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Oncogene as transcription activator
Molecular Biology
Vandana
M.S. Pharm.(Biotechnology)
NIPER (Hajipur)
Oncogene
Oncogenes produce proteins that have the capacity to
stimulate growth and proliferation
They are dominant or ga...
Discovery of oncogene
 First discovered through the ability of Rous sarcoma
virus (RSV) to cause cancer in chickens. Src ...
Product and function of proto-
oncogene
Extracellular growth factors
Transmembrane growth factor receptors
Interacellul...
oncoproteins
• Growth factors – rare but an example is sis which
codes for a mutant PDGF (platelet derived growth
factor)
...
Intracellular transducers e.g., ras (a mutant form of an inner cell surface GTPase) ,
whose function activates a number of...
Nuclear transcription factor
Proto-oncogene code for the proteins that send a signal to the nucleus to stimulate
cell div...
Activation mechanism of proto-oncogene
oncogene as a transcription activator
oncogene as a transcription activator
oncogene as a transcription activator
oncogene as a transcription activator
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oncogene as a transcription activator

molecular biology

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oncogene as a transcription activator

  1. 1. Oncogene as transcription activator Molecular Biology Vandana M.S. Pharm.(Biotechnology) NIPER (Hajipur)
  2. 2. Oncogene Oncogenes produce proteins that have the capacity to stimulate growth and proliferation They are dominant or gain of function mutations They may lead to genetic instability, prevent a cell from becoming a apoptosis or promotes metastasis Protein encoded may function as growth factors or their receptors ,signal transducers, transcription factors or cell cycle component
  3. 3. Discovery of oncogene  First discovered through the ability of Rous sarcoma virus (RSV) to cause cancer in chickens. Src gene cause cancer.  Transfection of cells with src or other oncogenes. e.g., ras leads to neoplastic transformation.  These gene codes for a protein that has been associated with tyrosine kinase activity,that stimulated growth and proliferation via protein phosphorylation in signal transduction pathway.  All oncogenes have been found in normal cell equivalent genes or proteins and are termed “proto- oncogenes”.  proto-oncogenes produces protein products that normally enhance cell division or inhibit normal cell death.
  4. 4. Product and function of proto- oncogene Extracellular growth factors Transmembrane growth factor receptors Interacellular signal transduction proteins Interacellular transcription factors
  5. 5. oncoproteins • Growth factors – rare but an example is sis which codes for a mutant PDGF (platelet derived growth factor) • Sis is present in cancer causing Simian Sarcoma Virus • Growth factor receptors- Oncogenes encoding cell surface receptors that transduce growth promoting signals have been associated with several types of cancer. • e.g., erb b is a mutant form of epidermal growth factor receptor. This receptor functions as a tyrosine protein kinase (CT of protein) located on the cytoplamic side of the membrane with the ligand binding region (NT of protein) facing the cell exterior.
  6. 6. Intracellular transducers e.g., ras (a mutant form of an inner cell surface GTPase) , whose function activates a number of other regulatory factors including another oncogene termed raf (a protein kinase) that work in concert to regulate cell proliferation via the MAP Kinase Pathway which activates transcription factor proto-oncogene = ras Oncogene = mutated ras Always activated Always stimulating proliferation
  7. 7. Nuclear transcription factor Proto-oncogene code for the proteins that send a signal to the nucleus to stimulate cell division. These signaling proteins act in a series of steps called signal transduction cascade or pathway. These cascade includes a membrane receptor for the signal molecule.transcription factor in the nucleus that activate the genes for cell division. Myc is a proto-oncogene that codes for a transcription factor . Mutations in Myc convert it into an oncogene associated with seventy percent of cancers. RAS is a another oncogene that normally functions as an ‘on off’ switch in the signal cascade . Mutation in RAS cause the signaling pathway to remain “on” leading to uncontrolled cell growth.
  8. 8. Activation mechanism of proto-oncogene

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