Nucleo-Loss: Characterization of Ribosome Biogenesis Factor DIMT1 / Julian Stoute.

Format:

Book

Thesis/Dissertation

Author/Creator:

Stoute, Julian, author.

Contributor:

University of Pennsylvania. Biochemistry and Molecular Biophysics, degree granting institution.

Language:

English

Subjects (All):

Biochemistry.

Biophysics.

Molecular biology.

Biochemistry and Molecular Biophysics--Penn dissertations.

Penn dissertations--Biochemistry and Molecular Biophysics.

Local Subjects:

Biochemistry.

Biophysics.

Molecular biology.

Biochemistry and Molecular Biophysics--Penn dissertations.

Penn dissertations--Biochemistry and Molecular Biophysics.

Physical Description:

1 online resource (170 pages)

Distribution:

Ann Arbor : ProQuest Dissertations & Theses, 2023

Contained In:

Dissertations Abstracts International 84-12B.

Place of Publication:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2022.

Language Note:

English

Summary:

The ribosome is an essential component of the central dogma of life. It is primarily responsible for translation, in which mRNA transcripts are decoded, and proteins are synthesized. The ribosome consists primarily of ribosomal RNA (rRNA). After transcription, it is processed in a series of steps where it is folded, cut, and chemically modified until mature ribosome subunits are formed and exported out of the nucleus. One of the early steps of the process of ribosome biogenesis involves the methyltransferase enzyme DIMT1. This enzyme is essential for processing 18S rRNA, which makes up the ribosome's small subunit (SSU). DIMT1 specifically binds during the post-A1 stage of SSU processing to helix 45 of 18S rRNA, where it installs m26,6A modification at sites 1850 and 1851 in the mammalian ribosomal sequence. The installation of m26,6A at these sites in the SSU is highly conserved across the kingdoms of life.Additionally, knockout (KO) of DIMT1 is known to be lethal. However, the exact details of DIMT1 functions in 18S biogenesis and what function 18S m26,6A serves for ribosome activity are not fully understood. In this thesis, we delve into the science behind DIMT1 and describe the properties behind its operation in cell biology. Firstly, our high throughput sequencing experiments show that DIMT1 significantly impacts several transcripts' transcription and translation efficiency. These transcripts are associated with various Gene Ontology (GO) terms. In particular, we identified transcripts related to cell cycle regulation, translation, DNA damage response, cell adhesion/migration, and immune response pathways. We find that DIMT1's catalytic activity is non-essential for cell survival or ribosome biogenesis.Additionally, our cell line model for catalytically inactive DIMT1 displays only a minor effect on translation rates and the fidelity of internal ribosome entry, while catalysis is dispensable for ribosome biogenesis. Secondly, we find that the DIMT1's RNA binding ability plays a huge role in cell biology. Our RNA-binding deficient DIMT1 model demonstrates that without DIMT1's ability to bind to RNA, RNA biogenesis is impaired, and cell viability is lost. Additionally, DIMT1 RNA binding is essential for DIMT1's ability to phase separate and localize to the nucleolus, the primary site of rRNA processing. Finally, we also provide evidence of DIMT1-mediated m26,6A modification on a species of small RNAs. Together, our data expands on the role DIMT1 plays in ribosome processing and cell function and expands on the importance of ribosome biogenesis factors, the role of phase separation, and the diversity of factors that drive phase separation. Additionally, our data provide more context for perceiving DIMT1 as an oncogene and provides evidence to support targeting DIMT1 as a treatment for a variety of cancer, including multiple hematopoietic malignancies and gastric carcinomas in particular.

Notes:

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

Advisors: Liu, Kathy; Bonasio, Roberto; Committee members: Conn, Crystal; Nishikura, Kazuko; Cooperman, Barry.

Department: Biochemistry and Molecular Biophysics.

Ph.D. University of Pennsylvania 2023.

Local Notes:

School code: 0175

ISBN:

9798379750565

Access Restriction:

Restricted for use by site license.