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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,
Mickey Tsai

Niceness a combination of genetics and environment, the Neurogenics of Niceness study f... - 0 views

www.heraldsun.com.au/...story-fn7x8me2-1226324345541

genetics environment research

shared by Mickey Tsai on 14 Apr 12 - No Cached
  • BEING a nice person could come down to having a good set of genes
  • "kind" behaviour of more than 700 individuals was partly linked to receptor genes for oxytocin and vasopressin.
  • uch of the hormone you have, it's how responsive your brain is to the hormo
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  • It's not about how much of the hormone you have, it's how responsive your brain is to the hormones
  • "(Niceness) is a combination of genetics and your environment."
  • Mickey Tsai on 14 Apr 12
     
    A study shows that genetics could play a role in determining "niceness". The kind behavior is found to be linked to receptor genes for oxytopic and vasopressin. People that are more responsive to it are more inclined to donate money, pay taxes, give blood, report crime etc. It isn't about how much of the hormone you have but how responsive you are to it. Of course genetics isnt the only factor, if you are surrounded by nice people it is likely that it would rub off on you.
Pop karnchanapimonkul

The Ballooning Brain: Defective Genes May Explain Uncontrolled Brain Growth in Autism: ... - 0 views

www.scientificamerican.com/article.cfm

brain genes autism

shared by Pop karnchanapimonkul on 13 Apr 12 - No Cached
  • linked atypical gene activity to excessive growth in the autistic brain
  • autistic brain sprouts an excess of neurons and continues to balloon during the first five years of life, as all those extra neurons grow larger and form connections.
  • start to lose neural connections, faster than typical brains
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  • 67 percent more neurons in their prefrontal cortex (PFC) than typical children
  • executive functions"—high-level thinking, such as planning ahead, inhibiting impulses and directing attention.
  • In brain tissue from both autistic children and autistic adults, genes coding for proteins that identify and repair mistakes in DNA were expressed at unusually low levels. Additionally, all autistic brains demonstrated unusual activity levels for genes that determine when neurons grow and die and how newborn neurons migrate during early development
  • Some genes involved in immune responses, cell-to-cell communication and tissue repair, however, were expressed at unusual levels in adult autistic brains, but not in autistic children's brains
  • autistic child develops in the womb, something—an inherited mutation or an environmental factor like a virus, toxin or hormone—muffles the expression of genes coding for proteins that usually fix mistakes in sequences of DNA
  • Errors accumulate.
  • The genetic systems controlling the growth of new neurons go haywire, and brain cells divide much more frequently than usual, accounting for the excess neurons found in the PFC of autistic children.
  • autistic brain grow physically larger and form more connections than in a typical child's brain.
  • immune system reacts against the brain's overzealous growth,
  • Not all researchers, however, accept
  • If scientists definitively link autism to a characteristic sequence of changes in gene expression and unusual neural growth, then it becomes possible to target and reverse any one of the thousands of steps in that sequence.
  • Pop karnchanapimonkul on 13 Apr 12
     
    Article about how genetic expression may be the cause for autism.
Sasicha Manupipatpong

New genes linked to brain size, intelligence - 2 views

www.sciencedaily.com/...120415150123.htm

genes linked brain size intelligence

shared by Sasicha Manupipatpong on 16 Apr 12 - No Cached
  • genes that increase your risk for a single disease that your children can inherit
  • factors that cause tissue atrophy and reduce brain size, which is a biological marker for hereditary disorders
  • schizophrenia, bipolar disorder, depression, Alzheimer’s disease and dementia
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  • sample large enough to reveal clear patterns in genetic variation and show how these changes physically alter the brain
  • smaller brains
  • gene variants that deplete brain tissue beyond normal in a healthy person
  • unearth new genetic variants in people who have bigger brains as well as differences in regions critical to learning and memory
  • screened the genomes of people suffering from a specific brain disease and combed their DNA to uncover a common variant.
  • consistent relationship between subtle shifts in the genetic code and diminished memory centers
  • variations in their DNA that help boost or lower their brains’ susceptibility to a vast range of diseases
  • People also can take preventive steps through exercise, diet and mental stimulation to erase the effects of a bad gene
  • Once we identify the gene, we can target it with a drug to reduce the risk of disease
  • genes that explain individual differences in intelligence
  • gene called HMGA2 affected brain size as well as a person’s intelligence
  • People whose HMGA2 gene held a letter “C” instead of “T” on that location of the gene possessed larger brains and scored more highly on standardized IQ tests
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  • Sasicha Manupipatpong on 16 Apr 12
     
    Specific genes have been identified which affect brain size and intelligence--a difference of one nucleotide in the DNA sequence could determine how well you score on a standardized IQ test.
Nitchakan Chaiprukmalakan

How a single gene mutation leads to uncontrolled obesity - 0 views

www.sciencedaily.com/...120318143904.htm

shared by Nitchakan Chaiprukmalakan on 13 Apr 12 - No Cached
  • Researchers at Georgetown University Medical Center have revealed how a mutation in a single gene is responsible for the inability of neurons to effectively pass along appetite suppressing signals from the body to the right place in the brain.
  • The research team specifically found that a mutation in the brain-derived neurotrophic factor (Bdnf) gene in mice does not allow brain neurons to effectively pass leptin and insulin chemical signals through the brain. In humans, these hormones, which are released in the body after a person eats, are designed to "tell" the body to stop eating. But if the signals fail to reach correct locations in the hypothalamus, the area in the brain that signals satiety, eating continues.
  • He has found that the gene produces a growth factor that controls communication between neurons.
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  • The Bdnf gene generates one short transcript and one long transcript. He discovered that when the long-form Bdnf transcript is absent, the growth factor BDNF is only synthesized in the cell body of a neuron but not in its dendrites. The neuron then produces too many immature synapses, resulting in deficits in learning and memory in mice. Xu also found that the mice with the same Bdnf mutation grew to be severely obese
  • large-scale genome-wide association studies showed Bdnf gene variants are, in fact, linked to obesity.
  • both leptin and insulin stimulate synthesis of BDNF in neuronal dendrites in order to move their chemical message from one neuron to another through synapses. The intent is to keep the leptin and insulin chemical signals moving along the neuronal highway to the correct brain locations, where the hormones will turn on a program that suppresses appetite.
  • "If there is a problem with the Bdnf gene, neurons can't talk to each other, and the leptin and insulin signals are ineffective, and appetite is not modified
  • One possible strategy would be to produce additional long-form Bdnf transcript using adeno-associated virus-based gene therapy, Xu says. But although this kind of gene therapy has proven to be safe, it is difficult to deliver across the brain blood barrier,
nidthamsirisup

Epigenetics: DNA Isn't Everything - 0 views

www.sciencedaily.com/...090412081315.htm

epigenetics genetics gene

shared by nidthamsirisup on 15 Apr 12 - Cached
  • Research into epigenetics has shown that environmental factors affect characteristics of organisms. These changes are sometimes passed on to the offspring.
  • A certain laboratory strain of the fruit fly Drosophila melanogaster has white eyes. If the surrounding temperature of the embryos, which are normally nurtured at 25 degrees Celsius, is briefly raised to 37 degrees Celsius, the flies later hatch with red eyes.
  • crossed the flies for six generations. In this experiment, they were able to prove that the temperature treatment changes the eye colour of this specific strain of fly, and that the treated individual flies pass on the change to their offspring over several generations. However, the DNA sequence for the gene responsible for eye colour was proven to remain the same for white-eyed parents and red-eyed offspring.
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  • Epigenetics examines the inheritance of characteristics that are not set out in the DNA sequence.
  • important factors are the histones, a kind of packaging material for the DNA, in order to store DNA in an ordered and space-saving way. It is now clear that these proteins have additional roles to play. Depending on the chemical group they carry, if they are acetylated or methylated, they permanently activate or deactivate genes.
  • New methods now allow researchers to sometimes directly show which genes have been activated or deactivated by the histones
  • The genetic information of the DNA is passed on along with the relevant epigenetic information for the respective cell type.
  • A similar question remains for the inheritance of the epigenetic characteristics from parents to offspring. They now know that when the gametes are formed, certain epigenetic markers remain and are passed on to the offspring. The questions, which are currently being researched, are how much and which part of the epigenetic information is preserved and subsequently inherited.
  • Diet and epigenetics appear to be closely linked. The most well known example is that of the Agouti mice: they are yellow, fat and are prone to diabetes and cancer. If Agouti females are fed with a cocktail of vitamin B12, folic acid and cholin, directly prior to and during pregnancy, they give birth to mainly brown, slim and healthy offspring. They in turn mainly have offspring similar to themselves.
  • Environmental factors, which change the characteristics of an individual and are then passed on to its offspring, do not really fit into Darwin’s theory of evolution. According to his theory, evolution is the result of the population and not the single individual. “Passing on the gained characteristics fits more to Lamarck’s theory of evolution”, says Paro.
nidthamsirisup

Study suggests why some animals live longer - 1 views

www.physorg.com/...2012-03-animals-longer.html

animals dna project genetics

shared by nidthamsirisup on 02 Apr 12 - No Cached
    • nidthamsirisup
      nidthamsirisup on 02 Apr 12
       
      A new method to detect proteins associated with longevity which helps further our understanding into why some animals live longer than others.
  • The study, led by Dr. Joao Pedro Magalhaes and postgraduate student, Yang Li, is the first to show evolutionary patterns in biological repair systems in long-lived animals and could, in the future, be used to help develop anti-ageing interventions by identifying proteins in long-lived species that better respond to, for example, DNA damage
  • these species have optimised pathways that repair molecular damage, compared to shorter-lived animals, such as mice
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  • found a similar pattern in proteins associated with metabolism, cholesterol and pathways involved in the recycling of proteins
  • Proteins associated with the degradation of damaged proteins, a process that has been connected to ageing, were also linked with the evolution of longevity in mammals.
  • If we can identify the proteins that allow some species to live longer than others we could use this knowledge to improve human health and slow the ageing process.
  • “We developed a method to detect proteins whose molecular evolution correlates with longevity of a species. The proteins we detected changed in a particular pattern, suggesting that evolution of these proteins was not by accident, but rather by design to cope with the biological processes impacted by ageing, such as DNA damage. The results suggest that long-lived animals were able to optimise bodily repair which will help them fend off the ageing process.”
Kaoko Miyazaki

Long Intergenic Noncoding RNAs: New Links in Cancer Progression - 1 views

cancerres.aacrjournals.org/...3.full

research gene epigenetics RNA

shared by Kaoko Miyazaki on 16 Apr 12 - No Cached
  • Kaoko Miyazaki on 16 Apr 12
     
    The newly discovered and currently being researched lincRNAs are seen to be one of the causes of cancer. The function of lincRNAs to control gene expression by regulating the number of histones according to specific chromatin, may cause cancer when done wrong or are altered in some way. The epigenetic alterations that occur when this function is done wrong may lead to the disease and the inheritance of it. Which could be hypothesized as to why people with a history of cancer (and other diseases) within their families have higher likelihood to being diagnosed with the disease. But because lincRNA is a very recent discovery and only less than 1% of it has has been characterized in the human body, evidence of this is still being researched, tested and studied.
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