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A retrovirus is a type of virus that inserts a copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. Once inside the host cell's cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backwards). The new DNA is then incorporated into the host cell genome by an integrase enzyme, at which point the retroviral DNA is referred to as a provirus. The host cell then treats the viral DNA as part of its own genome, transcribing and translating the viral genes along with the cell's own genes, producing the proteins required to assemble new copies of the virus.
Mouse mammary tumor virus (MMTV) is a milk-transmitted retrovirus like the HTL viruses, HI viruses, and BLV. It belongs to the genus Betaretrovirus. MMTV was formerly known as Bittner virus, and previously the "milk factor", referring to the extra-chromosomal vertical transmission of murine breast cancer by adoptive nursing, demonstrated in 1936, by John Joseph Bittner while working at the Jackson Laboratory in Bar Harbor, Maine. Bittner established the theory that a cancerous agent, or "milk factor", could be transmitted by cancerous mothers to young mice from a virus in their mother's milk. The majority of mammary tumors in mice are caused by mouse mammary tumor virus.
An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term "oncornaviruses" was used to denote their RNA virus origin. With the letters "RNA" removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with "tumor virus" or "cancer virus". The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology, but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein.
Gammaretrovirus is a genus in the Retroviridae family. Example species are the murine leukemia virus and the feline leukemia virus. They cause various sarcomas, leukemias and immune deficiencies in mammals, reptiles and birds.
The murine leukemia viruses are retroviruses named for their ability to cause cancer in murine (mouse) hosts. Some MLVs may infect other vertebrates. MLVs include both exogenous and endogenous viruses. Replicating MLVs have a positive sense, single-stranded RNA (ssRNA) genome that replicates through a DNA intermediate via the process of reverse transcription.
Env is a viral gene that encodes the protein forming the viral envelope. The expression of the env gene enables retroviruses to target and attach to specific cell types, and to infiltrate the target cell membrane.
MN1 is a gene found on human chromosome 22, with gene map locus 22q12.3-qter. Its official full name is meningioma 1 because it is disrupted by a balanced translocation (4;22) in a meningioma.
Wilms' tumor protein is a protein that in humans is encoded by the WT1 gene on chromosome 11p.
Homeobox protein Hox-A9 is a protein that in humans is encoded by the HOXA9 gene.
Friend leukemia integration 1 transcription factor (FLI1), also known as transcription factor ERGB, is a protein that in humans is encoded by the FLI1 gene, which is a proto-oncogene.
Transcription factor PU.1 is a protein that in humans is encoded by the SPI1 gene.
Protein CBFA2T1 is a protein that in humans is encoded by the RUNX1T1 gene.
Protein SET, also known as Protein SET 1, is a protein that in humans is encoded by the SET gene.
Proto-oncogene serine/threonine-protein kinase Pim-1 is an enzyme that in humans is encoded by the PIM1 gene.
Tyrosine-protein kinase receptor UFO is an enzyme that in humans is encoded by the AXL gene. The gene was initially designated as UFO, in allusion to the unidentified function of this protein. However, in the years since its discovery, research into AXL's expression profile and mechanism has made it an increasingly attractive target, especially for cancer therapeutics. In recent years, AXL has emerged as a key facilitator of immune escape and drug-resistance by cancer cells, leading to aggressive and metastatic cancers.
ERG is an oncogene. ERG is a member of the ETS family of transcription factors. The ERG gene encodes for a protein, also called ERG, that functions as a transcriptional regulator. Genes in the ETS family regulate embryonic development, cell proliferation, differentiation, angiogenesis, inflammation, and apoptosis.
MDS1 and EVI1 complex locus protein EVI1 (MECOM) also known as ecotropic virus integration site 1 protein homolog (EVI-1) or positive regulatory domain zinc finger protein 3 (PRDM3) is a protein that in humans is encoded by the MECOM gene. EVI1 was first identified as a common retroviral integration site in AKXD murine myeloid tumors. It has since been identified in a plethora of other organisms, and seems to play a relatively conserved developmental role in embryogenesis. EVI1 is a nuclear transcription factor involved in many signaling pathways for both coexpression and coactivation of cell cycle genes.
Serine/threonine-protein kinase Pim-2 is an enzyme that in humans is encoded by the PIM2.
In molecular biology MicroRNA-223 (miR-223) is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms. miR-223 is a hematopoietic specific microRNA with crucial functions in myeloid lineage development. It plays an essential role in promoting granulocytic differentiation while also being associated with the suppression of erythrocytic differentiation. miR-223 is commonly repressed in hepatocellular carcinoma and leukemia. Higher expression levels of miRNA-223 are associated with extranodal marginal-zone lymphoma of mucosa-associated lymphoid tissue of the stomach and recurrent ovarian cancer. In some cancers the microRNA-223 down-regulation is correlated with higher tumor burden, disease aggressiveness, and poor prognostic factors. MicroRNA-223 is also associated with rheumatoid arthritis, sepsis, type 2 diabetes, and hepatic ischemia.
DNA-directed RNA interference (ddRNAi) is a gene-silencing technique that utilizes DNA constructs to activate an animal cell's endogenous RNA interference (RNAi) pathways. DNA constructs are designed to express self-complementary double-stranded RNAs, typically short-hairpin RNAs (shRNA), that once processed bring about silencing of a target gene or genes. Any RNA, including endogenous mRNAs or viral RNAs, can be silenced by designing constructs to express double-stranded RNA complementary to the desired mRNA target.
References
- ↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ↑ Askew DS, Bartholomew C, Buchberg AM, et al. (November 1991). "His-1 and His-2: identification and chromosomal mapping of two commonly rearranged sites of viral integration in a myeloid leukemia". Oncogene. 6 (11): 2041–2047. PMID 1682866.
- ↑ Askew DS, Li J, Ihle JN (March 1994). "Retroviral insertions in the murine His-1 locus activate the expression of a novel RNA that lacks an extensive open reading frame". Mol. Cell. Biol. 14 (3): 1743–1751. doi:10.1128/MCB.14.3.1743. PMC 358532 . PMID 8114708.
- ↑ Li J, Rhodes JC, Askew DS (January 1997). "Evolutionary conservation of putative functional domains in the human homolog of the murine His-1 gene". Gene. 184 (2): 169–176. doi:10.1016/S0378-1119(96)00591-4. PMID 9031624.
- ↑ Li J, Witte DP, Van Dyke T, Askew DS (April 1997). "Expression of the putative proto-oncogene His-1 in normal and neoplastic tissues". Am. J. Pathol. 150 (4): 1297–1305. PMC 1858164 . PMID 9094986.