Expression and function of microRNA-9 in the mid-hindbrain area of embryonic chick.
BACKGROUND
MiR-9 is a small non-coding RNA that is highly conserved between species and primarily expressed in the central nervous system (CNS). It is known to influence proliferation and neuronal differentiation in the brain and spinal cord of different vertebrates. Different studies have pointed to regional and species-specific differences in the response of neural progenitors to miR-9.


METHODS
In ovo and ex ovo electroporation was used to overexpress or reduce miR-9 followed by mRNA in situ hybridisation and immunofluorescent stainings to evaluate miR- expression and the effect of changed miR-9 expression.


RESULTS
We have investigated the expression and function of miR-9 during early development of the mid-hindbrain region (MH) in chick. Our analysis reveals a closer relationship of chick miR-9 to mammalian miR-9 than to fish and a dynamic expression pattern in the chick neural tube. Early in development, miR-9 is diffusely expressed in the entire brain, bar the forebrain, and it becomes more restricted to specific areas of the CNS at later stages. MiR-9 overexpression at HH9-10 results in a reduction of FGF8 expression and premature neuronal differentiation in the mid-hindbrain boundary (MHB). Within the midbrain miR-9 does not cause premature neuronal differentiation it rather reduces proliferation in the midbrain.


CONCLUSION
Our findings indicate that miR-9 has regional specific effects in the developing mid-hindbrain region with a divergence of response of regional progenitors.
['Alwin Prem Anand|A|A|', 'Huber|Carola|C|', 'Asnet Mary|John|J|', 'Gallus|Nancy|N|', 'Leucht|Christoph|C|', 'Klafke|Ruth|R|', 'Hirt|Bernhard|B|', 'Wizenmann|Andrea|A|0000-0001-9766-2315']
D000818:Animals D030161:Avian Proteins D002455:Cell Division D002642:Chick Embryo D017124:Conserved Sequence D015536:Down-Regulation D019143:Evolution, Molecular D018507:Gene Expression Regulation, Developmental D008636:Mesencephalon D035683:MicroRNAs D054259:Neural Tube D055495:Neurogenesis D012249:Rhombencephalon D013234:Stem Cells
Mid-hindbrain area Chick miR-9 Brain development microRNA