Corporate Banner
Satellite Banner
Genotyping & Gene Expression
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

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 2,500+ scientific posters on ePosters
  • More than 3,800+ 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 TechnologyNetworks.com 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

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
May the Cellular Force be With You
Like tiny construction workers, cells sculpt embryonic tissues and organs in 3D space.
Friday, December 13, 2013
Chemical Signature for Fast Form of Parkinson's Found
The physical decline experienced by Parkinson's disease patients eventually leads to disability and a lower quality of life.
Monday, November 25, 2013
Researchers Un-Junking Junk DNA
A study shines a new light on molecular tools our cells use to govern regulated gene expression.
Wednesday, November 13, 2013
Single Gene Mutation Linked to Neurological Disorders
Mutation could offer insights into Alzheimer’s, Parkinson’s and Huntigton’s Diseases.
Wednesday, October 16, 2013
Discovery Could Lead to Saliva Test for Pancreatic Cancer
The disease is typically diagnosed through an invasive and complicated biopsy.
Tuesday, October 15, 2013
Dentistry School Receives $5M to Study Saliva Biomarkers
Imagine having a sample of your saliva taken at the dentist's office, and then learning within minutes whether your risk for stomach cancer is higher than normal.
Thursday, August 15, 2013
Brain Anomolies are Potential Biomarkers for Autism
Brain anomalies may serve as potential biomarkers for the early identification of the neurodevelopmental disorder.
Wednesday, July 10, 2013
Second Amyloid May Play a Role in Alzheimer's
The study is the first to identify deposits of the protein, called amylin, in the brains of people with Alzheimer's disease.
Monday, July 01, 2013
Absence of Gene Leads to Earlier, More Severe Case of Multiple Sclerosis
UCSF finding in animal study may lead to biomarker that predicts course of disease in humans.
Tuesday, June 25, 2013
Studies Illuminate Functions of RNA
Researchers at the University of California illuminate the functional importance of a relatively new class of RNA molecules.
Tuesday, June 11, 2013
Gene Mutation Gives Boost to Brain Cancer Cells
An international team of researchers has found that a singular gene mutation helps brain cancer cells to not just survive, but grow tumors rapidly.
Monday, June 10, 2013
Potential New Way to Suppress Tumor Growth Discovered
The new mechanism opens up the possibility of developing a new class of anti-cancer drugs.
Monday, June 10, 2013
Scientists ID New Kidney Cancer Subtypes
Breakthrough will help physicians tailor treatment to individual kidney cancer patients, moving cancer care one step closer to personalized medicine.
Thursday, April 18, 2013
FDA Names Breast Cancer Drug a Breakthrough Therapy
An experimental drug being investigated for the treatment of advanced breast cancer by researchers at UCLA this week received breakthrough therapy designation from the U.S. FDA.
Monday, April 15, 2013
Scientific News
Poor Survival Rates in Leukemia Linked to Persistent Genetic Mutations
For patients with an often-deadly form of leukemia, new research suggests that lingering cancer-related mutations – detected after initial treatment with chemotherapy – are associated with an increased risk of relapse and poor survival.
Marijuana Genome Unraveled
A study by Canadian researchers is providing a clearer picture of the evolutionary history and genetic organization of cannabis, a step that could have agricultural, medical and legal implications for this valuable crop.
Growing Hepatitis C in the Lab
Recent discovery allows study of naturally occurring forms of hepatitis C virus (HCV) in the lab.
Signature of Microbiomes Linked to Schizophrenia
Studying microbiomes in throat may help identify causes and treatments of brain disorder.
Study Identifies the Off Switch for Biofilm Formation
New discovery could help prevent the formation of infectious bacterial films on hospital equipment.
Genetic Overlapping in Multiple Autoimmune Diseases May Suggest Common Therapies
CHOP genomics expert leads analysis of genetic architecture, with eye on repurposing existing drugs.
Fat in the Family?
Study could lead to therapeutics that boost metabolism.
Combo Tool
Joining molecular components expands ability to manipulate genes in specific cell types.
Team Identifies Structure of Tumor-Suppressing Protein
An international group of researchers led by Carnegie Mellon University physicists Mathias Lösche and Frank Heinrich have established the structure of an important tumor suppressing protein, PTEN.
Genes Associated With Improved Survival for Pancreatic Cancer Patients
Use of non-invasive liquid biopsies could predict in which patients the cancer could recur following surgery.
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
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,800+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!