DOI

https://doi.org/10.25772/8YW3-4N88

Defense Date

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Human and Molecular Genetics

First Advisor

Dr. Larisa Litovchick

Abstract

Human Dual specificity tyrosine (Y)-Regulated Kinase 1A (DYRK1A) is a protein kinase encoded by a dosage-dependent gene. An extra copy of DYRK1A contributes to Down syndrome (DS) pathogenesis while loss of one allele causes severe mental retardation and autism. DYRK1A is involved in phosphorylation of several proteins that regulate cell cycle control and tumor suppression. However, the function and regulation of this kinase is not well understood and current knowledge does not fully explain dosage-dependent function of this important kinase. Our previous proteomic studies identified several novel DYRK1A interacting proteins including RNF169, FAM117B, TROAP, LZTS1, LZTS2 and DCAF7. In this dissertation, we report the proteomic, biochemical and functional characterization of this DYRK1A protein-protein interaction network. Firstly, we show that DYRK1A regulates that recruitment of 53BP1 to DNA double strand breaks (DSBs) in part through its interaction with RNF169. This revealed a novel role of DYRK1A in DSB repair pathway choice. Secondly, we identify LZTS1 and LZTS2 as novel regulators of DYRK1A activity towards LIN52. Thirdly, we observed that DCAF7 interacts with several other DYRK1A-binding proteins including RNF169, TROAP, FAM117B, LZTS1 and LZTS2 giving rise to various multi-subunit protein complexes, but it does not act as a scaffold for these interactions. We also observed an unexpected role of DYRK1A in mediating the interaction between these DYRK1A-binding proteins and DCAF7, which could explain some aspects of the dosage-dependent function of DYRK1A.

As DCAF7 was the most highly enriched DYRK1A-interacting protein, we generated and analyzed the DCAF7 interactome in order to understand the functional significance of the DYRK1A-DCAF7 interaction. We show that DCAF7 interacts with the components of a multi-subunit Polycomb Repressive Complex 1.3/5 (PRC1.3/5) independent of DYRK1A, but DYRK1A could influence the molecular size of the PRC1.3/5 complex. Furthermore, our data suggest that DYRK1A and DCAF7 regulate the monoubiquitination of H2A at K119 by PRC1.3/5. Using RNA-seq analysis, we identified a common set of genes regulated by DYRK1A and DCAF7. Our data shows that DCAF7 requires DYRK1A for its transcriptional effect. Future studies will be focused to determine the molecular mechanism by which DYRK1A and DCAF7 regulate the transcription of the PRC1.5 target genes.

In conclusion, DYRK1A interacting proteins could regulate the activity and function of DYRK1A and play a role in its biological functions including tumor suppression, the DNA damage response and transcription.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

4-26-2020

Available for download on Monday, April 26, 2021

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