Kapsimali, M., Kloosterman, W.P., de Bruijn, E., Rosa, F., Plasterk, R.H., and Wilson, S.W. (2007) MicroRNAs show a wide diversity of expression profiles in the developing and mature central nervous system. Genome biology. 8(8):R173.
BACKGROUND: miRNA encoding genes are abundant in vertebrate genomes but very few have been studied in any detail. Bioinformatic tools allow prediction of miRNA targets and this information coupled with knowledge of miRNA expression profiles facilitates formulation of hypotheses of miRNA function. Although the central nervous system (CNS) is a prominent site of miRNA expression, virtually nothing is known about the spatial and temporal expression profiles of miRNAs in the brain. To provide an overview of the breadth of miRNA expression in the CNS, we performed a comprehensive analysis of the neuroanatomical expression profiles of 38 abundant conserved miRNAs in developing and adult zebrafish brain. RESULTS: Our results show miRNAs have a wide variety of different expression profiles in neural cells including: expression in neuronal precursors and stem cells (eg. miR-92b); expression associated with transition from proliferation to differentiation (eg. miR-124); constitutive expression in mature neurons (miR-124 again); expression in both proliferative cells and their differentiated progeny (eg. miR-9); regionally restricted expression (eg. miR-222 in telencephalon) and cell-type specific expression (eg. miR-218a in motor neurons). CONCLUSIONS: The data we present facilitate prediction of likely modes of miRNA function in the CNS and many miRNA expression profiles are consistent with the mutual exclusion mode of function in which there is spatial or temporal exclusion of miRNAs and their targets. However some miRNAs, such as those with cell-type specific expression, are more likely to be co-expressed with their targets. Our data provides an important resource for future functional studies of miRNAs in the CNS.