| The discovery of microRNA as an additional | | | | microarray was used. Expression of miRNA was |
| regulatory mechanism has been a revolution to the | | | | evaluated using miRNA microarrays (provided by LC |
| field of Developmental Biology. While early research | | | | Sciences). Both mRNA and miRNA expression was |
| has focused on the identification of miRNAs using a | | | | validated using qRT-PCR. |
| combination of experimental and computational | | | | Bio-informatics analysis was then carried out on the |
| techniques, subsequent studies have focused on | | | | two data-sets to show the negative correlation |
| identification of miRNA-target mRNA pairs as a | | | | between predicted mRNA targets and miRNA |
| means of identifying regulatory networks. It has been | | | | expression, indicating a gene expression regulatory |
| shown that the relationship between messenger RNA | | | | network at work. The negative correlation found in |
| and microRNA (often an inverse relationship) plays a | | | | this study supports the theory that miRNAs play a |
| large role in cell functionality, especially in the early | | | | larger role in modulating the expression of genes |
| stages of cell development. | | | | which are essential for cortical neurogenesis. As |
| The identification of miRNAs, their target mRNAs, | | | | neuronal differentiation progresses, up-regulated |
| and the construction of their regulatory networks will | | | | miRNA may down-regulate the expression of genes |
| provide new insights into complex biological | | | | which are no longer required. |
| procedures. There has been extensive computational | | | | The availability of mRNA and miRNA profiles from the |
| analysis of transcriptome and microRNAome data; | | | | same cell type represents a major limitation in the |
| however, many of the data-sets are derived from | | | | network analysis of genetic circuits. A platform |
| separate studies. There is a need for studies | | | | capable of generating integrated data-sets, not only |
| encompassing both data-sets from cells within the | | | | from the same cell type, but from cells within the |
| same context for better understanding of miRNA - | | | | same context would be an important new tool for |
| target interaction. Access to both data-sets plus new | | | | analysis of miRNA - target interaction. Such a tool |
| bio-informatics capabilities represents a powerful new | | | | may provide a solution for:o Validation of |
| functional genomics tool for construction of cell | | | | computational methods of target predictiono |
| development networks/pathways and also for | | | | Discovery of novel regulatory pathwayso Elucidating |
| unraveling the complex mechanism of action of | | | | the mechanism of action of miRNAso Providing |
| miRNA. | | | | datasets for the development of new pathway |
| In a recent study, researchers at the NIH used | | | | analysis algorithmso A diagnostic device for improving |
| microarray analysis to show the correlation between | | | | bio-molecular classification of human cancers |
| mRNA and miRNA in neuronal cortical development*. | | | | * Nielsen JA, Lau P, Maric D, Barker JL, Hudson LD. |
| Rat neuronal progenitors were obtained at days 11, | | | | (2009) Integrating microRNA and mRNA expression |
| 12, and 13 and their total RNA extracted. To evaluate | | | | profiles of neuronal progenitors to identify regulatory |
| the expression of mRNA a gene expression profile | | | | networks underlying the onset of cortical |
| using the Affymetrix Rat Expression 230 2.0 | | | | neurogenesis. BMC Neurosci 10(1), 98. |