Expression of glutathione peroxidase 1 in the spheno-occipital synchondrosis and its role in ROS-induced apoptosis

4-Carbomethoxyl-10-Epigyrosanoldie E Extracted from Cultured Soft Coral Sinularia sandensis Induced Apoptosis and Autophagy via ROS and Mitochondrial Dysfunction and ER Stress in Oral Cancer Cells

Oral cancer is a malignant neoplasia that is more common in Asian than other regions, and men are at higher risk than women. Currently, clinical treatment for oral cancer consists of radiation therapy combined with chemotherapy. Therefore, it is important to find a drug that can inhibit the growth of cancer cells more effectively and safely. In this study, we examined the cytotoxicity of 4-carbomethoxyl-10-epigyrosanoldie E extracted from cultured soft coral Sinularia sandensis towards oral cancer cells. MTT cell proliferation and colony formation assays were used to evaluate cell survival, and immunofluorescence staining and Western blotting were employed to analyze the effects of 4-carbomethoxyl-10-epigyrosanoldie E on apoptosis and autophagy. 4-Carbomethoxyl-10-epigyrosanoldie E treatment also induced the formation of reactive oxygen species (ROS), which are associated with 4-carbomethoxyl-10-epigyrosanoldie E-induced cell death. In addition, the 4-carbomethoxyl-10-epigyrosanoldie E-induced antiproliferation effects on Ca9-22 and Cal-27 cells were associated with the release of cytochrome c from mitochondria, activation of proapoptotic proteins (such as caspase-3/-9, Bax, and Bad), and inhibition of antiapoptotic proteins (Bcl-2, Bcl-xl, and Mcl-1). 4-Carbomethoxyl-10-epigyrosanoldie E treatment also triggered endoplasmic reticulum (ER) stress, leading to activation of the PERK/elF2α/ATF4/CHOP apoptotic pathway. Moreover, increased expressions of Beclin-1, Atg3, Atg5, Atg7, Atg12, Atg 16, LC3-I, and LC3-II proteins indicated that 4-carbomethoxyl-10-epigyrosanoldie E triggered autophagy in oral cancer cells. In conclusion, our findings demonstrated that 4-carbomethoxyl-10-epigyrosanoldie E suppressed human oral cancer cell proliferation and should be further investigated with regard to its potential use as a chemotherapy drug for the treatment of human oral cancer.

Shared genetic liability between major depressive disorder and osteoarthritis

Aims

Deciphering the genetic relationships between major depressive disorder (MDD) and osteoarthritis (OA) may facilitate an understanding of their biological mechanisms, as well as inform more effective treatment regimens. We aim to investigate the mechanisms underlying relationships between MDD and OA in the context of common genetic variations.

Methods

Linkage disequilibrium score regression was used to test the genetic correlation between MDD and OA. Polygenic analysis was performed to estimate shared genetic variations between the two diseases. Two-sample bidirectional Mendelian randomization analysis was used to investigate causal relationships between MDD and OA. Genomic loci shared between MDD and OA were identified using cross-trait meta-analysis. Fine-mapping of transcriptome-wide associations was used to prioritize putatively causal genes for the two diseases.

Results

MDD has a significant genetic correlation with OA (r_g = 0.29) and the two diseases share a considerable proportion of causal variants. Mendelian randomization analysis indicates that genetic liability to MDD has a causal effect on OA (b_xy = 0.24) and genetic liability to OA conferred a causal effect on MDD (b_xy = 0.20). Cross-trait meta-analyses identified 29 shared genomic loci between MDD and OA. Together with fine-mapping of transcriptome-wide association signals, our results suggest that Estrogen Receptor 1 (ESR1), SRY-Box Transcription Factor 5 (SOX5), and Glutathione Peroxidase 1 (GPX1) may have therapeutic implications for both MDD and OA.

Conclusion

The study reveals substantial shared genetic liability between MDD and OA, which may confer risk for one another. Our findings provide a novel insight into phenotypic relationships between MDD and OA.

Cite this article: Bone Joint Res 2022;11(1):12–22.

Isothiocyanate Iberin inhibits cell proliferation and induces cell apoptosis in the progression of ovarian cancer by mediating ROS accumulation and GPX1 expression

Ovarian cancer (OC) is one of the most common gynecologic malignancies with poor survival rate, and Iberin is a member of isothiocyanate family with anti-tumor activity. However, the role of Iberin in OC development has not been reported yet. In this study, A2780 and OVCAR-3 cells were treated with gradient concentrations of Iberin to investigate the effect of Iberin on OC in vitro. Meanwhile, the in vivo tumorgenesis experiment was performed using female BALB/c nude mice treated with Iberin. Iberin inhibited cell proliferation, induced G2 cell cycle arrest and promoted cell apoptosis in OC cells. Besides, Iberin reduced GSH/GSSG level, enhanced ROS accumulation, and activated MAPK signaling in OC cells. More interestingly, ROS scavenger (NAC) compensated the anti-proliferative and pro-apoptotic effects of Iberin on OC cells, suggesting the involvement of ROS in the regulation of Iberin on OC cell growth. Notably, Iberin induced down-regulation of glutathione peroxidase-1 (GPX1), and over-expression of GPX1 reversed Iberin-mediated alterations in the proliferation, apoptosis and ROS accumulation of OC cells. The in vivo tumorgenesis study further evidenced the protection of Iberin against OC development. Besides, Iberin displayed a synergistic effect on the enhancement of chemo-sensitivity in OC cells. In summary, our study demonstrates the anti-tumor effect of Iberin on OC and its potential as a therapeutic agent against OC in the future.

Myeloid HIF1α Is Involved in the Extent of Orthodontically Induced Tooth Movement

During orthodontic tooth movement, transcription factor hypoxia-inducible factor 1α (HIF1α) is stabilised in the periodontal ligament. While HIF1α in periodontal ligament fibroblasts can be stabilised by mechanical compression, in macrophages pressure application alone is not sufficient to stabilise HIF1α. The present study was conducted to investigate the role of myeloid HIF1α during orthodontic tooth movement. Orthodontic tooth movement was performed in wildtype and Hif1α^Δmyel mice lacking HIF1α expression in myeloid cells. Subsequently, µCT images were obtained to determine periodontal bone loss, extent of orthodontic tooth movement and bone density. RNA was isolated from the periodontal ligament of the control side and the orthodontically treated side, and the expression of genes involved in bone remodelling was investigated. The extent of tooth movement was increased in Hif1α^Δmyel mice. This may be due to the lower bone density of the Hif1α^Δmyel mice. Deletion of myeloid Hif1α was associated with increased expression of Ctsk and Acp5, while both Rankl and its decoy receptor Opg were increased. HIF1α from myeloid cells thus appears to play a regulatory role in orthodontic tooth movement.

Estrogen deficiency affects tooth formation and gene expression in the odontogenic region of female rats

BACKGROUND

There is some evidence that estrogen regulates the expression of several genes in different cells, including dental cells. Therefore, the aim of this study was to investigate the role of estrogen deficiency during tooth development regarding tooth structure morphology and its impact on the expression of odontogenesis-related genes.

METHODS

A total of 40 female Wistar rats was divided into OVX (estrogen deficiency) and Sham (control) groups. Bilateral ovariectomy was performed in the OVX group, while Sham surgery was performed in the control group at the age of 21 days. At an age of 56 days, 16 rats were euthanized for gene expression analyses of Bmp4, Smad6, Tgfb1 and Runx2. At the age of 63 days, the remaining rats were euthanized for histological and morphometric analyses of teeth. The mandibles of the rats were submitted to μCT analysis. Tooth structures (enamel, dentin and dental pulp) were analyzed. T test was used to compare the mean differences between groups (p<0.05).

RESULTS

In the μCT analysis, enamel and dentin thickness were significantly increased in the control group (p<0.0001). Pulp dimensions were significantly larger in the OVX group (p<0.0001). A reduction of tooth structures in the OVX group was confirmed in HE staining. Smad6 was differentially expressed in the OVX group (p=0.04).

CONCLUSION

Estrogen deficiency affects gene expression in the odontogenic region and tooth structure morphology.

Role and Regulation of Mechanotransductive HIF-1α Stabilisation in Periodontal Ligament Fibroblasts

Orthodontic tooth movement (OTM) creates compressive and tensile strain in the periodontal ligament, causing circulation disorders. Hypoxia-inducible factor 1α (HIF-1α) has been shown to be primarily stabilised by compression, but not hypoxia in periodontal ligament fibroblasts (PDLF) during mechanical strain, which are key regulators of OTM. This study aimed to elucidate the role of heparan sulfate integrin interaction and downstream kinase phosphorylation for HIF-1α stabilisation under compressive and tensile strain and to which extent downstream synthesis of VEGF and prostaglandins is HIF-1α-dependent in a model of simulated OTM in PDLF. PDLF were subjected to compressive or tensile strain for 48 h. In various setups HIF-1α was experimentally stabilised (DMOG) or destabilised (YC-1) and mechanotransduction was inhibited by surfen and genistein. We found that HIF-1α was not stabilised by tensile, but rather by compressive strain. HIF-1α stabilisation had an inductive effect on prostaglandin and VEGF synthesis. As expected, HIF-1α destabilisation reduced VEGF expression, whereas prostaglandin synthesis was increased. Inhibition of integrin mechanotransduction via surfen or genistein prevented stabilisation of HIF-1α. A decrease in VEGF expression was observed, but not in prostaglandin synthesis. Stabilisation of HIF-1α via integrin mechanotransduction and downstream phosphorylation of kinases seems to be essential for the induction of VEGF, but not prostaglandin synthesis by PDLF during compressive (but not tensile) orthodontic strain.

The role of HIF-1α in nicotine-induced root and bone resorption during orthodontic tooth movement

BACKGROUND

In orthodontic tooth movement (OTM), pseudo-inflammatory processes occur that are similar to those of nicotine-induced periodontitis. Previous studies have shown that nicotine accelerates OTM, but induces periodontal bone loss and dental root resorption via synergistically increased osteoclastogenesis. This study aimed to investigate the role of hypoxia-inducible factor 1 alpha (HIF-1α) in nicotine-induced osteoclastogenesis during OTM.

MATERIALS/METHODS

Male Fischer-344 rats were treated with l-Nicotine (1.89 mg/kg/day s.c., N = 10) or NaCl solution (N = 10). After a week of premedication, a NiTi spring was inserted to mesialize the first upper left molar. The extent of dental root resorption, osteoclastogenesis, and HIF-1α protein expression was determined by (immuno)histology, as well as bone volume (BV/TV) and trabecular thickness (TbTh) using µCT. Receptor activator of nuclear factor of activated B-cells ligand (RANK-L), osteoprotegerin (OPG), and HIF-1α expression were examined at the protein level in periodontal ligament fibroblasts (PDLF) exposed to pressure, nicotine and/or hypoxia, as well as PDLF-induced osteoclastogenesis in co-culture experiments with osteoclast progenitor cells.

RESULTS

Nicotine favoured dental root resorptions and osteoclastogenesis during OTM, while BV/TV and TbTh were only influenced by force. This nicotine-induced increase does not appear to be mediated by HIF-1α, since HIF-1α was stabilized by force application and hypoxia, but not by nicotine. The in vitro data showed that the hypoxia-induced increase in RANK-L/OPG expression ratio and PDLF-mediated osteoclastogenesis was less pronounced than the nicotine-induced increase.

CONCLUSIONS

Study results indicate that the nicotine-induced increase in osteoclastogenesis and periodontal bone resorption during OTM may not be mediated by hypoxic effects or HIF-1α stabilization in the context of nicotine-induced vasoconstriction, but rather by an alternative mechanism.

Impact of salt and the osmoprotective transcription factor NFAT-5 on macrophages during mechanical strain

Myeloid cells regulate bone density in response to increased salt (NaCl) intake via the osmoprotective transcription factor, nuclear factor of activated T cells-5 (NFAT-5). Because orthodontic tooth movement (OTM) is a pseudoinflammatory immunological process, we investigated the influence of NaCl and NFAT-5 on the expression pattern of macrophages in a model of simulated OTM. RAW264.7 macrophages were exposed for 4 h to 2 g cm^-2 compressive or 16% tensile or no mechanical strain (control), with or without the addition of 40 mm NaCl. We analyzed the expression of inflammatory genes and proteins [tumor necrosis factor (TNF), interleukin (IL)-6 and prostaglandin endoperoxide synthase-2 (Ptgs-2)/prostaglandin E2 (PG-E2)] by real-time-quantitative PCR and ELISA. To investigate the role of NFAT-5 in these responses, NFAT-5 was both constitutively expressed and silenced. Salt and compressive strain, but not tensile strain increased the expression of NFAT-5 and most tested inflammatory factors in macrophages. NaCl induced the expression of Ptgs-2/PG-E2 and TNF, whereas secretion of IL-6 was inhibited. Similarly, a constitutive expression of NFAT-5 reduced IL-6 expression, while increasing Ptgs-2/PG-E2 and TNF expression. Silencing of NFAT-5 upregulated IL-6 and reduced Ptgs-2/PG-E2 and TNF expression. Salt had an impact on the expression profile of macrophages as a reaction to compressive and tensile strain that occur during OTM. This was mediated via NFAT-5, which surprisingly also seems to play a regulatory role in mechanotransduction of compressive strain. Sodium accumulation in the periodontal ligament caused by dietary salt consumption might propagate local osteoclastogenesis via increased local inflammation and thus OTM velocity, but possibly also entail side effects such as dental root resorptions or periodontal bone loss.

Morphometric characteristics of anencephalic skulls - A comparative study

Anencephaly is the most severe form of a neural tube defect resulting from the incomplete occlusion of the anterior neuropore in the fourth week of development and associated with a severely underdeveloped brain mass. As desmal ossification of the neurocranium is induced by the presence of soft tissues (brain), no bone develops as direct consequence of the missing brain. The cranial base, by contrast, is formed by chondral ossification, which is genetically determined, and thus present also in anencephaly. Morphometric characteristics of anencephalic skulls, however, have not yet been investigated in sufficient detail before. In this study we therefore comparatively assessed macroscopic morphological-anatomical and cephalometric CT data on structures and dimensions of 11 macerated anencephalic and 4 normal neonatal skulls highlighting skeletal morphological differences. The most striking results were the missing skullcap and the greatly changed morphology of the existing skull bones, which were reduced in size. The parameters of the skull base, the transverse orbital diameter and maxillary width were significantly smaller in anencephalic skulls. The morphology of the viscerocranium appeared similar to that of normal neonatal skulls. The results of this study can be used in diagnosis and skeletal classification for anencephaly. This can help identify bones that are incomplete, fragmented and taphonomically altered, which is often the case in historical and forensic studies.

Impact of NSAID etoricoxib on side effects of orthodontic tooth movement

OBJECTIVES

The non-steroidal anti-inflammatory drug etoricoxib is the most highly selective inhibitor of cyclooxygenase-2 available (344:1) and has been approved for postoperative pain therapy following dental interventions in Europe. At clinically relevant doses it has been reported to only have marginal effects on the velocity of orthodontic tooth movement (OTM). Its effects on associated dental root resorptions, osteoclastogenesis, trabecular number in the alveolar bone and periodontal bone loss during OTM, however, have not yet been investigated.

MATERIAL AND METHODS

40 male Fischer344 rats were divided into four groups: 1.5ml tap water/day p.o. (control, 1), additional 7.8mg/kg/day etoricoxib (normal dose) for three (2) or seven (3) days/week and 13.1mg/kg/day (high dose) for seven days/week, respectively (4). After a week of premedication, OTM in anterior direction of the first left upper molar was performed for 28 days by means of a nickel-titanium coil spring (0.25N). We quantified OTM-associated dental root resorptions, osteoclastogenesis, trabecular number and periodontal bone loss by histomorphometrical, histochemical and μCT analyses of the disected tooth-bearing upper jaw sections.

RESULTS

After 28 days of OTM, associated reduction of trabecular number seemed to be slightly alleviated by high doses of etoricoxib, whereas no significant other etoricoxib effects in the doses administered could be detected regarding OTM-induced or -associated dental root resorptions, osteoclastogenesis or periodontal bone loss.

CONCLUSIONS

Dental root resorptions, osteoclastogenesis and periodontal bone loss during OTM in rats were not significantly affected by etoricoxib in the clinically relevant dosages investigated with only a slight inhibitory effect on bone remodelling to be expected at high dosages. Etoricoxib is therefore not suitable for the prevention of these detrimental effects, but could be a suitable analgesic during OTM, as it has been reported not to affect tooth movement.

Effects of histamine on human periodontal ligament fibroblasts under simulated orthodontic pressure

As type-I-allergies show an increasing prevalence in the general populace, orthodontic patients may also be affected by histamine release during treatment. Human periodontal ligament fibroblasts (PDLF) are regulators of orthodontic tooth movement. However, the impact of histamine on PDLF in this regard is unknown. Therefore PDLF were incubated without or with an orthodontic compressive force of 2g/cm² with and without additional histamine. To assess the role of histamine-1-receptor (H1R) H1R-antagonist cetirizine was used. Expression of histamine receptors and important mediators of orthodontic tooth movement were investigated. PDLF expressed histamine receptors H1R, H2R and H4R, but not H3R. Histamine increased the expression of H1R, H2R and H4R as well as of interleukin-6, cyclooxygenase-2, and prostaglandin-E2 secretion even without pressure application and induced receptor activator of NF-kB ligand (RANKL) protein expression with unchanged osteoprotegerin secretion. These effects were not observed in presence of H1R antagonist cetirizine. By expressing histamine receptors, PDLF seem to be able to respond to fluctuating histamine levels in the periodontal tissue. Increased histamine concentration was associated with enhanced expression of proinflammatory mediators and RANKL, suggesting an inductive effect of histamine on PDLF-mediated osteoclastogenesis and orthodontic tooth movement. Since cetirizine inhibited these effects, they seem to be mainly mediated via histamine receptor H1R.

Role of Oxygen Supply in Macrophages in a Model of Simulated Orthodontic Tooth Movement

Apart from periodontal ligament fibroblasts, immune cells like macrophages also play an important mediating role in orthodontic tooth movement (OTM). Upon orthodontic force application to malpositioned teeth, macrophages in the periodontal ligament get exposed to both mechanical strain and hypoxic conditions (via a compression of blood vessels). In this study, we assessed the relative impact of orthodontically induced mechanical strain and hypoxic conditions on macrophages for the mediation and regulation of OTM. Macrophages were stimulated with physiological orthodontic compressive forces of 2 g/cm² for 4 h and 24 h on gas-impermeable or gas-permeable cell culture plates under normoxic or hypoxic cell culture conditions. We quantified expression of genes involved in inflammation (Tnf, Il-6, and Cox-2), extracellular remodelling (Mmp-9), and angiogenesis (Vegf) by RT-qPCR. Furthermore, we analysed HIF-1α, prostaglandin-E2, and VEGF protein expression via immunoblotting or ELISA. Mechanical strain and oxygen supply both differentially affected expression of genes and proteins involved in inflammation and angiogenesis. In this context, we found that HIF-1α protein levels were elevated by combined mechanical strain and hypoxic conditions, whereas gas-permeable plates providing sufficient oxygen supply prevented HIF-1α stabilization at the protein level after pressure application on macrophages. Our results thus indicate that macrophages involved in the mediation of OTM are affected by and respond differently to hypoxic conditions and mechanical compressive strain, which occur concomitantly during OTM, than periodontal ligament fibroblasts (PDLF), thus indicating different roles of these cells in the regulation of OTM at the cellular-molecular level. We further observed that contrary to PDLF HIF-1α stabilization in macrophages is rather induced via the decreased oxygen supply associated with OTM than via mechanotransduction by mechanical strain.

Comparative assessment of mouse models for experimental orthodontic tooth movement

Animal experiments are essential for the elucidation of biological-cellular mechanisms in the context of orthodontic tooth movement (OTM). So far, however, no studies comparatively assess available mouse models regarding their suitability. OTM of first upper molars was induced in C57BL/6 mice either via an elastic band or a NiTi coil spring for three, seven or 12 days. We assessed appliance survival rate, OTM and periodontal bone loss (µCT), root resorptions, osteoclastogenesis (TRAP⁺ area) and local expression of OTM-related genes (RT-qPCR). Seven days after the elastic bands were inserted, 87% were still in situ, but only 27% after 12 days. Survival rate for the NiTi coil springs was 100% throughout, but 8.9% of the animals did not survive. Both methods induced significant OTM, which was highest after 12 (NiTi spring) and 7 days (band), with a corresponding increase in local gene expression of OTM-related genes and osteoclastogenesis. Periodontal bone loss and root resorptions were not induced at a relevant extent by neither of the two procedures within the experimental periods. To induce reliable OTM in mice beyond 7 days, a NiTi coil spring is the method of choice. The elastic band method is recommended only for short-term yes/no-questions regarding OTM.

Early OA Stage Like Response Occurs after Dynamic Stretching of Human Synovial Fibroblasts

As events triggering early osteoarthritis onset can be related to mechanical stress and proinflammatory signaling, we investigated the effect of different mechanical strain protocols on the expression of proinflammatory genes, as well as extracellular matrix remodelling in human synovial fibroblasts. Three distinct models of tensile stretching were applied: static isotropic tensile strain at 0 Hz, 16% tension for 48 h; short-term high-frequency cyclic tension at 1 Hz, 10% tension for 4 h; and dynamic tensile stretching for 48 h, consisting of two blocks of moderate stretching at 0.2 Hz, 2%, advanced stretching at 0.5 Hz, 15%, or a combination of both. General signs of inflammation were present after static isotropic tension, whereas short-term high-frequency cyclic tension showed increased levels of IL-6 paired with diminished levels of IL-1β. Reduced inflammatory effects of TNF-α, IL-6, and IL-1β were observed when exposed to advanced stretching. Long-term tensile strain induced extracellular matrix remodelling at the gene and protein levels. While hyaluronan acid synthesis was increased with static tensile strain, dynamic tensile stretching had a reducing effect. Our study revealed that proinflammatory markers were activated by mechanical strain as seen in static isotropic tension and short-term high-frequency tensile strain, whereas long-term exposure induced extracellular matrix remodelling processes.

Effects of Compressive and Tensile Strain on Macrophages during Simulated Orthodontic Tooth Movement

During orthodontic tooth movement (OTM) to therapeutically correct the position of misaligned teeth, thus improving oral health and quality of life, fibroblasts, macrophages, and other immune cells within the periodontal ligament (PDL), which connects a tooth to its surrounding bone, are exposed to compressive and tensile strain. While it is known that PDL fibroblasts are critically involved in the biological regulation of OTM by a mechanotransductively triggered release of cytokines, it is unclear whether macrophages also react to pressure and tension in a similar manner thus impacting on or mediating OTM. RAW264.7 macrophages were seeded onto conventional 6-well cell culture plates for pressure or on Bioflex plates for tension assays and preincubated for 24 h. For in vitro simulation of physiological orthodontic compressive or tensile strain for 2 h, 4 h, 24 h, and 48 h, glass discs (2 g/cm²) were placed or adherent macrophages isotropically stretched for 16%, respectively. We determined cell number, cytotoxicity, and gene/protein expression of Vegf-a/VEGF-A (macrophage-mediated angiogenesis), Mmp-8/9 (extracellular matrix reorganization), and Cox-2/PG-E2, Il-6/IL-6, and Tnf-α/TNF-α (proinflammatory mediators) by RT-qPCR and ELISA. Compressive but not tensile strain resulted in a significant reduction in cell number after only 2 h. Mmp-8 and Mmp-9 expression was significantly enhanced within 24 h of compressive and in part tensile strain. Significantly increased Vegf-a/VEGF-A expression was detected within 4 h of pressure, but not during application of tensile strain. Expression of proinflammatory mediators Cox-2/PG-E2, Il-6/IL-6, and Tnf-α/TNF-α was significantly increased as early as 2-4 h after application of compressive or tensile strain. Our results indicate that macrophages respond early on to compressive and tensile strain occurring during OTM with an enhanced gene expression of proinflammatory cytokines, which could affect PDL fibroblasts, osteoblasts, and immune cells triggering or enhancing the biological mechanisms and osteoclastogenesis underlying OTM.

Housekeeping gene validation for RT-qPCR studies on synovial fibroblasts derived from healthy and osteoarthritic patients with focus on mechanical loading

Selection of appropriate housekeeping genes is essential for the validity of data normalization in reverse transcription quantitative PCR (RT-qPCR). Synovial fibroblasts (SF) play a mediating role in the development and progression of osteoarthritis (OA) pathogenesis, but there is no information on reliable housekeeping genes available. Therefore the goal of this study was to identify a set of reliable housekeeping genes suitable for studies of mechanical loading on SF from healthy and OA patients. Nine genes were evaluated towards expression stability and ranked according their relative stability determined by four different mathematical procedures (geNorm, NormFinder, BestKeeper and comparative ΔC_q). We observed that RPLP0 (ribosomal protein, large, P0) and EEF1A1 (eukaryotic translation elongation factor 1 alpha 1) turned out to be the genes with the most stable expression in SF from non-OA or OA patients treated with or without mechanical loading. According to geNorm two genes are sufficient for normalization throughout. Expression of one tested target gene varied considerably, if normalized to different candidate housekeeping genes. Our study provides a tool for accurate and valid housekeeping gene selection in gene expression experiments on SF from healthy and OA patients with and without mechanical loading in consistent with the MIQE (Minimum Information for Publication of Quantitative Real-Time PCR Experiments) guidelines and additionally demonstrates the impact of proper housekeeping gene selection on the expression of the gene of interest.

Valid gene expression normalization by RT-qPCR in studies on hPDL fibroblasts with focus on orthodontic tooth movement and periodontitis

Meaningful, reliable and valid mRNA expression analyses by real-time quantitative PCR (RT-qPCR) can only be achieved, if suitable reference genes are chosen for normalization and if appropriate RT-qPCR quality standards are met. Human periodontal ligament (hPDL) fibroblasts play a major mediating role in orthodontic tooth movement and periodontitis. Despite corresponding in-vitro gene expression studies being a focus of interest for many years, no information is available for hPDL fibroblasts on suitable reference genes, which are generally used in RT-qPCR experiments to normalize variability between samples. The aim of this study was to identify and validate suitable reference genes for normalization in untreated hPDL fibroblasts as well as experiments on orthodontic tooth movement or periodontitis (Aggregatibacter actinomycetemcomitans). We investigated the suitability of 13 candidate reference genes using four different algorithms (geNorm, NormFinder, comparative ΔC_q and BestKeeper) and ranked them according to their expression stability. Overall PPIB (peptidylprolyl isomerase A), TBP (TATA-box-binding protein) and RPL22 (ribosomal protein 22) were found to be most stably expressed with two genes in conjunction sufficient for reliable normalization. This study provides an accurate tool for quantitative gene expression analysis in hPDL fibroblasts according to the MIQE guidelines and shows that reference gene reliability is treatment-specific.

Control of the NADPH supply for oxidative stress handling in cancer cells

It has not been systematically analyzed whether the NADPH supply is a limiting factor for oxidative stress management in cancer cells. In the present work, it was determined in non-cancer and cancer cells the protein contents and kinetomics of (i) the cytosolic enzymes responsible for the NADPH production (i.e., Glc6PDH, 6PGDH, ME, IDH-1); and (ii) the two main enzymes responsible for NADPH/NADP⁺ and GSH/GSSG recycling (GR, GPx-1) associated to oxidative stress management. With these data, kinetic models were built and further validated. Rat liver and hepatoma AS-30D cytosolic fractions exhibited greater Vmax for IDH-1 than for Glc6PDH and 6PGDH whereas human cancer cells and platelets showed greater Vmax for Glc6PDH than for 6PGDH and IDH-1. The ME activity was comparatively low in all cell types tested. The Km values for the respective specific substrates were all similar among the different cell types. Most activities were lower in AS-30D cells than in liver. In contrast, IDH-1, Glc6PDH and GR activities in human cancer cells were similar or greater to those of platelets, but GPx-1 activity was severely suppressed, despite showing similar GPx-1 protein content vs. platelets. Kinetic analysis and pathway modeling revealed a previously unveiled feedback IDH-1 regulation by GSH. The oxidative stress management in cancer cells (i) was mainly controlled by GPx-1 and the main NADPH provider was Glc6PDH; and (ii) modeling indicated that NADPH supply was not a controlling step. These data suggested that Glc6PDH and GPx-1 are adequate and promising targets for anti-cancer therapeutic intervention.

GPx1 knockdown suppresses chondrogenic differentiation of ATDC5 cells through induction of reductive stress

Glutathione peroxidase 1 (GPx1) is a selenium (Se)-containing protein and is induced in cartilage formation. GPx1 eliminates reactive oxygen species (ROS), which are required for chondrogenic induction. The physiological properties of GPx1 in cartilage and the redox mechanisms involved are not known. The effects of GPx1 on chondrogenic differentiation of ATDC5 cells were examined through short hairpin RNA-mediated gene silencing. The results demonstrated that GPx1 knockdown impaired gene expression of sex determining region Y-box 9, collagen II (Col II), and aggrecan. GPx1 knockdown suppressed the accumulation of cartilage glycosaminoglycans (GAGs) and the proliferation of chondrocyte. GPx1 knockdown also induced cell apoptosis. However, cell sensitivity toward exogenous oxidative stress was not increased after GPx1 knockdown. Unexpectedly, GPx1 knockdown not only induced oxidative stress characterized by the increased production of ROS but also caused reductive stress indicated by an elevation of glutathione (GSH)/oxidized GSH (GSSG) ratio. Furthermore, GPx1 knockdown-mediated reductive and oxidative stress could be antagonized by a thiol-oxidizing agent diamide and a thiol-containing compound N-acetylcysteine (NAC), respectively. Moreover, NAC attenuated GPx1 knockdown-induced cell apoptosis, while diamide prevented GPx1 knockdown-suppressed chondrocyte proliferation. Finally, diamide but not NAC could rescue GPx1 knockdown-mediated impaired chondrogenic differentiation. In summary, GPx1 is essential for chondrogenic induction in ATDC5 cells mainly through modulation of intracellular GSH/GSSG ratio, rather than an antioxidant enzyme to detoxify ROS. In addition, GPx1 knockdown-induced impaired chondrogenesis may participate in the pathogenesis of the endemic osteoarthropathy due to Se deficiency. These observations offer novel insights for the development of therapeutic target during cartilage degeneration.

hucMSC Exosome-Derived GPX1 Is Required for the Recovery of Hepatic Oxidant Injury

Exosomes are small biological membrane vesicles secreted by various cells, including mesenchymal stem cells (MSCs). We previously reported that MSC-derived exosomes (MSC-Ex) can elicit hepatoprotective effects against toxicant-induced injury. However, the success of MSC-Ex-based therapy for treatment of liver diseases and the underlying mechanisms have not been well characterized. We used human umbilical cord MSC-derived exosome (hucMSC-Ex) administrated by tail vein or oral gavage at different doses and, in engrafted liver mouse models, noted antioxidant and anti-apoptotic effects and rescue from liver failure. A single systemic administration of hucMSC-Ex (16 mg/kg) effectively rescued the recipient mice from carbon tetrachloride (CCl₄)-induced liver failure. Moreover, hucMSC-Ex-derived glutathione peroxidase1 (GPX1), which detoxifies CCl₄ and H₂O₂, reduced oxidative stress and apoptosis. Knockdown of GPX1 in hucMSCs abrogated antioxidant and anti-apoptotic abilities of hucMSC-Ex and diminished the hepatoprotective effects of hucMSC-Ex in vitro and in vivo. Thus, hucMSC-Ex promote the recovery of hepatic oxidant injury through the delivery of GPX1.

Treatment with Twin-block appliance followed by fixed appliance therapy in a growing Class II patient

A girl, aged 11 years 4 months, with a skeletal Class II pattern and a severe overjet (10 mm) was treated with a Twin-block appliance. After 9 months of appliance therapy, the skeletal Class II was overcorrected. After 26 months of retention, when the occlusion was stable and the growth rate was diminishing, fixed orthodontic appliances using temporary skeletal anchorage devices were initiated. The total active treatment time with fixed orthodontic appliances was 30 months. Posttreatment records after 18 months demonstrated excellent stability: a functional occlusion and a pleasing facial balance. Cone-beam computed tomography was used to visualize temporomandibular joint adaptations after the functional and fixed orthodontic therapies.

MEMO1 drives cranial endochondral ossification and palatogenesis

The cranial base is a component of the neurocranium and has a central role in the structural integration of the face, brain and vertebral column. Consequently, alteration in the shape of the human cranial base has been intimately linked with primate evolution and defective development is associated with numerous human facial abnormalities. Here we describe a novel recessive mutant mouse strain that presented with a domed head and fully penetrant cleft secondary palate coupled with defects in the formation of the underlying cranial base. Mapping and non-complementation studies revealed a specific mutation in Memo1 - a gene originally associated with cell migration. Expression analysis of Memo1 identified robust expression in the perichondrium and periosteum of the developing cranial base, but only modest expression in the palatal shelves. Fittingly, although the palatal shelves failed to elevate in Memo1 mutants, expression changes were modest within the shelves themselves. In contrast, the cranial base, which forms via endochondral ossification had major reductions in the expression of genes responsible for bone formation, notably matrix metalloproteinases and markers of the osteoblast lineage, mirrored by an increase in markers of cartilage and extracellular matrix development. Concomitant with these changes, mutant cranial bases showed an increased zone of hypertrophic chondrocytes accompanied by a reduction in both vascular invasion and mineralization. Finally, neural crest cell-specific deletion of Memo1 caused a failure of anterior cranial base ossification indicating a cell autonomous role for MEMO1 in the development of these neural crest cell derived structures. However, palate formation was largely normal in these conditional mutants, suggesting a non-autonomous role for MEMO1 in palatal closure. Overall, these findings assign a new function to MEMO1 in driving endochondral ossification in the cranium, and also link abnormal development of the cranial base with more widespread effects on craniofacial shape relevant to human craniofacial dysmorphology.