Salk Institute scientists report in the journal Science that the type of mothering a female mouse provides her pups actually changes their DNA. The work lends support to studies about how childhood environments affect brain development in humans and could provide insights into neuropsychiatric disorders such as depression and schizophrenia.
According to Salk, most cells in the mammalian brain undergo changes to their DNA that make each neuron slightly different from its neighbor. Some of these changes are caused by “jumping” genes—known as long interspersed nuclear elements (LINEs)—that move from one spot in the genome to another. In 2005, Salk scientist Rusty Gage and his team discovered that a jumping gene called L1, which was already known to copy and paste itself into new places in the genome, could jump in developing neuronal brain cells.
As reported in Science, the team recently discovered a correlation between maternal care and L1 copy number: Mice with attentive mothers had fewer copies of the jumping gene L1, and those with neglectful mothers had more L1 copies, and thus more genetic diversity in their brains. Further research showed that mice with neglectful mothers had noticeably fewer methylated L1 genes than those with attentive mothers, suggesting that methylation is the mechanism responsible for the mobility of the L1 gene.