MicroRNA-145 Regulates Neural Stem Cell Differentiation Through the Sox2–Lin28/let-7 Signaling Pathway

Abstract

MicroRNAs (miRNAs or miRs) regulate several biological functions, including cell fate determination and differentiation. Although miR-145 has already been described to regulate glioma development, its precise role in neurogenesis has never been addressed. miR-145 represses sexdetermining region Y-box 2 (Sox2), a core transcription factor of embryonic stem cells (ESCs), to inhibit pluripotency and self-renewal in human ESCs. In addition, the Sox2-Lin28/let-7 signaling pathway regulates proliferation and neurogenesis of neural precursors. In this study, we aimed to investigate the precise role of miR-145 in neural stem cell (NSC) fate decision, and the possible involvement of the Sox2-Lin28/let-7 signaling pathway in miR-145 regulatory network. Our results show for the first time that miR-145 expression significantly increased after induction of mouse NSC differentiation, remaining elevated throughout this process. Forced miR-145 downregulation decreased neuronal markers, namely bIII-tubulin, NeuN, and MAP2. Interestingly, throughout NSC differentiation, protein levels of Sox2 and Lin28, a well-known suppressor of let-7 biogenesis, decreased. Of note, neuronal differentiation also resulted in let-7a and let-7b upregulation. Transfection of NSCs with anti-miR-145, in turn, increased both Sox2 and Lin28 protein levels, while decreasing both let-7a and let-7b. More importantly, Sox2 and Lin28 silencing partially rescued the impairment of neuronal differentiation induced by miR-145 downregulation. In conclusion, our results demonstrate a novel role for miR-145 during NSC differentiation, where miR-145 modulation of Sox2-Lin28/let-7 network is crucial for neurogenesis progression. STEM CELLS 2016;34:1386-1395 SIGNIFICANCE STATEMENTNeural stem cells (NSCs) are a potential source of repairing cells. Although neurogenesis occurs in adult mammalian brain, NSCs produce very few neurons during aging or after injury. Thus, the identification of novel players that improve neural plasticity can have a huge impact in age-associated neurogenesis and cognitive decline. Recent evidence suggests that microRNAs (miRNAs or miRs), small noncoding RNA molecules that regulate gene expression, affect NSC fate. However, the underlying molecular mechanisms driving the enhancement of neuroplasticity by miRNAs remain largely unknown. Using in vitro models of mouse NSC, we revealed the molecular mechanisms by which miR-145 drives NSCs toward neuronal differentiation. The results from our study might add significant new information on key players responsible for neuroplasticity enhancement, thus contributing to improve the health and life quality of the aging population.

Acquisition cancer stemness, mesenchymal transdifferentiation, and chemoresistance properties by chronic exposure of oral epithelial cells to arecoline

“…miR-145 inhibits cancer stemness in various cancer types, including lung cancer [32], hepatocarcinoma [33], prostate cancer [34], and glioma [35]. This molecule is also associated with the cell cycle [36], differentiation [37], and apoptosis [38], metastasis [39], and chemoresistance [40]. Here, we confirmed that miR-145 negatively regulates cancer stemness in chronic arecoline-exposed OE (AOE) cells.…”

The dynamic changes of main cell types in the microenvironment of sciatic nerves following sciatic nerve injury and the influence of let-7 on their distribution

“…In recent years, the applications of miRNAs have been widely put forward and reported, 44,45 let-7 widely regulates important biological events related to the microenvironment of nerve regeneration, including cell differentiation, proliferation, migration, apoptosis, inammatory response, axonal regeneration, and myelin formation. 3,26,[28][29][30]46,47 Therefore, let-7 is as an ideal molecule for regulating regeneration environment to promote nerve regeneration. SCs, broblasts, and macrophages are main cells that regulate the microenvironment of nerve regeneration in nerve regeneration.…”

“…3 In addition, let-7 could regulate inammatory response by targeting inammatory factors including interleukin-6 (IL-6) and interleukin-10 (IL-10), 26,27 which also involved in regulating cell apoptosis, cell differentiation, cell proliferation, cell migration, and myelin formation. [28][29][30][31] In a word, let-7 widely regulates important biological events related to the microenvironment of nerve regeneration.…”

Lin28 overexpression inhibits neurite outgrowth of primary cortical neurons in vitro

“…In-terestingly in support of our findings, overexpression of Lin28 in C. elegans hermaphrodite-specific motor neurons inhibited axon extension during development, while loss-of-function mutations of Lin28 promoted precocious axon outgrowth (Olsson-Carter and Slack 2010). Moreover, though indirect evidence, downregulation of miR-145 resulted in a reduction in the number of neurites by increasing Lin28 expression (Morgado et al 2016). Given that neurite development is a complex process controlled by diverse molecular players, it will be interesting to investigate how Lin28 interacts with established regulators of neurite outgrowth.…”