Modulation of αβ Integrin via Transactivation of β Integrin Gene on Murine Bone Marrow Macrophages by 1,25(OH)D, Retinoic Acid and Interleukin-4.

The interleukin (IL)-4, 1,25(OH)D and retinoic acid, increase surface expression of functional integrin αβ on murine osteoclast precursors. All three agonists stimulate transcription of the β gene, leading to increased steady-state levels of mRNA this protein. By contrast, mRNA levels of α remain unchanged. In each instance, the increase in the surface expression of the integrin results in increased migration of the cells onto an αβ substrate. Because β subunit, except platelet where β subunit conform a dimer with α, associates solely with α subunit monogamously, while promiscuous α subunit combines with various subunit, our present data support the idea that the β subunit governs the surface-expressed functional integrin complex.