The MECP2 gene involved in the development of a developmental disorder called Rett syndrome influences the activity of the mobile element of the DNA responsible for regulating gene expression and the functioning of the nervous system, according to scientists from the US in the journal Nature.
Rett syndrome is a developmental disorder caused by a mutation in the MECP2 gene located in the X chromosome of the sex chromosome. on the gradual deterioration of the child’s physical functioning (children stop walking, use deliberate hand movements), the aggravation of mental retardation, which is accompanied by autism.
One of the most common moving elements of DNA in the genome are the so-called retrotransposons – RNA molecules containing genes encoding enzymes that enable them to move and the so-called reverse transcription, i.e. DNA synthesis based on a template – RNA strands. When the retrotransposon is active, first a double-stranded molecule made of one strand of RNA and one strand of DNA is formed, then appropriate enzymes remove the RNA strand and in its place other strands synthesize the second strand of DNA, and in this form a new DNA fragment can be inserted into the genome.
The role of retrotransposons has not been fully explained so far – it is known that they constitute about one fifth of the genetic material of mammals, can regulate gene expression and are also involved in the modification of the nervous system.
Alysson Muotri and colleagues at the University of California have shown that mutant MECP2 cells from patients with Rett syndrome have increased activity of a retrotransposon called L1. A similar situation was observed in rodents, where also the lack of the MECP2 gene is associated with increased L1 activity.
Scientists do not yet know whether the increase in retrotransposone activity is a consequence or the cause of the disease. Nevertheless, the authors suspect that inserting new DNA fragments into the genome, especially in the early stages of development, may affect the functioning of the nervous system later in life. (PAP)