Polycomb Regulation in Cell Differentiation
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Questions and Answers

What is the main focus of histone modification in normal cells?

  • Producing energy for the cell
  • Regulating cell division
  • Repairing damaged DNA
  • Regulating access to genes (correct)

    • According to the learning outcomes, which of the following is a key aspect of nucleosome structure?

  • DNA replication process
  • Polycomb and trithorax protein functions
  • Cell differentiation mechanisms
  • Dynamic nature of chromatin structure (correct)

    • How do cells differentiate and maintain their identity according to the learning outcomes?

  • By altering their DNA sequences
  • Through epigenetic mechanisms (correct)
  • By changing their cell types frequently
  • Through metabolic processes

    • What are histones subjected to in normal cells?

    <p>A large array of post-translational modifications</p> Signup and view all the answers

    What is the main function of polycomb and trithorax proteins according to the learning outcomes?

    <p>Regulating gene expression</p> Signup and view all the answers

    How can cell differentiation pathways be conceptualized, based on the given information?

    <p>As a cell traversing an epigenetic landscape</p> Signup and view all the answers

    What is the effect of EZH2 inhibition on DLBCL cells?

    <p>Decreases proliferation</p> Signup and view all the answers

    Which gene mutation is associated with reduction in the level of H3K27me3 and an increase in H3K27ac?

    <p>H3F3A</p> Signup and view all the answers

    Which inhibitors can block DIPG tumor growth?

    <p>EZH2 and BET inhibitors</p> Signup and view all the answers

    What is the effect of gain-of-function EZH2 mutations?

    <p>Repressing pro-differentiation and apoptosis genes</p> Signup and view all the answers

    Which histone modifier is implicated in maintaining cell identity and regulating transcription in cancer?

    <p>EZH2</p> Signup and view all the answers

    What is the role of BET domain protein inhibitors?

    <p>Counteracting the oncogenic effects of C-Myc and H3K27M</p> Signup and view all the answers

    Which genes exhibit increased H3K27me3 despite H3K27M mutations?

    <p>CDKN2A</p> Signup and view all the answers

    What is the main function of Polycomb group proteins (PRC2 and PRC1) in the context of cell differentiation?

    <p>They are selectively lost from genes specific for other cell types to maintain the new specialized cell state.</p> Signup and view all the answers

    Which statement about Trithorax (Trx) and MLL1 is true?

    <p>They catalyze trimethylation of H3K4 (H3K4me3).</p> Signup and view all the answers

    What is the effect of histone acetylation on chromatin structure?

    <p>It opens chromatin, making it more accessible.</p> Signup and view all the answers

    How can alterations to histone mark writers, readers, and erasers cause cancer?

    <p>By dysregulating gene expression and cellular processes.</p> Signup and view all the answers

    What is the effect of MLL-AF4 fusion protein in leukemic cells?

    <p>It activates gene expression ectopically.</p> Signup and view all the answers

    Which statement about BRD4 inhibitors is true?

    <p>They repress the growth of MLL-AF4-driven leukemic cells.</p> Signup and view all the answers

    What is the impact of EZH2-Y641F mutations on gene expression in B cell lymphoma?

    <p>It promotes B cell proliferation and blocks plasma cell differentiation.</p> Signup and view all the answers

    What is the role of EZH2 histone methyltransferase inhibitors in blocking the growth of certain tumor types?

    <p>They compete with the methyl donor SAM for the EZH2 active site.</p> Signup and view all the answers

    How do alterations to histone mark writers, readers, and erasers contribute to cancer?

    <p>They dysregulate gene expression and cellular processes.</p> Signup and view all the answers

    What is the impact of EZH2 gain-of-function mutations on gene expression in B cell lymphoma?

    <p>They promote B cell proliferation and block plasma cell differentiation.</p> Signup and view all the answers

    What is the main function of Polycomb group proteins (PRC2 and PRC1) in maintaining cell identity during differentiation?

    <p>They are lost from genes specific for other cell types to maintain the new specialized cell state.</p> Signup and view all the answers

    What is the definition of epigenetics?

    <p>The study of any potentially stable change in gene expression without changes in DNA sequence</p> Signup and view all the answers

    What is the main function of chromatin?

    <p>To control cell differentiation and identity by regulating access to genes</p> Signup and view all the answers

    What is the composition of a nucleosome?

    <p>DNA wrapped around a histone octamer composed of 2 histone H3-H4 dimers and 2 histone H2A-H2B dimers</p> Signup and view all the answers

    What is the role of closed chromatin (heterochromatin) in gene transcription?

    <p>It inhibits transcription factor binding</p> Signup and view all the answers

    What is the effect of histone acetylation on chromatin structure?

    <p>It reduces interaction between histone tails and DNA, increasing nucleosome mobility</p> Signup and view all the answers

    Which enzymes add histone marks to specific lysine residues?

    <p>Methyltransferases</p> Signup and view all the answers

    What is the main function of Polycomb group proteins (PRC2 and PRC1) in regulating gene expression?

    <p>They compact chromatin to inhibit gene expression</p> Signup and view all the answers

    What does the balance between Polycomb and Trithorax proteins regulate?

    <p>Gene expression and cell differentiation</p> Signup and view all the answers

    How does DNA methylation affect transcription?

    <p>It represses transcription by adding methyl marks to specific lysine residues in histones</p> Signup and view all the answers

    What is the role of nucleosome remodelling in allowing transcription to proceed?

    <p>It allows transcription factor binding by remodeling nucleosomes</p> Signup and view all the answers

    What is the impact of histone methylation on gene expression?

    <p>It can be activating or repressive depending on the specific lysine residue methylated</p> Signup and view all the answers

    What are the primary readers of histone modifications?

    <p>Regulatory proteins</p> Signup and view all the answers

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