Ultrasound stimulates MMP-13 expression through p38 and JNK pathway in osteoblasts

Low-Intensity Focused Ultrasound Stimulation Ameliorates Working Memory Dysfunctions in Vascular Dementia Rats via Improving Neuronal Environment

Working memory impairment is one of the remarkable cognitive dysfunctions induced by vascular dementia (VD), and it is necessary to explore an effective treatment. Recently, low-intensity focused ultrasound stimulation (LIFUS) has been found notable neuroprotective effects on some neurological diseases, including VD. However, whether it could ameliorate VD-induced working memory impairment was still not been clarified. The purpose of this study was to address this issue and the underlying mechanism. We established VD rat model using the bilateral common carotid artery occlusion (BCCAO) and applied the LIFUS (center frequency = 0.5 MHz; I_spta = 500 mW/cm², 10 mins/day) to bilateral medial prefrontal cortex (mPFC) for 2 weeks since 2 weeks after the surgery. The main results showed that the LIFUS could significantly improve the performance of VD rats in the specific working memory tasks (delayed nonmatch-to-sample task and step-down task), which might be associated with the improved synaptic function. We also found the improvement in the cerebral blood flow (CBF) and reduced neuroinflammation in mPFC after LIFUS treatment indicated by the inhibition of Toll-like receptor (TLR4)/nuclear factor kappa B (NF-κB) pathway and the decrease of proinflammatory cytokines. The amelioration of CBF and neuroinflammation may promote the living environment of the neurons in VD which then contribute to the survival of neurons and the improvement in synaptic function. Taken together, our findings indicate that LIFUS targeted mPFC can effectively ameliorate reward-based spatial working memory and fear working memory dysfunctions induced by VD via restoring the living environment, survivability, and synaptic functions of the neurons in mPFC of VD rats. This study adds to the evidence that LIFUS could become a promising and non-invasive treatment strategy for the clinical treatment of central nervous system diseases related to cognitive impairments in the future.

Casein kinase 1 epsilon facilitates cartilage destruction in osteoarthritis through JNK pathway

Osteoarthritis (OA) is a high-morbidity skeletal disease worldwide and the exact mechanisms underlying OA pathogenesis are not fully understood. Casein kinase 1 epsilon (CK1ε) is a serine/threonine protein kinase, but its relationship with OA is still unknown. We demonstrated that CK1ε was upregulated in articular cartilage of human patients with OA and mice with experimentally induced OA. Activity of CK1ε, demonstrated by analysis of phosphorylated substrates, was significantly elevated in interleukin (IL)-1β-induced OA-mimicking chondrocytes. CK1ε inhibitor or CK1ε short hairpin RNA (shRNA) partially blocked matrix metalloproteinase (MMP) expression by primary chondrocytes induced by IL-1β, and also inhibited cartilage destruction in knee joints of experimental OA model mice. Conversely, overexpression of CK1ε promoted chondrocyte catabolism. Previous studies indicated that CK1ε was involved in canonical Wnt/β-catenin signaling and noncanonical Wnt/c-Jun N-terminal kinase (JNK) signaling pathway. Interestingly, the activity of JNK but not β-catenin decreased after CK1ε knockdown in IL-1β-treated chondrocytes in vitro, and JNK inhibition reduced MMP expression in chondrocytes overexpressing CK1ε, which illustrated that CK1ε-mediated OA was based on JNK pathway. In conclusion, our results demonstrate that CK1ε promotes OA development, and inhibition of CK1ε could be a potential strategy for OA treatment in the future.

p38 MAPK Signaling in Osteoblast Differentiation

The skeleton is a highly dynamic tissue whose structure relies on the balance between bone deposition and resorption. This equilibrium, which depends on osteoblast and osteoclast functions, is controlled by multiple factors that can be modulated post-translationally. Some of the modulators are Mitogen-activated kinases (MAPKs), whose role has been studied in vivo and in vitro. p38-MAPK modifies the transactivation ability of some key transcription factors in chondrocytes, osteoblasts and osteoclasts, which affects their differentiation and function. Several commercially available inhibitors have helped to determine p38 action on these processes. Although it is frequently mentioned in the literature, this chemical approach is not always as accurate as it should be. Conditional knockouts are a useful genetic tool that could unravel the role of p38 in shaping the skeleton. In this review, we will summarize the state of the art on p38 activity during osteoblast differentiation and function, and emphasize the triggers of this MAPK.

Osteoblastogenesis of Mesenchymal Stem Cells in 3-D Culture Enhanced by Low-Intensity Pulsed Ultrasound through Soluble Receptor Activator of Nuclear Factor Kappa B Ligand

This study was performed to investigate osteoblastogenesis of human mesenchymal stem cells (hMSCs) cultured in 3-D scaffolds stimulated with low-intensity pulsed ultrasound and to identify the underlying mechanism mediated by soluble receptor activator of nuclear factor kappa B ligand (sRANKL) secreted by hMSCs. The results indicate that the mRNA levels of core-binding factor subunit alpha subunit 1 (CBFA1), osterix (OSX), alkaline phosphatase (ALP), osteocalcin and osteoprotegerin (OPG) and sRANKL production of hMSCs stimulated by ultrasound were significantly increased compared with the levels without ultrasound stimulation. Attenuating the sRANKL activity of ultrasound-treated hMSCs significantly reduced the mRNA expression of CBFA1, OSX, ALP and OPG. Adding sRANKL in hMSC culture significantly increased the mRNA expression of CBFA1, OSX and OPG. Together, the results suggest that osteoblastogenesis of hMSCs enhanced by ultrasound stimulation is mediated by endogenous sRANKL.

In vitro biological evaluation of glyburide as potential inhibitor of collagenases

In tissues with upregulated MMP activity, MMP inhibition remains one of the key strategies. Potential inhibitors of MMPs have been tested for almost 30 years, but none have reached clinical utility due to bioavailability issues and adverse effects. This study utilized the approach of drug repurposing for exploring glyburide as a potential inhibitor against collagenases. In silico molecular docking studies were carried out to probe the interactions of glyburide with the active site Zn. Collagenase enzyme activity measurements and zymography analyses using conditioned medium from lung fibroblasts, rheumatoid synovial fibroblasts, and osteoblasts were carried out to confirm the inhibitory activity. Glyburide binds and interacts with the catalytic Zn residues of the collagenases, as evidenced by in silico molecular docking studies. Fluorescence enzyme activity measurements reveal that glyburide inhibits peptide substrate cleavage by all three collagenases in a dose-dependent manner. Collagen zymography studies validated inhibition of these collagenases by glyburide. These results identify glyburide as a potential inhibitor of collagenases and provide an insight into the mechanism of action of this small molecule. Thus, glyburide may offer additional advantages in diabetics, in controlling MMP activation and collagen degradation and could aid in the treatment of diseases with aberrant MMP activity.

Osteogenic differentiation of human adipose-derived stem cells can be accelerated by controlling the frequency of continuous ultrasound

OBJECTIVES

The purpose of this study was to demonstrate that the effects of continuous ultrasound on the osteogenic differentiation of human adipose-derived stem cells (hASCs) are dependent on the frequency in vitro.

METHODS

Before stimulation, we characterized the hASCs using cluster of differentiation marker profiles and tridifferentiation. Then we selected effective frequencies in the range of 0.5 to 1.5 MHz (with a peak negative pressure of 52 kPa), which upregulated runt-related transcription factor 2 messenger RNA expression. Next, the effects of ultrasound at the selected frequencies on the osteogenic differentiation were evaluated at the protein level. Alkaline phosphatase activity and the formation of mineralized nodules were measured. We additionally identified the cellular mechanisms underlying the effects of ultrasound stimulation using Western blotting.

RESULTS

The hASCs showed general cluster of differentiation marker profiles of stem cells and confirmed their potentials to yield adipogenic, chondrogenic, and osteogenic differentiation. Frequencies of 0.5, 1.0, and 1.5 MHz were selected for higher runt-related transcription factor 2 expression in the range of 0.5 to 1.5 MHz. Among the 3 groups, alkaline phosphatase activity and the formation of mineralized nodules were increased in cells exposed to 1.5-MHz ultrasound compared with cells exposed to 0.5-or 1.0-MHz ultrasound and nontreated control cells. We additionally confirmed that this acceleration of osteogenic differentiation was related to p38 and protein kinase B signaling pathways.

CONCLUSIONS

In this study, we found that, in the selected range, 1.5 MHz was the most effective frequency for inducing the osteogenic differentiation of hASCs.

Bradykinin enhances cell migration in human prostate cancer cells through B2 receptor/PKCδ/c-Src dependent signaling pathway

BACKGROUND

Prostate cancer is the most commonly diagnosed malignancy in men and shows a predilection for metastasis to the bone. Bradykinin (BK) is an inflammatory mediator, and shows elevated levels in regions of severe injury and inflammatory diseases. The aim of this study was to investigate whether Bradykinin is associated with migration of prostate cancer cells.

METHODS

Cancer cells migration activity was examined using the Transwell assay. The c-Src and PKCδ phosphorylation was examined by using Western blot method. The qPCR was used to examine the mRNA expression of metalloproteinase. A transient transfection protocol was used to examine NF-κB activity.

RESULTS

We found that bradykinin increased the chemomigration and the expression of MMP-9 of human prostate cancer cells. Bradykinin-mediated chemomigration and metalloproteinase expression was attenuated by PKCδ inhibitor (rottlerin), PKCδ siRNA, c-Src inhibitor (PP2) and c-Src mutant. Activations of PKCδ, c-Src and NF-κB pathways after bradykinin treatment was demonstrated, and bradykinin-induced expression of metalloproteinase and chemomigration activity was inhibited by the specific inhibitor and mutant of PKCδ, c-Src, and NF-κB cascades.

CONCLUSIONS

This study showed for the first time that the bradykinin mediates migration of human prostate cancer cells. One of the mechanisms underlying bradykinin directed migration was transcriptional up-regulation of MMP-9 and activation of B2 receptor, PKCδ, c-Src, and NF-κB pathways.

Angiotensin II induces the production of MMP-3 and MMP-13 through the MAPK signaling pathways via the AT(1) receptor in osteoblasts

Angiotensin II (Ang II) plays an important role in the maintenance of bone mass and integrity by activation of the mitogen-activated protein kinases (MAPKs) and by modulation of balance between resorption by osteoclasts and formation by osteoblasts. However, the role of Ang II in the turnover of extracellular matrix (ECM) in osteoid by osteoblasts remains unclear. Therefore, we examined the effect of Ang II on the expression of matrix metalloproteinases (MMPs), plasminogen activators (PAs), and their inhibitors [i.e., tissue inhibitors of metalloproteinases (TIMPs) and PA inhibitor-1 (PAI-1)] using osteoblastic ROS17/2.8 cells. Treatment with Ang II strikingly increased the expressions of MMP-3 and -13 and promoted cell proliferation associated with reduced alkaline phosphatase activity as well as enhanced phosphorylated expression of extracellular signal-regulated kinase (ERK)1/2, p38 MAPK, and stress-activated protein kinases/c-jun N-terminal kinases (SAPK/JNK) in ROS17/2.8 cells. However, Ang II had no effect on the expression of MMP-2, -9, -14, urokinase-type PA, tissue-type PA, TIMP-1, -2, -3, and PAI-1 in cells. Losartan (AT1 receptor blocker) blocked Ang II-induced expression of MMP-3 and -13, whereas PD123319 (AT2 receptor blocker) did not completely block these responses. Losartan also blocked the Ang II-induced phosphorylation of ERK1/2, p38 MAPK, and SAPK/JNK. MAPK kinase 1/2 inhibitor PD98059 and JNK inhibitor SP600125 suppressed Ang II-induced expression of MMP-3 and -13. These results suggested that Ang II stimulated the degradation process that occurs during ECM turnover in osteoid by increasing the production of MMP-3 and -13 through MAPK signaling pathways via the AT1 receptor in osteoblasts. Furthermore, our findings suggest that Ang II does not influence the plasminogen/plasmin pathway in osteoblasts.

CCN3 increases cell motility and MMP-13 expression in human chondrosarcoma through integrin-dependent pathway

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. CCN3, also called nephroblastoma overexpressed gene (NOV), regulates proliferation and differentiation of cancer cells. However, the effect of CCN3 on migration activity in human chondrosarcoma cells is mostly unknown. Here, we found that CCN3 increased the migration and expression of matrix metalloproteinase (MMP)-13 in human chondrosarcoma cells (JJ012 cells). αvβ3 or αvβ5 monoclonal antibody (mAb), phosphatidylinositol 3-kinase (PI3K) inhibitors (Ly294002 and wortmannin) and Akt inhibitor inhibited the CCN3-induced increase of the migration and MMP-13 upregulation of chondrosarcoma cells. CCN3 stimulation increased the phosphorylation of focal adhesion kinase (FAK), PI3K, and Akt. In addition, NF-κB inhibitors also suppressed the cell migration and MMP-13 expression enhanced by CCN3. Moreover, CCN3 increased NF-κB luciferase activity and binding of p65 to the NF-κB element on the MMP-13 promoter. Taken together, our results indicate that CCN3 enhances the migration of chondrosarcoma cells by increasing MMP-13 expression through the αvβ3/αvβ5 integrin receptor, FAK, PI3K, Akt, p65, and NF-κB signal transduction pathway.

15-deoxy-Δ(12,14) -prostaglandin-J2 and ciglitazone inhibit TNF-α-induced matrix metalloproteinase 13 production via the antagonism of NF-κB activation in human synovial fibroblasts

Collagenase-3 (matrix metalloproteinase, MMP-13) plays an important role in the degradation of cartilage in pathologic conditions. MMP-13 is elevated in joint tissues in both rheumatoid arthritis (RA) and osteoarthritis (OA). In addition, inflammation-stimulated synovial fibroblasts are able to release MMP-13 and other cytokines in these diseases. The peroxisome proliferator-activated receptor-γ (PPARγ) ligands are recently considered as new anti-inflammatory compounds and these ligands were reported to ameliorate inflammatory arthritis. The aim of this study is to evaluate the mechanisms how PPARγ ligands inhibit the inflammatory response in synovial fibroblasts. Two PPARγ ligands, cyclopentenone prostaglandin 15-deoxy-Δ(12,14) -prostaglandin-J2 (15d-PGJ2) and synthetic thiazolidinedione compound ciglitazone were examined in this study. Here we found that 15d-PGJ2 and ciglitazone markedly inhibited TNF-α-induced MMP-13 production in human synovial fibroblasts. In addition, activation of nuclear factor κB (NF-κB) is strongly associated with MMP-13 induction by TNF-α and the activation of NF-κB was determined by Western blot, reporter assay, and immunofluorescence. It was found that 15d-PGJ2 markedly attenuated the translocation of NF-κB by direct inhibition of the activation of IKK via a PPARγ-independent manner. Ciglitazone also inhibits TNF-α-induced MMP-13 expression by suppressing NF-κB activation mainly via the modulation of p38-MAPK. Collectively, our data demonstrate that 15d-PGJ2 and ciglitazone attenuated TNF-α-induced MMP-13 expression in synovial fibroblasts primarily through the modulation of NF-κB signaling pathways. These compounds may have therapeutic application in inflammatory arthritis.

Involvement of activated transcriptional process in efficient gene transfection using unmodified and mannose-modified bubble lipoplexes with ultrasound exposure

Recently, our group developed ultrasound (US)-responsive and mannose-modified gene carriers (Man-PEG(2000) bubble lipoplexes), and successfully obtained a high level of gene expression in mannose receptor-expressing cells following gene transfection using Man-PEG(2000) bubble lipoplexes and US exposure. We also reported that large amounts of plasmid DNA (pDNA) were transferred into the cytoplasm of the targeted cells in the gene transfection using this method. In the present study, we investigated the involvement of transcriptional processes on enhanced gene expression obtained by unmodified and Man-PEG(2000) bubble lipoplexes with US exposure. The transcriptional process related to activator protein-1 (AP-1) and nuclear factor-κB (NFκB) was activated by US exposure, and was founded to be involved in enhanced gene expression obtained by gene transfection using unmodified and Man-PEG(2000) bubble lipoplexes with US exposure. On the other hand, activation of AP-1 and NFκB pathways followed by US exposure was hardly involved in the inflammatory responses in the gene transfection using this method. These findings suggest that activation of AP-1 and NFκB followed by US exposure is involved in the enhanced gene expression using unmodified and Man-PEG(2000) bubble lipoplexes with US exposure, and the selection of pDNAs activated by US exposure is important in this gene transfection method.

The cross-talk between transforming growth factor-beta1 and ultrasound stimulation during mechanotransduction of rat tenocytes

Ultrasound is an effective noninvasive treatment for various tendinopathies. However, how tenocytes convert ultrasound stimulation into cascades of cellular and molecular events is not well understood. The purpose of this study is to elucidate the signaling pathways of tenocytes during ultrasound stimulation. Primary cultures of tenocytes were harvested from Achilles tendons of Sprague-Dawley rats. The viability and proliferation of tenocytes, their genes expression, and the signaling pathways after ultrasound treatment with or without specific inhibitors were evaluated and analyzed. The results showed that ultrasound treatment (100 mW/cm(2) for 20 min) significantly enhanced matrix metalloproteinase 13 (MMP-13), c-Fos, and c-Jun gene expression, increased JNK and p38, but not extracellular signal-regulated kinase-1/2 (ERK1/2), phosphorylation at 5 min, and sustained up to 60 min. JNK inhibitor and p38 inhibitor, but not ERK1/2 inhibitor, attenuated ultrasound-dependent induction of MMP-13 expression, indicating that the JNK and p38 pathways are required for ultrasound-induced MMP-13 expression in tenocytes. We also found that SB431542 (transforming growth factor-beta (TGF-β) receptor kinases inhibitor) suppressed ultrasound-induced MMP?13 and c-Fos gene expression, and p38 phosphorylation. This study revealed that ultrasound treatment stimulates tenocytes proliferation and regulates their matrix metabolism through the cross-talk between TGF-β and ultrasound-induced mitogen-activated protein kinases (MAPKs) signaling pathways.

The SIE, SRE, CRE, and FAP-1 four intracellular signal pathways between stimulus and the expression of c-fos promoter

c-fos gene has a close relationship with the osteoblasts. Mechanical signal effect on osteoblasts would change the expression level of c-fos. Authors introduce the signal pathways of four cis-response elements on the promoter of c-fos, that is, CRE (cAMP responsive element), FAP-1 (Fbs-AP-1 site), SRE (serum response element), and SIE (sis-inducible element), as the regulatory mechanism for c-fos gene expression following various stimuli.

Cyr61 increases migration and MMP-13 expression via alphavbeta3 integrin, FAK, ERK and AP-1-dependent pathway in human chondrosarcoma cells

Cysteine-rich 61 (Cyr61), from the CCN gene family, is a secreted and matrix-associated protein, which is involved in many cellular activities such as growth and differentiation. However, the effect of Cyr61 on migration activity in human chondrosarcoma cells is mostly unknown. Here, we found that Cyr61 increased the migration and expression of matrix metalloproteinase (MMP)-13 in human chondrosarcoma cells (JJ012 cells). RGD peptide, alphavbeta3 monoclonal antibody and mitogen-activated protein kinase (MEK) inhibitors (PD98059 and U0126) but not RAD peptide inhibited the Cyr61-induced increase of the migration and MMP-13 upregulation of chondrosarcoma cells. Cyr61 stimulation increased the phosphorylation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK). In addition, activator protein-1 (AP-1) decoy oligodeoxynucleotide also suppressed the MMP-13 messenger RNA and enzyme activity enhanced by Cyr61. Moreover, Cyr61 increased the binding of c-Fos and c-Jun to the AP-1 element on the MMP-13 promoter. Taken together, our results indicated that Cyr61 enhances the migration of chondrosarcoma cells by increasing MMP-13 expression through the alphavbeta3 integrin receptor, FAK, ERK, c-Fos/c-Jun and AP-1 signal transduction pathway.