'Junk DNA' could be culprit behind schizophrenia

Researchers have suggested that stretches of DNA called retrotransposons, often dubbed “junk DNA”, might be playing an important role in schizophrenia.

A Japanese team revealed that LINE-1 retrotransposons are abnormally abundant in the schizophrenia brain, and modify the expression of genes related to schizophrenia during brain development, and could be one of the causes of schizophrenia.

Retrotransposons are short sequences of DNA that autonomously amplify and move around the genome.

One class of retrotransposons named Long Interspersed Nuclear Elements (LINE) make up a large part of the eukaryotic genome and it is believed that they may contribute to a number of disorders and diseases such as cancer.

The team led by Dr Kazuya Iwamoto from the University of Tokyo and Dr Tadafumi Kato from the RIKEN Brain Science Institute demonstrated that the number of LINE-1 copies is elevated in the post-mortem brains of patients with schizophrenia.

They show using mouse and macaque models for schizophrenia and iPS cells that exposure to environmental risk factors during development, as well as the presence of genetic risk factors for schizophrenia, can lead to increased levels of LINE-1 in neurons.

The authors reveal employing whole genome analysis that in schizophrenia patients LINE-1 reinserts into genes involved in synaptic function or schizophrenia and may result in disruptions in their normal functions.

The study has been published in the journal Neuron.