The nucleolus acts as a key stress sensor and responds to changes in cellular growth rate and metabolic activity. In addition to its major role as the site of ribosome biogenesis, high-throughput proteomic analyses of purified nucleoli have highlighted the multi-functional nature of these organelles, and several SR family splicing factors, including SRSF1 and SRSF2, have been detected in human nucleolar proteome analysis. Here we provide evidence that pNO40, a 60s ribosomal protein associated with nucleoli, acts as a mediator for recruitment of SR family splicing factors into nucleoli. As a nucleolar protein, pNO40 was originally identified by yeast two-hybrid analysis as interacting with pnn, an SR-like protein involved in pre-mRNA splicing. To explore its functional interaction with pnn, we characterized the interplay between pNO40 and SR family proteins and demonstrated that pNO40 plays a role in recruiting SR splicing factors into the nucleoli. The targeting of pNO40 to the nucleoli is dependent on its extreme-carboxyl-terminus nuclear localization signals while the sequence at the amino-terminus of pNO40 enables its interaction with pnn. Nucleolar association of SR proteins results in defects in mRNA metabolism leading to global nuclear accumulation of poly(A) RNA and splicing defects. Animal studies confirmed aberrant mRNA splicing in transgenic muscles overexpressing pNO40 which displayed histological features of muscular dystrophy. Thus it appears that by pNO40 overexpression, we created mimics of nucleolar association of SR proteins occurring in the presence of transcription inhibitors which induce nucleolar segregation and redistribute SR proteins to the periphery of the nucleolar region. We therefore provide an extra-ribosomal function for pNO40 and, based on our data, it is conceivable that pNO40 may function as a general recruiter for nucleolar association of SR proteins and regulation of its expression may be crucial in cellular homeostasis.
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http://dx.doi.org/10.1016/j.cellsig.2017.01.010 | DOI Listing |
Zhong Nan Da Xue Xue Bao Yi Xue Ban
July 2024
Southern Hospital affiliated with Shenzhen University, Shenzhen Guangdong 518001, China.
Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype with poor prognosis. RNA alternative splicing dysregulation plays a critical role in the initiation and progression of TNBC. This article systematically introduces the basic process of RNA splicing and then focuses on reviewing the aberrant alternative splicing events and their biological effects in TNBC: 1) Multiple splicing-related factors promote tumor cell proliferation and mediate chemotherapy resistance by regulating the alternative splicing of genes involved in cell survival and drug response; 2) dysregulation of splicing regulatory networks leads to altered splicing of multiple metastasis-related genes, promoting tumor invasion and metastasis; 3) aberrant alternative splicing events participate in tumor progression by affecting the expression of DNA damage repair genes; 4) dysregulation of alternative splicing is also involved in the regulation of tumor immune evasion and stem cell properties.
View Article and Find Full Text PDFInt J Med Sci
January 2025
Department of Gastrointestinal Surgery, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
Chemotherapy resistance is a great challenge in the treatment of gastric cancer (GC), so it is urgent to explore the prognostic markers of chemoresistance. PUF60 (Poly (U)-binding splicing factor 60) is a nucleic acid-binding protein that has been shown to regulate transcription and link to tumorigenesis in various cancers. However, its biological role and function in chemotherapy resistance of GC is unclear.
View Article and Find Full Text PDFReprod Biol Endocrinol
January 2025
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Background: Heterogeneous nuclear ribonucleoprotein M (HnRNPM) is a key splicing factor involved in various biological processes, including the epithelial‒mesenchymal transition and cancer development. Alternative splicing is widely involved in the process of spermatogenesis. However, the function of hnRNPM as a splicing factor during spermatogenesis remains unknown.
View Article and Find Full Text PDFGenes Genomics
January 2025
Medical Genetic Diagnosis and Therapy Center of Fujian Maternity and Child Health Hospital College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Medical University, Fujian Provincial Key Laboratory of Prenatal Diagnosis and Birth Defect, Fuzhou, Fujian, China.
Background: Hearing loss adversely impacts language development, acquisition, and the social and cognitive maturation of affected children. The hearing loss etiology mainly includes genetic factors and environmental factors, of which the former account for about 50-60%.
Objective: This study aimed to investigate the genetic basis of autosomal recessive non-syndromic hearing loss (NSHL) by identifying and characterizing novel variants in the CDH23 gene.
Nucleic Acids Res
January 2025
Department of Orthopaedics and Traumatology, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong SAR, China.
Mammalian genome is hierarchically organized by CTCF and cohesin through loop extrusion mechanism to facilitate the organization of topologically associating domains (TADs). Mounting evidence suggests additional factors/mechanisms exist to orchestrate TAD formation and maintenance. In this study, we investigate the potential role of RNA-binding proteins (RBPs) in TAD organization.
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