How Some Brain Cells Escape Aging

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Researchers have discovered a mechanism that allows neural stem cells to stay relatively free of aging-related damage: A diffusion barrier regulates the sorting of damaged proteins during cell division.

A group of scientists led by Sebastian Jessberger of the Brain Research Institute of the University of Zurich showed that the stem cells of the adult mouse brain asymmetrically segregate aging factors between the mother and the daughter cells. Responsible for this is a diffusion barrier in the endoplasmic reticulum (a channel system within the cell that is for example important for protein synthesis and transport). The barrier prevents retention of damaged proteins in the stem cell daughter cell keeping the stem cells relatively clean. “Neural stem cell divisions appear to be much more asymmetric than we had previously anticipated,” said lead study author Darcie Moore.

The finding was published in the journal Science.

In addition, the authors found that the strength of the barrier weakens with advancing age. This leads to reduced asymmetry of damaged protein segregation with increasing age of the stem cell. This could be one of the mechanisms responsible for the reduced regeneration capacity in the aged brain as stem cells that retain larger amounts of damaged proteins require longer for the next cell division.

“This is an exciting new mechanism involved in stem cell division and aging. But as of now we are only just beginning to understand the molecular constituents and the true meaning of the barrier for stem cell division in the brain,” Jessberger said. One key question to be answered is whether the barrier is established in all somatic stem cells of the body. The answer to this question may open new routes to target age-dependent alterations of stem cell activity in human disease.