MicroRNA-92a-3p enhances functional recovery and suppresses apoptosis after spinal cord injury via targeting phosphatase and tensin homolog.

Spinal cord injury (SCI) is a neurological disease commonly caused by traumatic events on spinal cords. MiRNA-92a-3p is reported to be down-regulated after SCI. Our study investigated the effects of up-regulated miR-92a-3p on SCI and the underlying mechanisms. SCI mice model was established to evaluate the functional recovery of hindlimbs of mice through open-field locomotion and scored by Basso, Beattie, and Bresnahan (BBB) locomotion scale. Apoptosis of spinal cord cells was determined by flow cytometry. The effects of miR-92a-3p on SCI were detected by intrathecally injecting miR-92a-3p agomiR (agomiR-92) into the mice prior to the establishment of SCI. Phosphatase and tensin homolog (PTEN) was predicted as a target of miR-29a-3p by TargetScan. We further assessed the effects of agomiR-92 or/and overexpressed PTEN on apoptosis rates and apoptotic protein expressions in SCI mice. Moreover, the activation of protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling was determined by Western blot. The results showed that compared with the sham-operated mice, SCI mice had much lower BBB scores, and theapoptosis rate of spinal cord cells was significantly increased. After SCI, the expression of miR-92a-3p was down-regulated, and increased expression of miR-92a-3p induced by agomiR-92 further significantly increased the BBB score and decreased apoptosis. PTEN was specifically targeted by miR-92a-3p. In addition, the phosphorylation levels of Akt and mTOR were up-regulated under the treatment of agomiR-92. Our data demonstrated that the neuroprotective effects of miR-92a-3p on spinal cord safter SCI were highly associated with the activation of the PTEN/AKT/mTOR pathway.

He S ，Wang Z ，Li Y ，Dong J ，Xiang D ，Ren L ，Guo L ，Shu J ... -  《-》

MiR-212-3p improves rat functional recovery and inhibits neurocyte apoptosis in spinal cord injury models via PTEN downregulation-mediated activation of AKT/mTOR pathway.

Multiple cellular and molecular changes are involved in the etiology of spinal cord injury (SCI) and the recovery from SCI. Accumulating studies showed aberrant expression of microRNAs (miRNAs) after SCI. Here, we established in vivo and in vitro models to analyze the role of miR-212-3p in SCI. An in vivo model of SCI was established in Sprague-Dawley rats. SCI-induced histopathological changes of the spinal cord were observed by hematoxylin-eosin staining. Functional recovery of rats with SCI was evaluated using the Basso-Beattie-and-Bresnahan scale. PC12 cells were stimulated by lipopolysaccharide (LPS) to establish SCI model of neuronal apoptosis in vitro. Dual-luciferase reporter assay was performed to validate the potential target of miR-212-3p predicted by TargetScan 7.2. MTT assay and flow cytometry were carried out to measure the viability and apoptosis of PC12 cell, respectively. The expressions of miR-212-3p, PTEN, phosphorylated (p)-AKT, AKT, p-mTOR, mTOR, Cleaved caspase-3 and BCl-2 in spinal cord tissues and PC12 cells were analyzed by qRT-PCR or Western blot. In the spinal cord of rats with SCI, the expressions of miR-212-3p, p-AKT, p-mTOR and BCl-2 were downregulated, whereas those of PTEN and Cleaved caspase-3 were upregulated. BBB scores were low, and there were histopathological changes, which were all reversed after the injection of agomiR-212-3p. MiR-212-3p directly targeted PTEN. Upregulated miR-212-3p in LPS-injured PC12 cells suppressed apoptosis, downregulated the expressions of PTEN and Cleaved caspase-3, promoted viability and upregulated the expressions of p-AKT, p-mTOR and BCl-2, which were all reversed by overexpressed PTEN. MiR-212-3p improved functional recovery of SCI rats and inhibited LPS-induced neurocyte apoptosis by targeting PTEN to activate AKT/mTOR pathway.

Guan C ，Luan L ，Li J ，Yang L ... -  《-》

MicroRNA-494 improves functional recovery and inhibits apoptosis by modulating PTEN/AKT/mTOR pathway in rats after spinal cord injury.

Multiple cellular, molecular, and biochemical changes contribute to the etiology and treatment outcome of contusion spinal cord injury (SCI). MicroRNAs (miRNAs) aberrant expression have been found after SCI in recent studies. However, little is known about the functional significance of the unique role of miRNAs in SCI. Here, we established a rat SCI model and performed the miRNA microarray to analyze miRNAs expression at different times post-SCI. Microarray data revealed that 14 miRNAs were upregulated and 46 miRNAs were downregulated by 2 times compared with sham rat spinal cords, and miR-494 was one of the miRNAs being most significantly downregulated. Subsequently, we investigated miR-494 function and found that upregulation of miR-494 by agomir-494 improves functional recovery, reduces lesion size and inhibits apoptotic cell in rats following SCI. Moreover, our data showed that miR-494 suppresses phosphatase and tensin homolog (PTEN), a negative regulator of AKT/mTOR pathway, through directly targeting its 3'-UTR in BV-2 cells. Most importantly, we demonstrated that overexpression of miR-494 activates AKT/mTOR signaling pathway via inhibiting PTEN expression in rat SCI model. These findings suggested that miR-494 harbored the protective effect after SCI by modulating PTEN/AKT/mTOR pathway in rats and it is a potential candidate for SCI therapeutics.

Zhu H ，Xie R ，Liu X ，Shou J ，Gu W ，Gu S ，Che X ... -  《-》

Gypenoside XVII protects against spinal cord injury in mice by regulating the microRNA‑21‑mediated PTEN/AKT/mTOR pathway.

Sun T ，Duan L ，Li J ，Guo H ，Xiong M ... -  《-》

MiR-17 targets PTEN and facilitates glial scar formation after spinal cord injuries via the PI3K/Akt/mTOR pathway.

We attempted to discover the regulatory role of miR-17 and PTEN in glial scar formation accompanied with spinal cord injuries. We established a spinal cord injury (SCI) model in mice which were transfected with different groups of adenoviruses: miR-17 mimics, miR-17 inhibitors and PTEN cDNAs. The improvement of hind limb functions was assessed using the 21-point Basso-Beattie-Bresnahan (BBB) locomotion scale. Immunohistochemistry was used to detect the expression levels of glial fibrillary acidic protein (GFAP), Vimentin and neurofilaments. The expression of miR-17 was quantified using Real time-PCR (RT-PCR). Western blot was conducted to detect the expressions of PTEN, PI3K, Akt, mTOR and S6. Finally, dual luciferase reporter gene assay was conducted to confirm the target relationship between miR-17 and PTEN. The model group exhibited significantly increased expression levels of GFAP, Vimentin, miR-17, PTEN, PI3K, Akt and mTOR. The above trend was enhanced by the transfection of miR-17 mimics (P<0.05). By contrast, the transfection of miR-17 inhibitors significantly down-regulated the expression of GFAP, Vimentin, PTEN, PI3K, Akt, mTOR and p-S6 whereas the expression of GFAP, Vimentin, PI3K, Akt, mTOR and p-S6 in the cells transfected with PTEN cDNAs significantly decreased (P<0.05). Also, the transfection of miR-17 inhibitors and PTEN cDNAs alleviated the astrogliosis in SCI lesions, contributed to the regeneration of nerve filament and improved the functional recovery of the hind limb of mice. Finally, the targeting relationship between miR-17 and PTEN was verified by the dual luciferase reporter gene assay. MiR-17 is able to target PTEN and stimulate the PI3K/Akt/mTOR pathway. The formation of glial scar resulted from spinal cord injuries can be reduced either by inhibiting miR-17 or by overexpressing PTEN.

Luan Y ，Chen M ，Zhou L 《-》