Loss of protein homeostasis is a hallmark of cellular senescence, and ribosome pausing plays a crucial role in the collapse of proteostasis. However, our understanding of ribosome pausing in senescent cells remains limited. In this study, we utilized ribosome profiling and G-quadruplex RNA immunoprecipitation sequencing techniques to explore the impact of RNA G-quadruplex (rG4) on the translation efficiency in senescent cells. Our results revealed a reduction in the translation efficiency of rG4-rich genes in senescent cells and demonstrated that rG4 structures within coding sequence can impede translation both in vivo and in vitro. Moreover, we observed a significant increase in the abundance of rG4 structures in senescent cells, and the stabilization of the rG4 structures further exacerbated cellular senescence. Mechanistically, the RNA helicase DHX9 functions as a key regulator of rG4 abundance, and its reduced expression in senescent cells contributing to increased ribosome pausing. Additionally, we also observed an increased abundance of rG4, an imbalance in protein homeostasis, and reduced DHX9 expression in aged mice. In summary, our findings reveal a novel biological role for rG4 and DHX9 in the regulation of translation and proteostasis, which may have implications for delaying cellular senescence and the aging process.
G-Quadruplexes ; Cellular Senescence ; Ribosomes/genetics* ; Humans ; Animals ; Mice ; DEAD-box RNA Helicases/genetics* ; Protein Biosynthesis ; RNA/chemistry* ; Neoplasm Proteins

Geminiviruses cause substantial crop yield losses worldwide. The replication initiator protein (Rep) encoded by geminiviruses is indispensable for geminiviral replication. The Rep protein encoded by beet severe curly top virus (BSCTV, genus Curtovirus, family Geminiviridae) induces VARIANT IN METHYLATION 5 (VIM5) expression in Arabidopsis leaves upon BSCTV infection. VIM5 functions as a ubiquitination-related E3 ligase to promote the proteasomal degradation of methyltransferases, resulting in reduction of methylation levels in the BSCTV C2-3 promoter. However, the specific domains of Rep responsible for VIM5 induction remain poorly characterized. Although Rep proteins from several geminiviruses act as viral suppressors of RNA silencing (VSRs), whether BSCTV Rep also possesses VSR activity remains to be illustrated. In this study, we employed a transient expression system in the 16c-GFP transgenic and the wild-type Nicotiana benthamiana plants to analyze the VSR and the VIM5-inducing activities of different truncated Rep proteins haboring distinct domains. We found that the N-terminal domain (amino acids 1-180) of Rep suppressed GFP silencing in 16c-GFP transgenic N. benthamiana leaves. The minimal N-terminal fragment (amino acids 1-104) induced VIM5 expression upon co-infiltration, while C-terminal truncations lacked VIM5-inducing activity. Our results indicate that the N-terminal domain of Rep encoded by BSCTV mediates the suppression of RNA silencing and induces VIM5 expression. Thus, our findings contribute to a better understanding of interactions between geminiviral Rep and plant hosts.
Geminiviridae/genetics* ; Nicotiana/metabolism* ; Arabidopsis/metabolism* ; RNA Interference ; Viral Proteins/metabolism* ; Arabidopsis Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Protein Domains ; Plant Diseases/virology* ; Methyltransferases/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; DNA Helicases/genetics*

OBJECTIVES: To investigate the regulatory mechanism of aurora kinase B (AURKB) for promoting malignant phenotype of osteosarcoma cells. METHODS: HA-Vector or HA-AURKB was transfected in 293T cells to identify the molecules interacting with AURKB using immunoprecipitation combined with liquid chromatography-tandem mass spectrometry followed by verification with co-immunoprecipitation and Western blotting. In cultured osteosarcoma cells with lentivirus-mediated RNA interference of AURKB or DHX9 or their overexpression, the changes in cell proliferation, migration, and invasion activities were observed with EDU and Transwell assays. Mechanistic analysis was performed using Co-IP and in vivo ubiquitination experiments to detect the interaction between AURKB and DHX9 and the phosphorylation and ubiquitination levels of DHX9. Western blotting was used to detect the effect of AURKB and DHX9 on activation of nuclear factor-κB (NF-κB) signaling. RESULTS: AURKB was highly expressed in osteosarcoma cell lines, and in osteosarcoma 143B cells, AURKB silencing significantly reduced cell proliferation, migration and invasion abilities. Interactions between AURKB and DHX9 were detected, and they were both highly expressed in osteosarcoma tissues; silencing AURKB reduced the protein expression of DHX9, and AURKB overexpression increased DHX9 phosphorylation. Silencing AURKB did not significantly affect the transcription and translation of DHX9 but accelerated its degradation and ubiquitination. Overexpression of DHX9 effectively reversed the effects of AURKB silencing on IKBα protein and phosphorylated p65, promoted nuclear translocation of p65 to activate the NF-κB signaling pathway, and enhanced the proliferation, migration, and invasion abilities of cultured osteosarcoma cells. CONCLUSIONS AURKB overexpression promotes the malignant phenotype of osteosarcoma cells by activating the NF-κB signaling pathway via regulating DHX9.
Humans ; Osteosarcoma/genetics* ; Cell Proliferation ; NF-kappa B/metabolism* ; Signal Transduction ; Cell Line, Tumor ; Cell Movement ; DEAD-box RNA Helicases/genetics* ; Aurora Kinase B/genetics* ; Phenotype ; Bone Neoplasms/genetics* ; Neoplasm Invasiveness ; Phosphorylation ; Neoplasm Proteins

We knocked out the retinoic acid-inducible gene I (RIG-I) in HEK293 cells via CRISPR/Cas9 to reveal the effects of RIG-I knockout on the key factors in the type I interferon signaling pathway. Three single guide RNAs (sgRNAs) targeting RIG-I were designed, and the recombination vectors were constructed on the basis of the pX459 vector and used to transfect HEK293 cells, which were screened by puromycin subsequently. Furthermore, a mimic of virus, poly I: C, was used to transfect the cells screened out. RIG-I knockout was checked by sequencing, real-time quantitative PCR, Western blotting, and immunofluorescence assay. Meanwhile, the expression levels of key factors of type I interferon signaling pathway such as melanoma differentiation-associated gene 5 (MDA5), interferonβ1 (IFNβ1), and nuclear factor-kappa B p65 [NF-κB(p65)], as well as cell viability, were determined. The results showed that two HEK293 cell lines (S1 and S3) with RIG-I knockout were obtained, which exhibited lower mRNA and protein levels of RIG-I than the wild type HEK293 cells (P < 0.05). The mRNA levels of MDA5 and IFNβ1 in S1 and S3 cells and the protein level of NF-κB(p65) in S3 cells were lower than those in the wild type (P < 0.05). More extranuclear NF-κB(p65) protein was detected in S1 cells than in the wild type after transfection with poly I: C. Plus, the wild-type and S1 cells transfected with poly I: C for 48 h showcased reduced viability (P < 0.05), while S3 cells did not display the reduction in cell viability. In summary, the present study obtained two HEK293 cell lines with RIG-I knockout via CRISPR/Cas9, which provided a stable cell model for exploring the mechanism of type I interferon signaling pathway.
Humans ; HEK293 Cells ; CRISPR-Cas Systems ; DEAD Box Protein 58/metabolism* ; Signal Transduction ; Receptors, Immunologic/metabolism* ; Gene Knockout Techniques ; Transfection ; DEAD-box RNA Helicases/metabolism* ; RNA, Guide, CRISPR-Cas Systems/genetics* ; Interferon-Induced Helicase, IFIH1/metabolism* ; Transcription Factor RelA/metabolism* ; Interferon-beta/metabolism*

Humans ; Carcinogenesis/genetics* ; Gene Expression Regulation, Neoplastic ; Genes, cdc ; Nasopharyngeal Carcinoma/genetics* ; Nasopharyngeal Neoplasms/genetics* ; RNA Helicases/metabolism*

BACKGROUND: Juvenile amyotrophic lateral sclerosis (JALS) is an uncommon form of amyotrophic lateral sclerosis whose age at onset (AAO) is defined as prior to 25 years. FUS mutations are the most common cause of JALS. SPTLC1 was recently identified as a disease-causative gene for JALS, which has rarely been reported in Asian populations. Little is known regarding the difference in clinical features between JALS patients carrying FUS and SPTLC1 mutations. This study aimed to screen mutations in JALS patients and to compare the clinical features between JALS patients with FUS and SPTLC1 mutations. METHODS: Sixteen JALS patients were enrolled, including three newly recruited patients between July 2015 and August 2018 from the Second Affiliated Hospital, Zhejiang University School of Medicine. Mutations were screened by whole-exome sequencing. In addition, clinical features such as AAO, onset site and disease duration were extracted and compared between JALS patients carrying FUS and SPTLC1 mutations through a literature review. RESULTS: A novel and de novo SPTLC1 mutation (c.58G>A, p.A20T) was identified in a sporadic patient. Among 16 JALS patients, 7/16 carried FUS mutations and 5/16 carried respective SPTLC1 , SETX , NEFH , DCTN1 , and TARDBP mutations. Compared with FUS mutation patients, those with SPTLC1 mutations had an earlier AAO (7.9 ± 4.6 years vs. 18.1 ± 3.9 years, P  < 0.01), much longer disease duration (512.0 [416.7-607.3] months vs. 33.4 [21.6-45.1] months, P  < 0.01), and no onset of bulbar. CONCLUSION Our findings expand the genetic and phenotypic spectrum of JALS and help to better understand the genotype-phenotype correlation of JALS.
Humans ; Amyotrophic Lateral Sclerosis/genetics* ; DNA Helicases/genetics* ; Genetic Association Studies ; Multifunctional Enzymes/genetics* ; Mutation/genetics* ; RNA Helicases/genetics* ; RNA-Binding Protein FUS/genetics* ; Serine C-Palmitoyltransferase/genetics* ; Child, Preschool ; Child ; Adolescent ; Young Adult

Humans ; Mutation ; Sarcoma/genetics* ; Ribonuclease III/genetics* ; DEAD-box RNA Helicases/genetics*

OBJECTIVES: This work aimed to construct N6-methyladenosine (m⁶A) regulator-based prognostic signature and evaluate the prognostic value and the intervention on tumor immune microenvironment of this m⁶A risk signature. METHODS: Using transcriptome and clinical data of head and neck squamous cell carcinoma (HNSCC) from The Cancer Genome Atlas (TCGA), we profiled m⁶A regulators and constructed an m⁶A risk signature. The relationship between m⁶A modulation and immune function was studied by differential gene expression, cell type enrichment, and correlation analyses. RESULTS: Fifteen m⁶A regulators had aberrant expression in HNSCC. A three-gene m⁶A prognostic signature (i.e., YTHDC2, IGF2BP2, and HNRNPC) was constructed and identified as an independent prognostic indicator for HNSCC. The m⁶A regulator signature-based high-risk group revealed pro-tumoral immune microenvironment due to the dysregulation of immune-related gene expression, abnormal enrichment of multiple immunocytes, and production of immunoregulatory factors. CONCLUSIONS This comprehensive analysis of m⁶A regulators and tumor immune landscape in HNSCC revealed that the m⁶A signature of YTHDC2, IGF2BP2, and HNRNPC could serve as a promising biomarker for monitoring HNSCC development and may be a potential target for tumor therapy in the future.
Humans ; Squamous Cell Carcinoma of Head and Neck/genetics* ; Gene Expression Regulation, Neoplastic ; Prognosis ; Head and Neck Neoplasms/genetics* ; Tumor Microenvironment/genetics* ; RNA-Binding Proteins/genetics* ; Heterogeneous-Nuclear Ribonucleoprotein Group C/genetics* ; RNA Helicases

OBJECTIVE: To analyze the clinical characteristics and genetic variant of a child featuring X-linked mental retardation. METHODS: Whole exome sequencing and Sanger sequencing were used for the detection of variant and pedigree validation, respectively. Clinical manifestation of patients with DDX3X gene variants were also reviewed. RESULTS: The child was found to harbor a heterozygous NM_001193416.3: c.1332_1333delCT (p.Leu445Serfs*19) variant of the DDX3X gene. The same variant was not found in either of her parents. CONCLUSION The child was diagnosed with X-linked mental retardation due to variant of the DDX3X gene. Above finding has enriched the spectrum of DDX3X gene variants and provided a basis for clinical diagnosis and prenatal diagnosis for this pedigrees.
Child ; DEAD-box RNA Helicases/genetics* ; Female ; Heterozygote ; Humans ; Intellectual Disability/genetics* ; Mental Retardation, X-Linked/genetics* ; Mutation ; Pedigree ; Pregnancy ; Exome Sequencing

OBJECTIVE: To develop a multiplex PCR method for a rapid detection of Y chromosome-specific sequences in patients with Turner syndrome. METHODS: Nine genes were selected from various regions of the Y chromosome for designing the primers, which included SRY, TBL1Y, TSPY on the short arm of the Y chromosome, DDX3Y, HSFY1, RPS4Y2 and CDY1 on the long arm of Y chromosome and SHOX in the short arm and SPRY3 in the long arm of the pseudoautosomal region (PAR) of X and Y chromosomes. A multiplex PCR method for the nine genes in Y chromosome was established and optimized. The sensitivity was tested by using different amounts of genomic DNA. A total of 36 patients with Turner syndrome and a patient with male dwarfism with karyotype of 46, X, +mar were examined by the multiplex PCR method for the existence of materials from the Y chromosome. RESULTS: The optimization results of the multiplex PCR reaction system (50 μL) showed that when the final concentration of upstream and downstream of each pair of primers was 0.1 μM, the multiplex PCR reaction of the 9 pairs of primers clearly amplified the target with the expected band size, and there was no non-specific amplification. The bands were clearly visible when the amount of genomic DNA in the multiple PCR reaction system was as low as 1 ng. By using the method, we have examined the 36 patients with Turner syndrome. One patient with Turner syndrome with karyotype of 45,X[40]/47XYY[21] amplified specific seven genes on Y chromosome, 35 patients with Turner syndrome amplified only two target genes SHOX and SPRY3, but not the other seven specific genes on the Y chromosome, which was in keeping with the clinical manifestations of such patients. CONCLUSION This study established a multiplex PCR reaction system with nine genes, which can quickly and accurately screen Y chromosome materials in patients with Turner syndrome. It has the advantages of low cost, simple operation, high specificity and rapid turn-around time, and can be used to detect Turner syndrome patients with Y chromosome material in time. The method has provided a diagnostic basis for preventive gonad resection to prevent malignant gonadal tumors.
Humans ; Male ; Turner Syndrome/genetics* ; Multiplex Polymerase Chain Reaction ; Y Chromosome ; Karyotyping ; DNA Primers ; DNA ; Chromosomes, Human, Y/genetics* ; Transducin/genetics* ; Minor Histocompatibility Antigens ; DEAD-box RNA Helicases/genetics*