title: Phospholipase Cγ1 (PLCγ1) Controls Osteoclast Numbers via Colony-stimulating Factor 1 (CSF-1)-dependent Diacylglycerol/β-Catenin/CyclinD1 Pathway.
abstract: Phospholipases Cγ (PLCγ) 1 and 2 are a class of highly homologous enzymes modulating a variety of cellular pathways through production of inositol 1,4,5-trisphosphate and diacylglycerol (DAG). Our previous studies demonstrated the importance of PLCγ2 in osteoclast (OC) differentiation by modulating inositol 1,4,5-trisphosphate-mediated calcium oscillations and the up-regulation of the transcription factor NFATc1. Surprisingly, despite being expressed throughout osteoclastogenesis, PLCγ1 did not compensate for PLCγ2 deficiency. Because both isoforms are activated during osteoclastogenesis, it is plausible that PLCγ1 modulates OC development independently of PLCγ2. Here, we utilized PLCγ1-specific shRNAs to delete PLCγ1 in OC precursors derived from wild type (WT) mice. Differently from PLCγ2, we found that PLCγ1 shRNA significantly suppresses OC differentiation by limiting colony-stimulating factor 1 (CSF-1)-dependent proliferation and β-catenin/cyclinD1 levels. Confirming the specificity toward CSF-1 signaling, PLCγ1 is recruited to the CSF-1 receptor following exposure to the cytokine. To understand how PLCγ1 controls cell proliferation, we turned to its downstream effector, DAG. By utilizing cells lacking the DAG kinase ζ, which have increased DAG levels, we demonstrate that DAG modulates CSF-1-dependent proliferation and β-catenin/cyclinD1 levels in OC precursors. Most importantly, the proliferation and osteoclastogenesis defects observed in the absence of PLCγ1 are normalized in PLCγ1/DAG kinase ζ double null cells. Taken together, our study shows that PLCγ1 controls OC numbers via a CSF-1-dependent DAG/β-catenin/cyclinD1 pathway.
authors.affiliation: From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: Zhengfeng
authors.initials: Z
authors.lastname: Yang
authors.affiliation: From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: Seokho
authors.initials: S
authors.lastname: Kim
authors.affiliation: From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: Sahil
authors.initials: S
authors.lastname: Mahajan
authors.affiliation: From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: Ali
authors.initials: A
authors.lastname: Zamani
authors.affiliation: From the Department of Orthopaedics, Washington University School of Medicine, St. Louis, Missouri 63110 faccior@wustl.edu.
authors.forename: Roberta
authors.initials: R
authors.lastname: Faccio
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000378:metabolism; D004075:Diglycerides / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: C530105:Ccnd1 protein, mouse; D004075:Diglycerides; D051176:beta Catenin; D019938:Cyclin D1; D016173:Macrophage Colony-Stimulating Factor; D019852:Diacylglycerol Kinase; D051966:Phospholipase C gamma; C117399:Plcg1 protein, mouse
keywords: diacylglycerol; macrophage; osteoclast; phospholipase C; β-catenin (B-catenin)