Up-regulation of miR-10a-5p expression inhibits the proliferation and differentiation of neural stem cells by targeting Chl1

Abstract

Neural tube defects (NTDs) are characterized by the failure of neural tube closure during embryogenesis and are considered the most common and severe central nervous system anomalies during early development. Recent microRNA (miRNA) expression profiling studies have revealed that the dysregulation of several miRNAs plays an important role in retinoic acid (RA)-induced NTDs. However, the molecular functions of these miRNAs in NTDs remain largely unidentified. Here, we show that miR-10a-5p is significantly upregulated in RA-induced NTDs and results in reduced cell growth due to cell cycle arrest and dysregulation of cell differentiation. Moreover, the cell adhesion molecule L1-like (Chl1) is identified as a direct target of miR-10a-5p in neural stem cells (NSCs) in vitro, and its expression is reduced in RA-induced NTDs. siRNA-mediated knockdown of intracellular Chl1 affects cell proliferation and differentiation similar to those of miR-10a-5p overexpression, which further leads to the inhibition of the expressions of downstream ERK1/2 MAPK signaling pathway proteins. These cellular responses are abrogated by either increased expression of the direct target of miR-10a-5p (Chl1) or an ERK agonist such as honokiol. Overall, our study demonstrates that miR-10a-5p plays a major role in the process of NSC growth and differentiation by directly targeting Chl1, which in turn induces the downregulation of the ERK1/2 cascade, suggesting that miR-10a-5p and Chl1 are critical for NTD formation in the development of embryos.

1. Introduction

Neural tube defects (NTDs), including spina bifida, anencephaly, myelomeningocele and encephalocele, are severe congenital anomalies caused by incomplete or defective neural tube closure during embryonic development [1–3]. NTDs are considered the second most common category of birth defects [4], affecting approximately one in every 1000 established pregnancies with a prevalence rate of 0.2–10 per 1000 in different areas [5]. The causes of NTDs appear to be complex and involve multiple genetic and environmental factors [6–8]. To date, few genes have been identified as the major contributors to NTD susceptibility, along with several known environmental risk factors, such as maternal diabetes, valproic acid, folic acid and retinoic acid (RA) [9].

RA is a vitamin A-derived metabolite that is involved in embryonic development, especially in the development of the central nervous system [10], including the migration of nerve fold cells, the closure of neural tubes, and the formation of the anterior, middle and posterior brain [11]. Excessive RA level in pregnant mammals can lead to abnormalities in brain development, including NTDs [12]. At present, excessive RA-induced animal models have been widely used to study the pathogenesis of NTDs [13,14].