Some so-called jumping genes that
copy and paste themselves throughout the genome may be linked to schizophrenia,
new research suggests. A new study suggests these jumping genes may alter how
neurons (or nerve cells in the brain) form during development, thereby
increasing the risk of schizophrenia. Jumping genes, or retrotransposons, are
mobile genetic elements that copy and paste themselves at different places
throughout the genome. About half of the human genome is made of these
mysterious elements, compared with the 1 percent of genes that actually code
for making proteins. Earlier studies had found that a certain type of jumping
gene, known as long interspersed nuclear element-1 (LINE-1), was active in
human brain cells. Kato and his colleagues wondered whether they might play a
role in mental illness. To find out, the team conducted a post-mortem analysis
of 120 human brains, 13 from patients who had been diagnosed with
schizophrenia.
Researchers at the RIKEN Brain
Science Institute in Japan found a higher number of LINE-1 copies in the brains
of schizophrenics compared with other groups. They also found that stem cells
derived from the brains of people with schizophrenia had a higher concentration
of LINE-1 genes than did those from people without the diagnosis. Mice and
primates with inflammation meant to mimic schizophrenia, introduced by the
researchers, also had more of these movable genetic elements than healthy
animals. They also found that in people with schizophrenia, LINE-1
concentrations were increased near genes associated with psychiatric disorders
that control how neurons in the brain communicate with one another. The
findings suggest these LINE-1 segments may be inserting themselves into genes
critical for brain development. When triggered by genetic and or environmental
factors, they may alter that brain development, leading to schizophrenia.
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