ABSTRACT
Osteoclasts originated from hematopoietic stem cells are multi-nucleated cells that can resorb the bone matrix. Receptor activator of nuclear factor kappa-B (RANK)/RANK ligand (RANKL) signaling pathway is crucial for the differentiation and activation of osteoclasts. In this study, we investigated for the first time whether or not RANKL induced mitogen- and stress-activated kinase 1 (MSK1) phosphorylation at Ser 376. Activation of MSK1 was detected as soon as 5 min after RANKL stimulation and sparsely detected at 30 min after stimulation. RANKL-induced MSK1 phosphorylation occurred in a dose-dependent manner. MSK1 is known as a downstream signaling molecule of cAMP-dependent protein kinase (PKA). Treatment with the PKA inhibitor H89 significantly suppressed c-Fos and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) induction upon RANKL stimulation. In addition, cAMP response element-binding protein (CREB) phosphorylation was extremely inhibited by H89 treatment. Mitogen-activated protein kinases (MAPKs) have been investigated for induction of MSK1 phosphorylation. Specific signaling pathway inhibitors for p38 and extracellular signal-regulated kinases (ERKs) significantly blocked RANKL-induced MSK1 activation. Finally, as a downstream effector of the p38-MSK1 pathway, c-Fos transcriptional activity was determined. RANKL-mediated elevation of c-Fos transcriptional activity was significantly suppressed by p38 inhibitor. Moreover, a dominant negative form of CREB suppressed activation of NFATc1. In conclusion, RANKL-stimulated MSK1 phosphorylation could play a role in induction of NFATc1 through CREB and c-Fos activation as a downstream molecule of p38, ERK MAPKs, and PKA. Our results support basic information for the development of osteoclast specific inhibitors.
Subject(s)
Bone Matrix , Cyclic AMP Response Element-Binding Protein , Cyclic AMP-Dependent Protein Kinases , Extracellular Signal-Regulated MAP Kinases , Hematopoietic Stem Cells , Mitogen-Activated Protein Kinases , NFATC Transcription Factors , Osteoclasts , Phosphorylation , PhosphotransferasesABSTRACT
PURPOSE: To evaluate the effect of HA on the MMP-2 expression level during the healing process of an acute rotator cuff tear in rats by immunohistochemistry and RT-PCR. MATERIALS AND METHODS: Mature Sprague-Dawley rats were used in this animal study. In each rat, 2x2mm partial thickness defect of the rotator cuff was made. The rats were assigned to receive either subacromial injection of HA (HA group) or saline (saline group). The rotator cuff was examined by immunohistochemistry and RT-PCR at 4 weeks after surgery and the results were compared the results. RESULTS: A gross inspection showed that the defects were covered with granulation tissue, which were similar in both groups. The histopathological findings from the HA group revealed collagen bundles with a more dense regular arrangement and small number of inflammatory cells. Semiquantitative RT-PCR for MMP-2 in the HA group demonstrated a higher expression level than in the saline group. CONCLUSION: A subacromial injection of extrinsic HA increased MMP-2 expression level during the healing process of a rotator cuff tear in rats and might play a key role in the acute healing process of an injured rotator cuff.
Subject(s)
Animals , Rats , Collagen , Granulation Tissue , Hyaluronic Acid , Immunohistochemistry , Rats, Sprague-Dawley , Rotator CuffABSTRACT
One lung ventilation with a double-lumen endotracheal tube or Univent tube may be achieved difficultly or dangerously in some patient such as young age, anatomic anomaly, low body weight and tracheostomy patient. Bronchial blocker with a Fogarty catheter has been used successfully for such situations. Here, we reported the clinical experience in using a Fogarty embolectomy catheter as a bronchial blocker in patient with tracheostomy after pharyngectomy and laryngectomy. The patient was received left upper lobectomy with thoracotomy due to metastatic lung cancer.