Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mice stressed in simulated weightlessness show organ atrophy

04.09.2007
Rutgers researchers track osteopontin-dependent changes in thymus and spleen

A ground-based, experimental model used to simulate astronaut weightlessness in space has provided Rutgers scientists an opportunity to study the effects of stress on immune organs.

Earlier collaborative research with Japanese scientists employing this model implicated the protein osteopontin (OPN) in bone mineral loss associated with simulated weightlessness in mice. This research was made possible by the creation at Rutgers of a mouse unable to make OPN (a “knock-out” mouse). Studies with this Rutgers mouse have demonstrated that OPN likely plays a role in a variety of human problems including cancer metastasis, multiple sclerosis and other autoimmune diseases, osteoporosis and certain inflammatory responses.

The new study, which also simulated weightlessness, demonstrated that OPN is required for the atrophy of immune organs brought on by the stress resulting from hindlimb unloading – a technique employed to simulate weightless conditions by lifting the animal’s body weight off its hind legs. Results are presented Sept. 3 online in the Proceedings of the National Academy of Sciences (PNAS) and in the Sept. 11 print issue.

... more about:
»Condition »OPN »Thymus »atrophy »bone loss »simulated

“The bone loss seen in astronauts or bedridden patients is not a stress issue,” explained David Denhardt, a professor in the Department of Cell Biology and Neuroscience at Rutgers, The State University of New Jersey. “They are experiencing a loss of weight bearing on the bones, and the loss of bone mineral is a direct result of this load reduction.”

The presence of OPN, a feature common to both the bone loss and the organ atrophy, is produced by two different causes – weightlessness and stress – coincidentally related to the same laboratory conditions.

OPN is the continuing focus of Denhardt’s research interests. His long-term goal is to develop an OPN antibody – a monoclonal or target-specific antibody – that will inhibit OPN function in lab mice, and ultimately, in humans. This antibody could prove useful in treating the many destructive diseases associated with OPN.

Denhardt’s graduate student Kathryn Wang, a co-author on the PNAS paper, had previously conducted experiments in which the mouse was positioned in such a way as to produce hind limb unloading. This simulated weightless condition produced OPN-dependent bone loss in the hind limbs and provided a potential testing ground for possible OPN antibodies. The specialized equipment for that experiment was supplied by another co-author on the paper, Yufang Shi, a professor in the Department of Molecular Genetics, Microbiology and Immunology at Robert Wood Johnson Medical School–University of Medicine and Dentistry of New Jersey.

Shi, an authority on stress, suggested that along with the bone loss studies, the Rutgers researchers should look at the spleen and thymus – the organs responsible for most of the animal’s immune cells. If stress affects the spleen and thymus so that they atrophy, the immune system becomes impaired. People under severe stress often get sick.

The Rutgers scientists took their colleague’s advice and compared the OPN-deficient knock-out mice to normal mice, with some dramatic results.

“To our astonishment and surprise, the OPN-deficient animals responded differently to the stress than the normal controls,” Denhardt said. “We had no basis to expect this, but the spleen and thymus of the OPN-deficient animals remained normal whereas there was atrophy of the spleen and thymus in the normal controls. This was a novel and totally unexpected result for which we have no explanation at this time. The next phase of our research will ask what exactly is going on.”

The stressed normal mice also displayed elevated levels of corticosterone – a hormone known to induce apoptosis (programmed cell death), a process evident in the spleen and thymus of these mice and a possible mechanism underlying the atrophy.

Denhardt said that their results indicate that OPN needs to be present for these stress related symptoms to occur, pointing to a whole new physiological realm in which the culprit osteopontin is causing problems.

Joseph Blumberg | EurekAlert!
Further information:
http://www.rutgers.edu

Further reports about: Condition OPN Thymus atrophy bone loss simulated

More articles from Life Sciences:

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>