Oxidative Stress Triggers Body-Wide Skipping of Multiple Exons of the Spinal Muscular Atrophy Gene.
Humans carry two nearly identical copies of Survival Motor Neuron gene: SMN1 and SMN2. Loss of SMN1 leads to spinal muscular atrophy (SMA), the most frequent genetic cause of infant mortality. While SMN2 cannot compensate for the loss of SMN1 due to predominant skipping of exon 7, correction of SMN2 exon 7 splicing holds the promise of a cure for SMA. Previously, we used cell-based models coupled with a multi-exon-skipping detection assay (MESDA) to demonstrate the vulnerability of SMN2 exons to aberrant splicing under the conditions of oxidative stress (OS). Here we employ a transgenic mouse model and MESDA to examine the OS-induced splicing regulation of SMN2 exons. We induced OS using paraquat that is known to trigger production of reactive oxygen species and cause mitochondrial dysfunction. We show an overwhelming co-skipping of SMN2 exon 5 and exon 7 under OS in all tissues except testis. We also show that OS increases skipping of SMN2 exon 3 in all tissues except testis. We uncover several new SMN2 splice isoforms expressed at elevated levels under the conditions of OS. We analyze cis-elements and transacting factors to demonstrate the diversity of mechanisms for splicing misregulation under OS. Our results of proteome analysis reveal downregulation of hnRNP H as one of the potential consequences of OS in brain. Our findings suggest SMN2 as a sensor of OS with implications to SMA and other diseases impacted by low levels of SMN protein.
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Joonbae
J
Seo
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Natalia N
NN
Singh
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Eric W
EW
Ottesen
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Senthilkumar
S
Sivanesan
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Maria
M
Shishimorova
Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, United States of America.
Ravindra N
RN
Singh
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001681:Biological Assay; D004195:Disease Models, Animal; D005091:Exons; D015870:Gene Expression; D006801:Humans; D007438:Introns; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009134:Muscular Atrophy, Spinal / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009690:Nucleic Acid Conformation; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology; D055533:Survival of Motor Neuron 1 Protein / Q000235:genetics* / Q000378:metabolism; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes
C000597152:SMN2 protein, mouse; C526472:Smn1 protein, mouse; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D010269:Paraquat