Shunsuke Uehara1, Hideyuki Mukai2,3, Teruhito Yamashita4, Masanori Koide4, Kohei Murakami5, Nobuyuki Udagawa1, Yasuhiro Kobayashi6. 1. Department of Biochemistry, Matsumoto Dental University, Nagano, 399-0781, Japan. 2. Biosignal Research Center, Kobe University, Hyogo, 657-8501, Japan. 3. Department of Clinical Laboratory, Kitano Hospital, Osaka, 530-8480, Japan. 4. Institute for Oral Science, Matsumoto Dental University, 1780 Gobara, Hiro-oka , Shiojiri-shi, Nagano, 399-0781, Japan. 5. Laboratory of Immunology, Faculty of Veterinary Medicine, Okayama University of Science, Ehime, 794-8555, Japan. 6. Institute for Oral Science, Matsumoto Dental University, 1780 Gobara, Hiro-oka , Shiojiri-shi, Nagano, 399-0781, Japan. yasuhiro.kobayashi@mdu.ac.jp.
Abstract
INTRODUCTION: The long-term inhibition of bone resorption suppresses new bone formation because these processes are coupled during physiological bone remodeling. The development of anti-bone-resorbing agents that do not suppress bone formation is urgently needed. We previously demonstrated that Wnt5a-Ror2 signaling in mature osteoclasts promoted bone-resorbing activity through protein kinase N3 (Pkn3). The p38 MAPK inhibitor SB202190 reportedly inhibited Pkn3 with a low Ki value (0.004 μM). We herein examined the effects of SB202190 on osteoclast differentiation and function in vitro and in vivo. MATERIALS AND METHODS: Bone marrow cells were cultured in the presence of M-csf and GST-Rankl to differentiate into multinucleated osteoclasts. Osteoclasts were treated with increasing concentrations of SB202190. For in vivo study, 10-week-old female mice were subjected to ovariectomy (OVX). OVX mice were intraperitoneally administered with a Pkn3 inhibitor at 2 mg/kg or vehicle for 4 weeks, and bone mass was analyzed by micro-CT. RESULTS: SB202190 suppressed the auto-phosphorylation of Pkn3 in osteoclast cultures. SB202190 significantly inhibited the formation of resorption pits in osteoclast cultures by suppressing actin ring formation. SB202190 reduced c-Src activity in osteoclast cultures without affecting the interaction between Pkn3 and c-Src. A treatment with SB202190 attenuated OVX-induced bone loss without affecting the number of osteoclasts or bone formation by osteoblasts. CONCLUSIONS: Our results showed that Pkn3 has potential as a therapeutic target for bone loss due to increased bone resorption. SB202190 is promising as a lead compound for the development of novel anti-bone-resorbing agents.
INTRODUCTION: The long-term inhibition of bone resorption suppresses new bone formation because these processes are coupled during physiological bone remodeling. The development of anti-bone-resorbing agents that do not suppress bone formation is urgently needed. We previously demonstrated that Wnt5a-Ror2 signaling in mature osteoclasts promoted bone-resorbing activity through protein kinase N3 (Pkn3). The p38 MAPK inhibitor SB202190 reportedly inhibited Pkn3 with a low Ki value (0.004 μM). We herein examined the effects of SB202190 on osteoclast differentiation and function in vitro and in vivo. MATERIALS AND METHODS: Bone marrow cells were cultured in the presence of M-csf and GST-Rankl to differentiate into multinucleated osteoclasts. Osteoclasts were treated with increasing concentrations of SB202190. For in vivo study, 10-week-old female mice were subjected to ovariectomy (OVX). OVX mice were intraperitoneally administered with a Pkn3 inhibitor at 2 mg/kg or vehicle for 4 weeks, and bone mass was analyzed by micro-CT. RESULTS: SB202190 suppressed the auto-phosphorylation of Pkn3 in osteoclast cultures. SB202190 significantly inhibited the formation of resorption pits in osteoclast cultures by suppressing actin ring formation. SB202190 reduced c-Src activity in osteoclast cultures without affecting the interaction between Pkn3 and c-Src. A treatment with SB202190 attenuated OVX-induced bone loss without affecting the number of osteoclasts or bone formation by osteoblasts. CONCLUSIONS: Our results showed that Pkn3 has potential as a therapeutic target for bone loss due to increased bone resorption. SB202190 is promising as a lead compound for the development of novel anti-bone-resorbing agents.
Authors: Henry G Bone; Michael R McClung; Christian Roux; Robert R Recker; John A Eisman; Nadia Verbruggen; Carolyn M Hustad; Carolyn DaSilva; Arthur C Santora; B Avery Ince Journal: J Bone Miner Res Date: 2010-05 Impact factor: 6.741
Authors: In Young Jung; Jung Ju Kim; Se Ju Lee; Jinnam Kim; Hye Seong; Wooyong Jeong; Heun Choi; Su Jin Jeong; Nam Su Ku; Sang Hoon Han; Jun Yong Choi; Young Goo Song; Jung Won Park; June Myung Kim Journal: Biomed Res Int Date: 2017-12-31 Impact factor: 3.411