Corporate Banner
Satellite Banner
Scientific Community
Become a Member | Sign in
Home>News>This Article

Did Inefficient Cellular Machinery Evolve to Fight Viruses and Jumping Genes?

Published: Monday, November 11, 2013
Last Updated: Monday, November 11, 2013
Bookmark and Share
UCSF scientist poses new theory on origins of eukaryotic gene expression.

It might seem obvious that humans are elegant and sophisticated beings in comparison to lowly bacteria. But when it comes to genes, a UC San Francisco scientist wants to turn conventional wisdom about human and bacterial evolution on its head.

Far from being sleekly performing and fine-tuned athletes, the molecules guiding the activity of our genes are like sour bureaucrats that clog up the works and create unnecessary inefficiency, asserts Hiten Madhani, MD, PhD, a professor of biochemistry and biophysics at UCSF. In contrast, bacteria carry out these processes efficiently with less frustration for the gene to express itself.

Madhani presented his viewpoint in an essay entitled “The Frustrated Gene: Origins of Eukaryotic Gene Expression,” published online Nov. 7 in the journal Cell.

Although his thinking was stimulated by his own research findings, Madhani described his Cell essay as a “just so” story, a conjecture that challenges conventional thinking, but that so far is without data to back it up.

He paraphrased a source of inspiration, the renowned scientist Sydney Brenner, who won a Nobel Prize for his own studies of gene regulation: “Biology is awash in a sea of data, but it needs new theories,” Madhani said.

Parasitic DNA May Be Driver of Eukaryotic Evolution

Most scientists believe that the complexity of the molecular mechanisms that guide the expression of genes and the production of proteins within a human cell is needed to allow for flexible responses that drive the development and maintenance of multifaceted organisms, Madhani said.

But he proposes that this complexity in genetic regulatory machinery did not originally evolve to allow for the development of the whole human. Instead, he suggested, complexity in gene expression might have first evolved in early eukaryotes to thwart infection by “parasitic DNA,” such as retroviruses, that would otherwise invade the cell nucleus and disrupt normal genes.

In contrast to humans, bacteria control their genes and have adaptively evolved in myriad ways without complex mechanisms like those that guide human gene expression. In fact, humans, whose cells number in the many trillions, and disease-causing bacteria, which are but a single cell, have been doing battle and evolving together for ages, with multidrug-resistant bacteria perhaps being latest type of villain to emerge in this epic struggle.

Bacteria have persisted despite their simplicity. They have only one gene-bearing chromosome and lack any kind of cell nucleus. The bacterial chromosome itself lacks the modifiable, protective sheath known as chromatin. Many other details of gene expression differ between human and bacterial cells. Bacteria are known as “prokaryotes,” a name that refers to the fact that they arose before cells evolved that had a nucleus – more than 3 billion years ago, according to some estimates made from fossils. Human cells have a nucleus and numerous other features that peg them as “eukaryotes.”

While humans evolved from apes just a few million years ago, eukaryotes have been around since the ancestors of single-celled yeast arose, perhaps 1.5 billion years ago – with the same complex features, Madhani said.

“It might be tempting to think that the complex attributes of human gene expression evolved to drive the evolution of complex, multicellular organisms,” Madhani said, “But the core elements of eukaryotic gene expression were established within the ancient unicellular progenitor of modern eukaryotes.” In other words, the early eukaryotic cell already was adapting to ward off parasitic DNA, he suggested.

Previous Lab Studies on Jumping Gene Nemesis

Madhani said his idea stems from research he published earlier this year. His research group discovered that a eukaryotic cellular machine known as SCANR plays a previously unrecognized role in thwarting corruption of the genome by parasitic DNA.

SCANR guards against DNA called jumping genes, or transposons, which long ago invaded the human genome. Transposons replicate multiple times, and insert themselves at random places within genomic DNA. When transposons insert themselves in the middle of an important gene, they may cause malfunction, disease or birth defects.

Madhani began thinking about how other mechanisms in the cell might similarly stymie certain viruses, which unlike bacterial pathogens, depend on the genetic machinery of their human hosts in order to replicate.

In addition to the chromatin that restricts access to DNA, eukaryotic cells also have embellishments to their RNA, and molecular inspectors that check to see that these eukaryotic modifications are present before protein production proceeds. The nucleus itself is gated to allow only certain molecules to get in and out. Many other eukaryotic cellular phenomena might have first evolved to defend against viruses and transposable elements, Madhani said.

UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. It includes top-ranked graduate schools of dentistry, medicine, nursing and pharmacy, a graduate division with nationally renowned programs in basic biomedical, translational and population sciences, as well as a preeminent biomedical research enterprise and two top-ranked hospitals, UCSF Medical Center and UCSF Benioff Children’s Hospital.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

RNA-Based Drugs Give More Control Over Gene Editing
CRISPR/Cas9 gene editing technique can be transiently activated and inactivated using RNA-based drugs, giving researchers more precise control in correcting and inactivating genes.
Monday, November 23, 2015
Clearest Ever Images of Enzyme that Plays Key Roles in Aging, Cancer
UCLA-led research on telomerase could lead to new strategies for treating disease
Monday, October 19, 2015
Crop Cure
Scientists in new center to use medical research techniques to help food crops withstand drought and climate change.
Friday, October 16, 2015
Rare Childhood Leukemia Reveals Surprising Genetic Secrets
A coalition of leukemia researchers led by scientists from UC San Francisco has discovered surprising genetic diversity in juvenile myelomonocytic leukemia (JMML), a rare but aggressive childhood blood cancer.
Thursday, October 15, 2015
Double Enzyme Hit May Explain Common Cancer Drug Side Effect
Mouse study suggests genomic screening before treatment may help prevent anemia.
Wednesday, October 14, 2015
New Autism Genes Are Revealed in Largest-Ever Study
Work draws more detailed picture of genetic risk, sheds light on sex differences in diagnosis.
Wednesday, September 30, 2015
Scientists Create CRISPR/Cas9 Knock-In Mutations in Human T Cells
In a project spearheaded by investigators at UC San Francisco, scientists have devised a new strategy to precisely modify human T cells using the genome-editing system known as CRISPR/Cas9.
Tuesday, July 28, 2015
Simple Technology Makes CRISPR Gene Editing Cheaper
University of California, Berkeley, researchers have discovered a much cheaper and easier way to target a hot new gene editing tool, CRISPR-Cas9, to cut or label DNA.
Friday, July 24, 2015
Engineers Crack DNA Code of Autoimmune Disorders
Researchers have identified an unexpectedly general set of rules that determine which molecules can cause the immune system to become vulnerable to the autoimmune disorders lupus and psoriasis.
Wednesday, June 10, 2015
Genetic Markers for Detecting and Treating Ovarian Cancer
Custom bioinformatics algorithm identifies human mRNAs that distinguish ovarian cancer cells from normal cells and provide new therapeutic targets
Wednesday, May 27, 2015
Industry-Sponsored Academic Inventions Spur Increased Innovation
Analysis questions assumption that corporate support skews science toward inventions that are less useful than those funded by the government or non-profit organizations.
Monday, March 24, 2014
Researchers Change Cell Types by Flipping a Single Switch
New findings have identified a method for changing one cell type into another in a process called forced transdifferentiation.
Friday, December 06, 2013
Scientists Pinpoint Cell Type and Brain Region Affected by Gene Mutations in Autism
UCSF-led study zeroes in on when and where disrupted genes exert effects.
Tuesday, November 26, 2013
Digging Deeper Into Cancer
What a pathologist looks for in a Pap test sample, but hopes not to find, are oddly shaped cells with abnormally large nuclei. The same is true for prostate and lung cancer biopsies.
Tuesday, November 19, 2013
Nanotech Method Show Promise Against Pancreatic Cancer
Researchers at UCLA's Jonsson Comprehensive Cancer Center have developed a new technique for fighting deadly and hard-to-treat pancreatic cancer.
Monday, November 18, 2013
Scientific News
New Tech Vastly Improves CRISPR/Cas9 Accuracy
A new CRISPR/Cas9 technology developed by scientists at UMass Medical School is precise enough to surgically edit DNA at nearly any genomic location, while avoiding potentially harmful off-target changes typically seen in standard CRISPR gene editing techniques.
New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Biologists Induce Flatworms to Grow Heads and Brains of Other Species
Findings shed light on role of a new kind of epigenetic signaling in evolution, could yield clues for understanding birth defects and regeneration.
Turning up the Tap on Microbes Leads to Better Protein Patenting
Mining millions of proteins could become faster and easier with a new technique that may also transform the enzyme-catalyst industry, according to University of California, Davis, researchers.
Mathematical Model Forecasts the Path of Breast Cancer
Chances of survival depend on which organs breast cancer tumors colonize first.
Exploring the Causes of Cancer
Queen's research to understand the regulation of a cell surface protein involved in cancer.
Ancient Viral Molecules Essential for Human Development
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
Tardigrade's Are DNA Master Thieves
Tardigrades, nearly microscopic animals that can survive the harshest of environments, including outer space, hold the record for the animal that has the most foreign DNA.
The Secret Behind the Power of Bacterial Sex
Migration between different communities of bacteria is the key to the type of gene transfer that can lead to the spread of traits such as antibiotic resistance, according to researchers at Oxford University.
Farming’s in Their DNA
Ancient genomes reveal natural selection in action.
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos