Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers discover 'modus operandi' of heart muscle protein

14.04.2008
Implications for cardiac development and health

Researchers at the University of Pennsylvania School of Medicine have discovered that a protein called leiomodin (Lmod) promotes the assembly of an important heart muscle protein called actin. What’s more, Lmod directs the assembly of actin to form the pumping unit of the heart. The findings appear in this week’s issue of Science.

“Very little was known about Lmod when we began this study,” says lead author Roberto Dominguez, PhD, Associate Professor of Physiology.

“It appeared that this protein was present in muscle cells but this had not been demonstrated directly and nobody knew what it did,” explains Dominguez. “We compared the amino acid sequence of Lmod with the sequence of another protein called tropomodulin [Tmod] that was already known to bind actin filaments in muscle cells. We found that one part of Lmod was very similar to Tmod, but Lmod was a bigger protein than Tmod and contained unique features that made us suspect that it could assemble the actin filaments of the heart muscle. This is exactly what we found.”

... more about:
»Control »Lmod »Muscle »actin »cardiac »filaments

The results answer a question that scientists studying the heart have long asked: What controls the assembly of the pumping unit of the heart?

Actin is the most abundant protein in most animal cells and forms long polymers, or filaments, that make up the cell skeleton. In the cells that make up muscles and the heart, interactions of actin filaments with motor proteins produce the contractions that pump blood through the body.

Actin spontaneously forms polymers in test tubes, but living cells use nucleator proteins to control the time and place where actin filaments forms. “For a long time, physiologists have wondered what serves as the nucleator protein in cardiac muscle cells,” says co-author Professor Thomas Pollard, PhD, of Yale University. “It was very satisfying after all these years to discover that Lmod can serve as the nucleator protein to initiate the forming of actin polymers in heart muscle cells.”

Lmod also directs actin filaments to the sarcomere, the part of the heart that controls contractions or pumping. When Lmod was knocked down in cardiac muscle cells by an RNA silencing technique, the sarcomeres became completely disorganized and could not direct muscles to contract.

Proper localization of Lmod in heart cells is critical, because even moderately elevated levels promote the formation of abnormal actin bundles in the nuclei of cardiac muscle cells where actin does not belong. A similar disorganization of actin bundles is characteristic of a disease of skeletal muscle weakness called intranuclear rod myopathy. Although this disease is caused by a mutation in a skeletal muscle-specific actin gene, the similarity in appearance suggests that mutations in Lmod could cause the same type of disease in cardiac muscle cells.

The Penn team is currently studying how the heart regulates the level of Lmod and how Lmod might be relevant to cardiac muscle disease. In addition, the team is attempting to crystallize Lmod in order to study its structure directly.

Malgorzata Boczkowska of Penn and David Chereau of Boston Biomedical Institute are co-first authors of this study. Other key contributors are Pekka Lappalainen and Aneta Skwarbek-Maruszewska of the University of Helsinki; Ikuko Fujiwara of Yale; David B. Hayes of Boston Biomedical Institute; and Grzegorz Rebowski of Penn. The study was supported by grants from the National Heart Lung and Blood Institute and the National Institute of General Medical Sciences.

PENN Medicine is a $3.5 billion enterprise dedicated to the related missions of medical education, biomedical research, and excellence in patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is currently ranked #3 in the nation in U.S.News & World Report's survey of top research-oriented medical schools; and, according to most recent data from the National Institutes of Health, received over $379 million in NIH research funds in the 2006 fiscal year. Supporting 1,400 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

The University of Pennsylvania Health System includes three hospitals — its flagship hospital, the Hospital of the University of Pennsylvania, rated one of the nation’s “Honor Roll” hospitals by U.S.News & World Report; Pennsylvania Hospital, the nation's first hospital; and Penn Presbyterian Medical Center — a faculty practice plan; a primary-care provider network; two multispecialty satellite facilities; and home care and hospice.

Karen Kreeger | EurekAlert!
Further information:
http://www.uphs.upenn.edu

Further reports about: Control Lmod Muscle actin cardiac filaments

More articles from Life Sciences:

nachricht The world's tiniest first responders
21.06.2018 | University of Southern California

nachricht A new toxin in Cholera bacteria discovered by scientists in Umeå
21.06.2018 | Schwedischer Forschungsrat - The Swedish Research Council

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Better model of water under extreme conditions could aid understanding of Earth's mantle

21.06.2018 | Earth Sciences

What are the effects of coral reef marine protected areas?

21.06.2018 | Life Sciences

The Janus head of the South Asian monsoon

21.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>