Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Growth hormone activates gene involved in healing damaged tissue


Growth hormone is known to increase lean body mass and bone density in the elderly, but it does something else, too.

It activates a gene critical for the body’s tissues to heal and regenerate, says Robert Costa, professor of biochemistry and molecular genetics at the University of Illinois at Chicago and a member of the UIC Cancer Center.

That discovery could help explain why we age.

"Growth hormone levels decline as we grow older; as a result, the Foxm1b gene stops working and our bodies are less capable of repairing damage," Costa said.

In a paper published in the December issue of Hepatology, Costa and his colleagues report the results of studies on liver regeneration in aged (12-month-old) and young (2-month-old) mice -- a model system for studying the molecular mechanisms the body enlists to restore tissue damaged by injury or age. The liver is the only organ in the body capable of completely regenerating from mature cells.

The scientists focused on the Foxm1b gene, which is involved in the entire life cycle of the mammalian cell -- its proliferation, maturation and death. The gene’s activity is elevated in dividing cells in young mammals but diminishes in old age.

In previous studies, the researchers inserted the human Foxm1b gene in aged mice whose livers had been partially removed (the two species have virtually identical forms of the gene). The experiments showed that the gene restored levels of Foxm1b proteins and induced the animals’ livers to grow back at a rate typical of young mice. Further research detailed how the gene directs the busy molecular traffic inside cells to make them divide and multiply.

In the present study, the scientists tested the effects of human growth hormone because of its purported role in stimulating cell proliferation. Growth hormone, a substance secreted by the pituitary gland in the brain, is responsible for growth in children and young adults, but its levels decline during aging.

"The literature had suggested that growth hormone therapy in elderly men stimulates cells to divide," said Costa, leading to increases in muscle mass and skin thickness and greater bone density in the spine, while decreasing body fat.

"We wanted to find out how the hormone worked at a molecular level."

When aged mice whose livers had been partially removed were injected with human growth hormone, histological and other tests showed that the activity of the Foxm1b gene increased dramatically, as did levels of various enzymes and proteins that cause cells to divide. At the same time, the livers of these animals regenerated at a pace found in young mice. Cell proliferation peaked at just two days, and the liver was fully restored within a week.

By comparison, in aged mice that did not receive hormone injections, complete regeneration took a month or longer. Without growth hormone to turn on Foxm1b, the gene remained stuck at the low level of activity found in old age, and liver cells failed to multiply rapidly enough for a quick recovery.

Further tests were done with genetically engineered mice in whose liver cells the Foxm1b gene had been disabled. In these mice, growth hormone injections failed to stimulate recovery when the liver was partially removed.

"These results clearly demonstrate that Foxm1b is essential for growth hormone to spur liver regeneration," Costa said.

The study is apt to provide impetus for high-end clinics and spas already offering growth hormone injections to "treat" old age, but Costa is cautious about drawing any conclusions from his research about the merits of the therapy.

"Our liver regeneration studies tell us a great deal about how growth hormone works at a molecular level, but the injections occurred only over short periods of time, giving us no information about any long-term consequences," Costa said.

While several studies have shown that prolonged growth hormone therapy has dangerous side effects ranging from diabetes to carpal tunnel syndrome, Costa believes that short-term treatment with growth hormone could be used to speed repair after injuries or surgery in the elderly, shortening recovery time.

The National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute on Aging provided funding for the study. Other UIC scientists involved in the research were Katherine Krupczak-Hollis, Xinhe Wang and Margaret Dennewitz.

Sharon Butler | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht When fat cells change their colour
28.10.2016 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Aquaculture: Clear Water Thanks to Cork
28.10.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel light sources made of 2D materials

Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape.

So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been...

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...

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

Prototype device for measuring graphene-based electromagnetic radiation created

28.10.2016 | Power and Electrical Engineering

Gamma ray camera offers new view on ultra-high energy electrons in plasma

28.10.2016 | Physics and Astronomy

When fat cells change their colour

28.10.2016 | Life Sciences

More VideoLinks >>>