Oncostatin M (OSM) and Leukemia Inhibitory factor (LIF) treatment of osteoblasts via LIF and OSM receptors. Mus musculus

Oncostatin M (OSM) and Leukemia Inhibitory Factor (LIF) signal within cells via the gp130 (Il6st) coreceptor bound either to the LIF receptor (LIFR) or the oncostatin M receptor (OSMR), but whether murine OSM can act through both receptors is controversial. Both LIF and OSM stimulate bone formation, inhibit adipocyte differentiation, and promote osteoclast differentiation, but our earlier work suggested this may depend on the receptor subtype used. This project aimed to identify those gene targets regulated by murine OSM via OSMR and LIFR by using wild type and OSMR null primary osteoblasts. Cells were differentiated to their most mature state (i.e. osteocytes) because the only prior target gene known to be regulated by murine OSM via the LIFR was an osteocyte-specific gene, sclerostin. Overall design: Primary calvarial osteoblasts were generated from wild type and OSMR null mice, both on C57BL/6 background (cousin-bred litters), and frozen down for later treatment. On three occasions, WT and OSMR null cells were defrosted, expanded, and differentiated for 17 days in osteoblast differentiation media. At 17 days, when the cells have reached a stage of expressing osteocyte-specific genes, they were treated with human OSM (which acts only through LIFR in mouse cells), mouse LIF (which acts only through LIFR in mouse cells) or murine OSM (which can act through both OSMR and LIFR). RNA was analysed at 1 and 6 hours after commencement of treatment.