Spastin, a microtubule-severing enzyme, is important for neurite outgrowth. However, the mechanisms underlying the post-transcriptional regulation of spastin during microtubule-related processes are largely unknown. We demonstrated that the spastin expression level is controlled by a long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/microRNA-30 (miR-30) axis during neurite outgrowth. The miR-30 expression level decreased in hippocampal neurons with increasing days in culture, and miR-30 overexpression suppressed while miR-30 inhibition promoted neurite outgrowth in hippocampal neurons. Spastin was validated as a target gene of miR-30 using the luciferase reporter assay. The protein expression, microtubule severing activity, and neurite promoting effect of spastin were suppressed by the overexpression of miR-30 mimics and increased by miR-30 inhibitors. MALAT1 expression increased during neurite outgrowth and MALAT1 silencing impaired neurite outgrowth. miR-30 was a sponge target of MALAT1 and MALAT1/miR-30 altered neurite outgrowth in hippocampal neurons. MALAT1 overexpression reversed the inhibitory effect of miR-30 on the activity of a luciferase reporter construct containing spastin, as well as spastin mRNA and protein expression, indicating that spastin was a downstream effector of MALAT1/miR-30. The MALAT1/miR-30 cascade also modulated spastin-induced microtubule severing, and the MALAT1/miR-30/spastin axis regulated neurite outgrowth in hippocampal neurons. This study suggests a new mechanism governing neurite outgrowth in hippocampal neurons involving MALAT1/miR-30-regulated spastin expression.

Spastin是一种微管切断酶，对于神经突增生很重要。然而，在微管相关过程中，spastin转录后调控的基本机制尚不清楚。我们证明了spastin的表达水平是由长的非编码RNA（lncRNA）转移相关的肺腺癌转录本1（MALAT1）/ microRNA-30（miR-30）轴控制的。随着培养天数的增加，海马神经元中miR-30的表达水平降低，miR-30的过表达被抑制，而miR-30的抑制则促进了海马神经元的神经突生长。使用荧光素酶报告基因测定，Spastin被确认为miR-30的靶基因。蛋白质表达，微管切断活性，miR-30模拟物的过表达抑制了spastin的神经胶质和神经突促进作用，而miR-30抑制剂则增强了这种作用。在神经突长出过程中，MALAT1表达增加，而MALAT1沉默则削弱了神经突长出。miR-30是MALAT1的海绵靶标，而MALAT1 / miR-30改变了海马神经元的神经突向外生长。MALAT1的过表达逆转了miR-30对含spastin的荧光素酶报道基因构建物的活性以及spastin mRNA和蛋白质表达的抑制作用，表明spastin是MALAT1 / miR-30的下游效应子。MALAT1 / miR-30级联反应还调节了spastin诱导的微管切断，而MALAT1 / miR-30 / spastin轴调节了海马神经元的神经突生长。