Cell and molecular biology seminar discusses DNA

10/15/09 - Many people may want to change their genetic makeup, or at least the physical appearance that their genes express. According to professor Jeffrey Laney, yeast cells have the ability to do just that. Laney's presentation, "Phenotypic Transitions in Yeast: Critical Roles for Ubiquitin-Mediated Remodeling and Rapid Transcriptional Switches," was given Friday as part of the Cell and Molecular Biology Fall 2009 Seminar Series in the Center for Biotechnology and Life Sciences.

Lanely has been a faculty member at Brown University in Providence since 2002. The presentation marked his first trip to URI.

Laney's research focuses on how cells can "change [their own] fate." He examines the "underlying molecular mechanisms" needed to make those changes. In simplified terms, Laney said he looks at how cells "get from point A to point B."

Laney studies gene expression in the yeast cells that are commonly used to make beer and bread. He explained that such cells have the ability to change their own phenotype, or the way their genes are physically expressed. Laney said these changes occur to enable the organism to "get to a more advantageous form."

According to Laney, "Upon switching from one cell type to another" transcription factors - proteins bound to the DNA - must be somehow disposed or inactivated for the new cell type to divide and survive.

If these proteins that are incompatible with the cell's changed form remain, Laney said they will "wreak havoc on the lineage and biology of the organism."

The inactivation is able to occur, Laney said, "Because all of these transcription factors are extremely short-lived." Usually the protein remains for no longer than four to five minutes in the case of Alpha-2, one of the proteins Laney zeroed in on in his discussion.

Laney said, "This is the basic problem that we're interested in: How does the cell know how to make these transitions and what . allows cells to do such a thing?"

Cells in many biological settings, Laney explained, can change their structure even when they appear to be terminally differentiated. For example, Laney said membranous cells could transform to become neurons. These cells are essentially reversing their fate.

Laney also looks at how frequently those cells with the ability to switch phenotypes actually do so. He pointed out that enzymes play a major role in this, because they have the ability to "basically yank apart" proteins and render them inactive.

Depending on whether they have enzymes to degrade the protein Alpha-2, the cells can switch phenotypes anywhere from 3 percent to 75 percent of the time.

Laney called these findings "dramatic," and said that "interesting biological consequences" can follow from them.

Further complicating things is the presence of "molecular chaperones" which, according to Laney, "appear to influence the dynamics of binding behavior."

Laney also took time to acknowledge the National Institute of General Medical Sciences and the March of Dimes for funding his research. He expressed gratitude for Alex Wilcox, a postdoctoral research associate, and Alec DeSimone, a former graduate student, both of Brown's Cell and Molecular Biology Department, for their assistance.

Kezhen Huang, one of the lecture's attendees and a graduate student at URI, said that he liked Laney's presentation, particularly because Laney "provided great background information" that made the presentation easier to understand.

Huang is studying for a PhD. in cell and molecular biology. He said Laney's seminar "was a very good presentation. I enjoyed it."

The upcoming lecture in the seminar series, "Fish Playing Poker with Immunity; I'm All In" will be given on Oct. 16 by Erin Bromage of University of Massachusetts Dartmouth, again set to be held in Room 10 of the CBLS at 3 p.m.