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Quantitative Analysis of L1-Retrotransposons in Alzheimer’s Disease and Aging

M. S. Protasova1*, F. E. Gusev1, A. P. Grigorenko1,2, I. L. Kuznetsova1, E. I. Rogaev1,2,3, and T. V. Andreeva1

1Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; E-mail: maria2100@list.ru

2University of Massachusetts Medical School, Brudnick Neuropsychiatric Research Institute, Department of Psychiatry, 303 Belmont Street, Worcester, MA 01604, USA

3Faculty of Biology, Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia

* To whom correspondence should be addressed.

Received April 3, 2017
LINE1 retrotransposons are members of a class of mobile genetic elements capable of retrotransposition in the genome via a process of reverse transcription. LINE1 repeats, integrating into different chromosomal loci, affect the activity of genes and cause different genomic mutations. Somatic variability of the human genome is linked to the activity of some subfamilies of LINE1, in particular, a high level of LINE1 retrotranspositions has been observed in brain tissues. However, the contribution of LINE1 to genomic variability during normal aging and in age-related neurodegenerative diseases is poorly understood. We conducted quantitative real-time PCR analysis of active subfamilies of LINE1 repeats (aL1) using genomic DNA extracted from brain specimens of Alzheimer’s disease (AD) patients and individuals without neuropsychiatric pathologies, as well as DNA extracted from blood specimens of individuals of different ages (healthy and AD subjects). Inter-individual quantitative variations of active families of aL1 repeats in the genome were observed. No significant age-dependent differences were identified. Likewise, no difference of aL1 copy number in brain and blood were indicated between AD patients and the aged-matched control group without dementia. These data imply that aging and the AD-associated neurodegenerative process are not the major factors contributing to the retrotransposition processes of active LINE1 repeats.
KEY WORDS: LINE1, retrotransposons, Alzheimer’s disease, aging, quantitative analysis

DOI: 10.1134/S0006297917080120