Navigation Links
CSHL researchers map changing epigenetic modifications that enable transposons to run amok
Date:12/10/2008

Cold Spring Harbor, N.Y. Much like cancer cells, plant cells grown for a long time outside of their normal milieu, in culture dishes, have highly unstable genomes. Changes in gene activity, or how genes are "expressed," help cells cope with challenging culture conditions but inadvertently also leave genes prone to mis-regulation by transposons -- bits of DNA that can jump around in the genome, inserting themselves into random genetic locations, often disrupting normal gene function and regulation.

Such genomic chaos, found in cancer and other diseases, is normally prevented by a host of mechanisms that scientists call epigenetic: they modify the expression of genes, although not by causing mutations in the sequence of the genome's DNA "letters."

How transposons (sometimes called mobile genetic elements) escape these controls is one of the questions driving the research of Professor Robert Martienssen -- a pioneer of plant epigenetics -- at Cold Spring Harbor Laboratory (CSHL). By undertaking the ambitious task of mapping the changing epigenetic landscape of continuously dividing plant cells, Martienssen's team has succeeded in capturing in detail epigenetic alterations and the molecular players that allow transposons to run amok. Their findings are described in a paper published in the December 9th issue of PLoS Biology.

Shifting RNA patterns

The numerous and diverse transposons present within the plant genome are normally rendered inactive by a series of complicated steps masterminded by small molecules of RNA, called small interfering RNA (siRNA). They perform this feat in a phenomenon known as RNA interference (RNAi). The discovery that modifications of heterochromatin -- densely packed, genetically "inactive" regions of DNA -- are targeted by RNAi was made by Martienssen's team in yeast cells and heralded as one of the leading scientific breakthroughs of 2002.

Martienssen's team now has found that in immortalized cells -- cells that are coaxed to grow endlessly in culture dishes -- the epigenetic changes resulting in a loss of heterochromatin and transposon "re-activation" are not due to a loss of the proteins that regulate heterochromatin. Instead, they find that the epigenetic modifications are due to a change in the population of siRNAs produced in the continuously dividing cells. When this occurs in the vicinity of genes, this epigenetic control can have important consequences for the organism. According to Martienssen, "our work implicates RNAi in epigenetic chromatin changes that occur in immortalized cells."

Epigenetic "restructuring" by siRNA

The CSHL researchers find that transposons that have lost heterochromatic marks are no longer associated with siRNA that are 24 nucleotides, or RNA "letters," in length. Rather, these re-activated transposons become associated with siRNAs that are 21nucleotides in length. In contrast, the transposons that retain their original heterochromatic marks and therefore remain silent continue to stay associated with 24-nucleotide siRNAs.

The team's eventual goal is to understand the mechanism responsible for the creation of epialleles epigenetic variations in gene expression patterns that stem from the creation of particular chromatin states. These predispose particular genes to become active when they shouldn't be and shut off the activity of genes that are essential. The team's epigenetic profiling study now implicates siRNA-driven heterochromatin restructuring as a mechanism that might lead to epiallele formation.


'/>"/>

Contact: Hema Bashyam
bashyam@cshl.edu
516-367-6822
Cold Spring Harbor Laboratory
Source:Eurekalert

Related biology news :

1. Researchers identify proteins involved in new neurodegenerative syndrome
2. Texas researchers and educators head for Antarctica
3. MGH researchers describe new way to identify, evolve novel enzymes
4. University of Pennsylvania researchers develop formula to gauge risk of disease clusters
5. U of MN researchers discover noninvasive diagnostic tool for brain diseases
6. U of Minnesota researchers discover noninvasive diagnostic tool for brain diseases
7. Researchers discover new strategies for antibiotic resistance
8. Researchers find new taste in fruit flies: carbonated water
9. Binghamton University researchers investigate evolving malaria resistance
10. UIC researchers find promising new targets for antibiotics
11. Researchers develop simple method to create natural drug products
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/26/2016)... LONDON , April 26, 2016 ... a product subsidiary of Infosys (NYSE: ... to integrate the Onegini mobile security platform with ... http://photos.prnewswire.com/prnh/20151104/283829LOGO ) The integration will ... to access and transact across channels. Using this ...
(Date:4/15/2016)...  A new partnership announced today will help ... in a fraction of the time it takes ... life insurance policies to consumers without requiring inconvenient ... Diagnostics, rapid testing (A1C, Cotinine and HIV) and ... weight, pulse, BMI, and activity data) available at ...
(Date:4/13/2016)... 13, 2016  IMPOWER physicians supporting Medicaid patients in ... new clinical standard in telehealth thanks to a new ... higi platform, IMPOWER patients can routinely track key health ... mass index, and, when they opt in, share them ... to a local retail location at no cost. By ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... CA (PRWEB) , ... June 27, 2016 , ... ... for clinical trials, announced today the Clinical Reach Virtual Patient Encounter CONSULT ... care circle with the physician and clinical trial team. , Using the CONSULT module, ...
(Date:6/27/2016)... , June 27, 2016  Liquid Biotech ... the funding of a Sponsored Research Agreement with ... tumor cells (CTCs) from cancer patients.  The funding ... CTC levels correlate with clinical outcomes in cancer ... data will then be employed to support the ...
(Date:6/24/2016)... 2016 Epic Sciences unveiled a liquid ... to PARP inhibitors by targeting homologous recombination deficiency ... new test has already been incorporated into numerous ... types. Over 230 clinical trials are ... including PARP, ATM, ATR, DNA-PK and WEE-1. Drugs ...
(Date:6/23/2016)... WA (PRWEB) , ... June 23, 2016 , ... ... announces the release of its second eBook, “Clinical Trials Patient Recruitment and Retention ... recruitment and retention in this eBook by providing practical tips, tools, and strategies ...
Breaking Biology Technology: