Gentile Juliana E, Corridon Taylor L, Mortberg Meredith A, D'Souza Elston Neil, Whiffin Nicola, Minikel Eric Vallabh, Vallabh Sonia M
McCance Center for Brain Health and Department of Neurology, Massachusetts General Hospital, Boston, MA 02114.
Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142.
bioRxiv. 2023 Dec 19:2023.12.19.572439. doi: 10.1101/2023.12.19.572439.
Lowering expression of prion protein (PrP) is a well-validated therapeutic strategy in prion disease, but additional modalities are urgently needed. In other diseases, small molecules have proven capable of modulating pre-mRNA splicing, sometimes by forcing inclusion of cryptic exons that reduce gene expression. Here, we characterize a cryptic exon located in human 's sole intron and evaluate its potential to reduce PrP expression through incorporation into the 5' untranslated region (5'UTR). This exon is homologous to exon 2 in non-primate species, but contains a start codon that would yield an upstream open reading frame (uORF) with a stop codon prior to a splice site if included in mRNA, potentially downregulating PrP expression through translational repression or nonsense-mediated decay. We establish a minigene transfection system and test a panel of splice site alterations, identifying mutants that reduce PrP expression by as much as 78%. Our findings nominate a new therapeutic target for lowering PrP.
降低朊病毒蛋白（PrP）的表达是朊病毒疾病中一种经过充分验证的治疗策略，但迫切需要其他治疗方式。在其他疾病中，小分子已被证明能够调节前体mRNA剪接，有时是通过促使隐蔽外显子的包含来降低基因表达。在此，我们鉴定了位于人类PrP唯一内含子中的一个隐蔽外显子，并评估其通过并入5'非翻译区（5'UTR）来降低PrP表达的潜力。该外显子与非灵长类物种的外显子2同源，但包含一个起始密码子，如果包含在mRNA中，在剪接位点之前会产生一个带有终止密码子的上游开放阅读框（uORF），可能通过翻译抑制或无义介导的衰变来下调PrP表达。我们建立了一个小基因转染系统，并测试了一组剪接位点改变，鉴定出能将PrP表达降低多达78%的突变体。我们的研究结果为降低PrP提名了一个新的治疗靶点。
