Team discovers genetic material in blood cells that may affect malaria parasites

August 15, 2012, Duke University Medical Center

Researchers at Duke University Medical Center may finally have discovered why people with sickle cell disease get milder cases of malaria than individuals who have normal red blood cells.

In a finding that has eluded scientists for years, Duke researchers discovered that genetic material in may help alter parasite activity via a novel mechanism that alters parasite gene regulation.

"One of the most interesting findings in our study is that the human microRNA (very small units of genetic material) found in sickle red cells directly participate in the of malaria parasites," said Dr. Jen-Tsan Chi, M.D., Ph.D., senior author and associate professor in the Duke Institute for and Policy and Department of and Microbiology. "These microRNAs enriched in the sickle red cells reduce the parasite's ability to propagate, so that certain people stay more protected."

MicroRNAs are small units of RNA, which come from DNA. MicroRNAs are only 20-25 nucleotides long and help to regulate .

The scientists also showed that when two different microRNAs were introduced at higher levels in normal red cells, the parasite growth also was decreased.

The findings appear in the journal .

"This finding should lead to greater understanding of the host-parasite interaction and parasite lifecycle, which may eventually develop into a new approach to therapy for malaria, which up to 500 million people develop each year worldwide," Chi said.

Every year about 1.5 to 3 million people die from the disease, most of them children, according to the (WHO). Between 1,000 and 2,000 cases occur in the United States.

"I think this work will expand our understanding of the interaction between the and its , given that this is a completely new mode of interaction between them, and will give us a far greater understanding of the parasite life cycle," said lead author Greg LaMonte, a scientist in the Chi laboratory.

The malaria parasites grow in the human red cells, cells that scientists thought lacked any genetic material. Many scientists had looked for the components in sickle cells that could help them resist the parasite, but the Duke researchers found one component by thinking outside of scientific norms.

The Duke team found microRNAs in the red and showed that their composition is dramatically different in the sickle red blood cells. Counter to what they expected, they showed that these differences directly contribute to the malaria resistance in sickle cell disease.

The scientists also conducted a different experiment that showed blocking these microRNAs (miR-451 and Let-7i is particular) in sickle cells reduced the ability of the cells to protect against malaria.

"If you block the miRNAs, the parasite grows two or three times as well," Chi said.

Another surprise in this investigation was the presence of a chimera, a fusion of human microRNA with the parasites' mRNAs.

"We never expected to find this," Chi said. "The fusion of human and parasite RNA represents a unique form of host-parasite interaction, and may reflect either a novel form of host-cell immunity or a mechanism by which the parasite is able to adapt to the host-cell environment."

Explore further: Sickle cell anemia as malaria defense

Related Stories

Sickle cell anemia as malaria defense

November 30, 2011
Sickle cell anemia causes pain, fatigue and delayed growth, all because of a lack of enough healthy red blood cells. And yet genetic mutations that cause it - recessive genes for the oxygen-carrying hemoglobin protein - have ...

Malaria parasite requires a single receptor to invade human red blood cells

November 9, 2011
Researchers have today revealed a key discovery in understanding how the most deadly species of malaria parasite, Plasmodium falciparum, invades human red blood cells. Using a technique developed at the Wellcome Trust Sanger ...

Mystery solved: How sickle hemoglobin protects against malaria

April 28, 2011
The latest issue of the journal Cell carries an article that is likely to help solve one of the long-standing mysteries of biomedicine. In a study that challenges currently held views, researchers at the Instituto Gulbenkian ...

Recommended for you

Researchers devise decoy molecule to block pain where it starts

January 16, 2018
For anyone who has accidentally injured themselves, Dr. Zachary Campbell not only sympathizes, he's developing new ways to blunt pain.

Scientists unleash power of genetic data to identify disease risk

January 16, 2018
Massive banks of genetic information are being harnessed to shed new light on modifiable health risks that underlie common diseases.

Blood-vessel-on-a-chip provides insight into new anti-inflammatory drug candidate

January 15, 2018
One of the most important and fraught processes in the human body is inflammation. Inflammatory responses to injury or disease are crucial for recruiting the immune system to help the body heal, but inflammation can also ...

Molecule produced by fat cells reduces obesity and diabetes in mice

January 15, 2018
UC San Francisco researchers have discovered a new biological pathway in fat cells that could explain why some people with obesity are at high risk for metabolic diseases such as type 2 diabetes. The new findings—demonstrated ...

Obese fat becomes inflamed and scarred, which may make weight loss harder

January 12, 2018
The fat of obese people becomes distressed, scarred and inflamed, which can make weight loss more difficult, research at the University of Exeter has found.

Optimized human peptide found to be an effective antibacterial agent

January 11, 2018
A team of researchers in the Netherlands has developed an effective antibacterial ointment based on an optimized human peptide. In their paper published in the journal Science Translational Medicine, the group describes developing ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.