• The Microorganisms and Industry
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• v.19 no.4
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• pp.27-31
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• 1993

Certain bacterial species possess the capability of differentiation through several morphogenetic changes which enable them to adapt to certain internal and external stimuli(Losick and Shapiro 1984). Upon induction, cells of A. vinelandii undergo a morphological process which leads to the production of one cyst per cell (Sadoff, 1975). The cysts are considerably resistant to desiccation, which confers a survival advantages upon the organism(Socolofsky and Wyss 1962). Like other prokaryotic differentiations encystment provides a relatively simple model of cellular differentiation. Like in other differentiating bacteria, vegetative growth can be separated from differentiation. Furthermore, the differentiation cycle can be synchronized by specific inducer. There have been a great deal of morphological and physiological studies on this process. However, the mechanisms used to regulate cell differentiation can be clearly defined by careful genetic analysis of the process. Unfortunately, A. vinelandii has proven to be difficult for genetic analysis (Sadoff 1975). For example, it has been shown that a variety of metabolic mutants of Azotobacter speicies are difficult to isolate after mutagenesis with chemical mutagens or UV irradiation. Nevertheless recent advances in molecular genetics in Azotobacter species, especially in the nitrogen fixation research area, appear to be able to overcome this difficulty (Robinson et al. 1986; Kennedy et al. 1986).

• Molecules and Cells
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• v.39 no.2
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• pp.156-162
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• 2016

Estrogen receptor ${\alpha}$ (ER-${\alpha}$), which is involved in bone metabolism and breast cancer, has been shown to have transcriptional targets. Dlx3 is essential for the skeletal development and plays an important role in osteoblast differentiation. Various osteogenic stimulators and transcription factors can induce the protein expression of Dlx3. However, the regulatory function of ER-${\alpha}$ in the Dlx3 mediated osteogenic process remains unknown. Therefore, we investigated the regulation of Dlx3 and found that ER-${\alpha}$ is a positive regulator of Dlx3 transcription in BMP2-induced osteoblast differentiation. We also found that ER-${\alpha}$ interacts with Dlx3 and increases its transcriptional activity and DNA binding affinity. Furthermore, we demonstrated that the regulation of Dlx3 activity by ER-${\alpha}$ is independent of the ligand (estradiol) binding domain. These results indicate that Dlx3 is a novel target of ER-${\alpha}$, and that ER-${\alpha}$ regulates the osteoblast differentiation through modulation of Dlx3 expression and/or interaction with Dlx3.

• Natural Product Sciences
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• v.12 no.4
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• pp.175-192
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• 2006

Screening for the cytotoxicity from plant origin is the first stage for anti-cancer drug development. A variety of terpenoids with exomethylene, epoxide, allyl, $\alpha,\beta-unsaturated$ carbonyl, acetylenes, and $\alpha-methylene-\gamma-lactone$ induces apoptosis and/or differentiation as well as cytotoxicity through the ROS signal transduction pathways. These are found among monoterpenes, sesquiterpenes, triterpenes, flavonoids, coumarins, diarylheptanoids, and even organosulfuric compounds. The most essential characteristics of natural cytotoxic substances is to possess the strong electrophilicity that is susceptible to nucleophilic biomolecules in the cell. Thiol-reductants and superoxide dismutase can block or delay apoptosis. Thus, ROS and the resulting cellular redox-potential changes can be parts of the signal transduction pathway during apoptosis. Disturbance of the balance of oxireduction by the pigment of natural quinones also caused the induction of the differentiation and apoptosis. Saponins with the cytotoxicity are restricted to their monodesmosides, rather than to bisdesmosides. Those saponins exhibited calcium ion-mediated apoptosis in addition to cytotoxicity whereas they showed also differentiation without extracellular calcium ion. The properties on cytotoxicity, apoptosis, and differentiation were assumed to depend on resultant oxidative stress to the cells. In this review, we describe a spectrum of cytotoxic compounds with various action mechanisms.

• Molecules and Cells
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• v.38 no.10
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• pp.904-910
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• 2015

Negative regulator of reactive oxygen species (NRROS) is known to repress ROS generation in phagocytes. In this study, we examined the roles of NRROS in both osteoclasts and osteoblasts. Our results demonstrate that NRROS negatively regulates the differentiation of osteoclasts, but not osteoblasts. Further, overexpression of NRROS in osteoclast precursor cells attenuates RANKL-induced osteoclast differentiation. Conversely, osteoclast differentiation is enhanced upon siRNA-mediated knock-down of NRROS. Additionally, NRROS attenuates RANKL-induced $NF-{\kappa}B$ activation, as well as degradation of the NOX1 and NOX2 proteins, which are required for ROS generation. Based on our observations, we present NRROS as a novel negative regulator of RANKL-induced osteoclastogenesis.

• Molecules and Cells
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• v.40 no.5
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• pp.371-377
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• 2017

Despite the importance of the receptor activator of nuclear factor (NF)-kappaB ligand (RANKL)-RANK signaling mechanisms on osteoclast differentiation, little has been studied on how RANK expression is regulated or what regulates its expression during osteoclastogenesis. We show here that insulin signaling increases RANK expression, thus enhancing osteoclast differentiation by RANKL. Insulin stimulation induced RANK gene expression in time- and dose-dependent manners and insulin receptor shRNA completely abolished RANK expression induced by insulin in bone marrow-derived monocyte/macrophage cells (BMMs). Moreover, the addition of insulin in the presence of RANKL promoted RANK expression. The ability of insulin to regulate RANK expression depends on extracellular signal-regulated kinase 1/2 (ERK1/2) since only PD98059, an ERK1/2 inhibitor, specifically inhibited its expression by insulin. However, the RANK expression by RANKL was blocked by all three mitogen-activated protein (MAP) kinases inhibitors. The activation of RANK increased differentiation of BMMs into tartrate-resistant acid phosphatase-positive ($TRAP^+$) osteoclasts as well as the expression of dendritic cell-specific transmembrane protein (DC-STAMP) and d2 isoform of vacuolar ($H^+$) ATPase (v-ATPase) Vo domain (Atp6v0d2), genes critical for osteoclastic cell-cell fusion. Collectively, these results suggest that insulin induces RANK expression via ERK1/2, which contributes to the enhancement of osteoclast differentiation.

• Molecules and Cells
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• v.44 no.5
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• pp.318-327
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• 2021

CD4+ T helper (Th) cells play a crucial role in the modulation of innate and adaptive immune responses through the differentiation of Th precursor cells into several subsets, including Th1, Th2, Th17, and regulatory T (Treg) cells. Effector Th and Treg cells are distinguished by the production of signature cytokines and are important for eliminating intracellular and extracellular pathogens and maintaining immune homeostasis. Stimulation of naive Th cells by T cell receptor and specific cytokines activates master transcription factors and induces lineage specification during the differentiation of Th cells. The master transcription factors directly activate the transcription of signature cytokine genes and also undergo post-translational modifications to fine-tune cytokine production and maintain immune balance through cross-regulation with each other. This review highlights the post-translational modifications of master transcription factors that control the differentiation of effector Th and Treg cells and provides additional insights on the immune regulation mediated by protein argininemodifying enzymes in effector Th cells.

• Molecules and Cells
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• v.24 no.3
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• pp.431-436
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• 2007

Stem cell-based therapy is being considered as an alternative treatment for cardiomyopathy. Hence understanding the basic molecular mechanisms of cardiomyocyte differentiation is important. Besides BMP or Wnt family proteins, $TGF-{\beta}$ family members are thought to play a role in cardiac development and differentiation. Although $TGF-{\beta}$ has been reported to induce cardiac differentiation in embryonic stem cells, the differential role of $TGF-{\beta}$ isoforms has not been elucidated. In this study, employing the DMSO-induced cardiomyocyte differentiation system using P19CL6 mouse embryonic teratocarcinoma stem cells, we investigated the $TGF-{\beta}$-induced signaling pathway in cardiomyocyte differentiation. $TGF-{\beta}1$, but not the other two isoforms of $TGF-{\beta}$, was induced at the mRNA and protein level at an early stage of differentiation, and Smad2 phosphorylation increased in parallel with $TGF-{\beta}1$ induction. Inhibition of $TGF-{\beta}1$ activity with $TGF-{\beta}1$-specific neutralizing antibody reduced cell cycle arrest as well as expression of the CDK inhibitor $p21^{WAF1}$. The antibody also inhibited induction of the cardiac transcription factor Nkx2.5. Taken together, these results suggest that $TGF-{\beta}1$ is involved in cardiomyocyte differentiation by regulating cell cycle progression and cardiac gene expression in an autocrine or paracrine manner.

• Journal of Periodontal and Implant Science
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• v.40 no.1
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• pp.39-44
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• 2010

Purpose: Bone tissues for clinical application can be improved by studies on osteoblast differentiation. Runx2 is known to be an important transcription factor for osteoblast differentiation. However, bone morphogenetic protein (BMP)-2 treatment to stimulate Runx2 is not sufficient to acquire enough bone formation in osteoblasts. Therefore, it is necessary to find other regulatory factors which can improve the transcriptional activity of Runx2. The erythroblast transformation-specific (ETS) transcription factor family is reported to be involved in various aspects of cellular proliferation and differentiation. Methods: We have noticed that the promoters of osteoblast differentiation markers such as alkaline phosphatase (Alp), osteopontin (Opn), and osteocalcin (Oc) contain Ets binding sequences which are also close to Runx2 binding elements. Luciferase assays were performed to measure the promoter activities of these osteoblast differentiation markers after the transfection of Runx2, myeloid Elf-1-like factor (MEF), and Runxs+MEF. Reverse-transcription polymerase chain reaction was also done to check the mRNA levels of Opn after Runx2 and MEF transfection into rat osteoblast (ROS) cells. Results: We have found that MEF, an Ets transcription factor, increased the transcriptional activities of Alp, Opn, and Oc. The addition of Runx2 resulted in the 2- to 6-fold increase of the activities. This means that these two transcription factors have a synergistic effect on the osteoblast differentiation markers. Furthermore, early introduction of these two Runx2 and MEF factors significantly elevated the expression of the Opn mRNA levels in ROS cells. We also showed that Runx2 and MEF proteins physically interact with each other. Conclusions: Runx2 interacts with MEF proteins and binds to the promoters of the osteoblast markers such as Opn nearby MEF to increase its transcriptional activity. Our results also imply that osteoblast differentiation and bone formation can be increased by activating MEF to elicit the synergistic effect of Runx2 and MEF.

• Molecules and Cells
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• v.38 no.11
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• pp.941-949
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• 2015

Rheumatoid arthritis is a chronic inflammatory disease that leads to bone and cartilage erosion. The inhibition of osteoblast differentiation by the inflammatory factor TNF-${\alpha}$ is critical for the pathogenesis of rheumatoid arthritis. To modulate TNF-${\alpha}$ mediated inhibition of osteoblast differentiation is required to improve therapeutic efficacy of rheumatoid arthritis. Here, we explored the potential role of rocaglamide-A, a component of Aglaia plant, in osteoblast differentiation. Rocaglamide-A prevented TNF-${\alpha}$ mediated inhibition of osteoblast differentiation, and promoted osteoblast differentiation directly, in both C2C12 and primary mesenchymal stromal cells. Mechanistically, Rocaglamide-A inhibited the phosphorylation of NF-${\kappa}B$ component p65 protein and the accumulation of p65 in nucleus, which resulted in the diminished NF-${\kappa}B$ responsible transcriptional activity. Oppositely, overexpression of p65 reversed rocaglamide-A's protective effects on osteoblast differentiation. Collectively, rocaglamide-A protected and stimulated osteoblast differentiation via blocking NF-${\kappa}B$ pathway. It suggests that rocaglamide-A may be a good candidate to develop as therapeutic drug for rheumatoid arthritis associated bone loss diseases.

• Molecules and Cells
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• v.41 no.5
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• pp.476-485
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• 2018

Although tectorigenin (TG), a major compound in the rhizome of Belamcanda chinensis, is conventionally used for the treatment of inflammatory diseases, its effects on osteogenesis and osteoclastogenesis have not been reported. The objective of this study was to investigate the effects and possible underlying mechanism of TG on in vitro osteoblastic differentiation and in vivo bone formation, as well as in vitro osteoclast differentiation and in vivo bone resorption. TG promoted the osteogenic differentiation of primary osteoblasts and periodontal ligament cells. Moreover, TG upregulated the expression of the BMP2, BMP4, and Smad-4 genes, and enhanced the expression of Runx2 and Osterix. In vivo studies involving mouse calvarial bone defects with ${\mu}CT$ and histologic analysis revealed that TG significantly increased new bone formation. Furthermore, TG treatment inhibited osteoclast differentiation and the mRNA levels of osteoclast markers. In vivo studies of mice demonstrated that TG caused the marked attenuation of bone resorption. These results collectively demonstrated that TG stimulated osteogenic differentiation in vitro, increased in vivo bone regeneration, inhibited osteoclast differentiation in vitro, and suppressed inflammatory bone loss in vivo. These novel findings suggest that TG may be useful for bone regeneration and treatment of bone diseases.