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chanon chiarnpattanodom

Cancer epigenetics takes center stage - 1 views

www.pnas.org/...392.full

shared by chanon chiarnpattanodom on 16 Apr 12 - No Cached
    • chanon chiarnpattanodom
      chanon chiarnpattanodom on 16 Apr 12
       
      DNA methylation is a chemical process where a methyl group is added on either the cytosine ring or the adenine ring, used in "higher leveled" organisms. Important in cell differentiation since methylation will cause cells to "remember" and remain differenciated instead of expressing other genes. 
  • Epigenetics is defined as modifications of the genome, heritable during cell division, that do not involve a change in the DNA sequence.
  • Epigenetic alterations in cancer include global hypomethylation
  • ...18 more annotations...
  • the promoters of housekeeping genes that are generally protected from methylation.
  • may lead to aberrant silencing of tumor suppressor genes
  • discovered loss of imprinting (LOI) in cancer
  • Genomic imprinting, the subject of the report by Nakagawa et al. (2), is an epigenetic modification of a specific parental allele of a gene, or the chromosome on which it resides, in the gamete or zygote, leading to differential expression of the two alleles of the gene in somatic cells of the offspring.
  • we found that LOI can occur in the normal colonic mucosa of colorectal cancer patients with LOI in their tumors
  • This LOI was linked to cases showing microsatellite instability (MSI) in the tumors
  • However, these patients do not have mutations in mismatch repair genes
  • One potential cause of MSI in these sporadic cancers is hypermethylation and epigenetic silencing of the hMLH1 mismatch repair gene
  • Nakagawa et al. (2) now confirm the original study of Cui et al. that LOI occurs in both tumor and normal tissue of patients
  • The present study (2) also offers an intriguing mechanistic hypothesis to explain the relationship between H19 DMR methylation and LOI in these patients
  • Nevertheless, the study calls attention to this remarkable highly conserved multifunctional protein,
  • The potential link to CTCF suggested by this study also calls our attention to the link among DNA methylation, epigenetics, and chromatin.
  • A clue to the link between MSI and epigenetics may be provided by another sometimes overlooked common thread in epigenetics, namely DNA replication
  • repeat-induced gene silencing is thought to be propagated through hemimethylated intermediates during DNA replication
  • The studies of Cui et al. (11), Nishihara et al. (20), and Nakagawa et al. (2) suggest a new and provocative view of the timing of epigenetic changes in cancer.
  • Studies of transgenic mice with constitutive biallelic expression of IGF2, comparable to LOI, show reduced apoptosis and increased tumor formation
  • I conclude by noting that the distinction between cancer genetics and epigenetics has blurred considerably in recent years
  • Many conventional “genetic” mechanisms directly affect proteins that regulate chromatin,
avikan

New Hope Of a Cure For H.I.V. - NYTimes.com - 0 views

query.nytimes.com/...fullpage.html

shared by avikan on 11 Apr 12 - No Cached
  • So people with H.I.V. now must take drugs every day for life, which some researchers say is not a sustainable solution for tens of millions of infected people.
  • CCR5,
  • This is what was done with the Trenton patient. Some of the man's white blood cells were removed from his body and treated with a gene therapy developed by Sangamo BioSciences. The therapy induced the cells to produce proteins called zinc-finger nucleases that can disrupt the CCR5 gene.
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    • avikan
      avikan on 11 Apr 12
       
      Millions of people worldwide are currently affected by HIV and many have died from AIDS. Scientists have been trying for many years to find a cure for the epidemic, but now many are trying to find a way to prevent the passing on of the virus for future generations. Although no definite treatment has been discovered yet, recent findings have shown promising results for the future. 
    • avikan
      avikan on 11 Apr 12
       
      With the fast developing biological technologies we are seeing today, scientists hope's are growing stronger.  Maybe one of us one day will be a part of the phenomenon, in search of a way to help the millions affected by the epidemic  
    • avikan
      avikan on 11 Apr 12
       
      CD4 cells initiate the body's response to infections.
    • avikan
      avikan on 11 Apr 12
       
      Many forms of HIV, initially use CCR5 to enter and infect host cells. A few individuals carry a mutation known as CCR5 delta 32 in the CCR5 gene, protecting them against these strains of HIV.
    • avikan
      avikan on 11 Apr 12
       
      For over 30 years scientists have been trying to find a cure for the HIV/AIDs epidemic and so far have been unsuccessful 
    • avikan
      avikan on 11 Apr 12
       
      Incase some of us forgot, AIDs stands for Acquired immune deficiency syndrome, a disease in which there is a severe loss of the body's cellular immunity. And HIV stands for Human immunodeficiency virus, a virus that causes AIDs
Nitchakan Chaiprukmalakan

New study: Tracking proteins that repair DNA - 0 views

scitechstory.com/...cking-proteins-that-repair-dna

shared by Nitchakan Chaiprukmalakan on 13 Apr 12 - No Cached
  • DNA damage could be caused by many things including toxins, radiation, or a failure in molecular chemistry. If it happens in one cell, the damage may do nothing, or at worse cause the cell to die. If damage occurs in a reproductive cell (a zygote) it can be an inherited mutation; the consequences of which can go on for generations
  • The DNA repair workers are (so far as we know) protein molecules.
  • Under microscopic observations it was seen that the UvrA protein randomly jumps from one DNA molecule to the next, staying about 7 seconds before moving on. However, when UvrA formed a complex with two UvrB molecules (UvrAB), the search became more sophisticated and slower. The complex would slide along the DNA strand for as long as 40 seconds before moving to another molecule. Sometimes it was observed that the UvrAB motion would ‘pause,’ apparently checking for structural abnormalities that might indicate DNA damage.
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  • It’s assumed the protein complex is analyzing, but the mechanism of analysis is unknown. It’s also unknown if the UvrAB complex (or similar complex) actually does the repair, or if it signals for some other protein complex(es) to make the repair.
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