Dredge B Kate, Stefani Giovanni, Engelhard Caitlin C, Darnell Robert B
Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.
EMBO J. 2005 Apr 20;24(8):1608-20. doi: 10.1038/sj.emboj.7600630. Epub 2005 Mar 31.
The Nova family of neuron-specific RNA-binding proteins were originally identified as targets in an autoimmune neurologic disease characterized by failure of motor inhibition. Nova-1 regulates alternative splicing of pre-mRNAs encoding the inhibitory neurotransmitter receptor subunits GABA(A)Rgamma2 and GlyRalpha2 by directly binding intronic elements, resulting in enhancement of exon inclusion. Here we identify exon E4 in the Nova-1 pre-mRNA itself, encoding a phosphorylated protein domain, as an additional target of Nova-dependent splicing regulation in the mouse spinal cord. Nova binding to E4 is necessary and sufficient for Nova-dependent exon exclusion. E4 harbors five repeats of the known Nova-binding tetranucleotide YCAY and mutation of these elements destroys Nova-dependent regulation. Furthermore, swapping of the sites from Nova-1 and GABA(A)Rgamma2 indicates that the ability of Nova to enhance or repress alternative exon inclusion is dependent on the position of the Nova-binding element within the pre-mRNA. These studies demonstrate that in addition to its previously described role as a splicing activator, Nova autoregulates its own expression by acting as a splicing repressor.
神经元特异性RNA结合蛋白Nova家族最初被鉴定为一种自身免疫性神经疾病的靶点，该疾病的特征是运动抑制功能失效。Nova-1通过直接结合内含子元件来调节编码抑制性神经递质受体亚基GABA(A)Rγ2和GlyRα2的前体mRNA的可变剪接，从而增强外显子的包含。在这里，我们在Nova-1前体mRNA本身中鉴定出编码磷酸化蛋白结构域的外显子E4，它是小鼠脊髓中Nova依赖性剪接调控的另一个靶点。Nova与E4的结合对于Nova依赖性外显子排除是必要且充分的。E4含有已知的Nova结合四核苷酸YCAY的五个重复序列，这些元件的突变会破坏Nova依赖性调控。此外，将Nova-1和GABA(A)Rγ2的位点进行交换表明，Nova增强或抑制可变外显子包含的能力取决于Nova结合元件在前体mRNA中的位置。这些研究表明，除了其先前描述的作为剪接激活剂的作用外，Nova还通过作为剪接抑制剂来自动调节自身的表达。
