Nav: Home

How does estrogen protect bones? Unraveling a pathway to menopausal bone loss

March 22, 2019

Researchers at Tokyo Medical and Dental University (TMDU) and The University of Tokyo find a connection between estrogen and bone health that may offer a new way to treat osteoporosis in women experiencing menopause

Tokyo-Osteoporosis is a condition in which bones become weak and prone to fractures. Fractures typically occur in the wrist, spine, or hip, and can often lead to permanently impaired mobility. Women over 50 are at a high risk of developing osteoporosis, which may be due to the loss of estrogen that occurs after menopause. While studies have linked estrogen levels to bone health, the exact details of this connection are not entirely clear. Researchers at Tokyo Medical and Dental University (TMDU) describe a new molecular link between estrogen and bone aging, which may eventually lead to new strategies to treat postmenopausal osteoporosis.

Bone is a complex tissue, consisting of a matrix of proteins and minerals that give it the flexibility and strength to support body movement. Bone also contains several types of specialized cells, including osteocytes, that help to maintain this matrix. Over a person's lifetime, many factors can affect how healthy bone structure is maintained. One of these factors is the female sex hormone, estrogen.

"Over the last few decades, we've learned that estrogen plays an important role in maintaining a functional bone matrix," corresponding authors Tomoki Nakashima and Hiroshi Takayanagi explain. "Exactly how estrogen does this, though, is not fully understood. Our laboratory recently discovered that bone matrix is maintained by a protein called Sema3A, which is secreted by osteocytes. This led us to suspect that there might be a mechanistic relationship between estrogen and Sema3A."

Sema3A does indeed appear to be linked to estrogen: the researchers found that blood serum levels of the protein decrease in premenopausal women as they get older--and drop even further once women reach menopause. But how, at the biological level, are estrogen and Sema3A related? And what is Sema3A doing in bone tissue?

To answer these questions, the researchers turned to mice. When mice are given an ovariectomy (that is, when their ovaries are removed), the loss of estrogen causes their bone mass to decrease. This can be prevented, however, by giving the mice an extra supply of the hormone. The team took advantage of this to explore the function of Sema3A.

"When we genetically removed Sema3A from the osteoblast lineage cells (including osteocytes) of mice, we found that intravenous estrogen no longer prevented bones from deteriorating after an ovariectomy," lead author Mikihito Hayashi describes. "In addition, we found that Sema3A sets off a chain of signaling events that promote the survival of osteocytes in these mice. This suggests that Sema3A serves as a key mechanistic link between estrogen and bone maintenance .

We believe that, as women lose estrogen with age and Sema3A levels drop off, osteocytes begin to die and bone loses the ability to maintain its supportive structure."

The researchers hope that the discovery of Sema3A as a major player in bone health and the signaling molecules it controls in bone may offer new therapeutic approaches to treating osteoporosis.
-end-
The article, "Autoregulation of osteocyte Sema3A orchestrates estrogen action and counteracts bone aging" was published in Cell Metabolism at DOI: 10.1016/j.cmet.2018.12.021.

Tokyo Medical and Dental University

Related Osteoporosis Articles:

Osteoporosis treatment may also protect against pneumonia
A recent study published in the Journal of Bone and Mineral Research found that nitrogen-containing bisphosphonates (N-BPs) such as alendronate, which are widely used to treat postmenopausal osteoporosis, are linked with lower risks of pneumonia and of dying from pneumonia.
New pharmaceutical target reverses osteoporosis in mice
Biomedical engineers at Duke University have discovered that an adenosine receptor called A2B can be pharmaceutically activated to reverse bone degradation caused by osteoporosis in mouse models of the disease.
A link between mitochondrial damage and osteoporosis
In healthy people, a tightly controlled process balances out the activity of osteoblasts, which build bone, and osteoclasts, which break it down.
Many stroke patients not screened for osteoporosis, despite known risks
Many stroke survivors have an increased risk of osteoporosis, falls or breaks when compared to healthy people.
Many postmenopausal women do not receive treatment for osteoporosis
The benefits of treating osteoporosis in postmenopausal women outweigh the perceived risks, according to a Clinical Practice Guideline issued today by the Endocrine Society.
A new 'atlas' of genetic influences on osteoporosis
A ground-breaking new study led by researchers from the Lady Davis Institute (LDI) at the Jewish General Hospital (JGH) has succeeded in compiling an atlas of genetic factors associated with estimated bone mineral density (BMD), one of the most clinically relevant factors in diagnosing osteoporosis.
New recommendations for the conduct of economic evaluations in osteoporosis
An expert working group has established recommendations for the design and conduct of economic evaluations in osteoporosis, as well as guidance for reporting these evaluations.
From receptor structure to new osteoporosis drugs
Researchers at the University of Zurich have determined the three-dimensional structure of a receptor that controls the release of calcium from bones.
How a Mediterranean diet could reduce osteoporosis
Eating a Mediterranean-type diet could reduce bone loss in people with osteoporosis -- according to new research from the University of East Anglia.
Osteoporosis drug may benefit heart health
The osteoporosis drug alendronate was linked with a reduced risk of cardiovascular death, heart attack, and stroke in a Journal of Bone and Mineral Research study of patients with hip fractures.
More Osteoporosis News and Osteoporosis Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.