Establishment of Quantitative PCR Assays for Active Long Interspersed Nuclear Element-1 Subfamilies in Mice and Applications to the Analysis of Aging-Associated Retrotransposition

• Main Authors: Ryota Kuroki, Yui Murata, Satoshi Fuke, Yutaka Nakachi, Jun Nakashima, Gregory C. Kujoth, Tomas A. Prolla, Miki Bundo, Tadafumi Kato, Kazuya Iwamoto
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2020-09-01
• Series: Frontiers in Genetics
• Subjects: retrotransposition; mitochondrial DNA; non-LTR; basal ganglia; somatic mosaicism; POLG
• Online Access: https://www.frontiersin.org/article/10.3389/fgene.2020.519206/full

The retrotransposon long interspersed nuclear element-1 (LINE-1) can autonomously increase its copy number within a host genome through the retrotransposition process. LINE-1 is active in the germline and in neural progenitor cells, and its somatic retrotransposition activity has a broad impact on neural development and susceptibility to neuropsychiatric disorders. The method to quantify the genomic copy number of LINE-1 would be important in unraveling the role of retrotransposition, especially in the brain. However, because of the species-specific evolution of LINE-1 sequences, methods for quantifying the copy number should be independently developed. Here, we developed a quantitative PCR (qPCR) assay to measure the copy number of active LINE-1 subfamilies in mice. Using the assay, we investigated aging-associated alterations of LINE-1 copy number in several brain regions in wild-type mice and Polg+/D257A mice as a model for accelerated aging. We found that aged Polg+/D257A mice showed higher levels of the type GfII LINE-1 in the basal ganglia than the wild-type mice did, highlighting the importance of assays that focus on an individual active LINE-1 subfamily.