title: Role of Protein Phosphatase 2A in Osteoblast Differentiation and Function.
abstract: The reversible phosphorylation of proteins plays hugely important roles in a variety of cellular processes, such as differentiation, proliferation, and apoptosis. These processes are strictly controlled by protein kinases (phosphorylation) and phosphatases (de-phosphorylation). Here we provide a brief history of the study of protein phosphorylation, including a summary of different types of protein kinases and phosphatases. One of the most physiologically important serine/threonine phosphatases is PP2A. This review provides a description of the phenotypes of various PP2A transgenic mice and further focuses on the known functions of PP2A in bone formation, including its role in osteoblast differentiation and function. A reduction in PP2A promotes bone formation and osteoblast differentiation through the regulation of bone-related transcription factors such as Osterix. Interestingly, downregulation of PP2A also stimulates adipocyte differentiation from undifferentiated mesenchymal cells under the appropriate adipogenic differentiation conditions. In osteoblasts, PP2A is also involved in the ability to control osteoclastogenesis as well as in the proliferation and metastasis of osteosarcoma cells. Thus, PP2A is considered to be a comprehensive factor in controlling the differentiation and function of cells derived from mesenchymal cells such as osteoblasts and adipocytes.
authors.affiliation: Department of Histology and Oral Histology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto, Tokushima 770-8504, Japan. okamura@tokushima-u.ac.jp.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Okamura
authors.affiliation: Department of Oral healthcare educations, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto, Tokushima 770-8504, Japan. Kaya@tokushima-u.ac.jp.
authors.forename: Kaya
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahatanishi, Kitakyushu, Fukuoka 807-8555, Japan. morimoto@med.uoeh-u.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Morimoto
authors.affiliation: Department of Histology and Oral Histology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto, Tokushima 770-8504, Japan. jumptera@tokushima-u.ac.jp.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Teramachi
authors.affiliation: Department of Veterinary Nursing and Technology, School of Veterinary Science, Nippon Veterinary Nursing and Life Science University, Tokyo 180-8602, Japan. kochiai@nvlu.ac.jp.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ochiai
authors.affiliation: Department of Histology and Oral Histology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto, Tokushima 770-8504, Japan. tat-hane@tokushima-u.ac.jp.
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Haneji
authors.affiliation: Department of Histology and Oral Histology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto, Tokushima 770-8504, Japan. akihito@tokushima-u.ac.jp.
authors.forename: Akihito
authors.initials: A
authors.lastname: Yamamoto
keywords: adipogenesis; bone formation; osteoblast differentiation; osteoclastogenesis; osteosarcoma cells; protein phosphatase