Identification of Alternatively Spliced Forms of human OSCAR in Osteoclasts

다국어 초록 (Multilingual Abstract)

Objectives: Osteoclasts are multinucleated giant cells which can resorb bone and differentiated from hematopoietic cells. We have previously reported murine osteoclast-associated receptor (OSCAR) may be an important bone-specific regulator of osteoclast differentiation. We have cloned soluble form of human OSCAR (hOSCAR) and examined the role of hOSCAR on osteoclast differentiation.
Methods: Osteoclast differentiation was induced by treatment with macrophage colony-stimulating factor (M-CSF)and receptor activator of nuclear factor kappa B ligand (RANKL) and tartrate-resistant acid phosphatase (TRAP)staining and pit formation were performed. Expression was measured by flow cytometry analysis, Northern and Western blot analysis.
Results: hOSCAR is expressed in osteoclast cells and involved in the differentiation of osteoclasts from peripheral blood mononuclear cells (PBMC). Two alternatively spliced forms (soluble hOSCAR [hOSCAR-S]) of hOSCAR were identified from osteoclasts complementary deoxyribonucleic acid (cDNA) library derived from PBMC. Putative transmembrane domain was not found in hOSCAR-S forms and it suggested that these forms might be secreted from osteoclast cells. These secreted forms of hOSCAR attenuated RANKL-induced osteoclast formation and bone resorption.
Conclusions: Human osteoclasts express at least five different OSCAR messenger ribonucleic acid (mRNA) isoforms which could play different regulatory roles for differentiation. The secreted forms of hOSCAR might be a negative regulator of membrane-bounded forms of OSCAR.

국문 초록 (Abstract)

연구목적: 파골세포는 다핵 세포로서 골흡수를 유발한다. 생쥐에서 OSCAR는 파골세포 분화에서 중요한 역할을 함이 밝혀졌다. 인간 OSCAR의 분비형이 클로닝되었고 이들의 파골세포 분화에서의 역할을 분석하고자 하였다.
연구방법: 파골세포 분화는 M-CSF와 RANKL의 처리에 의해 유도하였으며 TRAP 염색법과 pit 형성도를 측정하였다. 발현 정도는 유세포분석, Northern, 및 Western 분석 방법을 사용하였다.
결 과: 인간 OSCAR는 파골세포에서 발현하였으며 PBMC로부터 유도되는 파골세포 형성에 관여하였다. 선택적 이어맞추기에 의해 만들어진 두 종류의 인간 OSCAR가 확인되었다. 이들은 막관통영역이 없는 구조로서 파골세포로부터분비되는 형태로 존재하였다. 이러한 분비형의 인간 OSCAR는 파골세포 분화 및 골흡수를 저해하였다.
결 론: 인간 OSCAR는 최소 5종류의 구조적아형을 갖고 있으며, 이들은 서로 다른 역할을 하고 있다. 특히 분비형인간 OSCAR는 파골세포 분화에서 음성 조절자로서 역할을 한다.

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