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The gene that triggers the formation of the nervous system is discovered
Last reviewed: 16.10.2021
The hypothesis that the nervous system in the fetus is formed by itself, without specific signals, has not been confirmed. Japanese researchers have found a gene that triggers the transformation of germ cells into nerve cells.
During the development of the embryo, an important stage of the formation of three embryonic leaves is isolated. In most multicellular cells at some stage, the embryo's body has a three-layered structure, and each of these layers - ectoderm, mesoderm and endoderm - is the precursor of a whole group of tissues. Thus, the exoderma derivatives will perform the integumentary and sensory functions in the future organism, that is, among other things, the ectodermal embryo leaf gives rise to the entire nervous system.
According to the results of studies of the formation of nervous tissue, a peculiar model was created, according to which the neural tissue is formed in the embryo in a passive way. In other words, when the other development alternatives have already been exhausted, and it is not necessary to form different integumentary tissues, then the nervous turn comes. This implies that there is no specific active signal at the beginning of this process: the cells of the ectoderm contain several protein-inhibitors that inhibit the development of nerve tissue. When everything else is formed, these inhibitors, figuratively speaking, release the reins, and the development of nervous tissue begins.
Researchers from the Center for Developmental Biology at the Institute of Physical and Chemical Research (RIKEN) managed to shake the passive development model of nervous tissue. The group, led by Yoshiki Sasai, investigated the activity of genes in the transformation of mouse embryonic progenitor cells of nervous tissue. It was found that the product of one of the genes, Zfp521, activates other genes involved in the process of creating nervous tissue, even in the presence of proteins that these genes usually suppress.
In the study of mouse embryos, it was found that the localization of the protein Zfp521 in the embryo and the time of its activity are related precisely to the place where the transformation of the ectoderm into nerve tissue begins. If mouse neoplasms at the early stage of development were injected with neuronal progenitor cells with the Zfp521 protein gene turned off, they could not be embedded in the developing nervous system of the embryo. Subsequent molecular genetic analysis has shown that this gene stimulates the transformation of the ectoderm into a neuroectoderm, from which, in turn, immediate neuronal precursors are obtained. Details of the experiments of Japanese researchers are described in the publication of the journal Nature.
Thus, the nervous tissue is formed not passively and not "by itself", but under the influence of a specific active regulator, which gives rise to its formation. Deciphering the mechanism can be extremely important for medicine if it can be shown that the formation of the nervous tissue in man is also triggered in exactly the same way.