Date of Award

2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Cell & Molecular Biology

First Advisor

P. Jeremy Wang

Abstract

GENETIC REQUIREMENT FOR THE RNA HELICASE MOV10L1 IN PIRNA BIOGENESIS

Qi Fu

P. Jeremy Wang

Piwi-interacting RNAs (piRNAs) are a class of small non-coding RNAs required for transposon silencing, germ cell development, and fertility in many eukaryotic species. However, many of the mechanisms underlying piRNA biogenesis have not been elucidated. Studies of MOV10L1 support its function as an RNA helicase in the processing of piRNA precursors. In this study, we elucidate the requirement for MOV10L1 RNA helicase activity in piRNA biogenesis.

To determine the requirement for MOV10L1 RNA helicase activity in piRNA biogenesis in vivo, we generated two knock-in mouse models containing mutations in residues of Mov10l1 that are critical for its RNA helicase activity. The two Mov10l1 knockin mutants displayed numerous phenotypes associated with impaired piRNA biogenesis. Adult male Mov10l1 knockin mutants exhibited meiotic arrest and sterility. piRNAs associated with the Piwi proteins MILI and MIWI2 were depleted in the Mov10l1 knockin mutants. The retrotransposons LINE1 and IAP were de-repressed in the germ cells of the Mov10l1 knockin mutants. Finally, the levels of piRNA precursor transcripts were upregulated in one of the Mov10l1 knockin mutants. Interestingly, the piRNA pathway proteins MOV10L1, MILI, and MIWI2 formed a polar conglomerate in the embryonic germ cells of the Mov10l1 knockin mutants, and MOV10L1 was not expressed post-natally in the Mov10l1 knockin mutants. Studies of the two Mov10l1 knockin mutants show that MOV10L1 RNA helicase activity is required for the processing of piRNA precursors and piRNA biogenesis.

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