TRIB1 (Tribbles Pseudokinase 1) is a protein containing a serine/threonine kinase-like domain which is expressed in skeletal muscle, thyroid, pancreas, peripheral blood leukocytes, and bone marrow. Trib1 is critical for the differentiation of tissue-resident macrophages and in musculoskeletal tissues it is highly expressed in the bone marrow of adult humans. However, its role in skeletal tissues is currently unknown.

In collaboration with Prof Drew Rowan at Newcastle University, we have been analysing a mouse model which overexpresses Trib1 in cartilage (under col2 promoter).

We have found that mice overexpressing Trib1 in cartilage (right) are much smaller than the wild type litter mates (left) and present with a pronounced hip dysplasia. The bones appear dense, shorter and broader and are very reminiscent of osteopetrosis (“the stone bone” disease).

Jennifer Gerbracht, an Erasmus student in the lab, generated this bone density image (above) using bone mineral content quantification by Faxitron X-ray microradiography. The image was pseudocoloured, showing the densest material in red. The knee joint of a wild type mouse (left) is shown compared to a mutant  mouse (right) with much higher bone density.