Embedded within bone tissue are osteocytes, and the tree-like communication cells known as dendrites. Loss of dendrites to ageing contributes to bone fragility and osteoporosis.
A study published in Nature Communications has revealed how osteocytes form dendrites – a discovery that might yield strategies to maintain these projections and therefore help maintain people’s bone health throughout their lives.
In their study, the researchers found that deletion of Sp7, a gene linked to both rare and common skeletal diseases, in osteocytes causes severe defects in osteocyte dendrites. This gene codes for a protein called a transcription factor, which controls the expression of other genes. The team found that the Sp7 transcription factor targets a gene called osteocrin, which promotes osteocyte dendrite formation. In mice, activating the osteocrin gene made up for the absence of Sp7 and reversed defects in osteocyte dendrites.
“In this work, we demonstrate key roles for the transcription factor Sp7 and its target osteocrin in orchestrating a gene regulatory network needed to promote healthy connections between bone cells,” said senior author Marc Wein, MD, PhD, an investigator in the endocrine unit at MGH and an assistant professor of medicine at Harvard Medical School. “Understanding how osteocytes maintain this network of connections opens up exciting possibilities for new ways to treat osteoporosis and other diseases where bones are prone to fracture.”
Source: Massachusetts General Hospital
