Author ORCID Identifier

0000-0002-4643-7078

Date of Graduation

5-2018

Document Type

Dissertation (PhD)

Program Affiliation

Genes and Development

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Guillermina Lozano

Committee Member

Swathi Arur

Committee Member

Richard Behringer

Committee Member

Anil Sood

Committee Member

William Mattox

Abstract

Altered DICER1 protein levels are associated with developmental disorders, infertility, macular degenerative blindness, aging, and cancer in humans. Recently, post-translational regulation of Dicer1 via phosphorylation has been described in C. elegans. Oscillation of Dicer1 phosphorylation to regulate its activity is essential for germ cell development and embryogenesis in worms. These observations led us to posit that Dicer1 protein levels and activity are under tight regulation for normal mammalian homeostasis. To test whether phosphorylation of Dicer1 regulates its activity in mammals, I generated phospho-mimetic knock-in mouse models by replacing Serines 1712 and 1836 with Aspartic acids individually or together (dual phosphorylation). Dicer1 functions are impaired by phosphorylation at Ser1836, and further augmented by Ser1712 phosphorylation. Constitutive Dicer1 phosphorylation at Ser1836 leads to highly penetrant post-natal lethality, and accelerates aging and causes infertility in survivors. Homozygosity of dual phosphorylated Dicer1 leads to a hypermetabolic phenotype in MEFs and mice, while heterozygosity is sufficient to promote tumor development and dissemination in two independent tumor models. I have identified a phospho-Dicer1 specific miRNA signature that is strongly associated with metabolic and oncogenic pathways. These data identify constitutive phosphorylation of Dicer1 as a driver of pathologies in mammals, with the phenotypes in mice resembling the spectrum of human diseases associated with dysregulated DICER1.

Keywords

Dicer, miRNA, Phosphorylation, ERK, KRas, p53, Aging, Cancer, Metabolism

Available for download on Friday, October 26, 2018

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