Information AboutOncogene |
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The first oncogene was discovered in 1970 and was termed SRC (pronounced ''SARK''). Src was in fact first discovered as an oncogene in a chicken retrovirus. Experiments performed by Dr G. Steve Martin of the University Of California Berkeley demonstrated that the SRC was indeed the oncogene of the virus. In 1976 Drs. J. Michael Bishop and Harold E. Varmus of the University Of California San Francisco demontrated that oncogenes were defective proto-oncogenes, found in many organisms including humans. For this discovery Bishop and Varmus were award the Nobel Prize in 1989 . PROTO-ONCOGENE A proto-oncogene is a normal gene that can become an oncogene, either after mutation or increased expression. Proto-oncogenes code for Protein s that help to regulate Cell Growth and Differentiation . Proto-oncogenes are often involved in Signal Transduction and execution of Mitogenic signals, usually through its Protein product. Upon ''activation'', it (or its product) becomes a tumor inducing agent, an oncogene. Activation The proto-oncogene can become an oncogene by a relatively small modification of its original function. There are two basic activation types:
ONCOGENE Growth factors Growth Factor s, or mitogens, are usually Secreted by a few specialized cells to induce cell proliferation in paracrine, autocrine, or endocrine manner. If a cell that usually does ''not'' produce growth factors suddenly starts to do so (because it developed an oncogene), it will thereby induce its own uncontrolled proliferation ('' Autocrine Loop ''), as well as the proliferation of neighboring cells. In addition, abnormal growth of endocrine glands often cause ectopic production of growth hormones that have secondary effects on other parts of the body. Protein Kinase s and related proteins There are six known classes of protein kinases and related proteins that can become an oncogene: # Receptor tyrosine kinases that become constitutively (permanently) active like the Epidermal Growth Factor Receptor (EGFR), Platelet-derived Growth Factor Receptor (PDGFR), and Vascular Endothelial Growth Factor receptor (VEGFR). # Cytoplasmic tyrosine kinases like the Src -family, Syk-ZAP-70 family and BTK family of tyrosine kinases. # Regulatory GTPase s, for example, the Ras Protein . # Cytoplasmic Serine / Threonine kinases and their regulatory subunits, for example, the Raf Kinase , and Cyclin-dependent Kinase s (through Overexpression ). # Adaptor Protein s in signal transduction. # Transcription Factor s. SEE ALSO |
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