Document Type

Dissertation - Open Access

Award Date

2020

Degree Name

Doctor of Philosophy (PhD)

Department / School

Pharmaceutical Sciences

First Advisor

Wenfeng An

Keywords

5'UTR promoter activity, in situ detection, L1, LINE-1, Retrotransposons, X-gal staining

Abstract

Apart from an evolutionary role, transposable elements have been implicated in animal development and also in pathophysiology. Non-LTR retrotransposons– LINE-1, Alu and SVA - are responsible for over 120 cases of human genetic diseases as heritable insertions, and are emerging as an important etiological factor for cancer and neurological disorders as somatic mutations. It is estimated that among the total number of 500,000 LINE-1s presents in the human genome, 80-100 LINE-1s remain competent for retrotransposition. Retrotransposition is only possible when LINE-1 is expressed. Because LINE-1 transcription is regulated by its 5’UTR promoter, it is essential to understand the spatiotemporal control of LINE-1 promoter activity. The huge abundance, repetitive nature and complex expression patterns of LINE-1s in the human and mouse genomes necessitate the development of innovative approaches and the careful design of experimental procedures used to study these elements. The primary objective of this dissertation was to develop and validate a mouse model, which can be utilized for studying LINE-1 promoter activity in vivo. Here, we utilized an in situ staining technique to quantify the endogenous LINE-1 promoter activity in different organs of the mouse model - to understand any organ-specific regulation of the mouse endogenous LINE-1 promoter activity. Moreover, by integrating the transgene into random or specific genomic loci in different orientations, we characterized the locus-dependent as well as the orientation-dependent expression patterns. In all these aspects, we attempted to understand LINE-1 promoter regulation during different periods of mouse development. Lastly, we also attempted to understand the cell-specific regulation, especially in the brain. We reported here organ-specific, agelinked, locus-associated, and orientation-dependent LINE-1 promoter activities in the mouse genome. Out study provides novel insights into LINE-1 biology and the new mouse model will serve as an invaluable tool to the LINE-1 field.

Library of Congress Subject Headings

Transposons.
Mobile genetic elements.
Genomes.
Transgenic mice.

Format

application/pdf

Number of Pages

175

Publisher

South Dakota State University

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Rights Statement

In Copyright