Researchers in Germany have uncovered a hidden receptor, GPR133, that performs an important function in bone energy.
By activating it with a brand new compound known as AP503, they boosted bone density in mice and even reversed osteoporosis-like signs.
Rising Want for Osteoporosis Therapies
There’s a sturdy want for drugs that may safely and successfully forestall bone loss over the long run. Osteoporosis, the medical time period for this situation, impacts roughly six million individuals in Germany, nearly all of them girls. To develop higher therapies with fewer unwanted side effects, scientists are working to establish new organic targets. One promising candidate is the adhesion G protein-coupled receptor GPR133, which belongs to a largely underexplored household of receptors. In a current investigation, researchers at Leipzig College confirmed that GPR133 is crucial for the formation and upkeep of sturdy bones.
“If this receptor is impaired by genetic modifications, mice present indicators of lack of bone density at an early age – much like osteoporosis in people. Utilizing the substance AP503, which was solely lately recognized through a computer-assisted display as a stimulator of GPR133, we have been in a position to considerably enhance bone energy in each wholesome and osteoporotic mice,” explains Professor Ines Liebscher, lead investigator of the examine from the Rudolf Schönheimer Institute of Biochemistry on the College of Medication.
How Bone Strengthening Alerts Work
Inside bone tissue, GPR133 is switched on by means of each interactions between neighboring bone cells and mechanical pressure. This activation launches a sign that enhances the exercise of bone-building cells (osteoblasts) whereas suppressing bone-breaking cells (osteoclasts). The end result is stronger, extra sturdy bones. AP503 has the power to copy this pure signaling course of. Trying forward, it might be used to boost bone well being in people with no illness and to rebuild bone in these with osteoporosis, notably girls after menopause.

Nice Potential for an Ageing Inhabitants
In an earlier examine, researchers at Leipzig College had already discovered that activation with AP503 additionally strengthens skeletal muscle. “The newly demonstrated parallel strengthening of bone as soon as once more highlights the good potential this receptor holds for medical functions in an ageing inhabitants,” says Dr Juliane Lehmann, lead writer of the examine and a researcher on the Rudolf Schönheimer Institute of Biochemistry. The Leipzig analysis staff is already engaged on a number of follow-up initiatives to discover using AP503 in numerous illnesses and to additional examine the function of GPR133 within the physique.
Background: A Decade of GPCR Analysis
For greater than ten years, the examine of adhesion G protein-coupled receptors has been a key focus at Leipzig College inside Collaborative Analysis Centre 1423, Structural Dynamics of GPCR Activation and Signaling. Internationally, Leipzig is considered a number one heart on this discipline of analysis.
Reference: “The mechanosensitive adhesion G protein-coupled receptor 133 (GPR133/ADGRD1) enhances bone formation” by Juliane Lehmann, Hui Lin, Zihao Zhang, Maren Wiermann, Albert M. Ricken, Franziska Brinkmann, Jana Brendler, Christian Ullmann, Luisa Bayer, Sandra Berndt, Anja Penk, Nadine Winkler, Franz Wolfgang Hirsch, Thomas Fuhs, Josef Käs, Peng Xiao, Torsten Schöneberg, Martina Rauner, Jin-Peng Solar and Ines Liebscher, 30 June 2025, Sign Transduction and Focused Remedy.
DOI: 10.1038/s41392-025-02291-y
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