Faulty Stem Cell Regulation may contribute to Cognitive Deficits Associated with Down Syndrome

Research Down Syndrome grantee Dr. Craig Garner was co-author of a just released paper out of Stanford University. The report described studies using both human skin cells and the Down syndrome mouse model Ts65Dn in deciphering the impact of a gene named Usp16 on stem cell growth. (Stem cells are unspecialized cells that renew themselves and function as a primal source of tissue or organ specific cells with special functions.) The gene Usp16 is found on human chromosome 21 and thus in triplicate copy in persons with Down syndrome. In experiments testing human cells, researchers discovered that an excess of Usp16 in cells from people without Down syndrome caused skin cells to grow more slowly. Also, reducing Usp16 in skin and nerve cells in people with Down syndrome allowed the cells to have normal growth patterns rather than to regenerate slowly.

In the model study using the Ts65Dn mouse with gene Usp16 in triplicate, researchers found that neural stem cells from the mice were less able to self-renew and grow normally than were cells from mice with a duplicate copy. When the researchers reduced the expression of Usp16 in the cells from the Ts65Dn mice to more normal levels, these functional defects were largely corrected. Dr. Garner said that the extra copy of chromosome 21 and the Usp16 gene may speed up the rate that stem cells are used during early development, exhausting the stem cell pools needed to regenerate tissues as adults. Dr. Garner stated further, "This study suggests that drug-based strategies to slow the rate of stem cell use could have profound effects on cognitive function, aging and risk for Alzheimer’s disease in people with Down syndrome".

Michael Clark M.D. was senior author of this paper.

More information on this interesting study may be found in this release issued by Stanford University:

http://med.stanford.edu/ism/2013/september/clarke.html