, it was observed that LINC00501 level was abnormal overexpression in GC tissue and was associated with GC progression and distant metastasis. Gain and loss molecular biological experiments suggested that LINC00501, promoted EMT process and angiogenesis of GC. Mechanically, the enrichment of H3K27 acetylation in LINC00501 promoter region contributed to the increase of LINC00501 in GC. LINC00501 transactivated transcription of SLUG, by recruiting hnRNPR to its promoter. The growth of GC was inhibited both in vitro and in vivo by suppressing the level of LINC00501 using pharmacological intervention from the histone acetyltransferase (HAT) inhibitor -C646.

CONCLUSIONS

This study suggests that LINC00501 promotes GC progression via hnRNPR/SLUG pathway, which indicates a promising biomarker and target for GC.

Cytoskeleton remodeling mediated by circRNA-YBX1 phase separation suppresses the metastasis of liver cancer

Metastasis, especially intrahepatic, is a major challenge for hepatocellular carcinoma (HCC) treatment. Cytoskeleton remodeling has been identified as a vital process mediating intrahepatic spreading. Previously, we reported that HCC tumor adhesion and invasion were modulated by circular RNA (circRNA), which has emerged as an important regulator of various cellular processes and has been implicated in cancer progression. Here, we uncovered a nuclear circRNA, circASH2, which is preferentially lost in HCC tissues and inhibits HCC metastasis by altering tumor cytoskeleton structure. Tropomyosin 4 (TPM4), a critical binding protein of actin, turned out to be the major target of circASH2 and was posttranscriptionally suppressed. Such regulation is based on messenger RNA (mRNA)/precursormRNA splicing and degradation process. Furthermore, liquid-liquid phase separation of nuclear Y-box binding protein 1 (YBX1) enhanced by circASH2 augments TPM4 transcripts decay. Together, our data have revealed a tumor-suppressive circRNA and, more importantly, uncovered a fine regulation mechanism for HCC progression.

Role of Heterogeneous Nuclear Ribonucleoproteins in the Cancer-Immune Landscape

Cancer remains the second leading cause of death, accounting for approximately 20% of all fatalities. Evolving cancer cells and a dysregulated immune system create complex tumor environments that fuel tumor growth, metastasis, and resistance. Over the past decades, significant progress in deciphering cancer cell behavior and recognizing the immune system as a hallmark of tumorigenesis has been achieved. However, the underlying mechanisms controlling the evolving cancer-immune landscape remain mostly unexplored. Heterogeneous nuclear ribonuclear proteins (hnRNP), a highly conserved family of RNA-binding proteins, have vital roles in critical cellular processes, including transcription, post-transcriptional modifications, and translation. Dysregulation of hnRNP is a critical contributor to cancer development and resistance. HnRNP contribute to the diversity of tumor and immune-associated aberrant proteomes by controlling alternative splicing and translation. They can also promote cancer-associated gene expression by regulating transcription factors, binding to DNA directly, or promoting chromatin remodeling. HnRNP are emerging as newly recognized mRNA readers. Here, we review the roles of hnRNP as regulators of the cancer-immune landscape. Dissecting the molecular functions of hnRNP will provide a better understanding of cancer-immune biology and will impact the development of new approaches to control and treat cancer.

Enhanced Competition at the Nano-Bio Interface Enables Comprehensive Characterization of Protein Corona Dynamics and Deep Coverage of Proteomes

Introducing engineered nanoparticles (NPs) into a biofluid such as blood plasma leads to the formation of a selective and reproducible protein corona at the particle-protein interface, driven by the relationship between protein-NP affinity and protein abundance. This enables scalable systems that leverage protein-nano interactions to overcome current limitations of deep plasma proteomics in large cohorts. Here the importance of the protein to NP-surface ratio (P/NP) is demonstrated and protein corona formation dynamics are modeled, which determine the competition between proteins for binding. Tuning the P/NP ratio significantly modulates the protein corona composition, enhancing depth and precision of a fully automated NP-based deep proteomic workflow (Proteograph). By increasing the binding competition on engineered NPs, 1.2-1.7× more proteins with 1% false discovery rate are identified on the surface of each NP, and up to 3× more proteins compared to a standard plasma proteomics workflow. Moreover, the data suggest P/NP plays a significant role in determining the in vivo fate of nanomaterials in biomedical applications. Together, the study showcases the importance of P/NP as a key design element for biomaterials and nanomedicine in vivo and as a powerful tuning strategy for accurate, large-scale NP-based deep proteomic studies.

High expression of HNRNPR in ESCA combined with 18F-FDG PET/CT metabolic parameters are novel biomarkers for preoperative diagnosis of ESCA

Background

The aim of this study was to determine the expression and function of heterogeneous nuclear ribonucleoprotein R (HNRNPR) in esophageal carcinoma (ESCA), the correlation between its expression and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computerized tomography scan (PET/CT)-related parameters. We also investigated whether ¹⁸F-FDG PET/CT can be used to predict the expression of HNRNPR in ESCA.

Methods

We analyzed patients with ESCA who underwent ¹⁸F-FDG PET/CT before surgery, and their tissues were stained with HNRNPR IHC. The associated parameters were derived using the ¹⁸F-FDG PET imaging data, and the correlation with the IHC score was evaluated. The Oncomine, TCGA, and GEO datasets were used to investigate HNRNPR expression in the pan- and esophageal cancers, as well as its relationship with N6-methyladenosine (m6A) modification and glycolysis. The R software, LinkedOmics, GeneMANIA, and StringOnline tools were used to perform GO/KEGG, GGI, and PPI analyses on the HNRNPR.

Results

HNRNPR is highly expressed in the majority of pan-cancers, including ESCA, and is associated with BMI, weight, and history of reflux in patients with ESCA. HNRNPR is somewhat accurate in predicting the clinical prognosis of ESCA. HNRNPR expression was positively correlated with SUV_max, SUV_mean, and TLG in ESCA (p < 0.05). The combination of these three variables provides a strong predictive value for HNRNPR expression in ESCA. GO/KEGG analysis showed that HNRNPR played a role in the regulation of cell cycle, DNA replication, and the Fannie anemia pathway. The analysis of the TCGA and GEO data sets revealed a significant correlation between HNRNPR expression and m6A and glycolysis-related genes. GSEA analysis revealed that HNRNPR was involved in various m6A and glycolysis related-pathways.

Conclusion

HNRNPR overexpression correlates with ¹⁸F-FDG uptake in ESCA and may be involved in the regulation of the cell cycle, m6A modification, and cell glycolysis. ¹⁸F-FDG PET/CT-related parameters can predict the diagnostic accuracy of HNRNPR expression in ESCA.