-
Jeannie Lee (Harvard) 1 - X Chromosome Inactivation: Making and Breaking the Silence
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for ove...
published: 08 May 2019
-
Secrets of the X chromosome - Robin Ball
View full lesson: http://ed.ted.com/lessons/secrets-of-the-x-chromosome-robin-ball
The sequence of DNA that we inherit from our parents encodes directions for making our cells and giving us specific traits. Identical twins have the same DNA sequence, so how can one twin end up with a genetic disorder while the other twin does not? Robin Ball explains how the secret lies in X chromosome inactivation.
Lesson by Robin Ball, animation by Anton Trofimov.
published: 18 Apr 2017
-
What is X-linked Recessive Inheritance?
This describes X-linked recessive inheritance and how an X-linked recessive trait is passed along on in families.
published: 17 Oct 2014
-
What is X Chromosome & how we can prevent diseases caused by it?
Subscribe our Channel: https://shorturl.at/dhn67
📞 Call us on 1800 3001 1000 or 7337328877
📧 Mail us at [email protected]
💻 Visit us at https://www.oasisindia.in
#oasisfertility #oasisivf #ivf
published: 07 Oct 2020
-
X Inactivation
Paul Andersen explains how X inactivation works in mammals. This process was first described by Mary Lyon. Each cell in a female will have on activated and one inactivated X chromosome. This explains why almost all calico cats are female.
Intro Music Atribution
Title: I4dsong_loop_main.wav
Artist: CosmicD
Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/
Creative Commons Atribution License
published: 27 Apr 2012
-
3D models reveal hidden process in X chromosome inactivation
Using new, supercomputer-driven three-dimensional (3D) dynamic modeling, researchers can now probe the process that turns off one X chromosome in female mammal embryos. This new capability is helping biologists understand the role of RNA and the chromosome’s structure in the X inactivation process, leading to a deeper understanding of gene expression and opening new pathways to drug treatments for gene-based disorders and diseases.
LA-UR-21-29378
published: 14 Oct 2021
-
X Inactivation and Epigenetics (2017) Etsuko Uno wehi.tv
X inactivation is a vital process that occurs in all DNA-containing cells of the female body. It is also an important research model and tool for studying epigenetics. Epigenetics refers to processes that tell our cells how, and when, to read the DNA blueprint. The epigenetic regulation of DNA is critical in both normal development and disease.
X inactivation is a type of gene dosage compensation.
In humans, the sex chromosomes X and Y determine the sex of an individual - females have two X chromosomes (XX), males have one X and one Y chromosome (XY). All of the genes on the Y chromosome are required in male development, while the genes on the X chromosome are needed for both male and female development.
Because females receive two X chromosomes, they inherit two copies of many ...
published: 25 Jan 2012
-
X and Y chromosomes explained
X linked chromosomes explained,Humans have 23 pairs of chromosomes. One pair determine the gender of the child.A female will have xx chromosomes and males will have an x and a y chromosome
The x and y chromosomes not only carry the genes that determine male and female traits but also some other characteristics as well.
Since only men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. The y chromosome carries around 200 genes.
There are about 1,100 human X-linked genes.
Most of them code for something other than female anatomical traits. Some X-linked genes are responsible for abnormal conditions such as hemophilia, red-green color blindness,
and "male pattern baldness".
published: 09 Jan 2019
-
PID/IEI - 7:30 PM - 4th Oct 2024
published: 05 Oct 2024
-
Jeannie Lee (Harvard) 2 - X Chromosome Inactivation: Making the Right Choice
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for ove...
published: 08 May 2019
45:44
Jeannie Lee (Harvard) 1 - X Chromosome Inactivation: Making and Breaking the Silence
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for thi...
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for over 50 years both because it is a physiologically important event and because it is an excellent model for studying epigenetic silencing of genes by long non-coding RNAs. In her first talk, Dr. Jeannie Lee gives an overview of the steps a cell must go through during X inactivation. These include “counting” the X chromosomes, deciding which X chromosome to inactivate, initiating the inactivation and spreading it across the chromosome, and finally maintaining inactivation of the same X chromosome for the rest of the life of the organism.
In her second talk, Lee elaborates on the early steps of X inactivation. Very early in development, cells “count” the number of X chromosomes and decide if one needs to be inactivated, and if so which one. There is a region of the X chromosome called the X inactivation center which is enriched in long non-coding RNAs (lncRNAs). Lee explains how she and others showed that by sensing the ratio of two specific lncRNAs the cell can determine how many X chromosomes are present. Further studies showed that two different lncRNAs are responsible for randomly determining which X chromosome will be inactivated. Finally, she discusses the hypothesis that the allelic choice mechanism depends on a transient chromosomal pairing event that occurs at the beginning of the dosage compensation process.
And in her last talk, Lee describes how X inactivation is nucleated and spreads across the X chromosome. The Xist lncRNA is known to be necessary and sufficient for X inactivation. Lee describes experiments that identified the factors that tether Xist to the X chromosome and showed how Xist spreads to cover the entire X chromosome. She then goes on to explain that Xist blocks transcription in three ways: 1) Xist recruits factors that repress transcription via epigenetic modification such as histone methylation 2) Xist repels factors that open chromatin preparing it for transcription and 3) Xist changes the 3 dimensional organization of chromosomes. Lee ends with a model of our current understanding of the complex but critical process of X chromosome inactivation.
Speaker Biography:
Dr. Jeannie Lee is a Professor in the Department of Genetics at Harvard Medical School and in the Department of Molecular Biology at Massachusetts General Hospital (MGH). Her lab uses X chromosome inactivation as a model to study epigenetic regulation by long noncoding RNAs.
Lee received her AB in biochemistry and molecular biology from Harvard University and her MD/PhD from the University of Pennsylvania School of Medicine. She was a postdoctoral fellow at the Whitehead Institute and a resident at MGH before joining Harvard/MGH as a faculty member in 1997. Lee was also an HHMI Investigator from 2001-2018. She is a member of the National Academy of Sciences and a Fellow of the American Association for the Advancement of Science. Lee has been honored with numerous awards including the 2016 Centennial Prize from the Genetics Society of America, the 2016 Lurie Prize from the Foundation for the National Institutes of Health, and the 2010 Molecular Biology Award from the National Academy of Sciences. In 2018, she was President of the Genetics Society of America.
Learn more about Dr. Lee’s research here: https://www.x-inactivation-lee-lab.org
https://wn.com/Jeannie_Lee_(Harvard)_1_X_Chromosome_Inactivation_Making_And_Breaking_The_Silence
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for over 50 years both because it is a physiologically important event and because it is an excellent model for studying epigenetic silencing of genes by long non-coding RNAs. In her first talk, Dr. Jeannie Lee gives an overview of the steps a cell must go through during X inactivation. These include “counting” the X chromosomes, deciding which X chromosome to inactivate, initiating the inactivation and spreading it across the chromosome, and finally maintaining inactivation of the same X chromosome for the rest of the life of the organism.
In her second talk, Lee elaborates on the early steps of X inactivation. Very early in development, cells “count” the number of X chromosomes and decide if one needs to be inactivated, and if so which one. There is a region of the X chromosome called the X inactivation center which is enriched in long non-coding RNAs (lncRNAs). Lee explains how she and others showed that by sensing the ratio of two specific lncRNAs the cell can determine how many X chromosomes are present. Further studies showed that two different lncRNAs are responsible for randomly determining which X chromosome will be inactivated. Finally, she discusses the hypothesis that the allelic choice mechanism depends on a transient chromosomal pairing event that occurs at the beginning of the dosage compensation process.
And in her last talk, Lee describes how X inactivation is nucleated and spreads across the X chromosome. The Xist lncRNA is known to be necessary and sufficient for X inactivation. Lee describes experiments that identified the factors that tether Xist to the X chromosome and showed how Xist spreads to cover the entire X chromosome. She then goes on to explain that Xist blocks transcription in three ways: 1) Xist recruits factors that repress transcription via epigenetic modification such as histone methylation 2) Xist repels factors that open chromatin preparing it for transcription and 3) Xist changes the 3 dimensional organization of chromosomes. Lee ends with a model of our current understanding of the complex but critical process of X chromosome inactivation.
Speaker Biography:
Dr. Jeannie Lee is a Professor in the Department of Genetics at Harvard Medical School and in the Department of Molecular Biology at Massachusetts General Hospital (MGH). Her lab uses X chromosome inactivation as a model to study epigenetic regulation by long noncoding RNAs.
Lee received her AB in biochemistry and molecular biology from Harvard University and her MD/PhD from the University of Pennsylvania School of Medicine. She was a postdoctoral fellow at the Whitehead Institute and a resident at MGH before joining Harvard/MGH as a faculty member in 1997. Lee was also an HHMI Investigator from 2001-2018. She is a member of the National Academy of Sciences and a Fellow of the American Association for the Advancement of Science. Lee has been honored with numerous awards including the 2016 Centennial Prize from the Genetics Society of America, the 2016 Lurie Prize from the Foundation for the National Institutes of Health, and the 2010 Molecular Biology Award from the National Academy of Sciences. In 2018, she was President of the Genetics Society of America.
Learn more about Dr. Lee’s research here: https://www.x-inactivation-lee-lab.org
- published: 08 May 2019
- views: 49162
5:06
Secrets of the X chromosome - Robin Ball
View full lesson: http://ed.ted.com/lessons/secrets-of-the-x-chromosome-robin-ball
The sequence of DNA that we inherit from our parents encodes directions for ...
View full lesson: http://ed.ted.com/lessons/secrets-of-the-x-chromosome-robin-ball
The sequence of DNA that we inherit from our parents encodes directions for making our cells and giving us specific traits. Identical twins have the same DNA sequence, so how can one twin end up with a genetic disorder while the other twin does not? Robin Ball explains how the secret lies in X chromosome inactivation.
Lesson by Robin Ball, animation by Anton Trofimov.
https://wn.com/Secrets_Of_The_X_Chromosome_Robin_Ball
View full lesson: http://ed.ted.com/lessons/secrets-of-the-x-chromosome-robin-ball
The sequence of DNA that we inherit from our parents encodes directions for making our cells and giving us specific traits. Identical twins have the same DNA sequence, so how can one twin end up with a genetic disorder while the other twin does not? Robin Ball explains how the secret lies in X chromosome inactivation.
Lesson by Robin Ball, animation by Anton Trofimov.
- published: 18 Apr 2017
- views: 1176203
1:07
What is X-linked Recessive Inheritance?
This describes X-linked recessive inheritance and how an X-linked recessive trait is passed along on in families.
This describes X-linked recessive inheritance and how an X-linked recessive trait is passed along on in families.
https://wn.com/What_Is_X_Linked_Recessive_Inheritance
This describes X-linked recessive inheritance and how an X-linked recessive trait is passed along on in families.
- published: 17 Oct 2014
- views: 69889
1:40
What is X Chromosome & how we can prevent diseases caused by it?
Subscribe our Channel: https://shorturl.at/dhn67
📞 Call us on 1800 3001 1000 or 7337328877
📧 Mail us at
[email protected]
💻 Visit us at https://www.oasisindia...
Subscribe our Channel: https://shorturl.at/dhn67
📞 Call us on 1800 3001 1000 or 7337328877
📧 Mail us at
[email protected]
💻 Visit us at https://www.oasisindia.in
#oasisfertility #oasisivf #ivf
https://wn.com/What_Is_X_Chromosome_How_We_Can_Prevent_Diseases_Caused_By_It
Subscribe our Channel: https://shorturl.at/dhn67
📞 Call us on 1800 3001 1000 or 7337328877
📧 Mail us at
[email protected]
💻 Visit us at https://www.oasisindia.in
#oasisfertility #oasisivf #ivf
- published: 07 Oct 2020
- views: 121
6:23
X Inactivation
Paul Andersen explains how X inactivation works in mammals. This process was first described by Mary Lyon. Each cell in a female will have on activated and on...
Paul Andersen explains how X inactivation works in mammals. This process was first described by Mary Lyon. Each cell in a female will have on activated and one inactivated X chromosome. This explains why almost all calico cats are female.
Intro Music Atribution
Title: I4dsong_loop_main.wav
Artist: CosmicD
Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/
Creative Commons Atribution License
https://wn.com/X_Inactivation
Paul Andersen explains how X inactivation works in mammals. This process was first described by Mary Lyon. Each cell in a female will have on activated and one inactivated X chromosome. This explains why almost all calico cats are female.
Intro Music Atribution
Title: I4dsong_loop_main.wav
Artist: CosmicD
Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/
Creative Commons Atribution License
- published: 27 Apr 2012
- views: 345640
1:00
3D models reveal hidden process in X chromosome inactivation
Using new, supercomputer-driven three-dimensional (3D) dynamic modeling, researchers can now probe the process that turns off one X chromosome in female mammal ...
Using new, supercomputer-driven three-dimensional (3D) dynamic modeling, researchers can now probe the process that turns off one X chromosome in female mammal embryos. This new capability is helping biologists understand the role of RNA and the chromosome’s structure in the X inactivation process, leading to a deeper understanding of gene expression and opening new pathways to drug treatments for gene-based disorders and diseases.
LA-UR-21-29378
https://wn.com/3D_Models_Reveal_Hidden_Process_In_X_Chromosome_Inactivation
Using new, supercomputer-driven three-dimensional (3D) dynamic modeling, researchers can now probe the process that turns off one X chromosome in female mammal embryos. This new capability is helping biologists understand the role of RNA and the chromosome’s structure in the X inactivation process, leading to a deeper understanding of gene expression and opening new pathways to drug treatments for gene-based disorders and diseases.
LA-UR-21-29378
- published: 14 Oct 2021
- views: 3748
11:04
X Inactivation and Epigenetics (2017) Etsuko Uno wehi.tv
X inactivation is a vital process that occurs in all DNA-containing cells of the female body. It is also an important research model and tool for studying epige...
X inactivation is a vital process that occurs in all DNA-containing cells of the female body. It is also an important research model and tool for studying epigenetics. Epigenetics refers to processes that tell our cells how, and when, to read the DNA blueprint. The epigenetic regulation of DNA is critical in both normal development and disease.
X inactivation is a type of gene dosage compensation.
In humans, the sex chromosomes X and Y determine the sex of an individual - females have two X chromosomes (XX), males have one X and one Y chromosome (XY). All of the genes on the Y chromosome are required in male development, while the genes on the X chromosome are needed for both male and female development.
Because females receive two X chromosomes, they inherit two copies of many of the genes that are needed for normal function. Extra copies of genes or chromosomes can affect normal development. An example is Down's syndrome, which is caused by an extra copy of part or all of chromosome 21.
In female mammals, a process called X inactivation has evolved to compensate for the extra X chromosome. In X inactivation, each cell 'switches off' one of its X chromosomes, chosen at random, to ensure the correct number of genes are expressed, and to prevent abnormal development.
https://wn.com/X_Inactivation_And_Epigenetics_(2017)_Etsuko_Uno_Wehi.Tv
X inactivation is a vital process that occurs in all DNA-containing cells of the female body. It is also an important research model and tool for studying epigenetics. Epigenetics refers to processes that tell our cells how, and when, to read the DNA blueprint. The epigenetic regulation of DNA is critical in both normal development and disease.
X inactivation is a type of gene dosage compensation.
In humans, the sex chromosomes X and Y determine the sex of an individual - females have two X chromosomes (XX), males have one X and one Y chromosome (XY). All of the genes on the Y chromosome are required in male development, while the genes on the X chromosome are needed for both male and female development.
Because females receive two X chromosomes, they inherit two copies of many of the genes that are needed for normal function. Extra copies of genes or chromosomes can affect normal development. An example is Down's syndrome, which is caused by an extra copy of part or all of chromosome 21.
In female mammals, a process called X inactivation has evolved to compensate for the extra X chromosome. In X inactivation, each cell 'switches off' one of its X chromosomes, chosen at random, to ensure the correct number of genes are expressed, and to prevent abnormal development.
- published: 25 Jan 2012
- views: 335310
2:25
X and Y chromosomes explained
X linked chromosomes explained,Humans have 23 pairs of chromosomes. One pair determine the gender of the child.A female will have xx chromosomes and males will ...
X linked chromosomes explained,Humans have 23 pairs of chromosomes. One pair determine the gender of the child.A female will have xx chromosomes and males will have an x and a y chromosome
The x and y chromosomes not only carry the genes that determine male and female traits but also some other characteristics as well.
Since only men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. The y chromosome carries around 200 genes.
There are about 1,100 human X-linked genes.
Most of them code for something other than female anatomical traits. Some X-linked genes are responsible for abnormal conditions such as hemophilia, red-green color blindness,
and "male pattern baldness".
https://wn.com/X_And_Y_Chromosomes_Explained
X linked chromosomes explained,Humans have 23 pairs of chromosomes. One pair determine the gender of the child.A female will have xx chromosomes and males will have an x and a y chromosome
The x and y chromosomes not only carry the genes that determine male and female traits but also some other characteristics as well.
Since only men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. The y chromosome carries around 200 genes.
There are about 1,100 human X-linked genes.
Most of them code for something other than female anatomical traits. Some X-linked genes are responsible for abnormal conditions such as hemophilia, red-green color blindness,
and "male pattern baldness".
- published: 09 Jan 2019
- views: 144010
29:31
Jeannie Lee (Harvard) 2 - X Chromosome Inactivation: Making the Right Choice
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for thi...
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for over 50 years both because it is a physiologically important event and because it is an excellent model for studying epigenetic silencing of genes by long non-coding RNAs. In her first talk, Dr. Jeannie Lee gives an overview of the steps a cell must go through during X inactivation. These include “counting” the X chromosomes, deciding which X chromosome to inactivate, initiating the inactivation and spreading it across the chromosome, and finally maintaining inactivation of the same X chromosome for the rest of the life of the organism.
In her second talk, Lee elaborates on the early steps of X inactivation. Very early in development, cells “count” the number of X chromosomes and decide if one needs to be inactivated, and if so which one. There is a region of the X chromosome called the X inactivation center which is enriched in long non-coding RNAs (lncRNAs). Lee explains how she and others showed that by sensing the ratio of two specific lncRNAs the cell can determine how many X chromosomes are present. Further studies showed that two different lncRNAs are responsible for randomly determining which X chromosome will be inactivated. Finally, she discusses the hypothesis that the allelic choice mechanism depends on a transient chromosomal pairing event that occurs at the beginning of the dosage compensation process.
And in her last talk, Lee describes how X inactivation is nucleated and spreads across the X chromosome. The Xist lncRNA is known to be necessary and sufficient for X inactivation. Lee describes experiments that identified the factors that tether Xist to the X chromosome and showed how Xist spreads to cover the entire X chromosome. She then goes on to explain that Xist blocks transcription in three ways: 1) Xist recruits factors that repress transcription via epigenetic modification such as histone methylation 2) Xist repels factors that open chromatin preparing it for transcription and 3) Xist changes the 3 dimensional organization of chromosomes. Lee ends with a model of our current understanding of the complex but critical process of X chromosome inactivation.
Speaker Biography:
Dr. Jeannie Lee is a Professor in the Department of Genetics at Harvard Medical School and in the Department of Molecular Biology at Massachusetts General Hospital (MGH). Her lab uses X chromosome inactivation as a model to study epigenetic regulation by long noncoding RNAs.
Lee received her AB in biochemistry and molecular biology from Harvard University and her MD/PhD from the University of Pennsylvania School of Medicine. She was a postdoctoral fellow at the Whitehead Institute and a resident at MGH before joining Harvard/MGH as a faculty member in 1997. Lee was also an HHMI Investigator from 2001-2018. She is a member of the National Academy of Sciences and a Fellow of the American Association for the Advancement of Science. Lee has been honored with numerous awards including the 2016 Centennial Prize from the Genetics Society of America, the 2016 Lurie Prize from the Foundation for the National Institutes of Health, and the 2010 Molecular Biology Award from the National Academy of Sciences. In 2018, she was President of the Genetics Society of America.
Learn more about Dr. Lee’s research here: https://www.x-inactivation-lee-lab.org
https://wn.com/Jeannie_Lee_(Harvard)_2_X_Chromosome_Inactivation_Making_The_Right_Choice
https://www.ibiology.org/development-and-stem-cells/x-chromosome-inactivation
The X chromosome is many time larger than the Y chromosome. To compensate for this genetic inequality, female mammalian cells undergo X chromosome inactivation of one X chromosome. Dr. Jeannie Lee explains the how and why of X chromosome inactivation.
Talk Overview:
In mammals, sex is determined by a pair of unequal sex chromosomes. Genetically male mammals have an X and a Y chromosome while genetically female mammals have two X chromosomes. The X chromosome is many times larger than the Y chromosome. To compensate for this genetic inequality, female mammals undergo X chromosome inactivation in which one of the X chromosomes is randomly chosen to be silenced. X chromosome inactivation has been studied for over 50 years both because it is a physiologically important event and because it is an excellent model for studying epigenetic silencing of genes by long non-coding RNAs. In her first talk, Dr. Jeannie Lee gives an overview of the steps a cell must go through during X inactivation. These include “counting” the X chromosomes, deciding which X chromosome to inactivate, initiating the inactivation and spreading it across the chromosome, and finally maintaining inactivation of the same X chromosome for the rest of the life of the organism.
In her second talk, Lee elaborates on the early steps of X inactivation. Very early in development, cells “count” the number of X chromosomes and decide if one needs to be inactivated, and if so which one. There is a region of the X chromosome called the X inactivation center which is enriched in long non-coding RNAs (lncRNAs). Lee explains how she and others showed that by sensing the ratio of two specific lncRNAs the cell can determine how many X chromosomes are present. Further studies showed that two different lncRNAs are responsible for randomly determining which X chromosome will be inactivated. Finally, she discusses the hypothesis that the allelic choice mechanism depends on a transient chromosomal pairing event that occurs at the beginning of the dosage compensation process.
And in her last talk, Lee describes how X inactivation is nucleated and spreads across the X chromosome. The Xist lncRNA is known to be necessary and sufficient for X inactivation. Lee describes experiments that identified the factors that tether Xist to the X chromosome and showed how Xist spreads to cover the entire X chromosome. She then goes on to explain that Xist blocks transcription in three ways: 1) Xist recruits factors that repress transcription via epigenetic modification such as histone methylation 2) Xist repels factors that open chromatin preparing it for transcription and 3) Xist changes the 3 dimensional organization of chromosomes. Lee ends with a model of our current understanding of the complex but critical process of X chromosome inactivation.
Speaker Biography:
Dr. Jeannie Lee is a Professor in the Department of Genetics at Harvard Medical School and in the Department of Molecular Biology at Massachusetts General Hospital (MGH). Her lab uses X chromosome inactivation as a model to study epigenetic regulation by long noncoding RNAs.
Lee received her AB in biochemistry and molecular biology from Harvard University and her MD/PhD from the University of Pennsylvania School of Medicine. She was a postdoctoral fellow at the Whitehead Institute and a resident at MGH before joining Harvard/MGH as a faculty member in 1997. Lee was also an HHMI Investigator from 2001-2018. She is a member of the National Academy of Sciences and a Fellow of the American Association for the Advancement of Science. Lee has been honored with numerous awards including the 2016 Centennial Prize from the Genetics Society of America, the 2016 Lurie Prize from the Foundation for the National Institutes of Health, and the 2010 Molecular Biology Award from the National Academy of Sciences. In 2018, she was President of the Genetics Society of America.
Learn more about Dr. Lee’s research here: https://www.x-inactivation-lee-lab.org
- published: 08 May 2019
- views: 16840