Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


U-M researchers solve a molecular mystery in muscle

The muscle-building abilities of hormones known as insulin-like growth factors (IGFs) are legendary. Just do an online search and you'll find not only scientific papers discussing the effects of IGFs on the cells that give rise to muscle tissue, but also scores of ads touting the purported benefits of IGF supplements for bodybuilding.

But in spite of widespread interest in these potent molecules, key details about how IGFs work on muscle cells have been lacking.

A research by a team led by University of Michigan molecular biologist Cunming Duan has cleared up a longstanding mystery about the workings of IGFs. The team's findings, scheduled to be published online this week in the Proceedings of the National Academy of Sciences, could lead to new treatments for muscle-wasting diseases and new ways of preventing the muscle loss that accompanies aging.

And because IGFs also are implicated in the growth and spread of malignant tumors, the new insights may have implications in cancer biology.

Like other peptide and protein hormones, IGFs work by binding to receptors on the cells they target. The binding then sets off a cascade of reactions that ultimately direct the cell to do something. You might think that a given hormone, binding to a particular receptor, would always elicit the same response from the cell, but that's not what happens in the case of IGF and myoblasts (immature cells that develop into muscle tissue).

During muscle formation, the binding of IGF to its receptor can prompt either of two very different responses in myoblasts, said Duan, a professor in the Department of Molecular, Cellular and Developmental Biology. Some of the cells are stimulated to divide, while others interpret the very same signal as an order to differentiate (become specialized).

"These are opposite and mutually exclusive cellular events—once a muscle cell divides, it can't differentiate, and once it differentiates, it can never divide again," Duan said. How activation of the same receptor by the same hormone can elicit two such distinctly different responses has been one of the most puzzling questions about IGF, but Duan and colleagues have found the answer.

"The myoblasts' response is controlled by oxygen availability," said Duan. When oxygen levels are normal, IGF promotes muscle cell differentiation; when oxygen levels are below normal, IGF promotes muscle cell division. Teasing out the molecular details, the researchers discovered that low oxygen activates an intermediary called the HIF-1 complex, which reprograms the cascade of steps that ultimately controls the cell's response.

The findings not only reveal how muscle cells respond to varying oxygen levels during normal development, but also have implications for human disease, Duan said. "For example, a major reason that muscle atrophy occurs as people get older is that the IGF signal gets weaker. If we can find a way to affect IGF signaling, we may be able to stop or reverse the loss." Although manipulating the oxygen levels in living cells could be difficult, it may be possible to manipulate HIF-1 in ways that would mimic changing oxygen levels.

The work also could help scientists better understand the processes involved in cancer progression and spread. It's known that IGF can promote tumor cell division and survival and also that oxygen levels are often lower in tumor tissue than in normal tissue. Finding the link between IGF activity and oxygen levels may lead to new strategies for cancer treatment.

Duan's coauthors on the paper are former graduate student Hongxia Ren, now a postdoctoral fellow at Columbia University, and Domenico Accili, professor of medicine at Columbia .

The research was funded by the National Institutes of Health, the National Science Foundation and the University of Michigan.

Contact: Nancy Ross-Flanigan
Phone: (734) 647-1853

Nancy Ross-Flanigan | EurekAlert!
Further information:

Further reports about: HIF-1 IGF Science TV cell division living cell muscle cells oxygen levels

More articles from Life Sciences:

nachricht The gene of autumn colours
27.10.2016 | Hokkaido University

nachricht Polymer scaffolds build a better pill to swallow
27.10.2016 | The Agency for Science, Technology and Research (A*STAR)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

The gene of autumn colours

27.10.2016 | Life Sciences

Polymer scaffolds build a better pill to swallow

27.10.2016 | Life Sciences

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>