Epigenetics, genetic or cellular memory: reality?

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by Christophe » 23/09/14, 00:18

Epigenetics explained by a "pro" in 3 minutes:

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by Janic » 23/09/14, 08:22

excellent!
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Re: Epigenetics, genetic or cellular memory: reality?




by Christophe » 03/11/18, 03:21

Proof that epigenetics exists with...honey???? Who wants to try the trick again? Right there?

: Shock: : Shock: : Shock: : Shock:

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Re: Epigenetics, genetic or cellular memory: reality?




by izentrop » 04/11/18, 00:29

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Re: Epigenetics, genetic or cellular memory: reality?




by Ahmed » 04/11/18, 12:44

This is probably the explanation of the expressions: "little genius" and "big dadais"! : Lol:
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Re: Epigenetics, genetic or cellular memory: reality?




by Christophe » 06/07/21, 16:38

Well gosh, I didn't know that Axel Kahn was defending the idea of epigenetics !

“Everything is innate and everything is acquired: genetics and epigenetics constantly interact”
Interview with the geneticist Axel Khan, president of the League against cancer.

About fifteen years ago, at the time of the first sequencing of the human genome (the interview dates from 2019), we were betting a lot on the identification of all our genes, and DNA was the great organizer of the cell...

Axel Kahn: It's true, this vision prevailed, but only among those who were nearsighted! at that time, I was notably an investment advisor in biotechnology, and my speech was clear. The potential for commercialization and value creation generated by genome sequencing was incredibly small. It was madness to want to follow the inflation of the costs of the companies placed on the stock exchange solely on the basis of the sequencing of the genome.

It was all an illusion, as there always are. Today, it has been reversed: some claim that the genome as a genetic sequence no longer has any importance; we would be in the world of all epigenetics. In reality it is neither, it is both at the same time, with very subtle interactions between the two.

Can you detail?

Axel Kahn: When he began to participate in the Human Genome project, which began in 1989, Walter Gilbert (Nobel Prize in 1980) claimed that we were going to read the program of life. But we hadn't believed in it for quite a long time.

From the beginning of the XNUMXst century, epigenetics was beginning to be well known, even if it was perhaps less fashionable. In particular, the modifications (phosphorylation, methylation, ADP-ribosylation, etc.) of histones, the proteins around which DNA wraps, to form chromatin have been the subject of studies for a very long time.

I myself was working on the regulation, and therefore on the adaptation, of liver genes to food. It is indeed a form of regulation not of the sequence, but of the level of gene expression. We had determined some of the fundamental mechanisms explaining how glucose per se affects gene transcription.

Also at this time, in 2002, the first studies were published linking the state of health of children to the abundance of food that their grandparents had known. We discovered a form of heredity without gene.

The paradigm remains Darwinian. It explains the fundamental elements of evolution, even if it needs to be refined. obviously, the genes are present and act as what they are, what their sequence encodes. But they are also controlled, in the short or long term, by all the epigenetic mechanisms. And this epigenetic regulation is the manifestation of the environment.

Progress concerns above all the perpetuation of imprints linked to epigenetics over a few generations. Remember, however, that only genetic modifications are transmitted to all generations. Then, we know better the dialogue between these two sides, even if we had already encountered it with the SOS system of bacteria. In harmful circumstances, such as a lack of food, or ionizing rays… a mechanism is triggered and creates a hypermutability which increases genetic diversity and therefore the chances that, by chance, a form resistant to these adverse conditions will appear and be selected. .

You have been the president of the League against Cancer since June. In this type of disease, epigenetics also intervene.

Axel Kahn: Certainly, but there again, the paradigm has not changed: cancer is always due to somatic mutations. to my knowledge, changes in the level of gene expression alone are incapable of causing cancer. It arises from particular conditions (ionizing rays, pollution, inflammation, etc.) which, as in the SOS system, create a hypermutability naturally increasing the risk that among the cells with different phenotypes generated, at random, there is one that is more proliferative. and invasive than its neighbours. And that's cancer.

Chance explains that in the presence of carcinogenic mutations, some will develop the disease and others will not.

That being said, in the various molecular processes involved, "quantity" modifications occur on the levels of gene expression, and it can therefore be said that epigenesis is involved in carcinogenesis. Nevertheless, no tumoral process is triggered without a gene mutation conferring a selective advantage on the cell.

Another discovery that has made DNA determinism somewhat wobble is that of the intervention of chance in the expression of genes. Does it have a role in cancer?

Axel Kahn: It is central to the appearance and development of cancers. He explains, for example, that in the presence of potentially carcinogenic mutations, some individuals will actually develop the disease and others will not. Mutations in the BRCA 1 or BRCA 2 genes have a high probability of causing breast cancer, but curiously about 20% of women carrying such a mutation will not be sick. In other words, the mutation potentiates the cell without automatically triggering tumorogenesis. Mutation only increases the frequency of a phenomenon.

This brings us back to the SOS system again, because the mutation involves either too weak DNA repair mechanisms or more pronounced hypermutability. The randomness nestles there. Many cancers, including Lynch syndrome (a familial colon cancer) are linked to abnormalities in repair mechanisms.

According to a recent study, we are all mosaics, harboring different “clones” all more or less committed to carcinogenesis. Is it related?

Axel Kahn: Yes, of course. And we can link this result to one of the major advances in therapy: immunotherapy. Our cells mutate very often. They are most often repaired, but not always. Sometimes, the beautiful balance of these cells is broken, they are disadvantaged and eliminated. And exceptionally, a cell can be favored from the point of view of proliferation, and that is cancer.

In this case, the mutations (there are always several) result in different encoded proteins. The cancerous cell is then strange, if not foreign, and the big question that arises is the following: why does our immune system, usually so eager to eliminate foreign cells, not target these cells? abnormal? We now know. Through Darwinian selection mechanisms, the cancerous cell is able to inactivate the immune cells so as not to be destroyed.

Immunotherapy consists of lifting the inhibition of the immune system by cancer cells. T lymphocytes regain all their cytolytic activity and attack cancer cells. Alas, not only, which explains the significant side effects sometimes encountered.

This study also opens up avenues in terms of diagnosis and prevention, for example by identifying pretumoral clones very early on?

Axel Kahn: Yes, it's a way to complete the tools we have today, starting with genetic studies. Much work focuses on circulating DNA, DNA fragments released into the blood by cells already committed to cancer.

Let's stay in the field of diagnosis. How much confidence can we have in predisposition tests for health-related risks, and especially cancer?

Axel Kahn: It all depends on the cancer. A mutation involved in familial colonic polyposis leads in 100% of cases to colon cancer. Preventive treatment is total removal of the colon. For breast cancer, a BRCA 1 mutation brings the risk to 75% and that of BRCA 2 to 50-60%. For other less inducing genes, we find the effect of chance: the mutation increases in varying proportions the probability of occurrence of cancer.

(...)




Like what... he was more open than he seemed in the end... too bad about the covid crisis and therefore the last months of his life, he passed for someone closed...
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Re: Epigenetics, genetic or cellular memory: reality?




by GuyGadeboisTheBack » 06/07/21, 16:47

This kind of character is quite iconoclastic in the French scientific landscape. He has "the card" and therefore was still obliged to eat at certain racks so that we would leave him alone and be able to continue his work. Apparently he was appreciated both by his community and by the political world who salute his integrity (to be taken with certain tweezers). Better still, he was highly respected by people in the village where he was born, who praised his simplicity and his kindness. The character is therefore complex but I have always found him benevolent, curious and open. The opposite of a Claude Allègre, for example, who is the very prototype of the detestable pretentious giver of lessons, the undrinkable scientist full of certainties and arrogance like we have on this forum. A hint: He wears a red nose without knowing it. : Mrgreen:
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Re: Epigenetics, genetic or cellular memory: reality?




by Janic » 06/07/21, 17:30

Like what... he was more open than he seemed in the end... too bad about the covid crisis and therefore the last months of his life, he passed for someone closed...
probably the effect of the treatments!
https://www.rtl.fr/actu/debats-societe/ ... 7800920216
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Re: Epigenetics, genetic or cellular memory: reality?




by Christophe » 18/07/22, 01:47

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Re: Epigenetics, genetic or cellular memory: reality?




by Christophe » 03/10/22, 18:54

Econology still ahead...as usual? : Mrgreen:

Your genes could carry a trace of the life of your grandparents

A study by researchers at UC Santa Cruz shows that epigenetic changes can potentially be passed on not only from parents to their children, but also to the next generation. This "transgenerational epigenetic inheritance" could explain how an individual's health can be influenced by the experiences of their parents and grandparents.

Epigenetic modifications do not involve modification at the level of DNA itself, but change the way genes are expressed, which directly affects the health and development of the individual. It is thanks to epigenetics that the cells of our body, which nevertheless all have the same DNA, are specialized in one or the other function (neurons, heart cells, muscle cells, etc.). Epigenetics determines which genes, among the approximately 25 that make up our DNA, should be expressed or not. The process involves particularly complex and not completely elucidated mechanisms.

These modifications, transmitted during cell division, are induced by the environment and certain behaviors; some are long-lasting (notably those that dictate the cell's function), others are transient (like those that regulate genes linked to the circadian rhythm). It is also known that epigenetic abnormalities can contribute to the development and progression of certain diseases, particularly cancers. These changes in gene expression can be inherited, but how parental epigenomes influence the development and health of offspring is still unclear.

(...)


https://trustmyscience.com/genes-pourra ... s-parents/
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