Multi-level regulation of even-skipped stripes by the ubiquitous factor Zelda.

The zinc-finger protein Zelda (Zld) is a key activator of zygotic transcription in early Drosophila embryos. Here, we study Zld-dependent regulation of the seven-striped pattern of the pair-rule gene even-skipped (eve). Individual stripes are regulated by discrete enhancers that respond to broadly distributed activators; stripe boundaries are formed by localized repressors encoded by the gap genes. The strongest effects of Zld are on stripes 2, 3 and 7, which are regulated by two enhancers in a 3.8 kb genomic fragment that includes the eve basal promoter. We show that Zld facilitates binding of the activator Bicoid and the gap repressors to this fragment, consistent with its proposed role as a pioneer protein. To test whether the effects of Zld are direct, we mutated all canonical Zld sites in the 3.8 kb fragment, which reduced expression but failed to phenocopy the abolishment of stripes caused by removing Zld in trans. We show that Zld also indirectly regulates the eve stripes by establishing specific gap gene expression boundaries, which provides the embryonic spacing required for proper stripe activation.

Delivery and Transcriptome Assessment of an In Vitro Three-Dimensional Proximal Tubule Model Established by Human Kidney 2 Cells in Clinical Gelatin Sponges.

The high prevalence of kidney diseases and the low identification rate of drug nephrotoxicity in preclinical studies reinforce the need for representative yet feasible renal models. Although in vitro cell-based models utilizing renal proximal tubules are widely used for kidney research, many proximal tubule cell (PTC) lines have been indicated to be less sensitive to nephrotoxins, mainly due to altered expression of transporters under a two-dimensional culture (2D) environment. Here, we selected HK-2 cells to establish a simplified three-dimensional (3D) model using gelatin sponges as scaffolds. In addition to cell viability and morphology, we conducted a comprehensive transcriptome comparison and correlation analysis of 2D and 3D cultured HK-2 cells to native human PTCs. Our 3D model displayed stable and long-term growth with a tubule-like morphology and demonstrated a more comparable gene expression profile to native human PTCs compared to the 2D model. Many missing or low expressions of major genes involved in PTC transport and metabolic processes were restored, which is crucial for successful nephrotoxicity prediction. Consequently, we established a cost-effective yet more representative model for in vivo PTC studies and presented a comprehensive transcriptome analysis for the systematic characterization of PTC lines.

MicroRNA-152-3p and MicroRNA-196a-5p Are Downregulated When Müller Cells Are Promoted by Components of the Internal Limiting Membrane: Implications for Macular Hole Healing.

Müller cells play a critical role in the closure of macular holes, and their proliferation and migration are facilitated by the internal limiting membrane (ILM). Despite the importance of this process, the underlying molecular mechanism remains underexplored. This study investigated the effects of ILM components on the microRNA (miRNA) profile of Müller cells. Rat Müller cells (rMC-1) were cultured with a culture insert and varying concentrations of ILM component coatings, namely, collagen IV, laminin, and fibronectin, and cell migration was assessed by measuring cell-free areas in successive photographs following insert removal. MiRNAs were then extracted from these cells and analyzed. Mimics and inhibitors of miRNA candidates were transfected into Müller cells, and a cell migration assay and additional cell viability assays were performed. The results revealed that the ILM components promoted Müller cell migration (p < 0.01). Among the miRNA candidates, miR-194-3p was upregulated, whereas miR-125b-1-3p, miR-132-3p, miR-146b-5p, miR-152-3p, miR-196a-5p, miR-542-5p, miR-871-3p, miR-1839-5p, and miR-3573-3p were significantly downregulated (p < 0.05; fold change > 1.5). Moreover, miR-152-3p and miR-196a-5p reduced cell migration (p < 0.05) and proliferation (p < 0.001), and their suppressive effects were reversed by their respective inhibitors. In conclusion, miRNAs were regulated in ILM component-activated Müller cells, with miR-152-3p and miR-196a-5p regulating Müller cell migration and proliferation. These results serve as a basis for understanding the molecular healing process of macular holes and identifying potential new target genes in future research.

Zelda overcomes the high intrinsic nucleosome barrier at enhancers during Drosophila zygotic genome activation.

The Drosophila genome activator Vielfaltig (Vfl), also known as Zelda (Zld), is thought to prime enhancers for activation by patterning transcription factors (TFs). Such priming is accompanied by increased chromatin accessibility, but the mechanisms by which this occurs are poorly understood. Here, we analyze the effect of Zld on genome-wide nucleosome occupancy and binding of the patterning TF Dorsal (Dl). Our results show that early enhancers are characterized by an intrinsically high nucleosome barrier. Zld tackles this nucleosome barrier through local depletion of nucleosomes with the effect being dependent on the number and position of Zld motifs. Without Zld, Dl binding decreases at enhancers and redistributes to open regions devoid of enhancer activity. We propose that Zld primes enhancers by lowering the high nucleosome barrier just enough to assist TFs in accessing their binding motifs and promoting spatially controlled enhancer activation if the right patterning TFs are present. We envision that genome activators in general will utilize this mechanism to activate the zygotic genome in a robust and precise manner.

Co-activation of microRNAs by Zelda is essential for early Drosophila development.

Transcription factors and microRNAs (miRNAs) are two important classes of trans-regulators in differential gene expression. Transcription factors occupy cis-regulatory motifs in DNA to activate or repress gene transcription, whereas miRNAs specifically pair with seed sites in target mRNAs to trigger mRNA decay or inhibit translation. Dynamic spatiotemporal expression patterns of transcription factors and miRNAs during development point to their stage- and tissue-specific functions. Recent studies have focused on miRNA functions during development; however, much remains to explore regarding how the expression of miRNAs is initiated and how dynamic miRNA expression patterns are achieved by transcriptional regulatory networks at different developmental stages. Here, we focused on the identification, regulation and function of miRNAs during the earliest stage of Drosophila development, when the maternal-to-zygotic transition (MZT) takes place. Eleven miRNA clusters comprise the first set of miRNAs activated in the blastoderm embryo. The transcriptional activator Zelda is required for their proper activation and regulation, and Zelda binding observed in genome-wide binding profiles is predictive of enhancer activity. In addition, other blastoderm transcription factors, comprising both activators and repressors, the activities of which are potentiated and coordinated by Zelda, contribute to the accurate temporal and spatial expression of these miRNAs, which are known to function in diverse developmental processes. Although previous genetic studies showed no early phenotypes upon loss of individual miRNAs, our analysis of the miR-1; miR-9a double mutant revealed defects in gastrulation, demonstrating the importance of co-activation of miRNAs by Zelda during the MZT.

The zinc-finger protein Zelda is a key activator of the early zygotic genome in Drosophila.

In all animals, the initial events of embryogenesis are controlled by maternal gene products that are deposited into the developing oocyte. At some point after fertilization, control of embryogenesis is transferred to the zygotic genome in a process called the maternal-to-zygotic transition. During this time, many maternal RNAs are degraded and transcription of zygotic RNAs ensues. There is a long-standing question as to which factors regulate these events. The recent findings that microRNAs and Smaug mediate maternal transcript degradation have shed new light on this aspect of the problem. However, the transcription factor(s) that activate the zygotic genome remain elusive. The discovery that many of the early transcribed genes in Drosophila share a cis-regulatory heptamer motif, CAGGTAG and related sequences, collectively referred to as TAGteam sites raised the possibility that a dedicated transcription factor could interact with these sites to activate transcription. Here we report that the zinc-finger protein Zelda (Zld; Zinc-finger early Drosophila activator) binds specifically to these sites and is capable of activating transcription in transient transfection assays. Mutant embryos lacking zld are defective in cellular blastoderm formation, and fail to activate many genes essential for cellularization, sex determination and pattern formation. Global expression profiling confirmed that Zld has an important role in the activation of the early zygotic genome and suggests that Zld may also regulate maternal RNA degradation during the maternal-to-zygotic transition.

Temporal coordination of gene networks by Zelda in the early Drosophila embryo.

In past years, much attention has focused on the gene networks that regulate early developmental processes, but less attention has been paid to how multiple networks and processes are temporally coordinated. Recently the discovery of the transcriptional activator Zelda (Zld), which binds to CAGGTAG and related sequences present in the enhancers of many early-activated genes in Drosophila, hinted at a mechanism for how batteries of genes could be simultaneously activated. Here we use genome-wide binding and expression assays to identify Zld target genes in the early embryo with the goal of unraveling the gene circuitry regulated by Zld. We found that Zld binds to genes involved in early developmental processes such as cellularization, sex determination, neurogenesis, and pattern formation. In the absence of Zld, many target genes failed to be activated, while others, particularly the patterning genes, exhibited delayed transcriptional activation, some of which also showed weak and/or sporadic expression. These effects disrupted the normal sequence of patterning-gene interactions and resulted in highly altered spatial expression patterns, demonstrating the significance of a timing mechanism in early development. In addition, we observed prevalent overlap between Zld-bound regions and genomic "hotspot" regions, which are bound by many developmental transcription factors, especially the patterning factors. This, along with the finding that the most over-represented motif in hotspots, CAGGTA, is the Zld binding site, implicates Zld in promoting hotspot formation. We propose that Zld promotes timely and robust transcriptional activation of early-gene networks so that developmental events are coordinated and cell fates are established properly in the cellular blastoderm embryo.

Recurrence Rate of Proximal Contact Loss Between Implant Restorations and Adjacent Teeth After Proximal Contact Repair: A Retrospective Study.

PURPOSE: Proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDPs) and adjacent teeth has been reported as a common complication of implant therapy. The prevalence of PCL and its potential risk factors have been extensively studied. However, few studies have discussed the recurrent PCL after intervention to restore the proximal contacts. Thus, this retrospective study aimed to evaluate the recurrence rate of PCL and its potential risk factors. MATERIALS AND METHODS: This study included 41 patients (with 45 implants in the posterior region), who had experienced PCL between implant restorations and adjacent teeth and had received contact repair. Recurrent PCL was recorded and evaluated during routine follow-ups with an interval of 6 to 12 months. The recurrence rates and time were measured. The potential influential factors of PCL were also assessed. Fisher exact test, t test, univariate logistic regression analyses, and multivariate logistic regression model were utilized to identify factors influencing PCL. RESULTS: The recurrence rates of mesial PCL were high (> 50%) and the recurrence time became progressively rapid after each repair (5, 3.2, and 2.2 years). Implants with the first PCL recurrence were more likely to be splinted than those implants without recurrence (54.5% vs 18.8%; P = .032). In addition, patients with the first recurrence were slightly older than those without recurrence (55.8 vs 50.1 years; P = .087). Age, implant restoration (splinted vs single), frequent use of interdental brushes, and time to first complaint were the candidate factors associated with recurrent PCL in the univariate logistic regression analysis. The multivariate logistic regression model revealed that only splinted implant restoration was independently associated with a higher risk of recurrence (odds ratio 4.99; 95% confidence interval 1.02-24.31; P = .047). CONCLUSION: The recurrence rates of mesial PCL were high and associated with the splinted-type design. Also, the recurrence time of PCL accelerated after each repair. Therefore, routine follow-up monitoring PCL and carefully assessing patient compliance after implant therapy are recommended.

Selenocystine induces oxidative-mediated DNA damage via impairing homologous recombination repair of DNA double-strand breaks in human hepatoma cells.

Selenocystine (SeC) has been identified as a novel compound with broad-spectrum anticancer activity. However, the effects of SeC on modifying DNA repair mechanism were less addressed. In this study, we demonstrated that SeC selectively induced cytotoxicity and genotoxicity against HepG2 hepatoma cell line. Comet assay revealed SeC-induced DNA damage in HepG2 cells, particularly in the form of DNA double strand breaks (DSBs), corroborated by the increase expression of the DSB marker, gamma-H2AX. We further demonstrated that SeC suppressed DNA homologous recombination repair, exacerbating DNA damage accumulation. Such effects on DNA damage and cell viability inhibition were alleviated by antioxidants, glutathione and Trolox, suggesting the involvement of reactive oxygen species (ROS). High levels of intracellular and mitochondrial ROS were detected in SeC-treated HepG2. In addition, SeC impaired the expression of antioxidant enzymes (superoxidase mutases and catalase), prompting the imbalance between antioxidant protection and excessive ROS formation and eliciting DSBs and cellular death. Decreased procaspase-3, 7, and 9 and Bcl-2 proteins and an increased Bax/Bcl-2 ratio, were observed after SeC treatment, but could be reversed by Torlox, confirming the action of SeC on ROS-induced apoptosis. In vivo, the xenograft tumor model of HepG2 cells validated the inhibition of SeC on tumor growth, and the induction of DSBs and apoptosis. In summary, SeC has the capability to induce ROS-dependent DNA damage and impeded DBS repair in HepG2 cells. Thus, SeC holds great promise as a therapeutic or adjuvant agent targeting DNA repair for cancer treatment.

Blockage of Nrf2 and autophagy by L-selenocystine induces selective death in Nrf2-addicted colorectal cancer cells through p62-Keap-1-Nrf2 axis.

Persistent Nrf2 activation is typically noted in many cancers, including colorectal cancer (CRC), aiding cancer cells in overcoming growth stress and promoting cancer progression. Sustained Nrf2 activation, which is beneficial for cancer cells, is called "Nrf2 addiction"; it is closely associated with malignancy and poor prognosis in patients with cancer. However, Nrf2 inhibitors may have adverse effects on normal cells. Here, we found that the selenocompound L-selenocystine (SeC) is selectively cytotoxic in the Nrf2-addicted CRC cell line WiDr cells, but not in non-Nrf2-addicted mesenchymal stem cells (MSCs) and normal human colon cells. Another CRC cell line, C2BBe1, which harbored lower levels of Nrf2 and its downstream proteins were less sensitive to SeC, compared with the WiDr cells. We further demonstrated that SeC inhibited Nrf2 and autophagy activation in the CRC cells. Antioxidant GSH pretreatment partially rescued the CRC cells from SeC-induced cytotoxicity and Nrf2 and autophagy pathway inhibition. By contrast, SeC activated Nrf2 and autophagy pathway in non-Nrf2-addicted MSCs. Transfecting WiDr cells with Nrf2-targeting siRNA decreased persistent Nrf2 activation and alleviated SeC cytotoxicity. In KEAP1-knockdown C2BBe1 cells, Nrf2 pathway activation increased SeC sensitivity and cytotoxicity. In conclusion, SeC selectively attacks cancer cells with constitutively activated Nrf2 by reducing Nrf2 and autophagy pathway protein expression through the P62-Nrf2-antioxidant response element axis and eventually trigger cell death.

Calcitriol and enamel matrix derivative differentially regulated cemento-induction and mineralization in human periodontal ligament-derived cells.

BACKGROUND: Alveolar bone and cementum share many biological and developmental similarities. The mineralizing effect of calcitriol has been previously reported. Yet, its cemento-inductivity has not been confirmed. This study evaluated the potential cemento-inductivity effect of calcitriol and enamel matrix derivative (EMD) on human periodontal ligament-derived cells (hPDLCs). METHODS: The hPDLCs obtained from extracted third molars or premolars were cultured with calcitriol, or EMD. Cementogenic gene expression was examined using real-time quantitative reverse transcription polymerase chain reaction. Expression analysis also included cementoblast-specific markers, cementum protein 1 (CEMP1), cementum attachment protein (CAP), and recently reported cementoblast-enriched genes, secreted frizzled related protein 1 (SFRP1), and Dickkopf-related protein 1 (DKK1). Mineralization capacities were evaluated by alkaline phosphatase (ALP) activity, Alizarin Red, and Von Kossa staining followed by scanning electron microscope imaging and element mapping. RESULTS: Among tested conditions, 10 nM calcitriol enhanced most cementogenic gene expression, transforming growth factor-ß1, bone morphogenetic proteins (BMP-2 and BMP-4), core-binding factor subunit alpha-1/Runt-related transcription factor 2, Type I collagen, ALP, bone sialoprotein, osteopontin), osteocalcin, CEMP1, and CAP, and Wnt signaling negative modulators, SFRP1 and DKK1, along with highest ALP activity and mineralization formation in hPDLCs. However, only moderate CEMP1 protein was observed. In contrast, EMD stimulated stronger CEMP1 and CAP protein, but presented weaker mineralization capacity, hinting at the possibility that strong stimulation of mineralization might dominate cemetogenic specific factors and vice versa. CONCLUSIONS: Calcitriol demonstrated not only great osteoinductivity, but also the potential to induce cementogenic gene expression by initiating hPDLC differentiation and promoting mineralization. Compared with calcitriol, EMD promoted cemento-inductivity in hPDLCs at a later time point via highly expressed CEMP1 and CAP protein, but with less mineralization. Thus, calcitriol and EMD could provide differential enhancement of cemento-induction and mineralization, likely acting at various differentiation stages.

Application of dental stem cells in three-dimensional tissue regeneration.

Dental stem cells can differentiate into different types of cells. Dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, stem cells from apical papilla, and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development. The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering. In recent years, three-dimensional (3D) tissue scaffolds have been used to reconstruct and restore different anatomical defects. With rapid advances in 3D tissue engineering, dental stem cells have been used in the regeneration of 3D engineered tissue. This review presents an overview of different types of dental stem cells used in 3D tissue regeneration, which are currently the most common type of stem cells used to treat human tissue conditions.

Di(2-ethylhexyl)phthalate exposure exacerbates metabolic disorders in diet-induced obese mice.

Both phthalate exposure and obesity are positively associated with metabolic disorders. The study aimed to investigate whether DEHP exposure caused metabolic disorders in an obesity-dependent manner. Both lean and diet-induced obese mice were subjected to environmentally relevant DEHP exposure. DEHP-treated obese mice exhibited higher glucose intolerance and insulin resistance than obese mice; the metabolic disorders were accompanied by increased blood levels of leptin, LDL cholesterol, and alanine transaminase. In obese mice, DEHP enhanced macrophage infiltration into epididymal white adipose tissue (eWAT) and hepatic tissue, and promoted hepatic steatosis/steatohepatitis. The DEHP effects were not observed in lean mice. Transcriptomic changes in eWAT and hepatic tissue were determined with microarray analysis. Results indicated that obesity and DEHP synergistically regulated carbohydrate uptake, lipolysis, and abnormality of adipose tissue, via the upstream regulators Pparg, Lipe, Cd44, and Irs1. Meanwhile, obesity and DEHP differentially modulated transcriptomic changes in hepatic tissue. Obesity was associated with lipid/cholesterol synthesis, lipid accumulation, and inflammation in hepatic tissue via the upstream regulators Zbtb20 and Nr1i2. In obese mice, DEHP exposure caused hepatic injury, cell migration, and changes in glycogen quantity mainly via Cd44. Microarray analysis suggested the potential mechanism underlying the early onset of metabolic disorders in DEHP-treated obese mice.

The prevalence and associated factors of proximal contact loss between implant restoration and adjacent tooth after function: A retrospective study.

BACKGROUND: Dental implant is widely used as a treatment for missing teeth. However, proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDP) and adjacent teeth has been reported as one of the common and adverse complications. PURPOSE: We aimed to evaluate the prevalence of PCL up to 18 years after implant prosthesis delivery and to analyze associated factors. MATERIALS AND METHODS: A total of 317 patients who had received implant FDP at the posterior regions were included in this study. Nineteen factors were assessed, including degrees of proximal contact tightness, oral hygiene, periodontal conditions, and food impaction. Chi-square test, univariate generalized estimating equation (GEE), and multivariate GEE were utilized to identify factors influencing PCL. RESULTS: Proximal contacts at both the mesial and distal (if present) sides were evaluated. The mesial contact loss rate (27%) was significantly higher than that of the distal contact loss (5%). Increased PCL rates over functional time were observed at both the mesial and distal sides. Six factors, including patient age, implant functional years, frequent use of interdental brushes, splinting or single implant, plunger cusp, and food impaction, were revealed to be associated with the mesial PCL using the chi-square test and univariate GEE analysis. However, only functional years (>5 years), frequent use of interdental brushes and food impaction showed significance in the multivariate GEE. CONCLUSIONS: Mesial PCL was frequent and increased over functional years. An occlusal retainer and routine follow-up may help prevent PCL. Although oral hygiene conditions contribute little to PCL, food impaction and frequent use of interdental brushes were influential factors.

4-Aminobiphenyl inhibits the DNA homologous recombination repair in human liver cells: The role of miR-630 in downregulating RAD18 and MCM8.

4-Aminobiphenyl (4-ABP), a well-known human carcinogen, has been shown to cause oxidative DNA damage and induce miR-630 expression in HepG2 cells treated with 18.75 µM-300 µM for 24 h. However, the underlying mechanism regarding the epigenetic regulation of miR-630 on DNA damage repair in liver cells is still not understood and needs to be investigated. In present study, our results showed that miR-630 was upregulated, resulting in mediating a decrease of DNA homologous recombination (HR) repair in L-02, HepG2 or Hep3B cells. Results from a luciferase reporting experiment showed that RAD18 and MCM8 were the potential targets of miR-630 during DNA damage induction. The downregulation of RAD18 or MCM8 by miR-630 was accompanied by inhibition of HR repair. Conversely, inhibiting miR-630 enhanced the expression of RAD18 and MCM8, and rescued HR repair. Additionally, we proved that the transcription factor CREB was related to miR-630 biogenesis in liver cells. Moreover, the levels of CREB, miR-630 expression, and double-strand breaks (DSBs) were attenuated by 5 mM N-acetyl-L-cysteine (NAC) pretreatment, indicating that reactive oxygen species (ROS)-dependent CREB-miR-630 was involved in DSB repair. These findings indicated that the ROS/CREB/-miR-630 axis plays a relevant role in the regulation of RAD18 and MCM8 in HR repair, which may facilitate our understanding of molecular mechanisms regarding the role of miR-630 downregulating DNA damage repair in liver cells.

Phthalate exposure causes browning-like effects on adipocytes in vitro and in vivo.

Mono(2-ethylhexyl)phthalate (MEHP) promotes adipogenesis via PPARγ. PPARγ agonists, e.g., rosiglitazone (RSG), enhance adipocyte browning. However, scientific evidence regarding MEHP as a browning chemical is lacking. This study combined 3T3-L1 adipocytes and C57BL/6J mice to examine the potential roles of MEHP in browning. MEHP and the browning agent RSG caused similar energy metabolism in adipocytes. Both MEHP and RSG caused transcriptional changes involved in browning-associated thermogenesis, energy homeostasis, inflammatory response, and glucose uptake. MEHP-treated adipocytes exhibited brown adipocyte-like characteristics, i.e., increased mitochondrial proton leak, triiodothyronine-induced Bmp8b expression, decreased inflammation, and smaller lipid droplets. Increased PDK4 and PEPCK1 in MEHP/RSG-treated adipocytes could block glucose utilization for mitochondrial respiration. Mitochondrial/peroxisomal biogenesis and fatty acid ß-oxidation in MEHP-treated adipocytes were enhanced. Candidate genes in promoting browning of MEHP-treated adipocytes were highlighted. In di(2-ethylhexyl)phthalate (DEHP)-treated mice, transcriptional changes in white adipose tissue (WAT) were associated with adipocyte differentiation, lipid synthesis, carbohydrate uptake, and WAT/brown adipose tissue (BAT) quantity. PPARγ and NR4A1 were predicted as the top two upstream regulators in orchestrating transcriptional changes. DEHP-treated mice exhibited actively expressed browning marker genes (i.e., Pparg, Adrb1, Adrb3, Ppargc1a, and Ucp1) in WAT, increased blood FGF21 levels, and higher amounts of BAT, supporting the browning-like effects in vivo.

Zelda potentiates morphogen activity by increasing chromatin accessibility.

Zygotic genome activation (ZGA) is a major genome programming event whereby the cells of the embryo begin to adopt specified fates. Experiments in Drosophila and zebrafish have revealed that ZGA depends on transcription factors that provide large-scale control of gene expression by direct and specific binding to gene regulatory sequences. Zelda (Zld) plays such a role in the Drosophila embryo, where it has been shown to control the action of patterning signals; however, the mechanisms underlying this effect remain largely unclear. A recent model proposed that Zld binding sites act as quantitative regulators of the spatiotemporal expression of genes activated by Dorsal (Dl), the morphogen that patterns the dorsoventral axis. Here we tested this model experimentally, using enhancers of brinker (brk) and short gastrulation (sog), both of which are directly activated by Dl, but at different concentration thresholds. In agreement with the model, we show that there is a clear positive correlation between the number of Zld binding sites and the spatial domain of enhancer activity. Likewise, the timing of expression could be advanced or delayed. We present evidence that Zld facilitates binding of Dl to regulatory DNA, and that this is associated with increased chromatin accessibility. Importantly, the change in chromatin accessibility is strongly correlated with the change in Zld binding, but not Dl. We propose that the ability of genome activators to facilitate readout of transcriptional input is key to widespread transcriptional induction during ZGA.

Increase of lipid peroxidation by cisplatin in WI38 cells but not in SV40-transformed WI38 cells.

Cisplatin (CPT) is an effective anticancer drug that causes cumulative toxicity to normal tissues. It has been suggested that CPT damages normal cells by causing oxidative stress, but it is not known whether it can induce similar oxidative damage to tumor cells. In this study, by using normal human lung fibroblast (W138) cells and SV40-transformed WI38 (VA13) cells as a model, we compared the effect of CPT on cytotoxicity, apoptosis, lipid peroxidation, and mitochondrial gene expression, which could be regulated by oxidative stress, between normal and tumor cells. CPT induced greater growth inhibition and percentage of apoptotic cells in VA13 cells. However, levels of esterified F(2)-isoprostanes and 4-hydroxy-2-nonenal, two specific products of lipid peroxidation, were increased by CPT in WI38 cells, but not in VA13 cells. Furthermore, the transcript level of mitochondrial 12S rRNA was augmented by CPT in both cells, but to a higher degree in WI38 cells. The data suggest a correlation between lipid peroxidation and cytotoxicity or increased mitochondrial transcript levels in WI38 cells but not in VA13 cells. The results also indicate an altered response of oxidative damage and mitochondrial gene regulation to CPT in the transformed phenotype of WI38 cells.