scholarly journals Nuclear speckle specific hnRNP D-like prevents age- and AD-related cognitive decline by modulating RNA splicing

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Qingyang Zhang ◽  
Juan Zhang ◽  
Jin Ye ◽  
Xiaohui Li ◽  
Hongda Liu ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Rna Splicing ◽  
Expression Patterns ◽  
Critical Role ◽  
Aged Mouse ◽  
Nuclear Speckles ◽  
Direct Role ◽  
Age Related ◽  
Hnrnp D ◽  
Behavioural Tests

Abstract Background Aberrant alternative splicing plays critical role in aging and age-related diseases. Heterogeneous nuclear ribonucleoproteins (hnRNPs) reportedly regulate RNA splicing process. Whether and how hnRNPs contribute to age-related neurodegenerative diseases, especially Alzheimer’s disease (AD), remain elusive. Methods Immunoblotting and immunostaining were performed to determine expression patterns and cellular/subcellular localization of the long isoform of hnRNP D-like (L-DL), which is a hnRNP family member, in mouse hippocampus. Downregulation of L-DL in WT mice was achieved by AAV-mediated shRNA delivery, followed by memory-related behavioural tests. L-DL interactome was analysed by affinity-precipitation and mass spectrometry. Alternative RNA splicing was measured by RNA-seq and analyzed by bioinformatics-based approaches. Downregulation and upregulation of L-DL in APP/PS1 mice were performed using AAV-mediated transduction. Results We show that L-DL is specifically localized to nuclear speckles. L-DL levels are decreased in the hippocampus of aged mouse brains and downregulation of L-DL impairs cognition in mice. L-DL serves as a structural component to recruit other speckle proteins, and regulates cytoskeleton- and synapse-related gene expression by altering RNA splicing. Mechanistically, these splicing changes are modulated via L-DL-mediated interaction of SF3B3, a core component of U2 snRNP, and U2AF65, a U2 spliceosome protein that guides U2 snRNP’s binding to RNA. In addition, L-DL levels are decreased in APP/PS1 mouse brains. While downregulation of L-DL deteriorates memory deficits and overexpression of L-DL improves cognitive function in AD mice, by regulating the alternative splicing and expression of synaptic gene CAMKV. Conclusions Our findings define a molecular mechanism by which hnRNP L-DL regulates alternative RNA splicing, and establish a direct role for L-DL in AD-related synaptic dysfunction and memory decline.

scholarly journals SOX2 Plays a Critical Role in the Pituitary, Forebrain, and Eye during Human Embryonic Development

2008 ◽  
Vol 93 (5) ◽  
pp. 1865-1873 ◽  
Author(s):  
Daniel Kelberman ◽  
Sandra C. P. de Castro ◽  
Shuwen Huang ◽  
John A. Crolla ◽  
Rodger Palmer ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Anterior Pituitary ◽  
De Novo ◽  
Hypogonadotropic Hypogonadism ◽  
Expression Patterns ◽  
Critical Role ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Direct Role

Abstract Context: Heterozygous, de novo mutations in the transcription factor SOX2 are associated with bilateral anophthalmia or severe microphthalmia and hypopituitarism. Variable additional abnormalities include defects of the corpus callosum and hippocampus. Objective: We have ascertained a further three patients with severe eye defects and pituitary abnormalities who were screened for mutations in SOX2. To provide further evidence of a direct role for SOX2 in hypothalamo-pituitary development, we have studied the expression of the gene in human embryonic tissues. Results: All three patients harbored heterozygous SOX2 mutations: a deletion encompassing the entire gene, an intragenic deletion (c.70_89del), and a novel nonsense mutation (p.Q61X) within the DNA binding domain that results in impaired transactivation. We also show that human SOX2 can inhibit β-catenin-driven reporter gene expression in vitro, whereas mutant SOX2 proteins are unable to repress efficiently this activity. Furthermore, we show that SOX2 is expressed throughout the human brain, including the developing hypothalamus, as well as Rathke’s pouch, the developing anterior pituitary, and the eye. Conclusions: Patients with SOX2 mutations often manifest the unusual phenotype of hypogonadotropic hypogonadism, with sparing of other pituitary hormones despite anterior pituitary hypoplasia. SOX2 expression patterns in human embryonic development support a direct involvement of the protein during development of tissues affected in these individuals. Given the critical role of Wnt-signaling in the development of most of these tissues, our data suggest that a failure to repress the Wnt-β-catenin pathway could be one of the underlying pathogenic mechanisms associated with loss-of-function mutations in SOX2.

scholarly journals Comprehensive Identification and Alternative Splicing of Microexons in Drosophila

2021 ◽  
Vol 12 ◽  
Author(s):  
Ting-Lin Pang ◽  
Zhan Ding ◽  
Shao-Bo Liang ◽  
Liang Li ◽  
Bei Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alternative Splicing ◽  
Sex Determination ◽  
Rna Splicing ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Pathway Gene ◽  
Mrna Transcripts ◽  
Bioinformatic Tool ◽  
Alternatively Spliced

Interrupted exons in the pre-mRNA transcripts are ligated together through RNA splicing, which plays a critical role in the regulation of gene expression. Exons with a length ≤ 30 nt are defined as microexons that are unique in identification. However, microexons, especially those shorter than 8 nt, have not been well studied in many organisms due to difficulties in mapping short segments from sequencing reads. Here, we analyzed mRNA-seq data from a variety of Drosophila samples with a newly developed bioinformatic tool, ce-TopHat. In addition to the Flybase annotated, 465 new microexons were identified. Differentially alternatively spliced (AS) microexons were investigated between the Drosophila tissues (head, body, and gonad) and genders. Most of the AS microexons were found in the head and two AS microexons were identified in the sex-determination pathway gene fruitless.

Abstract 12826: Age-related Sestrin2 Maintains OXPHOS Integrity to Modulate Cardiac Substrate Metabolism During Ischemia and Reperfusion

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Di Ren ◽  
Julia Fedorova ◽  
Jingwen Zhang ◽  
Zhibin He ◽  
Ji Li
Keyword(s):  
Critical Role ◽  
Scaffold Protein ◽  
Aged Mouse ◽  
Ischemia And Reperfusion ◽  
Sequencing Analysis ◽  
Metabolomics Data ◽  
Citrate Cycle ◽  
Functional Integrity ◽  
Mitochondrial Integrity ◽  
Age Related

Introduction: Sestrin2 (Sesn2) is a stress-inducible protein that declines with aging in the heart. We have reported that rescue Sesn2 levels of aged mouse hearts through gene therapy improves the resistance of aged hearts to ischemic insult caused by ischemia and reperfusion (I/R). Hypothesis: Sestrin2 as a scaffold protein maintains mitochondrial integrity to protect heart from ischemic injury during I/R. Methods: Young C57BL/6J (3-6 months), aged C57BL/6J (24-26 months), and young Sesn2-KO (3-6 months, C57BL/6J background) mice were subjected to 45 min of regional ischemia and 24 hours of reperfusion. The left ventricle of hearts were collected for transcriptomics, proteomics and metabolomics analysis. Results: The protein level of Sesn2 was declined in aged versus young heart. Seahorse measurements demonstrated that Sesn2 deficiency in aged versus young hearts lead to an impaired mitochondrial respiration rate with defects in Complex I and Complex II activity. The Sesn2 targeted proteomics revealed that Sesn2 plays a critical role in maintaining mitochondrial functional integrity through modulating mitochondrial biosynthesis and maintaining oxidative phosphorylation (OXPHOS) complexes. RNA-Sequencing analysis demonstrated that significant alterations in expression of mitochondrial compositional genes and metabolic regulation related genes occurred in both Sesn2 KO and aged hearts versus young hearts. Metabolomics data showed that Sesn2 deficiency in Sesn2 KO and aged versus young hearts augmented glycolysis but compromised citrate cycle process during I/R. The immunoprecipitation data showed that Sesn2 is translocated into mitochondria and directly interacts with OXPHOS components to maintain mitochondrial integrity in response to I/R stress. Furthermore, biochemical analysis revealed that Sesn2 is associated with citrate cycle components to modulate pyruvate dehydrogenase and isocitrate dehydrogenase activities in the mitochondria during I/R stress. Conclusions: Sesn2 serves as a scaffold protein to stabilize mitochondrial OXPHOS in the hearts under I/R stress conditions. Age-related downregulation of cardiac Sesn2 degraded mitochondrial functional integrity in response to ischemic stress in the elderly.

Chromosomal and cytoplasmic context determines predisposition to maternal age-related aneuploidy: brief overview and update on MCAK in mammalian oocytes

2010 ◽  
Vol 38 (6) ◽  
pp. 1681-1686 ◽  
Author(s):  
Ursula Eichenlaub-Ritter ◽  
Nora Staubach ◽  
Tom Trapphoff
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Maternal Age ◽  
Fluorescent Protein ◽  
Expression Patterns ◽  
Model Organisms ◽  
Aged Mouse ◽  
Protein Fusion ◽  
Mouse Oocytes ◽  
Age Related

It has been known for more than half a century that the risk of conceiving a child with trisomy increases with advanced maternal age. However, the origin of the high susceptibility to nondisjunction of whole chromosomes and precocious separation of sister chromatids, leading to aneuploidy in aged oocytes and embryos derived from them, cannot be traced back to a single disturbance and mechanism. Instead, analysis of recombination patterns of meiotic chromosomes of spread oocytes from embryonal ovary, and of origins and exchange patterns of extra chromosomes in trisomies, as well as morphological and molecular studies of oocytes and somatic cells from young and aged females, show chromosome-specific risk patterns and cellular aberrations related to the chronological age of the female. In addition, analysis of the function of meiotic- and cell-cycle-regulating genes in oogenesis, and the study of the spindle and chromosomal status of maturing oocytes, suggest that several events contribute synergistically to errors in chromosome segregation in aged oocytes in a chromosome-specific fashion. For instance, loss of cohesion may differentially predispose chromosomes with distal or pericentromeric chiasmata to nondisjunction. Studies on expression in young and aged oocytes from human or model organisms, like the mouse, indicate that the presence and functionality/activity of gene products involved in cell-cycle regulation, spindle formation and organelle integrity may be altered in aged oocytes, thus contributing to a high risk of error in chromosome segregation in meiosis I and II. Genes that are often altered in aged mouse oocytes include MCAK (mitotic-centromere-associated protein), a microtubule depolymerase, and AURKB (Aurora kinase B), a protein of the chromosomal passenger complex that has many targets and can also phosphorylate and regulate MCAK localization and activity. Therefore we explored the role of MCAK in maturing mouse oocytes by immunofluorescence, overexpression of a MCAK–EGFP (enhanced green fluorescent protein) fusion protein, knockdown of MCAK by RNAi (RNA interference) and inhibition of AURKB. The observations suggest that MCAK is involved in spindle regulation, chromosome congression and cell-cycle control, and that reductions in mRNA and protein in a context of permissive SAC (spindle assembly checkpoint) predispose to aneuploidy. Failure to recruit MCAK to centromeres and low expression patterns, as well as disturbances in regulation of enzyme localization and activity, e.g. due to alterations in activity of AURKB, may therefore contribute to maternal age-related rises in aneuploidy in mammalian oocytes.

scholarly journals Oncogenic fusion protein EWS-FLI1 is a network hub that regulates alternative splicing

2015 ◽  
Vol 112 (11) ◽  
pp. E1307-E1316 ◽  
Author(s):  
Saravana P. Selvanathan ◽  
Garrett T. Graham ◽  
Hayriye V. Erkizan ◽  
Uta Dirksen ◽  
Thanemozhi G. Natarajan ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Protein Interactions ◽  
Rna Splicing ◽  
Rna Binding ◽  
Expression Patterns ◽  
Human Mesenchymal Stem Cells ◽  
Exon Array ◽  
Telomerase Activity ◽  
Specific Protein ◽  
Alternatively Spliced

The synthesis and processing of mRNA, from transcription to translation initiation, often requires splicing of intragenic material. The final mRNA composition varies based on proteins that modulate splice site selection. EWS-FLI1 is an Ewing sarcoma (ES) oncoprotein with an interactome that we demonstrate to have multiple partners in spliceosomal complexes. We evaluate the effect of EWS-FLI1 on posttranscriptional gene regulation using both exon array and RNA-seq. Genes that potentially regulate oncogenesis, including CLK1, CASP3, PPFIBP1, and TERT, validate as alternatively spliced by EWS-FLI1. In a CLIP-seq experiment, we find that EWS-FLI1 RNA-binding motifs most frequently occur adjacent to intron–exon boundaries. EWS-FLI1 also alters splicing by directly binding to known splicing factors including DDX5, hnRNP K, and PRPF6. Reduction of EWS-FLI1 produces an isoform of γ-TERT that has increased telomerase activity compared with wild-type (WT) TERT. The small molecule YK-4–279 is an inhibitor of EWS-FLI1 oncogenic function that disrupts specific protein interactions, including helicases DDX5 and RNA helicase A (RHA) that alters RNA-splicing ratios. As such, YK-4–279 validates the splicing mechanism of EWS-FLI1, showing alternatively spliced gene patterns that significantly overlap with EWS-FLI1 reduction and WT human mesenchymal stem cells (hMSC). Exon array analysis of 75 ES patient samples shows similar isoform expression patterns to cell line models expressing EWS-FLI1, supporting the clinical relevance of our findings. These experiments establish systemic alternative splicing as an oncogenic process modulated by EWS-FLI1. EWS-FLI1 modulation of mRNA splicing may provide insight into the contribution of splicing toward oncogenesis, and, reciprocally, EWS-FLI1 interactions with splicing proteins may inform the splicing code.

PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9) Triggers Vascular Smooth Muscle Cell Senescence and Apoptosis: Implication of Its Direct Role in Degenerative Vascular Disease

2021 ◽  
Author(s):  
Yanan Guo ◽  
Zhihan Tang ◽  
Binjie Yan ◽  
Hao Yin ◽  
Shi Tai ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Vascular Disease ◽  
Cholesterol Metabolism ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Proprotein Convertase ◽  
Synthesis Inhibitor ◽  
Direct Role ◽  
Age Related

Objective: PCSK9 (proprotein convertase subtilisin/kexin type 9) plays a critical role in cholesterol metabolism via the PCSK9–LDLR (low-density lipoprotein receptor) axis in the liver; however, evidence indicates that PCSK9 directly contributes to the pathogenesis of various diseases through mechanisms independent of its LDL-cholesterol regulation. The objective of this was to determine how PCSK9 directly acts on vascular smooth muscle cells (SMCs), contributing to degenerative vascular disease. Approach and Results: We first examined the effects of PCSK9 on cultured human aortic SMCs. Overexpression of PCSK9 downregulated the expression of ApoER2 (apolipoprotein E receptor 2), a known target of PCSK9. Treatment with soluble recombinant human ApoER2 or the DNA synthesis inhibitor, hydroxyurea, inhibited PCSK9-induced polyploidization and other cellular responses of human SMCs. Treatment with antibodies against ApoER2 resulted in similar effects to those observed with PCSK9 overexpression. Inducible, SMC-specific knockout of Pcsk9 accelerated neointima formation in mouse carotid arteries and reduced age-related arterial stiffness. PCSK9 was expressed in SMCs of human atherosclerotic lesions and abundant in the “shoulder” regions of vulnerable atherosclerotic plaques. PCSK9 was also expressed in SMCs of abdominal aortic aneurysm, which was inversely related to the expression of smooth muscle α-actin. Conclusions: Our findings demonstrate that PCSK9 inhibits proliferation and induces polyploidization, senescence, and apoptosis, which may be relevant to various degenerative vascular diseases.

scholarly journals The Isoform II of SRSF1: A Potential Biomarker in the Progression of Pediatric Acute Lymphoblastic Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5275-5275
Author(s):  
Liting Xu ◽  
Huyong Zheng
Keyword(s):  
Alternative Splicing ◽  
Acute Lymphoblastic Leukemia ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Expression Patterns ◽  
Critical Role ◽  
Leukemia Cell ◽  
Malignant Neoplasm ◽  
Protein Isoforms ◽  
Potential Biomarker

Abstract Background: Acute lymphoblastic leukemia (ALL) is the most frequently occurring malignant neoplasm in children. Despite advances in treatment and outcomes for ALL patients, the pathogenesis of the disease remains unclear. Alternative splicing modulates the expression of many oncogene and tumor-suppressor isoforms. SRSF1, a prototypical SR protein has been recognized as an oncoprotein. SRSF1 has been reported to be auto-regulated into multiple isoforms that differ in function in various physiological or pathological conditions. Methods: Matched, newly diagnosed (ND), complete remission (CR) and relapse (RE) bone marrow samples from 50 patients were collected in order to evaluate the expression patterns of SRSF1 spliced isoforms. The function of isoforms of SRSF1 in leukemogenesis was investigated in leukemia cell lines. Results: Both in mRNA and protein level, we identified significant up-regulation of the three main spliced isoforms of SRSF1 and the isoform II is the main variant in the ND samples. Importantly, the expression of three isoforms of SRSF1 returned to normal levels after CR. But the protein isoforms rebound in the RE samples, and the isoform II is high expressed a short-term state prior to morphological or immunological change in the RE cases. We also observed the isoform II can promote significantly to the formation of cell clones. Conclusion: Our results indicate that the alternative splicing of SRSF1 may plays a critical role in leukemogenesis in pediatric ALL, and the isoform II may be a sensitive predictor of relapse and a potential target for the anti-leukemic therapy. Disclosures No relevant conflicts of interest to declare.

The Role of Glyoxalase in Glycation and Carbonyl Stress Induced Metabolic Disorders

2020 ◽  
Vol 21 (9) ◽  
pp. 846-859
Author(s):  
Mohd Saeed ◽  
Mohd Adnan Kausar ◽  
Rajeev Singh ◽  
Arif J. Siddiqui ◽  
Asma Akhter
Keyword(s):  
Protein Misfolding ◽  
Covalent Binding ◽  
Critical Role ◽  
Enzymatic Reaction ◽  
Treatment Strategies ◽  
Bioactive Molecules ◽  
Carbonyl Stress ◽  
Defense System ◽  
Pathological Conditions ◽  
Age Related

Glycation refers to the covalent binding of sugar molecules to macromolecules, such as DNA, proteins, and lipids in a non-enzymatic reaction, resulting in the formation of irreversibly bound products known as advanced glycation end products (AGEs). AGEs are synthesized in high amounts both in pathological conditions, such as diabetes and under physiological conditions resulting in aging. The body’s anti-glycation defense mechanisms play a critical role in removing glycated products. However, if this defense system fails, AGEs start accumulating, which results in pathological conditions. Studies have been shown that increased accumulation of AGEs acts as key mediators in multiple diseases, such as diabetes, obesity, arthritis, cancer, atherosclerosis, decreased skin elasticity, male erectile dysfunction, pulmonary fibrosis, aging, and Alzheimer’s disease. Furthermore, glycation of nucleotides, proteins, and phospholipids by α-oxoaldehyde metabolites, such as glyoxal (GO) and methylglyoxal (MGO), causes potential damage to the genome, proteome, and lipidome. Glyoxalase-1 (GLO-1) acts as a part of the anti-glycation defense system by carrying out detoxification of GO and MGO. It has been demonstrated that GLO-1 protects dicarbonyl modifications of the proteome and lipidome, thereby impeding the cell signaling and affecting age-related diseases. Its relationship with detoxification and anti-glycation defense is well established. Glycation of proteins by MGO and GO results in protein misfolding, thereby affecting their structure and function. These findings provide evidence for the rationale that the functional modulation of the GLO pathway could be used as a potential therapeutic target. In the present review, we summarized the newly emerged literature on the GLO pathway, including enzymes regulating the process. In addition, we described small bioactive molecules with the potential to modulate the GLO pathway, thereby providing a basis for the development of new treatment strategies against age-related complications.

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration

2019 ◽  
Vol 19 (10) ◽  
pp. 705-718 ◽  
Author(s):  
Naima Mansoor ◽  
Fazli Wahid ◽  
Maleeha Azam ◽  
Khadim Shah ◽  
Anneke I. den Hollander ◽  
...  
Keyword(s):  
Matrix Metalloproteinases ◽  
Macular Degeneration ◽  
Complement System ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Genetic Changes ◽  
Complement System Proteins ◽  
Age Related ◽  
Common Genetic Variants

: Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40–60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

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