Proteins involved in neural network development identified
Under the leadership of SATO Haruka (formerly, Specially Appointed Researcher, Cellular and Molecular Neurobioloy Laboratory, Graduate School of Frontier Biosciences, Osaka University; currently, researcher at Institute of Molecular Embryology and Genetics, Kumamoto University) and YAMAMOTO Nobuhiko , Professor, Cellular and Molecular Neurobioloy Laboratory, Graduate School of Frontier Biosciences, Osaka University, a group of researchers, have clarified that, in the process of a neuron projection extending from the thalamus to the cerebrum, two proteins secreted from the thalamic axon terminals, Neuritin and VGF, promote survival of cerebral cortical neurons and dendritic growth. Considering that the amount of Neuritin and VGF change according to brain activity, it has been clarified that not only genes, but also acquired actions by these proteins play an important role in the development of brain networks.
Abstract
" The mammalian neocortex is composed of various types of neurons that reflect its laminar and area structures. It has been suggested that not only intrinsic but also afferent-derived extrinsic factors are involved in neuronal differentiation during development. However, the role and molecular mechanism of such extrinsic factors are almost unknown. Here, we attempted to identify molecules that are expressed in the thalamus and affect cortical cell development. First, thalamus-specific molecules were sought by comparing gene expression profiles of the developing rat thalamus and cortex using microarrays, and by constructing a thalamus-enriched subtraction cDNA library. A systematic screening by in situ hybridization showed that several genes encoding extracellular molecules were strongly expressed in sensory thalamic nuclei. Exogenous and endogenous protein localization further demonstrated that two extracellular molecules, Neuritin-1 (NRN1) and VGF, were transported to thalamic axon terminals. Application of NRN1 and VGF to dissociated cell culture promoted the dendritic growth. An organotypic slice culture experiment further showed that the number of primary dendrites in multipolar stellate neurons increased in response to NRN1 and VGF, whereas dendritic growth of pyramidal neurons was not promoted. These molecules also increased neuronal survival of multipolar neurons. Taken together, these results suggest that the thalamus-specific molecules NRN1 and VGF play an important role in the dendritic growth and survival of cortical neurons in a cell type-specific manner. "
Figure 1
To learn more about this research, please read the full research report entitled " Thalamus-derived molecules promote survival and dendritic growth of developing cortical neurons " at this page of the J Neurosci website.
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