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:12/22/2016)... NEW YORK , December 22, 2016 ... global provider of secure solutions for the e-Government, Public Safety, HealthCare, ... a subsidiary of SuperCom, has been selected to implement and deploy ... county in Northern California , further expanding its ... ...
(Date:12/19/2016)... BARCELONA , España y TORONTO , 19 ... fusión con Northern Biologics Inc. que permitirá el desarrollo acelerado de ... ensayos clínicos en varios tipos de tumor en 2017, con múltiples ... ... de su clase con objetivo en el factor inhibidor de leucemia ...
(Date:12/16/2016)... global wearable medical device market, in terms of value, is projected ... in 2016, at a CAGR of 18.0% during the forecast period. ... Growth in ... launch of a growing number of smartphone-based healthcare apps compatible with ... increasing focus on physical fitness. Furthermore, growing trend ...
Breaking Biology News(10 mins):
(Date:1/19/2017)... , ... January 19, 2017 , ... FireflySci Inc. is ... rate. The tremendous growth is accounted to two main factors. The first ... the expanding network of vendors supplying FireflySci products all around the world. , 2016 ...
(Date:1/19/2017)... Jan. 18, 2017 BD (Becton, Dickinson and Company) (NYSE: ... that it will host a live webcast of its Annual Meeting ... The webcast can be accessed from the BD ... through Tuesday, January 31, 2017. ... About BD BD is a global medical ...
(Date:1/18/2017)... N.J. , Jan. 18, 2017   Parent ... the fight to end Duchenne muscular dystrophy (Duchenne) ... to the New Jersey Institute of Technology (NJIT) and ... exploration of robotic technology to assist people ... to incorporate NJIT,s technology – an embedded computer, software, ...
(Date:1/18/2017)... ... January 18, 2017 , ... MYOLYN, which ... it has submitted a 510(k) to the FDA, requesting clearance of the MyoCycle ... electrical stimulation (FES) technology. , The submission marks a major milestone for ...
Breaking Biology Technology: