| Email Article | Print |
Protein protects embryonic stem cells' versatility and self-renewal
March 24, 2008M. D. Anderson team connects REST to regenerative medicine, pediatric brain cancer
HOUSTON - A protein known as REST blocks the expression of a microRNA that prevents embryonic stem cells from reproducing themselves and causes them to differentiate into specific cell types, scientists at The University of Texas M. D. Anderson Cancer Center report in the journal Nature.
Researchers show RE1-silencing transcription factor (REST) plays a dual role in embryonic stem cells, said senior author Sadhan Majumder, Ph.D., professor in M. D. Anderson's Department of Cancer Genetics. "It maintains self-renewal, or the cell's ability to make more and more cells of its own type, and it maintains pluripotency, meaning that the cells have the potential to become any type of cell in the body."
The paper posted online March 23 in advance of publication grew from M. D. Anderson research on the protein's role in medulloblastoma - an exceptionally aggressive pediatric brain cancer.
Embryonic stem cells are essentially blank slates. They have the unique ability to develop from identical, unspecialized cells and then differentiate into distinct types of cells with special functions. In the laboratory, scientists have been able to induce embryonic stem cells to develop into heart muscle cells or insulin-producing cells of the pancreas. The hope is that embryonic stem cells might one day be used to restore or replace failing cells in the human body and perhaps treat a wide range of diseases.
"Embryonic stem cells have a very high potential in medicine," Majumder said. "The critical thing is to learn the mechanisms that could be used to generate a lot of self-renewing embryonic stem cells and be able to differentiate them into various cell types." REST could play a key role in maintaining a steady supply of these cells and in preserving their differentiation capability.
Suppressing MicroRNA-21
In studies using mouse embryonic stem cells, the researchers found that REST disarms a specific microRNA called microRNA-21 or miR-21. MicroRNAs are tiny pieces of RNA that control gene expression by binding to the gene's messenger RNA.
The team found that MiR-21 suppresses embryonic stem cell self-renewal and is associated with a corresponding loss of expression of critical self-renewal regulators, such as Oct4, Nanog, Sox2 and c-Myc. REST counters this by suppressing miR-21 to preserve the cells' self-renewal and pluripotency.
The researchers discovered the roles of REST and miR-21 in a series of experiments using cultured mouse embryonic stem cells in either a self-renewal state or a differentiating state. They found that REST expression was significantly higher in the self-renewal state. Withdrawing REST reduced the stem cells' ability to reproduce themselves and started differentiation - even when the cells were grown under conditions conducive to self-renewal. Adding REST to differentiating cells maintained their self-renewal.
These experiments also revealed that REST is bound to the gene chromatin of a set of microRNAs with the potential to target self-renewal genes. REST controls transcription of 11 microRNAs.
REST Implicated in Pediatric Brain Cancer
Previous laboratory research suggests that the qualities that make REST beneficial in stem cell production and pluripotency may contribute to the development of medulloblastoma, an aggressive type of children's brain tumor. Medulloblastomas are believed to develop from undifferentiated neural stem cells in the external granule layer of the cerebellum.
In earlier research, Majumder's group at M. D. Anderson discovered that about half of these tumors overexpress REST, which is not found in most neural cells. "We found that REST is a critical factor in this group of children's brain tumors," Majumder said, "and that its major function is to keep a group of specific brain stem cells, or progenitor cells, in a state of stemness."
The researchers hypothesize that by maintaining the neural stem cells' 'stemness,' REST prevents their differentiation into normal and distinct types of cells, leading instead to tumor formation. The M. D. Anderson scientists are now exploring whether microRNAs might also play a role in medulloblastomas.
Understanding REST function has applications in both medulloblastoma and embryonic stem cell biology. "Just as blocking REST function has therapeutic potential in medulloblastoma, blocking REST function to allow for differentiation of embryonic stem cells is a potentially critical step in regenerative medicine," Majumder said.
University of Texas M. D. Anderson Cancer Center
The paper posted online March 23 in advance of publication grew from M. D. Anderson research on the protein's role in medulloblastoma - an exceptionally aggressive pediatric brain cancer.
Embryonic stem cells are essentially blank slates. They have the unique ability to develop from identical, unspecialized cells and then differentiate into distinct types of cells with special functions. In the laboratory, scientists have been able to induce embryonic stem cells to develop into heart muscle cells or insulin-producing cells of the pancreas. The hope is that embryonic stem cells might one day be used to restore or replace failing cells in the human body and perhaps treat a wide range of diseases.
"Embryonic stem cells have a very high potential in medicine," Majumder said. "The critical thing is to learn the mechanisms that could be used to generate a lot of self-renewing embryonic stem cells and be able to differentiate them into various cell types." REST could play a key role in maintaining a steady supply of these cells and in preserving their differentiation capability.
Suppressing MicroRNA-21
In studies using mouse embryonic stem cells, the researchers found that REST disarms a specific microRNA called microRNA-21 or miR-21. MicroRNAs are tiny pieces of RNA that control gene expression by binding to the gene's messenger RNA.
The team found that MiR-21 suppresses embryonic stem cell self-renewal and is associated with a corresponding loss of expression of critical self-renewal regulators, such as Oct4, Nanog, Sox2 and c-Myc. REST counters this by suppressing miR-21 to preserve the cells' self-renewal and pluripotency.
The researchers discovered the roles of REST and miR-21 in a series of experiments using cultured mouse embryonic stem cells in either a self-renewal state or a differentiating state. They found that REST expression was significantly higher in the self-renewal state. Withdrawing REST reduced the stem cells' ability to reproduce themselves and started differentiation - even when the cells were grown under conditions conducive to self-renewal. Adding REST to differentiating cells maintained their self-renewal.
These experiments also revealed that REST is bound to the gene chromatin of a set of microRNAs with the potential to target self-renewal genes. REST controls transcription of 11 microRNAs.
REST Implicated in Pediatric Brain Cancer
Previous laboratory research suggests that the qualities that make REST beneficial in stem cell production and pluripotency may contribute to the development of medulloblastoma, an aggressive type of children's brain tumor. Medulloblastomas are believed to develop from undifferentiated neural stem cells in the external granule layer of the cerebellum.
In earlier research, Majumder's group at M. D. Anderson discovered that about half of these tumors overexpress REST, which is not found in most neural cells. "We found that REST is a critical factor in this group of children's brain tumors," Majumder said, "and that its major function is to keep a group of specific brain stem cells, or progenitor cells, in a state of stemness."
The researchers hypothesize that by maintaining the neural stem cells' 'stemness,' REST prevents their differentiation into normal and distinct types of cells, leading instead to tumor formation. The M. D. Anderson scientists are now exploring whether microRNAs might also play a role in medulloblastomas.
Understanding REST function has applications in both medulloblastoma and embryonic stem cell biology. "Just as blocking REST function has therapeutic potential in medulloblastoma, blocking REST function to allow for differentiation of embryonic stem cells is a potentially critical step in regenerative medicine," Majumder said.
University of Texas M. D. Anderson Cancer Center
Embryonic Stem Cells News and Current Embryonic Stem Cells Events RSSControlling embryonic fate by association
Association determines fate in embryonic stem cells, said Baylor College of Medicine researchers in a report that appears in the current issue of the journal Nature Cell Biology.
UCLA stem cell researchers create heart and blood cells from reprogrammed skin cells
Stem cell researchers at UCLA were able to grow functioning cardiac cells using mouse skin cells that had been reprogrammed into cells with the same unlimited properties as embryonic stem cells.
Heart derived stem cells develop into heart muscle
Dutch researchers at University Medical Center Utrecht and the Hubrecht Institute have succeeded in growing large numbers of stem cells from adult human hearts into new heart muscle cells.
Menstrual blood -- a valuable source of multipotential stem cells?
Researchers seeking new and more abundant sources of stem cells for use in regenerative medicine have identified a potentially unlimited, noncontroversial, easily collectable, and inexpensive source - menstrual blood.
Method to deliver molecules within embryonic stem cells improves differentiation
Embryonic stem cell therapies have been proposed for regenerative medicine and tissue replacement after injury or disease. However, the inability of stem cells to efficiently develop into the desired specific cell type - such as muscle, skin, blood vessels, bone or neurons - now limits the potential clinical utility of this therapy.
Heart stem cell scientist to honor pioneering woman scientist in keynote speech
Professor Christine Mummery, one of the world's leading heart stem cell experts, will later today (9 April) honour the memory of Dame Anne McLaren in the keynote lecture of the inaugural UK National Stem Cell Network Science Meeting in Edinburgh.
Scientists uncover the potential to control adult stem cells
Research being presented today (10 April) at the UK National Stem Cell Network Annual Science Meeting in Edinburgh represents a step towards the use of Adult Stem Cells (ASCs) to repair damaged tissue.
Stem cell breakthrough offers diabetes hope
Scientists have discovered a new technique for turning embryonic stem cells into insulin-producing pancreatic tissue in what could prove a significant breakthrough in the quest to find new treatments for diabetes.
UCLA researchers examine human embryonic stem cell genome
Stem cell researchers from UCLA used a high resolution technique to examine the genome, or total DNA content, of a pair of human embryonic stem cell lines and found that while both lines could form neurons, the lines had differences in the numbers of certain genes that could control such things as individual traits and disease susceptibility.
Therapeutic cloning treats Parkinson's disease in mice
Research led by investigators at Memorial Sloan-Kettering Cancer Center (MSKCC) has shown that therapeutic cloning, also known as somatic-cell nuclear transfer (SCNT), can be used to treat Parkinson's disease in mice. The study's results are published in the March 23 online edition of the journal Nature Medicine.
More Embryonic Stem Cells News Articles
| © 2008 BrightSurf.com |