Regulation of miR-34 Family in Neuronal Development

PLoS ONE, 2011

Background: MicroRNAs (miRNAs or miRs) participate in the regulation of several biological processes, including cell differentiation. Recently, miR-34a has been implicated in the differentiation of monocyte-derived dendritic cells, human erythroleukemia cells, and mouse embryonic stem cells. In addition, members of the miR-34 family have been identified as direct p53 targets. However, the function of miR-34a in the control of the differentiation program of specific neural cell types remains largely unknown. Here, we investigated the role of miR-34a in regulating mouse neural stem (NS) cell differentiation.

BMC Genomics, 2010

Background: MicroRNAs (miRs or miRNAs) regulate several biological processes in the cell. However, evidence for miRNAs that control the differentiation program of specific neural cell types has been elusive. Recently, we have shown that apoptosis-associated factors, such as p53 and caspases participate in the differentiation process of mouse neural stem (NS) cells. To identify apoptosis-associated miRNAs that might play a role in neuronal development, we performed global miRNA expression profiling experiments in NS cells. Next, we characterized the expression of proapoptotic miRNAs, including miR-16, let-7a and miR-34a in distinct models of neural differentiation, including mouse embryonic stem cells, PC12 and NT2N cells. In addition, the expression of antiapoptotic miR-19a and 20a was also evaluated.

Molecular and Cellular Biology, 2015

The cell cycle of neurons remains suppressed to maintain the state of differentiation and aberrant cell cycle re-entry results in loss of neurons, which is a feature in neurodegenerative disorders like Alzheimer's disease (AD). Present studies revealed that the expression of microRNA-34a (miR-34a) needs to be optimal in neurons as aberrant increase or decrease in its expression causes apoptosis. miR-34a keeps the neuronal cell cycle under check by preventing the expression of cyclin D1 and promotes cell cycle arrest. Neurotoxic Amyloid β1-42peptide (Aβ42) treatment of cortical neurons suppressed miR-34a resulting in unscheduled cell cycle re-entry, which resulted in apoptosis. The repression of miR-34a was a result of degradation of TAp73, which was mediated by aberrant activation of MEK-ERK pathway by Aβ42. A significant decrease in miR-34a and TAp73 was observed in the cortex of >12m old transgenic (Tg) mouse model of AD, which corroborated well with cell cycle re-entry obs...

The generation of differentiated and functional neurons is a complex process, which requires coordinated expression of several proteins and microRNAs (miRNAs). The present study using nerve growth factor (NGF)-differentiated PC12 cells led to the identification of miR-200, miR-221/222 and miR-34 families as major up-regulated miRNAs in fully differentiated neurons. Similar to PC12 cells, induction of miR-200 family was observed in differentiating neural stem cells, demonstrating a direct role of miR-200 family in neuronal differentiation. Overexpression of miR-200 induced neurite formation in PC12 cells and regulated neuronal markers in favour of differentiation. However, inhibition of miR-200 induced proliferation of PC12 cells. In differentiating PC12 cells and neural stem cells, an inverse relationship was observed between expression of reprogramming transcription factors (SOX2, KLF4, NANOG, OCT4 and PAX6) and miR-200. Over-expression of miR-200 in PC12 cells significantly down-regulated mRNA and protein levels of SOX2 and KLF4. Moreover, we observed two phases of dramatic down-regulation of miR-200 expression in developing rat brains correlating with periods of neuronal proliferation. In conclusion, our results indicate that increased expression of the miR-200 family promotes neuronal differentiation, while decreased expression of the miR-200 family promotes neuronal proliferation by targeting SOX2 and KLF4.

Nature Communications, 2014

microRNAs shape the identity and function of cells by regulating gene expression. It is known that brain-specific miR-9 is controlled transcriptionally; however, it is unknown whether posttranscriptional processes contribute to establishing its levels. Here we show that miR-9 is regulated transcriptionally and post-transcriptionally during neuronal differentiation of the embryonic carcinoma cell line P19. We demonstrate that miR-9 is more efficiently processed in differentiated than in undifferentiated cells. We reveal that Lin28a affects miR-9 by inducing the degradation of its precursor through a uridylation-independent mechanism. Furthermore, we show that constitutively expressed untagged but not GFP-tagged Lin28a decreases differentiation capacity of P19 cells, which coincides with reduced miR-9 levels. Finally, using an inducible system we demonstrate that Lin28a can also reduce miR-9 levels in differentiated P19 cells. Together, our results shed light on the role of Lin28a in neuronal differentiation and increase our understanding of the mechanisms regulating the level of brain-specific microRNAs.

Methods in molecular biology (Clifton, N.J.), 2013

The Mouse P19 cell line was derived from an embryonal carcinoma. The pluripotent P19 cells can be induced to differentiate into neuronal and glial cells. Here, we describe an miRNA microarray method to monitor the miRNA expression profiles during the course of P19 cells neuronal differentiation. The results indicated that there were significant differences between the miRNA expression in P19 EC cells and the resultant differentiated neural stem cells.

Proceedings of the National Academy of Sciences, 2011

The p53 family member TAp73 is a transcription factor that plays a key role in many biological processes, including neuronal development. In particular, we have shown that p73 drives the expression of miR-34a, but not miR-34b and c, in mouse cortical neurons. miR-34a in turn modulates the expression of synaptic targets including synaptotagmin-1 and syntaxin-1A. Here we show that this axis is retained in mouse ES cells committed to differentiate toward a neurological phenotype. Moreover, overexpression of miR-34a alters hippocampal spinal morphology, and results in electrophysiological changes consistent with a reduction in spinal function. Therefore, the TAp73/miR-34a axis has functional relevance in primary neurons. These data reinforce a role for miR-34a in neuronal development.

PloS one, 2017

Neurogenesis is a highly-regulated process occurring in the dentate gyrus that has been linked to learning, memory, and antidepressant efficacy. MicroRNAs (miRNAs) have been previously shown to play an important role in the regulation of neuronal development and neurogenesis in the dentate gyrus via modulation of gene expression. However, this mode of regulation is both incompletely described in the literature thus far and highly multifactorial. In this study, we designed sensors and detected relative levels of expression of 10 different miRNAs and found miR-338-3p was most highly expressed in the dentate gyrus. Comparison of miR-338-3p expression with neuronal markers of maturity indicates miR-338-3p is expressed most highly in the mature neuron. We also designed a viral "sponge" to knock down in vivo expression of miR-338-3p. When miR-338-3p is knocked down, neurons sprout multiple primary dendrites that branch off of the soma in a disorganized manner, cellular prolifera...

Cell Death and Disease, 2015

miR-34a influences neurogenesis and behaviour C Mollinari et al 2 Cell Death and Disease miR-34a influences neurogenesis and behaviour C Mollinari et al Cell Death and Disease miR-34a influences neurogenesis and behaviour C Mollinari et al

Molecular and Cellular Biology, 2009

Research on miRNAs has highlighted their importance in neural development, but the specific functions of neurally enriched miRNAs remain poorly understood. We report here the expression profile of miRNAs during neuronal differentiation in the human neuroblastoma cell line SH-SY5Y. Six miRNAs were significantly upregulated during differentiation induced by all-trans-retinoic acid and brain-derived neurotrophic factor. We demonstrated that the ectopic expression of either miR-124a or miR-125b increases the percentage of differentiated SH-SY5Y cells with neurite outgrowth. Subsequently, we focused our functional analysis on miR-125b and demonstrated the important role of this miRNA in both the spontaneous and induced differentiations of SH-SH5Y cells. miR-125b is also upregulated during the differentiation of human neural progenitor ReNcell VM cells, and miR-125b ectopic expression significantly promotes the neurite outgrowth of these cells. To identify the targets of miR-125b regulation, we profiled the global changes in gene expression following miR-125b ectopic expression in SH-SY5Y cells. miR-125b represses 164 genes that contain the seed match sequence of the miRNA and/or that are predicted to be direct targets of miR-125b by conventional methods. Pathway analysis suggests that a subset of miR-125b-repressed targets antagonizes neuronal genes in several neurogenic pathways, thereby mediating the positive effect of miR-125b on neuronal differentiation. We have further validated the binding of miR-125b to the miRNA response elements of 10 selected mRNA targets. Together, we report here for the first time the important role of miR-125b in human neuronal differentiation.