(Press-News.org) In fact, according to new research from Johns Hopkins, the fusion of muscle cells is a power struggle that involves a smaller mobile antagonist that points at, pokes and finally pushes into its larger, stationary partner using a newly identified finger-like projection.
In a report published Nov. 29 in the Journal of Cell Biology, the researchers described experiments using fruit fly embryos to identify an invasive projection propelled by the rapid elongation of actin filaments as the main player in the cellular power struggle.
"We found that two muscle cells don't simply open up their membranes and symmetrically fuse together," says Elizabeth H. Chen, Ph.D., an assistant professor in the department of molecular biology and genetics, Johns Hopkins University School of Medicine. "Muscle cell fusion is actually an invasive battle."
Before the new study, it was assumed that actin-enriched blobs sit atop the membranes of muscle cells preparing to fuse, equally dispersed. But by observing the accumulation of these blobs by genetics means, the team concluded that the actin structure is produced in only one of the two muscle cell types — the aggressive fusion-competent myoblast — and not in the stationary founder cell. Further analyses of the images, made with an electron microscope, showed the myoblast is extending multiple finger-like protrusions toward founder cells and ultimately forcing fusion with the founder cell by forming an open pore.
"Where we once saw only blobs of actin, now we could clearly see finger-like protrusions emanating from one cell into another," Chen says. "That really helped us make the connection between this structure and invasive podosomes."
The new work shows what is believed to be the first time that an invasive podosome-like structure has been found in developing tissue of any kind, Chen says, noting that although podosomes were discovered several decades ago in studies of cells growing in dishes, they have not been seen in a developing animal or implicated as a mechanism in cell fusion.
"It may be that this new understanding of muscle cell fusion will apply generally to other cells that fuse," Chen says, "such as egg and sperm, for instance, as well as bone resorption cells and cells that are vital for immune responses."
Muscle fusion is an integral part of muscle regeneration in genetic and acquired muscle diseases, and an accurate understanding of this basic cellular event could have important clinical applications in people with muscular dystrophy and other degenerative disorders, according to Chen.
INFORMATION:
The research was supported by the National Institutes of Health and the American Heart Association.
In addition to Elizabeth Chen, authors on the paper are Kristin L. Sens, Shiliang Zhang, Peng Jin, Rui Duan, Fengbao Luo and Lauren Parachini, all of Johns Hopkins; and Guofeng Zhang of the National Institute of Biomedical Imaging and Bioengineering.
On the Web:
Chen lab: http://www.jhu.edu/chenlab/elizabeth.html
Journal of Cell Biology: http://jcb.rupress.org/
Multimedia (Chen describes a podosome-like structure that promotes myoblast fusion during muscle development): http://jcb.rupress.org/site/biobytes/biobytes_dec_13_2010.xhtml
Media Contacts: Maryalice Yakutchik; 443-287-2251; myakutc1@jhmi.edu
Audrey Huang; 410-614-5105; audrey@jhmi.edu
Vanessa McMains; 410-502-9410; vmcmain1@jhmi.edu
END
Seniors with hearing loss are significantly more likely to develop dementia over time than those who retain their hearing, a study by Johns Hopkins and National Institute on Aging researchers suggests. The findings, the researchers say, could lead to new ways to combat dementia, a condition that affects millions of people worldwide and carries heavy societal burdens.
Although the reason for the link between the two conditions is unknown, the investigators suggest that a common pathology may underlie both or that the strain of decoding sounds over the years may overwhelm ...
In an opinion piece published Feb. 10 in the journal Science, a team of scholars led by a Johns Hopkins bioethicist urges the scientific community to act collectively to stem the negative effects of the patenting and privatizing of stem cell lines, data and pioneering technologies. This means grappling with the ambiguity of several fundamental distinctions typically made in ethics, law and common practice, the experts insist.
The team, led by Debra Mathews, Ph.D., M.A., of the Johns Hopkins Berman Institute of Bioethics, says failures to properly manage the widespread ...
University of Tennessee, Knoxville, researchers have found that blue-green algae may be responsible for producing an estrogen-like compound in the environment which could disrupt the normal activity of reproductive hormones and adversely affect fish, plants and human health. Previously, human activities were thought solely responsible for producing these impacts.
Theodore Henry, an adjunct professor for UT Knoxville's Center for Environmental Biotechnology and faculty at the University of Plymouth, and his colleagues looked into blue-green algae, or cyanobacteria, and ...
STANFORD, Calif. — A recently discovered biomarker could help doctors diagnose a common type of knee injury, according to a new study.
A team of researchers led by Gaetano Scuderi, MD, clinical assistant professor of orthopaedic surgery at Stanford University School of Medicine and an orthopaedic surgeon at Stanford Hospital & Clinics, has confirmed that a particular protein complex appears in patients with painful meniscal tears. The finding, to be published Feb. 16 in The Journal of Bone and Joint Surgery, could be used to prevent needless surgery and to save billions ...
A 22-year study of abnormally short individuals suggests that growth-stunting mutations also may stunt two of humanity's worst diseases.
Published in Science Translational Medicine, part of the Science family of journals, the study raises the prospect of achieving similar protection in full-grown adults by other means, such as pharmaceuticals or controlled diets.
The international study team, led by cell biologist Valter Longo of the University of Southern California and Ecuadorian endocrinologist Jaime Guevara-Aguirre, followed a remote community on the slopes of the ...
Messier 78 is a fine example of a reflection nebula. The ultraviolet radiation from the stars that illuminate it is not intense enough to ionise the gas to make it glow — its dust particles simply reflect the starlight that falls on them. Despite this, Messier 78 can easily be observed with a small telescope, being one of the brightest reflection nebulae in the sky. It lies about 1350 light-years away in the constellation of Orion (The Hunter) and can be found northeast of the easternmost star of Orion's belt.
This new image of Messier 78 from the MPG/ESO 2.2-metre telescope ...
A high proportion of patients with high blood pressure are failing to take their medication properly and would benefit clinically from a course of 'adherence therapy', according to new research from the University of East Anglia (UEA).
High blood pressure – or hypertension – is one of the major cardiovascular diseases worldwide. It leads to stroke and heart disease and costs more than $300 billion each year. Around a quarter of the adult population is affected – including 10 million people in the UK.
Around half of patients with hypertension fail to reduce their blood ...
DETROIT – Biopsies using ultrasound fusion imaging for detecting bone and soft tissue cancers are safe, effective and just as accurate as conventional biopsy methods, according to a Henry Ford Hospital study.
Researchers found that the ultrasound fusion imaging technique guides a needle biopsy with precise accuracy and ease, while making the biopsy experience more convenient for patients.
Ultrasound fusion merges real-time ultrasound images with previously acquired computed tomography or magnetic resonance imaging scans, providing physicians with high resolution, life-like ...
DETROIT – While the choices of knee implants are plentiful, the success of total knee replacement surgery still is dependent on the surgeon's skill, Henry Ford Hospital researchers say.
Researchers found that utilizing a series of common but nuanced surgical techniques is far more important to customizing the fit of a patient's implant than the implant's design.
The findings will be displayed at the annual meeting of the American Academy of Orthopaedic Surgeons Feb. 15-18 in San Diego.
"Customized knee implants will not replace the need for precise, methodical surgical ...
Almost 600 million years ago, before the rampant evolution of diverse life forms known as the Cambrian explosion, a community of seaweeds and worm-like animals lived in a quiet deep-water niche under the sea near what is now Lantian, a small village in Anhui Province of South China. Then they simply died, leaving some 3,000 nearly pristine fossils preserved between beds of black shale deposited in oxygen-free waters.
Scientists from the Chinese Academy of Sciences, Virginia Tech in the U.S., and Northwest University in Xi'an, China report the discovery of the fossils ...
