Stem cells have more reserves for DNA replication

In cell division, nothing is as important as the precise replication of billions of genetic letters that make up DNA. Since this genomic integrity is so fundamental to survival, scientists had assumed that replication mechanisms operate the same way in all cells, which depend in part on molecular reserves called dormant origins.   However, stem cells—which give rise to many different cell types—have more of these reserves at hand that help them deal with the ill effects of stress, reported Yale researchers on July 16 in the journal Stem Cell Reports.

Senior author Haifan Lin, director of the Yale Stem Cell Center, explains these molecular reinforcements are normally dormant but in times of stress are activated.   "They are like construction workers that can be called in during bad weather to make sure the job is completed," Lin said. 

Embryonic stem cells have more of these reinforcements than any type of cell, but if they lack these reserves, the specialized stem cells they generate, such as neural stem cells, will also lack dormant origins

Neural stem cells lacking these reserves do not respond well to stress, and in mice with this lack, brain development progresses much more slowly.  A shortage in dormant origins might cause the human condition Meier-Gorlin Syndrome, a form of dwarfism that starts during fetal development.