Acute transforming retroviruses

Normal Retrovirus Genome S LTR gag pol env LTRlV Rous Sarcoma Virus (RSV) Genome i lLTRlgagl pol env src LTR V 

Acute transforming retroviruses are a unique subset of retroviruses that have acquired the ability to produce cancer in rodents and avian species in a relatively short time period (several weeks). Examples of acute transforming retroviruses include the Rous sarcoma virus (RSV), which produces sarcomas in chickens, and the Harvey murine sarcoma virus (Ha-MSV), which produces sarcomas in rats and mice. Studies utilizing RSV provided the first evidence that cellular genes, now termed oncogenes, exist in vertebrate cells. 

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Protein kinase B, or Akt, was discovered as the product of an oncogene of the acutely transforming retrovirus AKT8, causing T-cell lymphomas in mice. It encodes a fusion product of a cellular serine/threonine protein kinase and the viral structural protein Gag. This kinase is similar to both protein kinase Ce (PKCe 73% identity to the catalytic domain) and protein kinase A (PKA 68%). It differs from other protein kinases in that it contains a pleckstrin homology (PH) domain, which allows it to bind to polyphosphoinositide head groups (and also to G-protein fly subunits). To date, three subtypes have been identified a, (3, and y, all of which show a broad tissue distribution. It... 

Figure 24.16. Genome of a normal retrovirus and the Rous sarcoma retrovirus. Rous sarcoma virus (RSV) is an acute transforming retrovirus that contains an assimilated cellular gene called Src, which is responsible for the cancer-causing properties of the virus.

Table XXXII approaches the mitochondria. Before their capture to become endosymbionts, they were independent proteobacteria dividing incessandy without senescence and namral death. In their host eukaryotic cells do they contribute to immortality (that is malignant transformation ), or induce cell death (intrinsic mitochondrial apoptosis) (Figure 23). Table XXXIII confronts the problem of pediatric acute leukemias. Are as yet hidden human retroviruses involved and therefore it has the characteristic pathogenesis that of extrinsically induced malignancies Table XXXIV deals with a clinical observation of experienced...

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