Date of Award

2017

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Biological Sciences (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Xiaoqing Tang

Committee Member 1

Guiliang Tang

Committee Member 2

Zhiying Shan

Committee Member 3

Jeremy Goldman

Abstract

In pancreatic beta cells, insulin biosynthesis and secretion is tightly regulated by a network of transcriptional activators and repressors that maintain the fate of beta cells and activate genes in response to the change of plasma glucose. The discovery of small non-coding microRNAs (miRNAs) has added a novel regulatory layer on modulating levels of key components involved in beta cell proliferation, survival, insulin biosynthesis and secretion.

In this thesis, we focused on dissecting the functions of miR-30d, a highly expressed and glucose-stimulated miRNA in pancreatic beta-cells by combining cellular and molecular techniques, high-throughput deep sequencing, mouse and cell line genetic approaches. We have shed light on the novel roles of miR-30d in regulating β-cell mass on the middle-aged mice under high-fat diet treatment. We further demonstrated it induced beta-cell apoptosis and inhibit beta-cell proliferation by targeting variety of gene expression including BCL2 interacting protein 3 (Bnip3) and Cyclin E2 (Ccne2). Furthermore, silencing of miR-30d by advanced CRISPR-CAS9 gene editing system promotes the insulin secretion, which is through potentiated expression of MAFA, an insulin transcription factor. High-Seq analysis and further target searching revealed 13 candidate targets of miR-30d in MIN6 cells involved in various functions. These studies uncovered novel functional roles of the miR-30d pathway in mediating β-cell function and fate. Further dissection shall uncover the mechanisms by which the β-cells utilized to maximize their efficiency during disease states such as T2D.

Available for download on Monday, July 09, 2018

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