Featured Research

from universities, journals, and other organizations

First Study Hints At Insights To Come From Genes Unique To Humans

Date:
March 23, 2008
Source:
Washington University School of Medicine
Summary:
Among the approximately 23,000 genes in human DNA, scientists estimate that there may be as few as 50 to 100 that have no counterparts in other species. Little is known about the distinctive contributions these genes likely make to our species. Now scientists have produced the first detailed analysis of the cellular functions of a gene found only in humans and primate relatives known as hominoids.

Among the approximately 23,000 genes found in human DNA, scientists currently estimate that there may be as few as 50 to 100 that have no counterparts in other species. Expand that comparison to include the primate family known as hominoids, and there may be several hundred unique genes.

Related Articles


Despite the distinctive contributions these genes likely make to our species, little is known about the roles they play. Now scientists at Washington University School of Medicine in St. Louis have produced the first detailed analysis of the cellular functions of a hominoid-only gene, TBC1D3. They affirmed earlier evidence linking the gene to cancer, showing that TBC1D3's protein can keep cellular growth factors active and helps turn on RAS, a protein that is active in a third of all human cancers.

"I was astounded at how little attention has been given to human-specific genes, which make us what we are and could potentially offer a great deal of insight into human physiology," says senior author Philip D. Stahl, Ph.D., the Edward Mallinckrodt Jr. Professor and head of Cell Biology and Physiology. "In addition, certain pathogens, such as the malaria parasite, have human specific-components in their infection cycle. Human-only genes could offer us unique insights into how the parasites take advantage of us and possibly provide potent new avenues for fighting back."

When scientists want to learn more about the function of a gene, they frequently disable or delete the gene in a laboratory animal and then look to see how the loss changes the animal. That won't be possible with genes unique to humans, Stahl notes. Researchers will have to resort to altering the genes' functions in human cell lines, or transplanting them into animals to see what effects they have.

TBC1D3 was originally identified by other scientists as a likely contributor to breast cancer. At the time of its discovery, researchers linked its protein to endocytosis, a process cells use to take in material from their surface.

Endocytosis plays an important role in the Stahl laboratory. His group studies how growth factor receptors, proteins important for both normal and cancerous growth, are turned on and off. Found on the surfaces of cells, growth factor receptors turn on when they bind to a growth factor protein. To turn them off, cells take in the combined receptor-protein through endocytosis and put it through a number of different processes before finally breaking down the growth factor receptor.

When Stahl and colleagues determined in 2006 that the TBC1D3 gene is only found in hominoids, their curiosity was piqued. Evolution, Stahl notes, naturally tends to retain genes involved in the most important components of metabolism. If one of these genes mutated too dramatically, that would lead to an organism so sickly that it wouldn't survive long enough to perpetuate the mutation in its descendants. So evolution "conserves" these genes, retaining them largely unchanged as one species evolves into another.

Therefore, if the genome is compared to an automobile, human-only genes are unlikely to be adding new wheels. But they could, for example, be contributing a new anti-lock braking system: a regulatory function that fine-tunes essential processes originally established millennia ago in other species.

Stahl found evidence that this is the case in TBC1D3. Human DNA has eight copies or paralogs of the TBC1D3 gene. His lab showed that the increased levels of the protein made by one of the paralogs makes human cells grow more rapidly. When they transplanted the gene for the protein into mouse cells, it had the same effect.

A closer look showed that the protein from the TBC1D3 paralog delays a process that labels growth factor receptors for breakdown, prolonging the time that their signal is active.

He also found evidence that the protein was helping to activate RAS, another gene whose protein is commonly found in human cancers.

Stahl and his colleagues plan additional research to learn whether the other paralogs of TBC1D3 have different roles. He also has several ideas for learning more about the functions of human-only genes.

"We might try an organ-by-organ approach, looking to see if any genes specific to a particular organs, such as fat, are specific to humans," he says. "We also should probably look at crystallizing the proteins from some of these genes, which can tell us more about what they interact with."

There may be human diseases where these genes are mutated or missing, Stahl speculates. The effects of such conditions could provide important clues to what the humans-only genes do.

"It's also going to be very interesting for evolutionary biologists to try to develop a sense for where these humans-only genes come from," Stahl says. "The building blocks of these genes may be present but not active in earlier species."

The paper appears online in The Journal of Biological Chemistry.

Journal reference: Wainszelbaum MJ, Charron AJ, Kong C, Kirkpatrick DS, Srikanth P, Barbieri MA, Gygi SP, Stahl PD. The hominoid-specific oncogene TBC1D3 activates RAS and modulates EGF receptor signaling and trafficking. Journal of Biological Chemistry, online publication.


Story Source:

The above story is based on materials provided by Washington University School of Medicine. Note: Materials may be edited for content and length.


Cite This Page:

Washington University School of Medicine. "First Study Hints At Insights To Come From Genes Unique To Humans." ScienceDaily. ScienceDaily, 23 March 2008. <www.sciencedaily.com/releases/2008/03/080321114414.htm>.
Washington University School of Medicine. (2008, March 23). First Study Hints At Insights To Come From Genes Unique To Humans. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2008/03/080321114414.htm
Washington University School of Medicine. "First Study Hints At Insights To Come From Genes Unique To Humans." ScienceDaily. www.sciencedaily.com/releases/2008/03/080321114414.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Best Tips to Curb Holiday Carbs

The Best Tips to Curb Holiday Carbs

Buzz60 (Dec. 19, 2014) It's hard to resist those delicious but fattening carbs we all crave during the winter months, but there are some ways to stay satisfied without consuming the extra calories. Vanessa Freeman (@VanessaFreeTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Sierra Leone Bikers Spread the Message to Fight Ebola

Sierra Leone Bikers Spread the Message to Fight Ebola

AFP (Dec. 19, 2014) More than 100 motorcyclists hit the road to spread awareness messages about Ebola. Nearly 7,000 people have now died from the virus, almost all of them in west Africa, according to the World Health Organization. Video provided by AFP
Powered by NewsLook.com
Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
The Best Protein-Filled Foods to Energize You for the New Year

The Best Protein-Filled Foods to Energize You for the New Year

Buzz60 (Dec. 19, 2014) The new year is coming and nothing will energize you more for 2015 than protein-filled foods. Fitness and nutrition expert John Basedow (@JohnBasedow) gives his favorite high protein foods that will help you build muscle, lose fat and have endless energy. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins