title: Osteopetrosis in TAK1-deficient mice owing to defective NF-κB and NOTCH signaling.
abstract: The MAP kinase TGFβ-activated kinase (TAK1) plays a crucial role in physiologic and pathologic cellular functions including cell survival, differentiation, apoptosis, inflammation, and oncogenesis. However, the entire repertoire of its mechanism of action has not been elucidated. Here, we found that ablation of Tak1 in myeloid cells causes osteopetrosis in mice as a result of defective osteoclastogenesis. Mechanistically, Tak1 deficiency correlated with increased NUMB-like (NUMBL) levels. Accordingly, forced expression of Numbl abrogated osteoclastogenesis whereas its deletion partially restored osteoclastogenesis and reversed the phenotype of Tak1 deficiency. Tak1 deletion also down-regulated Notch intracellular domain (NICD), but increased the levels of the transcription factor recombinant recognition sequence binding protein at Jκ site (RBPJ), consistent with NUMBL regulating notch signaling through degradation of NICD, a modulator of RBPJ. Accordingly, deletion of Rbpj partially corrected osteopetrosis in Tak1-deficient mice. Furthermore, expression of active IKK2 in RBPJ/TAK1-deficient cells significantly restored osteoclastogenesis, indicating that activation of NF-κB is essential for complete rescue of the pathway. Thus, we propose that TAK1 regulates osteoclastogenesis by integrating activation of NF-κB and derepression of NOTCH/RBPJ in myeloid cells through inhibition of NUMBL.
authors.affiliation: Department of Orthopaedic Surgery and Cell Biology & Physiology and.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Swarnkar
authors.affiliation: Department of Orthopaedic Surgery and Cell Biology & Physiology and.
authors.forename: Kannan
authors.initials: K
authors.lastname: Karuppaiah
authors.affiliation: Bone and Mineral Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Mbalaviele
authors.affiliation: Department of Orthopaedic Surgery and Cell Biology & Physiology and.
authors.forename: Tim Hung-Po
authors.initials: TH
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery and Cell Biology & Physiology and abuamery@wustl.edu.
authors.forename: Yousef
authors.initials: Y
authors.lastname: Abu-Amer
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D017353:Gene Deletion; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases / Q000172:deficiency / Q000378:metabolism; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000201:enzymology / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010010:Osteoclasts / Q000473:pathology; D010012:Osteogenesis; D010022:Osteopetrosis / Q000201:enzymology* / Q000473:pathology*; D010641:Phenotype; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D051880:Receptors, Notch; D000099151:MAP Kinase Kinase Kinase 7; C106292:Numbl protein, mouse; C497571:Rbpj protein, mouse
keywords: NUMBL; RBPJ; TAK1; osteoclast; osteopetrosis