LAMP-2 Is Involved in Surface Expression of RANKL of Osteoblasts In Vitro

• Published in: International journal of molecular sciences Vol. 21; no. 17; p. 6110
• Main Authors: Jansen, Ineke D C, Tigchelaar-Gutter, Wikky, Hogervorst, Jolanda M A, de Vries, Teun J, Saftig, Paul, Everts, Vincent
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 25.08.2020; MDPI
• Subjects: Animals; Biomedical materials; Bone marrow; Bone Marrow Cells - cytology; Bone Marrow Cells - drug effects; Bone Marrow Cells - metabolism; Calvaria; Cell Membrane - metabolism; Cells, Cultured; Coculture Techniques; Colony-stimulating factor; Down-Regulation; Enzymes; Flow cytometry; Fluorescence; Gene Knockout Techniques; LAMP-2; LAMP-2 protein; Long bone; Lysosomal-Associated Membrane Protein 2 - genetics; Lysosomal-Associated Membrane Protein 2 - metabolism; Lysosomes; Macrophage colony-stimulating factor; Macrophage Colony-Stimulating Factor - pharmacology; Macrophages; Male; Membrane proteins; Membranes; Mice; Microscopy; Neutrophils; Organelles; Osteoblasts; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - metabolism; Osteoclasts; Osteoclasts - cytology; Osteoclasts - metabolism; Osteoprogenitor cells; Pathogens; Phagosomes; Plasma; Precursors; Proteins; RANK Ligand - genetics; RANK Ligand - metabolism; RANKL; Receptor Activator of Nuclear Factor-kappa B - pharmacology; Skull - cytology; Tomography; TRANCE protein; United Kingdom > UK; United States > US; Netherlands; RANKL; osteoblasts; LAMP-2; osteoclasts
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms21176110

Lysosome associated membrane proteins (LAMPs) are involved in several processes, among which is fusion of lysosomes with phagosomes. For the formation of multinucleated osteoclasts, the interaction between receptor activator of nuclear kappa β (RANK) and its ligand RANKL is essential. Osteoclast precursors express RANK on their membrane and RANKL is expressed by cells of the osteoblast lineage. Recently it has been suggested that the transport of RANKL to the plasma membrane is mediated by lysosomal organelles. We wondered whether LAMP-2 might play a role in transportation of RANKL to the plasma membrane of osteoblasts. To elucidate the possible function of LAMP-2 herein and in the formation of osteoclasts, we analyzed these processes in vivo and in vitro using LAMP-2-deficient mice. We found that, in the presence of macrophage colony stimulating factor (M-CSF) and RANKL, active osteoclasts were formed using bone marrow cells from calvaria and long bone mouse bone marrow. Surprisingly, an almost complete absence of osteoclast formation was found when osteoclast precursors were co-cultured with LAMP-2 deficient osteoblasts. Fluorescence-activated cell sorting FACS analysis revealed that plasma membrane-bound RANKL was strongly decreased on LAMP-2 deficient osteoblasts. These results suggest that osteoblastic LAMP-2 is required for osteoblast-induced osteoclast formation in vitro.