12-03-2011, 02:54 AM
(This post was last modified: 12-03-2011, 05:04 AM by Administrator.)
Epigenetics is the study of heritable changes passed on through either mitosis or meiosis. This involves mechanisms other than changes in the underlying DNA sequence. Mechanisms involve changes in the genome without a change in the nucleotide sequence. Examples of such changes are DNA methylation or histone deacetylation, processes which suppresses gene expression without altering the sequence of the silenced genes. Essential epigenetic reprogramming events occur during germ cell development and early embryogenesis in mammals.
Understanding the mechanisms involved in the initiation, maintenance, and heritability of epigenetic states is an important aspect of research in current biology. Several distinct but interconnected molecular pathways have been discovered to date.
Brain is the very important organ of the body remains flexible and responsive to the outside world. Other than receiving signals from the various body parts they also receive from the outside world, the brain allows us to form memories and learn from our experiences. Many brain functions are accompanied at the cellular level by changes in gene expression. Epigenetic mechanisms such as histone modification and DNA methylation stabilize gene expression, which is important for long-term storage of information.
Such epigenetic changes in the brain may lead to brain diseases such as mental illness and addiction. Understanding epigenetics in the brain may help solve numerous such problems and may lead to effective treatments for brain diseases.
Interestingly it was studied by Dr. Moshe Szyf, Professor of Pharmacology and Therapeutics at McGill University, that there was an association between certain epigenetic patterns, suicide, and child abuse.
Scientists are just starting to study how changes in epigenetic tags affect behavior, and how behavior can change epigenetic tags. Some of the following are listed below.
• People who commit suicide have less-active ribosomal RNA (rRNA) genes than people who die of other causes. In people who commit suicide, Methyl levels are higher on rRNA genes in a part of the brain called the hippocampus, which is important for learning and memory. More methyl leads to less production of rRNA, which in turn leads to fewer ribosomes and less protein production.
• Children who are abused leave behind an epigenetic mark or a tag on the brain .it was noted that only the abused victims had mark on the GR gene and not those who committed suicide. Interestingly, the GR gene receives a similar epigenetic tag in rat pups who receive low quality care from their mothers.
• CBP is a protein that is needed for the activation of genes which are involved in learning and memory. One of its functions is to add acetyl tags to histones .It’s an epigenetic modification found on active genes. Even one defective copy of CBP gene causes Rubinstein-Taybi syndrome, a condition with a variety of characteristics, including mental disability.
• Reelin is an important potein in the brain needed for shaping the brain early in development and later on for learning. The gene for REELIN protein has less methyl and hence it is more active than normal in schizophrenic brains.
• One scan of epigenetic markers in the brain differentiated about 60 genes that are different between psychiatric patients and healthy people. Many of these genes code for proteins that are important for signaling between brain cells.
• Some drugs that are administered to treat mental sickness work by changing gene expression taking place in the brain .These changes in gene expression are stabilized through epigenetic mechanisms (DNA methylation and histone modification), reversing the effects of the disease.
• When a person is addicted to cocaine, they trigger epigenetic changes in certain brain regions which affects and damages hundreds of genes at a time. Some of them remain for a longer time than expected in the brain system. Research says that some of the long-term effects of drug abuse and addiction and high rates of their relapses are marked in epigenetic code.
There are three groups of signals that conclude in the establishment of a stably heritable epigenetic state: a signal that we to call the “Epigenator,” which originate from the environment and triggers an intracellular pathway; an “Epigenetic Initiator” signal, which responds to the Epigenator and is needed to define the precise location of the epigenetic chromatin environment; and an “Epigenetic Maintainer” signal, which sustains the chromatin environment in the first and subsequent generations.
Understanding the mechanisms involved in the initiation, maintenance, and heritability of epigenetic states is an important aspect of research in current biology. Several distinct but interconnected molecular pathways have been discovered to date.
Brain is the very important organ of the body remains flexible and responsive to the outside world. Other than receiving signals from the various body parts they also receive from the outside world, the brain allows us to form memories and learn from our experiences. Many brain functions are accompanied at the cellular level by changes in gene expression. Epigenetic mechanisms such as histone modification and DNA methylation stabilize gene expression, which is important for long-term storage of information.
Such epigenetic changes in the brain may lead to brain diseases such as mental illness and addiction. Understanding epigenetics in the brain may help solve numerous such problems and may lead to effective treatments for brain diseases.
Interestingly it was studied by Dr. Moshe Szyf, Professor of Pharmacology and Therapeutics at McGill University, that there was an association between certain epigenetic patterns, suicide, and child abuse.
Scientists are just starting to study how changes in epigenetic tags affect behavior, and how behavior can change epigenetic tags. Some of the following are listed below.
• People who commit suicide have less-active ribosomal RNA (rRNA) genes than people who die of other causes. In people who commit suicide, Methyl levels are higher on rRNA genes in a part of the brain called the hippocampus, which is important for learning and memory. More methyl leads to less production of rRNA, which in turn leads to fewer ribosomes and less protein production.
• Children who are abused leave behind an epigenetic mark or a tag on the brain .it was noted that only the abused victims had mark on the GR gene and not those who committed suicide. Interestingly, the GR gene receives a similar epigenetic tag in rat pups who receive low quality care from their mothers.
• CBP is a protein that is needed for the activation of genes which are involved in learning and memory. One of its functions is to add acetyl tags to histones .It’s an epigenetic modification found on active genes. Even one defective copy of CBP gene causes Rubinstein-Taybi syndrome, a condition with a variety of characteristics, including mental disability.
• Reelin is an important potein in the brain needed for shaping the brain early in development and later on for learning. The gene for REELIN protein has less methyl and hence it is more active than normal in schizophrenic brains.
• One scan of epigenetic markers in the brain differentiated about 60 genes that are different between psychiatric patients and healthy people. Many of these genes code for proteins that are important for signaling between brain cells.
• Some drugs that are administered to treat mental sickness work by changing gene expression taking place in the brain .These changes in gene expression are stabilized through epigenetic mechanisms (DNA methylation and histone modification), reversing the effects of the disease.
• When a person is addicted to cocaine, they trigger epigenetic changes in certain brain regions which affects and damages hundreds of genes at a time. Some of them remain for a longer time than expected in the brain system. Research says that some of the long-term effects of drug abuse and addiction and high rates of their relapses are marked in epigenetic code.
There are three groups of signals that conclude in the establishment of a stably heritable epigenetic state: a signal that we to call the “Epigenator,” which originate from the environment and triggers an intracellular pathway; an “Epigenetic Initiator” signal, which responds to the Epigenator and is needed to define the precise location of the epigenetic chromatin environment; and an “Epigenetic Maintainer” signal, which sustains the chromatin environment in the first and subsequent generations.
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