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Sunday, 13 November 2016 14:57

Species differences: Bone gene with new function in the brain

The fact that there are species differences between humans and animals is a truism which now getting new food. A research team led by Michael E. Greenberg from the Harvard Medical School in Boston has found a gene in human nerve cells which belongs to the bone and muscle cells and has been switched on in primate nerve cells in the course of the evolution. The activated gene could have led to an increased brain growth in primates.

The activated gene is called OSTN, a gene coding for the protein osteocrin. Normally, it regulates the differentiation of bone-forming cells (osteoblasts) into bones. In other cell types it is inactive, because a so-called enhancer is missing, which promotes the production of the messenger RNA in the gene reading process. In primates, however, due to the enhancer, OSTN has obtained an additional function in the nerve-cells of the cerebral cortex and other definite regions. Enhancers are DNA domains of several hundred base pairs that flank the genes in the 3' or 5' position, which have an important function in gene regulation by interacting with DNA proteins. The interaction brings the enhancer close to the promoter region thus affecting other proteins that are responsible for reading and implementation of the gene. The implementation of the gene into a protein - in this case osteocrin - is promoted. In mice and rats this enhancer function is absent. In macaques this gene is active during the processing of visual signals.

The authors suppose that by controlling the cross-linking of nerve cells in the cerebral cortex osteocrin has led to the differences in the development of the brain and thus the different cognitive abilities of mice and humans. In addition, the authors suspect that a mutation of the OSTN in the nerve cells could be responsible for certain impairments of the brain or disturbances in brain intelligence development or autistic disorders.

To considerate these findings, developmental neurotoxicological intelligence tests with rodents could possibly be seen in a different light.

The scientists have published their findings in Nature:
Bulent Ataman, Gabriella L. Boulting, David A. Harmin et al. (2016): Evolution of osteocrine as an activity-regulated factor in the primates Brain.


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