Navigation Links
Scientists identify key roadblock to gene expression

A team of scientists has provided, for the first time, a detailed map of how the building blocks of chromosomes, the cellular structures that contain genes, are organized in the fruit fly Drosophila melanogaster. The work identifies a critical stop sign for transcription, the first step in gene expression, and has implications for understanding how the AIDS virus regulates its genes. The findings will be published in the 15 May 2008 issue of the journal Nature.

The scientists found that nucleosomes--chromosomal building blocks made up of proteins around which DNA is coiled--occur at precise locations along genes that are actively undergoing transcription. They also showed that RNA polymerase--the enzyme that reads genes as the first step in making proteins--is stopped at the first nucleosome, where it remains idle until it is directed to continue moving forward. "This discovery is important because nucleosomes are barriers to transcription and we now are seeing the impact of nucleosome organization on RNA polymerase," said lead investigator B. Franklin Pugh, professor and Willaman Chair in Molecular Biology at Penn State University.

Using state-of-the-art ChIP-sequencing, a genome-mapping tool provided by collaborator Stephen S. Schuster, Penn State professor of biochemistry and molecular biology, and computational predictions developed by collaborators Ilya Ioshikhes, an assistant professor at Ohio State University, and Istvan Albert, a research assistant professor of bioinformatics at Penn State, the scientists precisely mapped the locations of hundreds of thousands of nucleosomes. The scientists then compared these maps to the team's earlier maps of the baker's yeast Saccharomyces cerevisiae, revealing that evolution has organized nucleosomes differently in simple life forms compared to more complex organisms like the fruit fly.

In yeast, a nucleosome sits on top of the transcription start site, so RNA polymerase must contend with that nucleosome as soon as it begins to transcribe the gene. In contrast, nucleosomes are positioned further downstream in fruit flies, so transcription starts but then soon pauses at the first nucleosome the RNA polymerase encounters. "This pause is maintained until chemical signals from the cell cue the removal of the nucleosome and encourage the RNA polymerase to continue along its path," said key collaborator David S. Gilmour, professor of molecular and cellular biology at Penn State and an expert on the pausing of RNA polymerase.

"A year ago, we could name about 10 genes that work this way. Now, we know of 1,000 in flies alone and we suspect there could be many more in humans," said Gilmour. "Even HIV genes have a paused RNA polymerase. Release of this pause may be key to activating HIV replication of otherwise latent viruses. Taking advantage of this new understanding might enable the development of more effective anti-viral drugs," he said.

"The bottom line is that we need to know how the expression of genes is regulated in order to understand the underpinnings of most human diseases, and these findings take us one step closer," said Pugh.


Contact: Barbara K. Kennedy
Penn State

Related medicine news :

1. Scientists identify interacting proteins key to melanoma development, treatment
2. The American Psychiatric Associations Awards for Young Scientists Encourage Research Expertise in China
3. Scientists identify gatekeepers of breast cancer transition to invasive disease
4. Scientists at Yale provide explanation for how cancer spreads
5. Brookhaven scientists explore brains reaction to potent hallucinogen
6. Scientists Discover How Stomach Tumors Form
7. U.S. Scientists Receive Japan Prize on April 23, 2008
8. Scientists discover a mechanism that can send cells on the road to cancer
9. Scientists identify novel way to prevent cardiac fibrosis
10. Scientists Explore Human Gene Pool With Help From Microsoft Research
11. Scientists obtain anticancer medicines from the elecampe, a wild plant growing in the Mediterranean
Post Your Comments:
(Date:12/1/2015)... , ... December 01, 2015 , ... According to an ... groups has filed a discrimination claim against the U.S. Department of Health and Human ... Affordable Care Act (ACA) plans are breaking the clause in the law prohibiting the ...
(Date:12/1/2015)... ... December 01, 2015 , ... Califia Farms , one ... its iconic bottle has won top honors in Beverage World Magazine’s Global Packaging Design ... announced that it has been selected as a 2015 U.S.A. Taste Champion in the ...
(Date:12/1/2015)... ... , ... Growth in medical payments per workers’ compensation claim in Louisiana slowed ... nonhospital care, according to a recent study by the Workers Compensation Research Institute (WCRI). ... medical payments per claim with more than seven days of lost time continued to ...
(Date:12/1/2015)... ... December 01, 2015 , ... CloudLIMS today announced ... Bridge Business Awards under the New Products and Services category for its innovative ... sample management software that helps labs organize data and track samples with ...
(Date:12/1/2015)... ... December 01, 2015 , ... Diabetic foot wounds ... Podiatrists are well aware that psychology-based patient non-compliance (disobedience of a health care ... to diseases of the diabetic foot. The American Board of Multiple Specialties ...
Breaking Medicine News(10 mins):
(Date:12/1/2015)... 1, 2015 --> ... report "Nucleic Acid Labeling Market by Product (Reagents & ... Primer, In Vitro Transcription, Reverse Transcription, End Labeling), by ... The global market is expected to reach USD 1,925.7 ... growing at a CAGR of 8.65%. Browse ...
(Date:12/1/2015)... Russia has always been a country of choice for ... Europe in 2015 were tested in phase II-III ... has always been a country of choice for global multi-center phase ... in 2015 were tested in phase II-III clinical trials ... always been a country of choice for global multi-center phase III clinical ...
(Date:12/1/2015)... Dec. 1, 2015 Relmada Therapeutics, Inc. (OTCQB: RLMD), ... chronic pain, announced today that the company will present at ... December 1-3 at the Luxe Sunset Boulevard Hotel in ... CEO of Relmada Therapeutics, will present on Thursday, December 3, ... . Please register at least 10 minutes prior ...
Breaking Medicine Technology: