A study of neural-related microRNAs in the developing amphioxus

Abstract

BackgroundMicroRNAs are small noncoding RNAs regulating expression of protein coding genes at post-transcriptional level and controlling several biological processes. At present microRNAs have been identified in various metazoans and seem also to be involved in brain development, neuronal differentiation and subtypes specification. An approach to better understand the role of microRNAs in animal gene expression is to determine temporal and tissue-specific expression patterns of microRNAs in different model organisms. Therefore, we have investigated the expression of six neural related microRNAs in amphioxus, an organism having an important phylogenetic position in terms of understanding the origin and evolution of chordates.ResultsIn amphioxus, all the microRNAs we examined are expressed in specific regions of the CNS, and some of them are correlated with specific cell types. In addition, miR-7, miR-137 and miR-184 are also expressed in endodermal and mesodermal tissues. Several potential targets expressed in the nervous system of amphioxus have been identified by computational prediction and some of them are coexpressed with one or more miRNAs.ConclusionWe identified six miRNAs that are expressed in the nervous system of amphioxus in a variety of patterns. miR-124 is found in both differentiating and mature neurons, miR-9 in differentiated neurons, miR-7, miR-137 and miR-184 in restricted CNS regions, and miR-183 in cells of sensory organs. Therefore, such amphioxus miRNAs may play important roles in regional patterning and/or specification of neuronal cell types.

Connecting Ears to Eye Muscles: Evolution of a ‘Simple' Reflex Arc

“…However, many deuterostomes have at least cellular precursors that presage the morphological evolution of the vertebrate hair cells Burighel et al, 2011;Fritzsch and Straka, 2014]. These primordial and definitive hair cells can be identified not only by their morphological similarities but also by their expression of a unique set of transcription factors and microRNAs [Pierce et al, 2008;Candiani et al, 2011;Joyce Tang et al, 2013]. Experimental evidence suggests that in vertebrates the respective gene products are essential for normal hair cell differentiation [Soukup et al, 2009;Pan et al, 2012].…”

“…A specific set of these regionally diverse vestibular projection neurons functions as the central element that transforms vestibular sensory signals generated by active and passive head and body movements into motor output through the extraocular muscles. The large dynamic range of motion-related sensory signals requires an organi-rons, and the lateral eyes and ears found in vertebrates [Fritzsch, 1996;Fritzsch and Glover, 2007] even though molecular data identify sensory precursor cells in deuterostome outgroups of vertebrates [Pierce et al, 2008;Candiani et al, 2011;Vopalensky et al, 2012;Joyce Tang et al, 2013]. While the functional organization of the three-neuron VOR arc that links vestibular sensory organs in the inner ear to eye muscles has long been established [Szentagothai, 1950], it has only recently become apparent how such a complex system of two sensors interconnected by spatially specific neural pathways may have evolved.…”

Convergent repression of Foxp2 3′UTR by miR-9 and miR-132 in embryonic mouse neocortex: implications for radial migration of neurons

“…miRNAs are a class of short (~22 nucleotide), non-coding RNAs that control gene expression at the post-transcriptional level, primarily by imperfect base pairing with specific mRNA targets (Krol et al, 2010). The expression patterns and targets of several miRNAs are conserved across chordate evolution, from amphioxus to mammals, suggesting an ancient origin and crucial function in evolutionarily conserved developmental processes (Candiani et al, 2011). Currently, more than 700 miRNAs have been identified in the mouse (http://www.mirbase.org/blog/2011/11/mirbase-18-released/).…”

Les multiples facettes d’un petit régulateur

“…La caractérisation des microARN exprimés dans les différents tissus de vertébrés a mis en évidence une expression très forte de miR-9 dans les tissus neuraux embryonnaires et adultes [9][10][11]. Ce pourrait être une caractéristique ancestrale, miR-9 étant exprimé dans des neurones de l'amphioxus ou d'un annélide [12,13]. Néanmoins, une situation différente s'observe chez la drosophile.…”