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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Chromatin Regulation By Rb-Interacting Proteins In Cellular Immune Functions, Seung June Kim Nov 2022

Chromatin Regulation By Rb-Interacting Proteins In Cellular Immune Functions, Seung June Kim

Electronic Thesis and Dissertation Repository

The retinoblastoma protein (RB) is historically known for its function in cell cycle control. However, mice carrying targeted Rb1 mutations have revealed that RB serves various non-cell cycle control roles. Notably, RB acts as a scaffold that recruits chromatin regulatory proteins, condensin II and enhancer of zeste homolog 2 (EZH2). These complexes protect the genome integrity through maintaining proper chromosome condensation, long range contacts, and transcriptionally repressive histone modification. This thesis explores the mechanistic links that regulate such RB-condensin II complex or that are leveraged upon pharmacological inhibition of the RB-EZH2 complex. First, I identified potential phosphorylation sites in the …


Functional Investigation Of The Role Of The Retinoblastoma Protein In Genome Stability, Aren E. Marshall Aug 2019

Functional Investigation Of The Role Of The Retinoblastoma Protein In Genome Stability, Aren E. Marshall

Electronic Thesis and Dissertation Repository

Genome instability is an enabling characteristic of cancerous cells. It has recently been discovered that the retinoblastoma protein (pRB), typically known for its role in cell cycle regulation, also aids in the maintenance of genome stability. Intriguingly, mutations to the pRB gene, RB1, can arise late in tumorigenesis in cancer cells whose cell cycle regulation is already compromised by another mutation. This suggests that pRB’s functions in genome stability could underlie cancer relevant characteristics that are independent of its ability to negatively regulate proliferation. The overall aim of this thesis is to characterize the different means through which pRB …


The Cdk-Resistant Prb-E2f1 Complex Recruits Chromatin-Organizing Proteins To Repetitive Dna Sequences, Charles A. Ishak Apr 2017

The Cdk-Resistant Prb-E2f1 Complex Recruits Chromatin-Organizing Proteins To Repetitive Dna Sequences, Charles A. Ishak

Electronic Thesis and Dissertation Repository

This thesis investigates mechanistic links between genome integrity and the recruitment of chromatin organizing proteins to repetitive DNA sequences mediated by the retinoblastoma tumor suppressor protein (pRB). I demonstrate that a CDK-resistant interaction between the pRB C-terminus and the E2F1 coiled-coil marked box domain establishes a scaffold that facilitates recruitment of multiple chromatin-organizing proteins to repetitive sequences across the genome throughout the cell cycle. Specifically, pRB recruits the enhancer-of-zeste-homologue 2 (EZH2) histone methyltransferase to establish repressive facultative heterochromatin at repetitive sequences, and the Condensin II complex to ensure proper DNA replication and mitotic progression. To disrupt the CDK-resistant pRB-E2F1 interaction …


Investigating E2f Independent Cell Cycle Control And Tumor Suppression By Prb, Michael J. Thwaites Apr 2017

Investigating E2f Independent Cell Cycle Control And Tumor Suppression By Prb, Michael J. Thwaites

Electronic Thesis and Dissertation Repository

Cellular division is primarily controlled at the G1 to S-phase transition of the cell cycle by the retinoblastoma tumor-suppressor protein (pRB). The ability of pRB to restrict S-phase entry is primarily attributed to the repression of E2F transcription factors required to upregulate cell cycle target genes necessary for cellular division. Interestingly, while pRB is disrupted in the vast majority of human cancers, mutations typically target upstream regulators of pRB leading to inactivation through hyperphosphorylation. The rarity of direct pRB mutations suggests that the regulation of the cell cycle by pRB may involve additional mechanisms outside of E2F repression, as this …


Characterizing The Contribution Of The Lxcxe Binding Cleft To Prb-Mediated Genome Stability And Tumor Suppression, Courtney H. Coschi Apr 2013

Characterizing The Contribution Of The Lxcxe Binding Cleft To Prb-Mediated Genome Stability And Tumor Suppression, Courtney H. Coschi

Electronic Thesis and Dissertation Repository

Condensation and segregation of mitotic chromosomes are critical processes for cellular propagation and if compromised, can lead to genomic instability. Genomic instability is known to be an active contributor to tumorigenesis, rather than being a by-product of malignant progression. The retinoblastoma protein (pRB) is the prototypic tumor suppressor. Its tumor suppressive properties are linked to its ability to negatively regulate proliferation by inhibiting E2F target gene transcription. Using a gene targeted mouse model defective for interactions mediated by the pRB LXCXE binding cleft that is distinct from E2F binding (Rb1ΔL/ΔL), I have demonstrated that LXCXE-interactions are an …