Involvement of AP-1 in p38MAPK signaling pathway in osteoblast apoptosis induced by high glucose

Regulation of CyR61 expression and release by 3-mercaptopyruvate sulfurtransferase in colon cancer cells

Cysteine-rich angiogenic inducer 61 (CYR61, also termed CCN family member 1 or CCN1), is a matricellular protein encoded by the CYR61 gene. This protein has been implicated in the regulation of various cancer-associated processes including tumor growth, angiogenesis, tumor cell adhesion, migration, and invasion as well as the regulation of anticancer drug resistance. Hydrogen sulfide (H₂S) is a gaseous endogenous biological mediator, involved in the regulation of cellular bioenergetics, angiogenesis, invasion, and chemotherapeutic resistance in several types of cancer. H₂S is produced by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current studies were set up to investigate if CBS or 3-MST regulates CyR61 in colon cancer cells in the context of the regulation of proliferation, migration, and survival. The study mainly utilized HCT116 cells, in which two of the principal H₂S-producing enzymes, CBS and 3-MST, are highly expressed. The H₂S donor GYY4137 and the polysulfide donor Na₂S₃ activated the CyR61 promoter in a concentration-dependent fashion. Aminooxyacetic acid (AOAA), a pharmacological inhibitor of CBS as well as HMPSNE: 2-[(4-hydroxy-6- methylpyrimidin-2-yl)sulfanyl]-1-(naphthalen-1-yl)ethan-1-one, a pharmacological inhibitor of 3-MST inhibited CyR61 mRNA expression. This effect was more pronounced in response to HMPSNE than to AOAA and occurred through the modulation of S1PR via ATF1 and CREB. CyR61 was found to play an active, but relatively minor role in maintaining colon cell proliferation. HMPSNE markedly suppressed the secretion/release of CyR61 from the colon cancer cells. Moreover, HMPSNE promoted colon cancer cell apoptosis; endogenously produced CyR61 was found to counteract this effect, at least in part via RhoA activation. Taken together, we conclude that the upregulation of 3-MST in cancer cells exerts cytoprotective effects and confers the cancer cells a more aggressive phenotype - at least in part via the modulation of CyR61 expression and release.

MicroRNA-495 downregulates AQP1 and facilitates proliferation and differentiation of osteoblasts in mice with tibial fracture through activation of p38 MAPK signaling pathway

Osteoblasts are implicated in the building of the vertebrate skeleton. The current study aimed to investigate the role of microRNA-495 (miR-495) in the osteoblasts of mice with tibial fractures and the underlying mechanism involving in aquaporin-1 (AQP1) and the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway. Initially, a microarray-based analysis was performed to screen the differentially expressed genes and miRNAs associated with tibial fracture. Following the establishment of a tibial fracture mouse model, the positive rate of the AQP1 protein in the fracture tissue was detected by immunohistochemistry (IHC). Next, to verify the binding site between miR-495 on AQP1, bioinformatics data were employed in addition to the application of a dual-luciferase reporter gene assay. The osteoblast cell line MC3T3-E1 was treated with miR-495 mimic, miR-495 inhibitor and Anisomycin to explore the potent effects of miR-495 on proliferation and differentiation of osteoblasts in mice with tibial fracture. The expression of miR-495, AQP1, p38 MAPK, PCNA, Cyclin D1, OCN, and OPN was subsequently evaluated by RT-qPCR and Western blot analysis. Cell viability, the number of calcium nodules and alkaline phosphatase (ALP) activity were detected by MTT assay, alizarin red staining, and ALP activity assay, respectively. Our results revealed that miR-495 was down-regulated while AQP1 was up-regulated in the mice with tibial fractures. AQP1 was verified as a target gene of miR-495. When the cells were treated with overexpressed miR-495 or activated p38 MAPK signaling pathway, elevated expression of PCNA, Cyclin, D1, OCN, and OPN along with an increased amount of calcium nodules, higher cell viability, and enhanced ALP activity was detected, while the expression of AQP1 was reduced. Collectively, the key findings of the present study support the notion that overexpressed miR-495 may activate the p38 MAPK signaling pathway to inhibit AQP1 and to promote the proliferation and differentiation of osteoblasts in mice with tibial fracture.

Tozasertib attenuates neuronal apoptosis via DLK/JIP3/MA2K7/JNK pathway in early brain injury after SAH in rats

BACKGROUND AND PURPOSE

Since tozasertib is neuroprotective for injured optic nerve, this study is intended to test whether tozasertib reduces early brain injury after subarachnoid hemorrhage (SAH) in a rat model.

METHODS

Two hundred sixteen (216) male Sprague-Dawley rats were randomly subjected to endovascular perforation model of SAH and sham group. SAH grade, neurological score, and brain water content were measured at 24 and 72 h after SAH. Dual leucine zipper kinase (DLK) and its downstream factors, JNK-interacting protein 3 (JIP3), MA2K7, p-JNK/JNK (c-Jun N-terminal kinase), and apoptosis related proteins cleaved caspase-3 (CC-3), Bim, Bcl-2, and cleaved caspase-9 (CC-9) were analyzed by western blot at 24 h after SAH. Apoptotic cells were detected by terminal deoxynucleotid transferase-deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL). DLK small interfering RNA (siRNA), JIP3 siRNA and MA2K7 siRNA, the JNK, p38MAPK, and MEK inhibitors SP600125, SB203580, and PD98059 were used for intervention.

RESULTS

Tozasertib reduced neuronal apoptosis, attenuated brain edema and improved neurobehavioral deficits 24 and 72 h after SAH. At 24 h After SAH, DLK/JIP3/MA2K7/p-JNK/CC-3 expressions were elevated markedly and tozasertib reduced DLK, MA2K7/p-JNK/CC-3 expressions but enhanced JIP3 expression. In the presence of tozasertib, DLK/JIP3/MA2K7 siRNA and SP600125, SB203580 and PD98059 deteriorated the neurobehavioral deficits, brain edema and increased the expression of CC-3. SAH potentiated the expression of Bim, CC-9, and CC-3 but reduced Bcl-2, while tozasertib reduced expression of Bim, CC-9, and CC-3 but enhanced Bcl-2.

CONCLUSIONS

Tozasertib reduced neuronal apoptosis and improved outcome possibly via DLK/JIP3/MA2K7/JNK pathways after SAH.

Naringin Stimulates Osteogenic Differentiation of Rat Bone Marrow Stromal Cells via Activation of the Notch Signaling Pathway

Naringin is a major flavonoid found in grapefruit and is an active compound extracted from the Chinese herbal medicine Rhizoma Drynariae. Naringin is a potent stimulator of osteogenic differentiation and has potential application in preventing bone loss. However, the signaling pathway underlying its osteogenic effect remains unclear. We hypothesized that the osteogenic activity of naringin involves the Notch signaling pathway. Rat bone marrow stromal cells (BMSCs) were cultured in osteogenic medium containing-naringin, with or without DAPT (an inhibitor of Notch signaling), the effects on ALP activity, calcium deposits, osteogenic genes (ALP, BSP, and cbfa1), adipogenic maker gene PPARγ2 levels, and Notch expression were examined. We found that naringin dose-dependently increased ALP activity and Alizarin red S staining, and treatment at the optimal concentration (50 μg/mL) increased mRNA levels of osteogenic genes and Notch1 expression, while decreasing PPARγ2 mRNA levels. Furthermore, treatment with DAPT partly reversed effects of naringin on BMSCs, as judged by decreases in naringin-induced ALP activity, calcium deposits, and osteogenic genes expression, as well as upregulation of PPARγ2 mRNA levels. These results suggest that the osteogenic effect of naringin partly involves the Notch signaling pathway.

Effect of Yaobitong capsule on histomorphology of dorsal root ganglion and on expression of p38mark phosphorylation in autologous nucleus pulposus transplantation model of rats

OBJECTIVE

To discuss the effect of Yaobitong capsule on histomorphology of dorsal root ganglion and on expression of p38MARK phosphorylation in autologous nucleus pulposus transplantation model of rats.

METHODS

A total of 60 SD rats were randomly divided into the blank group, model group and Yaobitong capsule group, with 20 rats in each group. The animal model of autologous nucleus pulposus transplantation around the lumbar nerve root was built. Three days after the modeling, rats were given the drugs for the first time, while rats in the model group were given the equivalent normal saline. After 30 d of continuous administration, samples were collected from rats. HE staining was performed on the dorsal root ganglion of L4 and L5 spinal cord of rats in each group and the expression of p38MARK phosphorylation was measured. All data were treated with the statistical analysis.

RESULTS

The histological examination showed that the histomorphology of dorsal root ganglion in the Yaobitong capsule group was more significantly improved than the one in the model group, while the results of western blot showed that Yaobitong capsule could significantly inhibit the level of p38MAPK phosphorylation of dorsal root ganglion cells.

CONCLUSIONS

Yaobitong capsule can improve the symptoms and nerve radiculopathy of autologous nucleus pulposus transplantation of rats and its mechanism may be associated with its inhibiting effect on the level of p38MAPK phosphorylation.