scholarly journals Small molecule splicing modifiers with systemic HTT-lowering activity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anuradha Bhattacharyya ◽  
Christopher R. Trotta ◽  
Jana Narasimhan ◽  
Kari J. Wiedinger ◽  
Wencheng Li ◽  
...  
Keyword(s):  
Rna Splicing ◽  
Messenger Rna ◽  
Neurodegenerative Disorder ◽  
Stop Codon ◽  
Premature Termination Codon ◽  
Protein Levels ◽  
Function Mechanism ◽  
Investigational Drugs ◽  
The Central Nervous System ◽  
Orally Bioavailable

AbstractHuntington’s disease (HD) is a hereditary neurodegenerative disorder caused by expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats in the huntingtin (HTT) gene. Consequently, the mutant protein is ubiquitously expressed and drives pathogenesis of HD through a toxic gain-of-function mechanism. Animal models of HD have demonstrated that reducing huntingtin (HTT) protein levels alleviates motor and neuropathological abnormalities. Investigational drugs aim to reduce HTT levels by repressing HTT transcription, stability or translation. These drugs require invasive procedures to reach the central nervous system (CNS) and do not achieve broad CNS distribution. Here, we describe the identification of orally bioavailable small molecules with broad distribution throughout the CNS, which lower HTT expression consistently throughout the CNS and periphery through selective modulation of pre-messenger RNA splicing. These compounds act by promoting the inclusion of a pseudoexon containing a premature termination codon (stop-codon psiExon), leading to HTT mRNA degradation and reduction of HTT levels.

A G-to-A mutation in IVS-3 of the human gamma fibrinogen gene causing afibrinogenemia due to abnormal RNA splicing

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2501-2505 ◽  
Author(s):  
Maurizio Margaglione ◽  
Rosa Santacroce ◽  
Donatella Colaizzo ◽  
Davide Seripa ◽  
Gennaro Vecchione ◽  
...  
Keyword(s):  
Amino Acid ◽  
Rna Splicing ◽  
Messenger Rna ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Autosomal Recessive Disorder ◽  
Chain Gene ◽  
Hemorrhagic Diathesis ◽  
Reading Frame ◽  
Congenital Afibrinogenemia

Abstract Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by a hemorrhagic diathesis of variable severity. Although more than 100 families with this disorder have been described, genetic defects have been characterized in few cases. An investigation of a young propositus, offspring of a consanguineous marriage, with undetectable levels of functional and quantitative fibrinogen, was conducted. Sequence analysis of the fibrinogen genes showed a homozygous G-to-A mutation at the fifth nucleotide (nt 2395) of the third intervening sequence (IVS) of the γ-chain gene. Her first-degree relatives, who had approximately half the normal fibrinogen values and showed concordance between functional and immunologic levels, were heterozygtes. The G-to-A change predicts the disappearance of a donor splice site. After transfection with a construct, containing either the wild-type or the mutated sequence, cells with the mutant construct showed an aberrant messenger RNA (mRNA), consistent with skipping of exon 3, but not the expected mRNA. Sequencing of the abnormal mRNA showed the complete absence of exon 3. Skipping of exon 3 predicts the deletion of amino acid sequence from residue 16 to residue 75 and shifting of reading frame at amino acid 76 with a premature stop codon within exon 4 at position 77. Thus, the truncated γ-chain gene product would not interact with other chains to form the mature fibrinogen molecule. The current findings show that mutations within highly conserved IVS regions of fibrinogen genes could affect the efficiency of normal splicing, giving rise to congenital afibrinogenemia.

scholarly journals Zinc transporters in Alzheimer’s disease

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingshuo Xu ◽  
Guiran Xiao ◽  
Li Liu ◽  
Minglin Lang
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Critical Role ◽  
Zinc Transporters ◽  
Protein Levels ◽  
Zinc Chelator ◽  
The Central Nervous System ◽  
Novel Therapeutic Strategies

AbstractAlzheimer’s disease (AD) is the most devastating neurodegenerative disorder. Due to the increase in population and longevity, incidence will triple by the middle of the twenty-first century. So far, no treatment has prevented or reversed the disease. More than 20 years of multidisciplinary studies have shown that brain zinc dyshomeostasis may play a critical role in AD progression, which provides encouraging clues for metal-targeted therapies in the treatment of AD. Unfortunately, the pilot clinical application of zinc chelator and/or ionophore strategy, such as the use of quinoline-based compounds, namely clioquinol and PBT2, has not yet been successful. The emerging findings revealed a list of key zinc transporters whose mRNA or protein levels were abnormally altered at different stages of AD brains. Furthermore, specifically modulating the expression of some of the zinc transporters in the central nervous system through genetic methods slowed down or prevented AD progression in animal models, resulting in significantly improved cognitive performance, movement, and prolonged lifespan. Although the underlying molecular mechanisms are not yet fully understood, it shed new light on the treatment or prevention of the disease. This review considers recent advances regarding AD, zinc and zinc transporters, recapitulating their relationships in extending our current understanding of the disease amelioration effects of zinc transport proteins as potential therapeutic targets to cure AD, and it may also provide new insights to identify novel therapeutic strategies for ageing and other neurodegenerative diseases, such as Huntington’s and Parkinson’s disease.

A G-to-A mutation in IVS-3 of the human gamma fibrinogen gene causing afibrinogenemia due to abnormal RNA splicing

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2501-2505
Author(s):  
Maurizio Margaglione ◽  
Rosa Santacroce ◽  
Donatella Colaizzo ◽  
Davide Seripa ◽  
Gennaro Vecchione ◽  
...  
Keyword(s):  
Amino Acid ◽  
Rna Splicing ◽  
Messenger Rna ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Autosomal Recessive Disorder ◽  
Chain Gene ◽  
Hemorrhagic Diathesis ◽  
Reading Frame ◽  
Congenital Afibrinogenemia

Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by a hemorrhagic diathesis of variable severity. Although more than 100 families with this disorder have been described, genetic defects have been characterized in few cases. An investigation of a young propositus, offspring of a consanguineous marriage, with undetectable levels of functional and quantitative fibrinogen, was conducted. Sequence analysis of the fibrinogen genes showed a homozygous G-to-A mutation at the fifth nucleotide (nt 2395) of the third intervening sequence (IVS) of the γ-chain gene. Her first-degree relatives, who had approximately half the normal fibrinogen values and showed concordance between functional and immunologic levels, were heterozygtes. The G-to-A change predicts the disappearance of a donor splice site. After transfection with a construct, containing either the wild-type or the mutated sequence, cells with the mutant construct showed an aberrant messenger RNA (mRNA), consistent with skipping of exon 3, but not the expected mRNA. Sequencing of the abnormal mRNA showed the complete absence of exon 3. Skipping of exon 3 predicts the deletion of amino acid sequence from residue 16 to residue 75 and shifting of reading frame at amino acid 76 with a premature stop codon within exon 4 at position 77. Thus, the truncated γ-chain gene product would not interact with other chains to form the mature fibrinogen molecule. The current findings show that mutations within highly conserved IVS regions of fibrinogen genes could affect the efficiency of normal splicing, giving rise to congenital afibrinogenemia.

scholarly journals The Ig heavy chain protein but not its message controls early B cell development

2020 ◽  
Vol 117 (49) ◽  
pp. 31343-31352
Author(s):  
Muhammad Assad Aslam ◽  
Mir Farshid Alemdehy ◽  
Bingtao Hao ◽  
Peter H. L. Krijger ◽  
Colin E. J. Pritchard ◽  
...  
Keyword(s):  
B Cells ◽  
Heavy Chain ◽  
Messenger Rna ◽  
Stop Codon ◽  
Receptor Gene ◽  
Premature Termination Codon ◽  
Cell Receptor ◽  
Allelic Exclusion ◽  
Nonsense Mediated Decay ◽  
Precursor B Cells

Development of progenitor B cells (ProB cells) into precursor B cells (PreB cells) is dictated by immunoglobulin heavy chain checkpoint (IgHCC), where the IgHC encoded by a productively rearrangedIghallele assembles into a PreB cell receptor complex (PreBCR) to generate signals to initiate this transition and suppressing antigen receptor gene recombination, ensuring that only one productiveIghallele is expressed, a phenomenon known asIghallelic exclusion. In contrast to a productively rearrangedIghallele, theIghmessenger RNA (mRNA) (IgHR) from a nonproductively rearrangedIghallele is degraded by nonsense-mediated decay (NMD). This fact prohibited firm conclusions regarding the contribution of stableIgHRto the molecular and developmental changes associated with the IgHCC. This point was addressed by generating theIghTer5H∆TMmouse model fromIghTer5Hmice having a premature termination codon at position +5 in leader exon ofIghTer5Hallele. This prohibited NMD, and the lack of a transmembrane region (∆TM) prevented the formation of any signaling-competent PreBCR complexes that may arise as a result of read-through translation across premature Ter5 stop codon. A highly sensitive sandwich Western blot revealed read-through translation ofIghTer5Hmessage, indicating that previous conclusions regarding a role ofIgHRin establishing allelic exclusion requires further exploration. As determined by RNA sequencing (RNA-Seq), this low amount of IgHC sufficed to initiate PreB cell markers normally associated with PreBCR signaling. In contrast, theIghTer5H∆TMknock-in allele, which generated stableIgHRbut no detectable IgHC, failed to induce PreB development. Our data indicate that the IgHCC is controlled at the level of IgHC and notIgHRexpression.

scholarly journals Genetic screens identify connections between ribosome recycling and nonsense mediated decay

2021 ◽  
Author(s):  
Karole N D'Orazio ◽  
Laura N. Lessen ◽  
Anthony J. Veltri ◽  
Zachary Neiman ◽  
Miguel E. Pacheco ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Premature Termination ◽  
Stop Codon ◽  
Premature Termination Codon ◽  
Termination Codon ◽  
Genetic Screens ◽  
Regulatory Pathway ◽  
Nonsense Mediated Decay ◽  
Stop Codons ◽  
Reported Data

The decay of messenger RNA with a premature termination codon (PTC) by nonsense mediated decay (NMD) is an important regulatory pathway for eukaryotes and an essential pathway in mammals. NMD is typically triggered by the ribosome terminating at a stop codon that is aberrantly distant from the poly-A tail. Here, we use a fluorescence screen to identify factors involved in NMD in S. cerevisiae . In addition to the known NMD factors, including the entire UPF family (UPF1, UPF2 and UPF3), as well as NMD4 and EBS1 , we identify factors known to function in post-termination recycling and characterize their contribution to NMD. We then use a series of modified reporter constructs that block both elongating and scanning ribosomes downstream of stop codons and demonstrate that a deficiency in recycling of 80S ribosomes or 40S subunits stabilizes NMD substrates. These observations in S. cerevisiae expand on recently reported data in mammals indicating that the 60S recycling factor ABCE1 is important for NMD (1,2) by showing that increased activities of both elongating and scanning ribosomes (80S or 40S) in the 3’UTR correlate with a loss of NMD.

Alternative Splicing Is Responsible for the Presence of Two Tissue Factor mRNA Species in LPS Stimulated Human Monocytes

1992 ◽  
Vol 67 (02) ◽  
pp. 272-276 ◽  
Author(s):  
C Paul ◽  
E van der Logt ◽  
Pieter H Reitsma ◽  
Rogier M Bertina
Keyword(s):  
Alternative Splicing ◽  
Tissue Factor ◽  
Stop Codon ◽  
Cell Types ◽  
Northern Analysis ◽  
Human Monocytes ◽  
Mrna Species ◽  
Protein Levels ◽  
Intron 1 ◽  
Tf Gene

SummaryAlthough normally absent from the surface of all circulating cell types, tissue factor (TF) can be induced to appear on circulating monocytes by stimulants like bacterial lipopolysaccharide (LPS) and phorbolesters. Northern analysis of RNA isolated from LPS stimulated human monocytes demonstrates the presence of 2.2 kb and 3.1 kb TF mRNA species. The 2.2 kb message codes for the TF protein. As demonstrated by Northern blot analysis with a variety of TF gene probes, the 3.1 kb message arises from an alternative splicing process which fails to remove 955 bp from intron 1. Because of a stop codon in intron 1 no TF protein is produced from the 3.1 kb transcript. This larger transcript should therefore not be taken into account when comparing TF gene transcription and TF protein levels.

Synbiotic-associated improvement in liver function in cirrhotic patients: Relation to changes in circulating cytokine messenger RNA and protein levels

2007 ◽  
Vol 19 (1) ◽  
Author(s):  
Stephen M. Riordan ◽  
Narelle A. Skinner ◽  
Christopher J. Mciver ◽  
Qing Liu ◽  
Stig Bengmark ◽  
...  
Keyword(s):  
Liver Function ◽  
Messenger Rna ◽  
Protein Levels ◽  
Cirrhotic Patients

scholarly journals A biallelic variant in CLRN2 causes non-syndromic hearing loss in humans

2021 ◽  
Author(s):  
Barbara Vona ◽  
Neda Mazaheri ◽  
Sheng-Jia Lin ◽  
Lucy A. Dunbar ◽  
Reza Maroofian ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Amino Acid ◽  
Rna Splicing ◽  
Stop Codon ◽  
Missense Variant ◽  
Homozygosity Mapping ◽  
Deafness Gene ◽  
Expression Studies ◽  
Hearing Function

AbstractDeafness, the most frequent sensory deficit in humans, is extremely heterogeneous with hundreds of genes involved. Clinical and genetic analyses of an extended consanguineous family with pre-lingual, moderate-to-profound autosomal recessive sensorineural hearing loss, allowed us to identify CLRN2, encoding a tetraspan protein, as a new deafness gene. Homozygosity mapping followed by exome sequencing identified a 14.96 Mb locus on chromosome 4p15.32p15.1 containing a likely pathogenic missense variant in CLRN2 (c.494C > A, NM_001079827.2) segregating with the disease. Using in vitro RNA splicing analysis, we show that the CLRN2 c.494C > A variant leads to two events: (1) the substitution of a highly conserved threonine (uncharged amino acid) to lysine (charged amino acid) at position 165, p.(Thr165Lys), and (2) aberrant splicing, with the retention of intron 2 resulting in a stop codon after 26 additional amino acids, p.(Gly146Lysfs*26). Expression studies and phenotyping of newly produced zebrafish and mouse models deficient for clarin 2 further confirm that clarin 2, expressed in the inner ear hair cells, is essential for normal organization and maintenance of the auditory hair bundles, and for hearing function. Together, our findings identify CLRN2 as a new deafness gene, which will impact future diagnosis and treatment for deaf patients.

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