Mutant p62P392L Stimulation of Osteoclast Differentiation in Paget's Disease of Bone

• Published in: Endocrinology (Philadelphia) Vol. 152; no. 11; pp. 4180 - 4189
• Main Authors: Sundaram, Kumaran, Shanmugarajan, Srinivasan, Rao, D. Sudhaker, Reddy, Sakamuri V
• Format: Journal Article
• Language: English
• Published: United States Endocrine Society 01.11.2011
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Bone Resorption - genetics; Bone Resorption - metabolism; Cell Differentiation - drug effects; Cell Differentiation - physiology; General Endocrinology; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Mice; Mutation; Osteitis Deformans - genetics; Osteitis Deformans - metabolism; Osteoclasts - physiology; RANK Ligand - metabolism; Receptor Activator of Nuclear Factor-kappa B - metabolism; Sequestosome-1 Protein; Signal Transduction - drug effects; Signal Transduction - physiology
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2011-1225

Paget's disease of the bone (PDB) is an autosomal dominant trait with genetic heterogeneity, characterized by abnormal osteoclastogenesis. Sequestosome 1 (p62) is a scaffold protein that plays an important role in receptor activator of nuclear factor κB (RANK) signaling essential for osteoclast (OCL) differentiation. p62P392L mutation in the ubiquitin-associated (UBA) domain is widely associated with PDB; however, the mechanisms by which p62P392L stimulate OCL differentiation in PDB are not completely understood. Deubiquitinating enzyme cylindromatosis (CYLD) has been shown to negatively regulate RANK ligand-RANK signaling essential for OCL differentiation. Here, we report that CYLD binds with the p62 wild-type (p62WT), non-UBA mutant (p62A381V) but not with the UBA mutant (p62P392L) in OCL progenitor cells. Also, p62P392L induces expression of c-Fos (2.8-fold) and nuclear factor of activated T cells c1 (6.0-fold) transcription factors critical for OCL differentiation. Furthermore, p62P392L expression results in accumulation of polyubiquitinated TNF receptor-associated factor (TRAF)6 and elevated levels of phospho-IκB during OCL differentiation. Retroviral transduction of p62P392L/CYLD short hairpin RNA significantly increased TRAP positive multinucleated OCL formation/bone resorption activity in mouse bone marrow cultures. Thus, the p62P392L mutation abolished CYLD interaction and enhanced OCL development/bone resorption activity in PDB.