Osteoclast-associated immunoglobulin-like receptor (OSCAR)

Osteoclast-associated immunoglobulin-like receptor (OSCAR) is a cell surface immunoglobulin-like receptor encoded by the OSCAR gene and primarily expressed on myeloid lineage cells, especially preosteoclasts and mature osteoclasts[1][4][5][6]. It is a member of the leukocyte receptor complex (LRC) protein family, structurally related to other Ig-like receptors, and signals through association with the immunoreceptor tyrosine-based activation motif (ITAM)-bearing FcRγ chain[1][3][4]. OSCAR functions as a costimulatory receptor in osteoclastogenesis, essential for the differentiation and activation of bone-resorbing osteoclasts, thereby playing a critical role in bone homeostasis and remodeling[1][4][5][8]. It is also expressed on other myeloid cells including monocytes, macrophages, and dendritic cells, suggesting a broader role in regulating innate and adaptive immunity[4][6][8]. The identified ligands for OSCAR include fibrillar collagens and surfactant protein D, both of which induce signaling pathways relevant to bone and immune function[2][3][7]. Structural studies reveal specific collagen-binding properties, offering avenues for therapeutic targeting to regulate osteoclast activity[2][4]. OSCAR is implicated in bone diseases such as osteoporosis due to its regulatory function in osteoclast activity and is also involved in immune-inflammatory processes[4]. No specific approved drugs are listed for direct targeting, but its function makes it a potential therapeutic target for conditions involving abnormal osteoclast activation or immune dysregulation[4][8]. There are no major errors linked to this target’s definition, but direct drug interactions or biomarker roles are not yet established in clinical practice. Safety concerns primarily relate to possible effects on bone density and immune response if OSCAR is modulated therapeutically[4][5].

Other names

Osteoclast-associated receptorhOSCARPIGR3PIgR-3Polymeric immunoglobulin receptor 3Poly-Ig receptor 3osteoclast-associated Ig-like receptor

Modulation of osteoclastogenesis via FcRγ-mediated signaling, Activation or inhibition of osteoclast differentiation by binding with collagen or surfactant protein D