OBJECTIVES: Osteoclasts (OCs) are bone-resorbing multinucleated cells derived from hematopoietic progenitors of the monocyte-macrophage lineage. OC precursors, such as bone marrow-derived macrophages (BMMs), are formed in the presence of macrophage colony-stimulating factor (M-CSF) and differentiate into OCs in response to M-CSF and receptor activator of nuclear factor kappaB ligand (RANKL). In this study, we investigated the role of mixed lineage kinases (MLKs)-c-Jun amino-terminal kinase (JNK) pathways in OC formation. METHODS: We performed an OC formation assay and reverse transcription polymerase chain reaction (RT-PCR) analysis. RESULTS: We first explored the role of JNK on osteoclst formation using mouse bone marrow (BM) culture system. We found that OC formation was impaired when the JNK inhibitor was added either in early or late stage, suggesting the requirement for JNK activation during OC formation. MLKs are serine/threonine kinases that regulate signaling by the JNK. Since the JNK activity is specifically required for osteoclastogenesis, we examined the messenger ribonucleic acid (mRNA) levels of MLKs in BMs, BMMs and OCs by RT-PCR. Among MLKs, the level of MLK3 mRNA expression is highest in BMs, BMMs and OCs. Moreover, we found that the mRNA expression of MLK2 and MLK3 is increased with the differentiation of BMs to BMMs, and is sustained in OCs. Finally we investigated the role of MLK3 in OC differentiation using gene knock-down techniques. The silencing of MLK3 in BMMs partly attenuated RANKL-induced OC differentiation. CONCLUSIONS: These data suggest that JNK and MLK3 may positively regulate OC formation.
Animals ; Bone Marrow ; Gene Knockdown Techniques ; Macrophage Colony-Stimulating Factor ; Macrophages ; Mice ; Osteoclasts ; Phosphotransferases ; Polymerase Chain Reaction ; RANK Ligand ; Reverse Transcription ; RNA ; RNA, Messenger

OBJECTIVES: Osteoclasts (OCs) are bone-resorbing multinucleated cells derived from hematopoietic progenitors of the monocyte-macrophage lineage. OC precursors, such as bone marrow-derived macrophages (BMMs), are formed in the presence of macrophage colony-stimulating factor (M-CSF) and differentiate into OCs in response to M-CSF and receptor activator of nuclear factor kappaB ligand (RANKL). In this study, we investigated the role of mixed lineage kinases (MLKs)-c-Jun amino-terminal kinase (JNK) pathways in OC formation. METHODS: We performed an OC formation assay and reverse transcription polymerase chain reaction (RT-PCR) analysis. RESULTS: We first explored the role of JNK on osteoclst formation using mouse bone marrow (BM) culture system. We found that OC formation was impaired when the JNK inhibitor was added either in early or late stage, suggesting the requirement for JNK activation during OC formation. MLKs are serine/threonine kinases that regulate signaling by the JNK. Since the JNK activity is specifically required for osteoclastogenesis, we examined the messenger ribonucleic acid (mRNA) levels of MLKs in BMs, BMMs and OCs by RT-PCR. Among MLKs, the level of MLK3 mRNA expression is highest in BMs, BMMs and OCs. Moreover, we found that the mRNA expression of MLK2 and MLK3 is increased with the differentiation of BMs to BMMs, and is sustained in OCs. Finally we investigated the role of MLK3 in OC differentiation using gene knock-down techniques. The silencing of MLK3 in BMMs partly attenuated RANKL-induced OC differentiation. CONCLUSIONS: These data suggest that JNK and MLK3 may positively regulate OC formation.
Animals ; Bone Marrow ; Gene Knockdown Techniques ; Macrophage Colony-Stimulating Factor ; Macrophages ; Mice ; Osteoclasts ; Phosphotransferases ; Polymerase Chain Reaction ; RANK Ligand ; Reverse Transcription ; RNA ; RNA, Messenger

Background: This study was performed to evaluate etiologies and secular trends in primary amenorrhea in South Korea. Methods: This retrospective multi-center study analyzed 856 women who were diagnosed with primary amenorrhea between 2000 and 2016. Clinical characteristics were compared according to categories of amenorrhea (hypergonadotropic/hypogonadotropic hypogonadism, eugonadism, disorders of sex development) or specific causes of primary amenorrhea. In addition, we assessed secular trends of etiology and developmental status based on the year of diagnosis. Results: The most frequent etiology was eugonadism (39.8%). Among specific causes, Müllerian agenesis was most common (26.2%), followed by gonadal dysgenesis (22.4%). Women with hypergonadotropic hypogonadism were more likely to have lower height and weight, compared to other categories. In addition, the proportion of cases with iatrogenic or unknown causes increased significantly in hypergonadotropic hypogonadism category, but overall, no significant secular trends were detected according to etiology. The proportion of anovulation including polycystic ovarian syndrome increased with time, but the change did not reach statistical significance. Conclusion The results of this study provide useful clinical insight on the etiology and secular trends of primary amenorrhea. Further large-scale, prospective studies are necessary.