The effect of curcumin on the cadmium-induced mitochondrial apoptosis pathway by metallothionein 2A regulation.

Cadmium (Cd) is one of the most toxic heavy metals used in various industries, including metal plating, batteries and plastics and environmental pollutant. Cd in the environment is a detrimental factor that cannot be biodegraded and accumulates in human organs. The skin is the first target organ after Cd topical exposure. Curcumin is a natural dietary polyphenolic compound with many beneficial effects, including antioxidant, anti-inflammatory and anticancer activities. However, the effect of curcumin against Cd-induced toxicity in human keratinocytes has not been reported. In this study, we investigated the effects of curcumin against Cd-induced apoptosis in keratinocytes and the underlying molecular mechanisms. Cd resulted in apoptosis as shown by Annexin V/7-AAD double staining. Cd promoted the cleavage of poly (ADP ribose) polymerase-1 (PARP-1) and caspase 3 and suppressed Bcl-2. In addition, Cd induced the release of cytochrome c and Smac from the mitochondria into the cytosol, which is an intrinsic apoptosis-specific process. Curcumin inhibited the early and late apoptosis caused by Cd. The changes in apoptotic markers induced by Cd were significantly reversed by curcumin. Next, we evaluated the effect of curcumin on metallothionein (MT), a cysteine-rich protein that plays a key role in metal detoxification. Curcumin increased the level of MT2A mRNA and the expression of MT2. Interestingly, the antiapoptotic effects of curcumin were reversed under the knockdown of MT2A, suggesting that MT2A is a critical target of curcumin. These findings indicate the potential of curcumin as a novel compound for protection against Cd-mediated skin damage by MT2A modulation.

Accelerating Detection of Variants During COVID-19 Surges by Diverse Technological and Public Health Partnerships: A Case Study From Indonesia.

Early detection of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) variants and use of data for public health action requires a coordinated, rapid, and high throughput approach to whole genome sequencing (WGS). Currently, WGS output from many low- and middle-income countries (LMIC) has lagged. By fostering diverse partnerships and multiple sequencing technologies, Indonesia accelerated SARS-CoV-2 WGS uploads to GISAID from 1,210 in April 2021 to 5,791 in August 2021, an increase from 11 submissions per day between January to May, to 43 per day between June to August. Turn-around-time from specimen collection to submission decreased from 77 to 5 days, allowing for timely public health decisions. These changes were enabled by establishment of the National Genomic Surveillance Consortium, coordination between public and private sector laboratories with WGS capability, and diversification of sequencing platform technologies. Here we present how diversification on multiple levels enabled a rapid and significant increase of national WGS performance, with potentially valuable lessons for other LMICs.

Amentoflavone-induced oxidative stress activates NF-E2-related factor 2 via the p38 MAP kinase-AKT pathway in human keratinocytes.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that responds to oxidative stress and xenobiotics. Multiple lines of evidence suggest that Nrf2 activation protects against aging, inflammation, and many diseases, including cancer. Nrf2 activators derived from natural sources have been widely studied. In this study, we investigated the effect of amentoflavone (AFN), a biflavonoid found in many plants, on Nrf2 signaling in human keratinocytes (HaCaT cells). AFN significantly increased ARE luciferase activity by Nrf2 accumulation in the nucleus. Subsequently, the levels of a Nrf2 target protein, NQO-1, were significantly increased by AFN in a dose- and time-dependent manner. To verify the mechanism of AFN-induced activation of Nrf2 signaling, we measured generation of reactive oxygen species (ROS). Interestingly AFN triggered mild ROS production. Additionally, AFN-induced Nrf2 activation was inhibited by N-acetyl cysteine. Therefore, we studied the effect of ROS-related signaling on Nrf2 by measuring the activation of AKT and members of the mitogen-activated protein kinase family, such as extracellular signal-regulated kinase (ERK1/2) and p38. The results showed that the pharmacological inhibitor of PI3K/AKT (LY294002) or p38 (SB 203580), but not ERK1/2 (U0126), abrogated AFN-induced Nrf2 activation. Subsequently, we found that silencing or inhibition of p38 resulted in decrease of AKT phosphorylation as well as inhibition of Nrf2 accumulation. Furthermore, we found that AFN stabilized Nrf2 by inhibiting its ubiquitination. Taken together, our results suggest that AFN contributes to Nrf2 activation through ROS-mediated activation of the p38-AKT pathway in HaCaT cells.

E-p-Methoxycinnamoyl-α-l-rhamnopyranosyl Ester, a Phenylpropanoid Isolated from Scrophularia buergeriana, Increases Nuclear Factor Erythroid-Derived 2-Related Factor 2 Stability by Inhibiting Ubiquitination in Human Keratinocytes.

The nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a key regulator of gene expression during oxidative stress and drug detoxification. Thus, identifying Nrf2 activators to protect from possible cell damage is necessary. In this study, we investigated whether E-p-methoxycinnamoyl-α-l-rhamnopyranosyl ester (MCR), a phenylpropanoid isolated from Scrophularia buergeriana, can activate Nrf2 signaling in human keratinocytes (HaCaT). First, we determined the dose- and time-dependent effects of MCR on the expression and activity of Nrf2. The antioxidant response element-luciferase reporter assay and western blot analysis results showed that MCR markedly induced Nrf2 activity and its protein expression, respectively. Further, MCR increased both the mRNA and protein levels of heme-oxygenase-1, one of the Nrf2 target genes, in the cells. Interestingly, we found that Nrf2 stability was remarkably enhanced by MCR. Furthermore, ubiquitin-dependent proteasomal degradation of Nrf2 was significantly reduced by MCR. Thus, MCR might afford skin protection by enhancing Nrf2 stability or by blocking its proteasomal degradation.

Nuclear Receptor PPARα Agonist Wy-14,643 Ameliorates Hepatic Cell Death in Hepatic IKKß-Deficient Mice.

Inhibitor of nuclear factor kappa-B kinase beta (IKKß) plays a critical role in cell proliferation and inflammation in various cells by activating NF-κB signaling. However, the interrelationship between peroxisome proliferator-activated receptor α (PPARα) and IKKß in cell proliferation is not clear. In this study, we investigated the possible role of PPARα in the hepatic cell death in the absence of IKKß gene using liver-specific Ikkb-null (IkkbF/F-AlbCre) mice. To examine the function of PPARα activation in hepatic cell death, wild-type (IkkbF/F) and IkkbF/F-AlbCre mice were treated with PPARα agonist Wy-14,643 (0.1% w/w chow diet) for two weeks. As a result of Wy-14,643 treatment, apoptotic markers including caspase-3 cleavage, poly (ADP-ribose) polymerase (PARP) cleavage and TUNEL-positive staining were significantly decreased in the IkkbF/F-AlbCre mice. Surprisingly, Wy-14,643 increased the phosphorylation of p65 and STAT3 in both Ikkb and IkkbF/F-AlbCre mice. Furthermore, BrdU-positive cells were significantly increased in both groups after treatment with Wy-14,643. Our results suggested that IKKß-derived hepatic apoptosis could be altered by PPARα activation in conjunction with activation of NF-κB and STAT3 signaling.

PPARα activation drives demethylation of the CpG islands of the Gadd45b promoter in the mouse liver.

Growth arrest and DNA damage-inducible beta (GADD45b) plays a pivotal role in many intracellular events in both cell survival- and cell death-related signaling. To date, the study of GADD35b has mainly focused on investigation of its function, as well as interacting molecules. However, studies of Gadd45b gene regulation are limited. In this study, we investigated the transcriptional regulation mechanism of Gadd45b. Since Gadd45b mRNA is highly induced by the PPARα agonist Wy-14,643 in the mouse liver, we analyzed the Gadd45b promoter using an in vivo reporter assay. Interestingly, the naked Gadd45b-luciferase construct strongly induced luciferase activity without any stimulant in our in vivo system. Therefore, we investigated the epigenetic changes in the Gadd45b promoter region using mouse liver genomic DNA, the methylation-specific restriction enzyme (HpaII), and disulfide conversion. Our results showed that two possible CpG methylation sites were methylated and demethylated by Wy-14,643 treatment. This study indicates that epigenetic change at the Gadd45b promoter is critical for Gadd45b induction.