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Genes Feb 2022Alternative splicing of pre-mRNA is a key mechanism for increasing the complexity of proteins in humans, causing a diversity of expression of transcriptomes and... (Review)
Review
Alternative splicing of pre-mRNA is a key mechanism for increasing the complexity of proteins in humans, causing a diversity of expression of transcriptomes and proteomes in a tissue-specific manner. Alternative splicing is regulated by a variety of splicing factors. However, the changes and errors of splicing regulation caused by splicing factors are strongly related to many diseases, something which represents one of this study's main interests. Further understanding of alternative splicing regulation mediated by cellular factors is also a prospective choice to develop specific drugs for targeting the dynamic RNA splicing process. In this review, we firstly concluded the basic principle of alternative splicing. Afterwards, we showed how splicing isoforms affect physiological activities through specific disease examples. Finally, the available treatment methods relative to adjusting splicing activities have been summarized.
Topics: Alternative Splicing; Humans; Prospective Studies; Protein Isoforms; RNA Precursors; RNA Splicing Factors
PubMed: 35327956
DOI: 10.3390/genes13030401 -
Cell Metabolism Oct 2021Nonalcoholic steatohepatitis (NASH) is an advanced stage of nonalcoholic fatty liver disease (NAFLD) with serious consequences that currently lacks approved...
Nonalcoholic steatohepatitis (NASH) is an advanced stage of nonalcoholic fatty liver disease (NAFLD) with serious consequences that currently lacks approved pharmacological therapies. Recent studies suggest the close relationship between the pathogenesis of NAFLD and the dysregulation of RNA splicing machinery. Here, we reveal death-associated protein kinase-related apoptosis-inducing kinase-2 (DRAK2) is markedly upregulated in the livers of both NAFLD/NASH patients and NAFLD/NASH diet-fed mice. Hepatic deletion of DRAK2 suppresses the progression of hepatic steatosis to NASH. Comprehensive analyses of the phosphoproteome and transcriptome indicated a crucial role of DRAK2 in RNA splicing and identified the splicing factor SRSF6 as a direct binding protein of DRAK2. Further studies demonstrated that binding to DRAK2 inhibits SRSF6 phosphorylation by the SRSF kinase SRPK1 and regulates alternative splicing of mitochondrial function-related genes. In conclusion, our findings reveal an indispensable role of DRAK2 in NAFLD/NASH and offer a potential therapeutic target for this disease.
Topics: Alternative Splicing; Animals; Apoptosis Regulatory Proteins; Disease Progression; Humans; Liver; Mice; Non-alcoholic Fatty Liver Disease; Phosphoproteins; Protein Serine-Threonine Kinases; RNA; Serine-Arginine Splicing Factors; Transcriptome
PubMed: 34614409
DOI: 10.1016/j.cmet.2021.09.008 -
Laboratory Investigation; a Journal of... Jul 2019In multiple neurodegenerative diseases, including Alzheimer's disease (AD), a prominent pathological feature is the aberrant aggregation and inclusion formation of the... (Review)
Review
In multiple neurodegenerative diseases, including Alzheimer's disease (AD), a prominent pathological feature is the aberrant aggregation and inclusion formation of the microtubule-associated protein tau. Because of the pathological association, these disorders are often referred to as tauopathies. Mutations in the MAPT gene that encodes tau can cause frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), providing the clearest evidence that tauopathy plays a causal role in neurodegeneration. However, large gaps in our knowledge remain regarding how various FTDP-17-linked tau mutations promote tau aggregation and neurodegeneration, and, more generally, how the tauopathy is linked to neurodegeneration. Herein, we review what is known about how FTDP-17-linked pathogenic MAPT mutations cause disease, with a major focus on the prion-like properties of wild-type and mutant tau proteins. The hypothesized mechanisms by which mutations in the MAPT gene promote tauopathy are quite varied and may not provide definitive insights into how tauopathy arises in the absence of mutation. Further, differences in the ability of tau and mutant tau proteins to support prion-like propagation in various model systems raise questions about the generalizability of this mechanism in various tauopathies. Notably, understanding the mechanisms of tauopathy induction and spread and tau-induced neurodegeneration has important implications for tau-targeting therapeutics.
Topics: Animals; Humans; Microtubules; Mutation; Parkinsonian Disorders; Protein Aggregation, Pathological; Protein Processing, Post-Translational; Protein Splicing; Tauopathies; tau Proteins
PubMed: 30742061
DOI: 10.1038/s41374-019-0197-x -
Theranostics 2022Splicing factors are essential for nascent pre-mRNA processing and critical in cancer progression, suggesting that proteins with splicing functions represent potential...
Splicing factors are essential for nascent pre-mRNA processing and critical in cancer progression, suggesting that proteins with splicing functions represent potential molecular targets for cancer therapy. Here, we investigate the role of splicing factors in glioblastoma multiforme (GBM) progression and the possibility of targeting them for the treatment of the disease. The TCGA and CGGA public databases were used to screen for differentially expressed mRNA splicing factors. Immunohistochemistry and qRT-PCR were used to analyze the expression of non-POU domain-containing octamer-binding protein (NONO), a Drosophila behavior human splicing (DBHS) protein. Knockdown/overexpression of NONO with siRNA and lentiviral expression constructs was used to examine cell growth, apoptosis, and invasion in GBM cells. RNA sequencing was used to identify potential downstream molecular targets of NONO. RIP-PCR and RNA pulldown were used to determine the interaction between NONO and pre-mRNA. JC-1 staining and the seahorse assay were performed to assess redox homeostasis. Expression of NONO was increased in GBM samples and associated with poor survival in patients ( = 0.04). Knockdown of NONO suppressed GBM growth, and overexpression of NONO promoted GBM tumorigenesis and . RNA sequencing-based transcriptomic profiling confirmed that knockdown of NONO in U251 and P3 cells resulted in global intron retention of pre-mRNA and led to abnormal splicing of specific pre-mRNAs for and . NONO bound to a consensus motif in the intron of pre-mRNA in association with another DBHS protein family member, PSPC1. Knockdown of NONO impaired tumor growth, invasion, and redox homeostasis through aberrant splicing of . Finally, Auranofin, a small molecule inhibitor of NONO, suppressed GBM tumor growth in an orthotopic xenograft model in mice. We demonstrated that intron retention was a critical alternative RNA splicing event to occur in GBM progression, and that NONO was a key regulator of mRNA splicing in GBM. Targeting NONO represents a novel, potential therapeutic strategy for GBM treatment.
Topics: Animals; Cell Line, Tumor; Cell Proliferation; Cysteine-Rich Protein 61; DNA-Binding Proteins; Disease Progression; Gene Expression Regulation, Neoplastic; Glioblastoma; Glutathione Peroxidase; Humans; Introns; Mice; RNA Precursors; RNA Splicing Factors; RNA, Messenger; RNA-Binding Proteins; Transcription Factors; Glutathione Peroxidase GPX1
PubMed: 35910786
DOI: 10.7150/thno.72248 -
Nature Communications Jun 2022Coordinated regulation of alternative pre-mRNA splicing is essential for germ cell development. However, the underlying molecular mechanism that controls alternative...
Coordinated regulation of alternative pre-mRNA splicing is essential for germ cell development. However, the underlying molecular mechanism that controls alternative mRNA expression during germ cell development remains elusive. Herein, we show that hnRNPH1 is highly expressed in the reproductive system and recruits the PTBP2 and SRSF3 to modulate the alternative splicing in germ cells. Conditional knockout Hnrnph1 in spermatogenic cells causes many abnormal splicing events, thus affecting the genes related to meiosis and communication between germ cells and Sertoli cells. This is characterized by asynapsis of chromosomes and impairment of germ-Sertoli communications, which ultimately leads to male sterility. Markedly, Hnrnph1 germline-specific mutant female mice are also infertile, and Hnrnph1-deficient oocytes exhibit a similar defective synapsis and cell-cell junction as seen in Hnrnph1-deficient male germ cells. Collectively, our data support a molecular model wherein hnRNPH1 governs a network of alternative splicing events in germ cells via recruitment of PTBP2 and SRSF3.
Topics: Alternative Splicing; Animals; Female; Germ Cells; Heterogeneous-Nuclear Ribonucleoproteins; Male; Mice; Nerve Tissue Proteins; Polypyrimidine Tract-Binding Protein; RNA Splicing; Serine-Arginine Splicing Factors; Sertoli Cells
PubMed: 35739118
DOI: 10.1038/s41467-022-31364-7 -
Molecular Cancer Jan 2021De novo and acquired resistance, which are mainly mediated by genetic alterations, are barriers to effective routine chemotherapy. However, the mechanisms underlying...
De novo and acquired resistance, which are mainly mediated by genetic alterations, are barriers to effective routine chemotherapy. However, the mechanisms underlying gastric cancer (GC) resistance to chemotherapy are still unclear. We showed that the long noncoding RNA CRNDE was related to the chemosensitivity of GC in clinical samples and a PDX model. CRNDE was decreased and inhibited autophagy flux in chemoresistant GC cells. CRNDE directly bound to splicing protein SRSF6 to reduce its protein stability and thus regulate alternative splicing (AS) events. We determined that SRSF6 regulated the PICALM exon 14 skip splice variant and triggered a significant S-to-L isoform switch, which contributed to the expression of the long isoform of PICALM (encoding PICALML). Collectively, our findings reveal the key role of CRNDE in autophagy regulation, highlighting the significance of CRNDE as a potential prognostic marker and therapeutic target against chemoresistance in GC.
Topics: Alternative Splicing; Autophagy; Cell Line, Tumor; Drug Resistance, Neoplasm; Fluorouracil; Humans; Monomeric Clathrin Assembly Proteins; Oxaliplatin; Phosphoproteins; Proteasome Endopeptidase Complex; Proteolysis; RNA, Long Noncoding; Serine-Arginine Splicing Factors; Stomach Neoplasms; Ubiquitination
PubMed: 33397371
DOI: 10.1186/s12943-020-01299-y -
Signal Transduction and Targeted Therapy Mar 2021Alternative splicing is a critical process to generate protein diversity. However, whether and how alternative splicing regulates autophagy remains largely elusive. Here...
Alternative splicing is a critical process to generate protein diversity. However, whether and how alternative splicing regulates autophagy remains largely elusive. Here we systematically identify the splicing factor SRSF1 as an autophagy suppressor. Specifically, SRSF1 inhibits autophagosome formation by reducing the accumulation of LC3-II and numbers of autophagosomes in different cell lines. Mechanistically, SRSF1 promotes the splicing of the long isoform of Bcl-x that interacts with Beclin1, thereby dissociating the Beclin1-PIK3C3 complex. In addition, SRSF1 also directly interacts with PIK3C3 to disrupt the interaction between Beclin1 and PIK3C3. Consequently, the decrease of SRSF1 stabilizes the Beclin1 and PIK3C3 complex and activates autophagy. Interestingly, SRSF1 can be degraded by starvation- and oxidative stresses-induced autophagy through interacting with LC3-II, whereas reduced SRSF1 further promotes autophagy. This positive feedback is critical to inhibiting Gefitinib-resistant cancer cell progression both in vitro and in vivo. Consistently, the expression level of SRSF1 is inversely correlated to LC3 level in clinical cancer samples. Our study not only provides mechanistic insights of alternative splicing in autophagy regulation but also discovers a new regulatory role of SRSF1 in tumorigenesis, thereby offering a novel avenue for potential cancer therapeutics.
Topics: A549 Cells; Alternative Splicing; Animals; Autophagosomes; Autophagy; Carcinogenesis; Class III Phosphatidylinositol 3-Kinases; Gene Expression Regulation, Neoplastic; Heterografts; Humans; Lung Neoplasms; Mice; Microtubule-Associated Proteins; Serine-Arginine Splicing Factors; bcl-X Protein
PubMed: 33664238
DOI: 10.1038/s41392-021-00495-6 -
Nature Communications Oct 2019Selectable markers are widely used in transgenesis and genome editing for selecting engineered cells with a desired genotype but the variety of markers is limited. Here...
Selectable markers are widely used in transgenesis and genome editing for selecting engineered cells with a desired genotype but the variety of markers is limited. Here we present split selectable markers that each allow for selection of multiple "unlinked" transgenes in the context of lentivirus-mediated transgenesis as well as CRISPR-Cas-mediated knock-ins. Split marker gene segments fused to protein splicing elements called "inteins" can be separately co-segregated with different transgenic vectors, and rejoin via protein trans-splicing to reconstitute a full-length marker protein in host cells receiving all intended vectors. Using a lentiviral system, we create and validate 2-split Hygromycin, Puromycin, Neomycin and Blasticidin resistance genes as well as mScarlet fluorescent proteins. By combining split points, we create 3- and 6-split Hygromycin resistance genes, demonstrating that higher-degree split markers can be generated by a "chaining" design. We adapt the split marker system for selecting biallelically engineered cells after CRISPR gene editing. Future engineering of split markers may allow selection of a higher number of genetic modifications in target cells.
Topics: CRISPR-Cas Systems; Cell Line, Tumor; Cinnamates; Drug Resistance, Bacterial; Gene Editing; Gene Transfer Techniques; Genetic Engineering; Genetic Vectors; HEK293 Cells; HeLa Cells; Humans; Hygromycin B; Induced Pluripotent Stem Cells; Inteins; Lentivirus; Luminescent Proteins; Neomycin; Nucleosides; Protein Splicing; Puromycin; Trans-Splicing; Transgenes
PubMed: 31672965
DOI: 10.1038/s41467-019-12891-2 -
RNA Biology 2018Spliceosomal proteins have been revealed as SUMO conjugation targets. Moreover, we have reported that many of these are in a SUMO-conjugated form when bound to a... (Review)
Review
Spliceosomal proteins have been revealed as SUMO conjugation targets. Moreover, we have reported that many of these are in a SUMO-conjugated form when bound to a pre-mRNA substrate during a splicing reaction. We demonstrated that SUMOylation of Prp3 (PRPF3), a component of the U4/U6 di-snRNP, is required for U4/U6•U5 tri-snRNP formation and/or recruitment to active spliceosomes. Expanding upon our previous results, we have shown that the splicing factor SRSF1 stimulates SUMO conjugation to several spliceosomal proteins. Given the relevance of the splicing process, as well as the complex and dynamic nature of its governing machinery, the spliceosome, the molecular mechanisms that modulate its function represent an attractive topic of research. We posit that SUMO conjugation could represent a way of modulating spliceosome assembly and thus, splicing efficiency. How cycles of SUMOylation/de-SUMOylation of spliceosomal proteins become integrated throughout the highly choreographed spliceosomal cycle awaits further investigation.
Topics: Animals; Humans; Nuclear Proteins; RNA Splicing; RNA Splicing Factors; Ribonucleoprotein, U4-U6 Small Nuclear; SUMO-1 Protein; Sumoylation
PubMed: 29741121
DOI: 10.1080/15476286.2018.1457936 -
Trends in Biochemical Sciences Apr 2020The collection of chemically different protein variants, or proteoforms, by far exceeds the number of protein-coding genes in the human genome. Major contributors are... (Review)
Review
The collection of chemically different protein variants, or proteoforms, by far exceeds the number of protein-coding genes in the human genome. Major contributors are alternative splicing and protein modifications. In this review, we focus on those proteoforms that differ at their N termini with a molecular link to disease. We describe the main underlying mechanisms that give rise to such N-terminal proteoforms, these being splicing, initiation of protein translation, and protein modifications. Given their role in several human diseases, it is becoming increasingly clear that several of these N-terminal proteoforms may have potential as therapeutic interventions and/or for diagnosing and prognosing their associated disease.
Topics: Alternative Splicing; Humans; Protein Biosynthesis; Protein Processing, Post-Translational
PubMed: 32001092
DOI: 10.1016/j.tibs.2019.12.009