Page 25 - G. Cell differentiation. division. and death

Blockage of ovariectomy-induced bone loss via suppressing
Ca /calmodulin-mediated osteoclast differentiation by a sphingolipid
2+
Ha Young Lee Kwang Min Cho , Min Kyung Kim , Mingyu Lee , Cheol Yong Choi , Kyeong Kyu Kim , Joon Seong Park ,
1,
1
4
5
1
2
3
3
Hong-Hee Kim and Yoe-Sik Bae 1,3, *
1 Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea.
2 Department of Cell and Developmental Biology, BK21 Program and Dental Research Institute, Seoul National University, Seoul, 03080, Republic of Korea.
3 Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351, Republic of Korea.
4 Department of Precision Medicine, Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419,
Republic of Korea.
5 Department of Hematology-Oncology, Ajou University School of Medicine, Suwon 16499, Republic of Korea
BACKGROUND AIM
Bones are maintained by the balance between bone resorption by osteoclasts (OCs) and bone formation by Osteoporosis is a disease in which bone mineral density
osteoblasts (OBs). If this balance is broken, a variety of bone diseases occur. Osteoporosis is a skeletal decreases due to excessive activity of osteoclasts. It is
disorder in which bone resorption occurs abnormally due to the imbalance between bone cells, resulting in commonly found in postmenopausal women who reduced
weakened and easily fractured bones. Osteoporosis can be caused by certain diseases, drugs, or natural estrogen levels due to loss of ovarian function due to aging.
aging, and in many cases, is found in postmenopausal women. Therefore, estrogen is used to treat Sphingolipids are important biological lipids that can
osteoporosis, but causes serious side effects.
Sphingolipids are a versatile class of membrane lipid. In addition to providing mechanical stability, regulate diverse biological responses. In this study, we
sphingolipids plays a role in molecular signaling, sorting and cell recognition. Sphingosine metabolites, such examined the effects of sphingosylphosphorylcholine on
as ceramide, sphingosine, and sphingosine-1- phosphate are lipid signaling molecules which are involved in the differentiation of OCs and mechanism involved in the
a diverse cellular processes. However, bone regulation by sphingolipids is not well discovered. process.
METHODS
1. OC differentiation and TRAP staining
BMDMs were differentiated into OCs using 30 ng/ml M-CSF and 100 ng/ml RANKL. Differentiated human macrophages were further differentiated into OCs by adding 30
ng/ml M-CSF and 100 ng/ml RANKL for 17 days.
2. Measurement of calcineurin (CaN) activity
Cellular CaN phosphatase activity was measured in cell extracts using a CaN cellular activity assay kit
3. OVX mouse model and SPC injection
Eight week-old C57BL/6 mice (Female) were used for ovariectomy. SPC was injected three times a week via subcutaneous injection (s.c.) from day
1 postoperatively. After 8 weeks, the mice were sacrificed and the femurs separated and used in subsequent experiments.
RESULTS

Figure 1. SPC inhibits RANKL-induced OC Figure 2. The inhibitory effect of SPC on Figure 3. SPC decreases RANKL-induced
formation. RANKL-induced OC formation is independent CaN activation.
of cell surface receptors.

In this study, we found that a sphingolipid strongly
inhibits RANKL-induced osteoclast differentiation.
The sphingolipid-induced inhibitory effects on
osteoclast differentiation were not affected by
several S1P receptors antagonists or pertussis
toxin. However, the sphingolipid inhibited RANKL-
induced calcineurin activation and NFATc1
translocation, leading to decrease of osteoclast
related gene expression. Moreover, we found that
bone mineral density was increased by the
sphingolipid injection in ovariectomized
(OVX) mouse model, showing increase of BV/TV
and Tb.N. The sphingolipid also blocked
ovariectomy-induced body weight increase and
Nfatc1 gene expression in mice. Collectively, we
suggest that the sphingolipid has potential as
Figure 4. SPC has beneficial effects in Figure 5. SPC inhibits RANKL-induced OC therapeutic agents for osteoporosis treatment
ovariectomy-induced osteoporosis in mice. formation in human monocyte-derived .
macrophages.
CONCLUSION REFERENCES Contact information

1. SPC inhibits RANKL-induced OC formation. 1) Nixon GF, Mathieson FA, Hunter I. The multi- Address correspondence to Yoe-Sik Bae, Department
of Biological Sciences, Sungkyunkwan University,
2. SPC-induced inhibitory effects on OC formation functional role of sphingosylphosphorylcholine. Prog
is not mediated by cell surface receptors. Lipid Res. 2008;47:62-75. Suwon 16419, Republic of Korea. Phone: 82-31-290-
5914; Fax: 82-31-290-7015; E-mail:yoesik@skku.edu
3. SPC inhibits OC formation via inhibition of CaN 2) Ryu J, Kim HJ, Chang EJ, Huang H, Banno Y,
activity. Kim HH. Sphingosine 1-phosphate as a regulator of Ha Young Lee, Department of Biological Sciences,
4. SPC administration shows beneficial effects on osteoclast differentiation and osteoclast-osteoblast Sungkyunkwan University, Suwon 16419, Republic of
Korea. Phone: 82-31-299-4509; Fax: 82-31-290-7015;
the OVX-induced osteoporosis mouse model. coupling. EMBO J. 2006;25:5840-5851.
5. SPC inhibits OC formation from human 3) Kovacs E, Liliom K. Sphingosylphosphorylcholine E-mail: hayoung@skku.edu
macrophages. as a novel calmodulin inhibitor. Biochem J.
2008;410:427-437