{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T05:11:28Z","timestamp":1774501888270,"version":"3.50.1"},"reference-count":35,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2020,11,19]],"date-time":"2020-11-19T00:00:00Z","timestamp":1605744000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Netherlands Organization for Scientific Research","award":["VIDI 91713319"],"award-info":[{"award-number":["VIDI 91713319"]}]},{"name":"AFM telethon","award":["AFM#21527"],"award-info":[{"award-number":["AFM#21527"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>OTC splicing mutations are generally associated with the severest and early disease onset of ornithine transcarbamylase deficiency (OTCD), the most common urea cycle disorder. Noticeably, splicing defects can be rescued by spliceosomal U1snRNA variants, which showed their efficacy in cellular and animal models. Here, we challenged an U1snRNA variant in the OTCD mouse model (spf\/ash) carrying the mutation c.386G &gt; A (p.R129H), also reported in OTCD patients. It is known that the R129H change does not impair protein function but affects pre-mRNA splicing since it is located within the 5\u2032 splice site. Through in vitro studies, we identified an Exon Specific U1snRNA (ExSpeU1O3) that targets an intronic region downstream of the defective exon 4 and rescues exon inclusion. The adeno-associated virus (AAV8)-mediated delivery of the ExSpeU1O3 to mouse hepatocytes, although in the presence of a modest transduction efficiency, led to increased levels of correct OTC transcripts (from 6.1 \u00b1 1.4% to 17.2 \u00b1 4.5%, p = 0.0033). Consistently, this resulted in increased liver expression of OTC protein, as demonstrated by Western blotting (~3 fold increase) and immunostaining. Altogether data provide the early proof-of-principle of the efficacy of ExSpeU1 in the spf\/ash mouse model and encourage further studies to assess the potential of RNA therapeutics for OTCD caused by aberrant splicing.<\/jats:p>","DOI":"10.3390\/ijms21228735","type":"journal-article","created":{"date-parts":[[2020,11,19]],"date-time":"2020-11-19T06:23:52Z","timestamp":1605767032000},"page":"8735","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["An Exon-Specific Small Nuclear U1 RNA (ExSpeU1) Improves Hepatic OTC Expression in a Splicing-Defective spf\/ash Mouse Model of Ornithine Transcarbamylase Deficiency"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6675-9429","authenticated-orcid":false,"given":"Dario","family":"Balestra","sequence":"first","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mattia","family":"Ferrarese","sequence":"additional","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2918-4010","authenticated-orcid":false,"given":"Silvia","family":"Lombardi","sequence":"additional","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1007-7266","authenticated-orcid":false,"given":"Nicole","family":"Ziliotto","sequence":"additional","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"},{"name":"School of Medicine and Surgery, University of Milano-Bicocca, 20900 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6113-2694","authenticated-orcid":false,"given":"Alessio","family":"Branchini","sequence":"additional","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naomi","family":"Petersen","sequence":"additional","affiliation":[{"name":"Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Piter","family":"Bosma","sequence":"additional","affiliation":[{"name":"Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands"},{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4114-7055","authenticated-orcid":false,"given":"Mirko","family":"Pinotti","sequence":"additional","affiliation":[{"name":"Department of Life Sciences and Biotechnology and LTTA, University of Ferrara, 44121 Ferrara, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4238-4359","authenticated-orcid":false,"given":"Stan F. J.","family":"van de Graaf","sequence":"additional","affiliation":[{"name":"Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands"},{"name":"Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1136\/adc.84.1.84","article-title":"Ornithine carbomoyltransferase deficiency","volume":"84","author":"Wraith","year":"2001","journal-title":"Arch. Dis. 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