Abstract
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.
Highlights
Spastin, a microtubule-cutting protein in the ‘‘ATPases associated with diverse cellular activities’’ (AAA) protein family (Sharp and Ross, 2012), was first discovered in hereditary spastic paraplegia (HSP; Hazan et al, 1999), a neurodegenerative disease involving the degeneration of axons in the bilateral corticospinal tract of the spinal cord (McDermott et al, 2000)
The 3 -untranslated region (UTR) of spastin that matched the miR-30 sequence is highly conserved among multiple species (Figure 1B), suggesting that miR-30 might affect the expression of spastin; the role of miR-30 in neurite outgrowth is unknown
Analysis of the expression levels of miR-30 and spastin revealed that miR-30 and spastin expression were inversely correlated; miR-30 (Figure 1C) expression decreased while spastin expression (Figure 1D) increased in hippocampal neurons with increasing days in culture
Summary
A microtubule-cutting protein in the ‘‘ATPases associated with diverse cellular activities’’ (AAA) protein family (Sharp and Ross, 2012), was first discovered in hereditary spastic paraplegia (HSP; Hazan et al, 1999), a neurodegenerative disease involving the degeneration of axons in the bilateral corticospinal tract of the spinal cord (McDermott et al, 2000). Silencing spastin changes microtubule stability, curls axons, and impairs anterograde and retrograde axonal transport in MALAT1/miR-30/Spastin in Hippocampal Neurite Outgrowth human HSP patients (Kasher et al, 2009), zebrafish (Wood et al, 2006), and cultured neurons (Yu et al, 2008; Korulu and Karabay, 2011; Fassier et al, 2013). We previously showed that spastin interacts with collapsing response-mediator protein-5 (CRMP5) to regulate neurite outgrowth (Ji et al, 2018). These reports suggest an important role in protein-protein interactions in the activity regulation of spastin during neuronal development. The post-transcriptional regulation of spastin is critical for spastin expression but the underlying mechanisms remain unknown
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
