title: Inhibition of SMG-8, a subunit of SMG-1 kinase, ameliorates nonsense-mediated mRNA decay-exacerbated mutant phenotypes without cytotoxicity.
abstract: Nonsense-mediated mRNA decay (NMD) is an mRNA surveillance mechanism that eliminates aberrant mRNAs containing premature termination codons (PTCs). NMD inhibits the production of aberrant proteins that still retain, at least in part, wild-type function as well as dominant-negative peptides. Therefore, the selective inhibition of NMD has the potential to ameliorate NMD-exacerbated mutant phenotypes. However, we do not have sufficient knowledge of how to effectively suppress NMD with minimum cytotoxic effects. In this study, we aimed to identify NMD-related factors that can be targeted to efficiently inhibit NMD without causing significant cytotoxicity to restore the levels of truncated but partially functional proteins. We evaluated the knockdown of 15 NMD components in Ullrich congenital muscular dystrophy fibroblasts, which have a homozygous frameshift mutation causing a PTC in the collagen type VI α 2 gene. Of the 15 NMD factors tested, knockdown of SMG-8 produced the best effect for restoring defective mRNA and protein levels without affecting cell growth, cell-cycle progression, or endoplasmic reticulum stress. The efficacy of SMG-8 knockdown to improve the mutant phenotype was confirmed using another cell line, from a cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy patient who carries a PTC-containing mutation in HtrA serine peptidase 1. Our results suggest that SMG-8 is an appropriate target for inhibiting NMD to improve NMD-exacerbated mutant phenotypes. NMD inhibition by knockdown of SMG-8 may also be useful to induce synergy in combining the use of read-through drugs for patients with nonsense mutation-associated diseases.
authors: Department of Clinical Medicine, National Institute for Minamata Disease, Minamata, Kumamoto 867-0008, Japan.
authors: Fusako
authors: F
authors: Usuki
authors: Akio
authors: A
authors: Yamashita
authors: Tadafumi
authors: T
authors: Shiraishi
authors: Atsushi
authors: A
authors: Shiga
authors: Osamu
authors: O
authors: Onodera
authors: Itsuro
authors: I
authors: Higuchi
authors: Shigeo
authors: S
authors: Ohno
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018389:Codon, Nonsense; D024142:Collagen Type VI / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009136:Muscular Dystrophies / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D059365:Nonsense Mediated mRNA Decay; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry / Q000235:genetics; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D034741:RNA, Small Interfering / Q000235:genetics; D012598:Sclerosis / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018389:Codon, Nonsense; D024142:Collagen Type VI; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits; D034741:RNA, Small Interfering; C504344:COL6A2 protein, human; C491494:MAGOH protein, human; C555938:SMG8 protein, human; C514704:SMG1 protein, human
keywords: genetic disorder with premature termination codon; siRNA; therapy
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