Determinants of wearer satisfaction factors for harnesses in upper-limb assistive wearable robots.

Wearable robots are increasingly being deployed for use in industrial fields. However, only a few studies have focused on the usability of wearable robots. The present study evaluated the factors affecting the usability of a harness in securing a wearable robot to the body because the harness directly affects the work efficiency, and thus its design and use require careful consideration. A comparative evaluation of the arrangement of the Vest Exoskeleton before and after improvements was conducted, in which participants performed a benchmark assembly task while wearing the robot. Results showed that wearability decreased after the improvements due to the additional straps and buckles used, but the overall wearing satisfaction improved as a result of increased stability. Stability and convenience were the main factors affecting the overall wearing satisfaction, while sub-indicators included wearing comfort and tactile sensation. Therefore, improvements in stability, such as those related to fixation strength and tactile sensation, had a direct positive impact on the overall wearing satisfaction.

The addition of evolocumab to maximal tolerated statin therapy improves walking performance in patients with peripheral arterial disease and intermittent claudication (Evol-PAD study).

OBJECTIVE: To test the hypothesis that in patients with peripheral arterial disease (PAD) and claudication, treated with maximal tolerated statin therapy, the addition of a monthly subcutaneous injection of evolocumab for 6 months improves treadmill walking performance. BACKGROUND: Lipid lowering therapy improves walking parameters in patients with PAD and claudication. Evolocumab decreases cardiac and limb adverse events in patients with PAD; however, the effect of evolocumab on walking performance is not known. METHODS: We performed a double-blind, randomized, placebo-controlled study to compare maximal walking time (MWT) and pain free walking time (PFWT) in patients with PAD and claudication treated with monthly subcutaneous injections of evolocumab 420 mg (n = 35) or placebo (n = 35). We also performed measurements of lower limb perfusion, brachial flow mediated dilatation (FMD), carotid intima media thickness (IMT), and serum biomarkers of PAD disease severity. RESULTS: After six-months of treatment with evolocumab MWT increased by 37.7 % (87.5 ± 24 s) compared to 1.4 % (-21.7 ± 22.9 s) in the placebo group, p = 0.01. PFWT increased by 55.3 % (67.3 ± 21.2 s) in the evolocumab group compared to 20.3 % (8.5 ± 20.3 s) in the placebo group, p = 0.051. There was no difference in lower extremity arterial perfusion measurements. FMD increased by 42.0 ± 73.9 % (1.01 ± 0.7 %) in the evolocumab group and decreased by 16.29 ± 20.06 % (0.99 ± 0.68 %) in the placebo group (p < 0.001). IMT decreased by 7.16 ± 4.6 % (0.06 ± 0.04 mm) in the evolocumab group and increased by 6.68 ± 4.9 % (0.05 ± 0.03 mm) in the placebo group, (p < 0.001). CONCLUSIONS: The addition of evolocumab to maximal tolerated statin therapy improves maximal walking time in patients with PAD and claudication, increases FMD, and decreases IMT. CONDENSED ABSTRACT: Peripheral arterial disease (PAD) impairs quality of life by causing lower extremity intermittent claudication, rest pain, or amputation. Evolocumab is a monthly injectable monoclonal antibody medication that reduces cholesterol. In this study, we randomly treated patients with PAD and claudication, and on background statin therapy, with evolocumab or placebo, and found that evolocumab improves walking performance on a treadmill test by increasing maximal walking time. We also found that evolocumab decreases plasma MRP-14 levels, a marker of PAD severity.

Mbnl2 loss alters novel context processing and impairs object recognition memory.

Patients with myotonic dystrophy type I (DM1) demonstrate visuospatial dysfunction and impaired performance in tasks requiring recognition or memory of figures and objects. In DM1, CUG expansion RNAs inactivate the muscleblind-like (MBNL) proteins. We show that constitutive Mbnl2 inactivation in Mbnl2ΔE2/ΔE2 mice selectively impairs object recognition memory in the novel object recognition test. When exploring the context of a novel arena in which the objects are later encountered, the Mbnl2ΔE2/ΔE2 dorsal hippocampus responds with a lack of enrichment for learning and memory-related pathways, mounting instead transcriptome alterations predicted to impair growth and neuron viability. In Mbnl2ΔE2/ΔE2 mice, saturation effects may prevent deployment of a functionally relevant transcriptome response during novel context exploration. Post-novel context exploration alterations in genes implicated in tauopathy and dementia are observed in the Mbnl2ΔE2/ΔE2 dorsal hippocampus. Thus, MBNL2 inactivation in patients with DM1 may alter novel context processing in the dorsal hippocampus and impair object recognition memory.

Concomitant genetic defects potentiate the adverse impact of prenatal alcohol exposure on cardiac outflow tract maturation.

BACKGROUND: Prenatal alcohol exposure (PAE) is associated with an increased incidence of congenital heart defects (CHD), in particular outflow tract (OFT) defects. However, the variability in the incidence of CHD following PAE has not been fully explored. We hypothesize that a concomitant, relevant genetic defect would potentiate the adverse effect of PAE and partially explain the variability of PAE-induced CHD incidence. METHODS: The OFT is formed by the second heart field (SHF). Our PAE model consisted of two intraperitoneal injections (3 g/kg, separated by 6 hr) of 30% ethanol on E6.5 during SHF specification. The impact of genetic defects was studied by SHF-specific loss of Delta-like ligand 4 (Dll4), fibroblast growth factor 8 (Fgf8) and Islet1. RESULTS: Acute PAE alone significantly increased CHD incidence (4% vs. 26%, p = .015) with a particular increase in OFT alignment defects, viz., double outlet right ventricle (0 vs. 9%, p = .02). In embryos with a SHF genetic defect, acute PAE significantly increased CHD incidence (14 vs. 63%, p < .001), including double outlet right ventricle (6 vs. 50%, p < .001) compared to controls. PAE (p = .01) and heterozygous loss of Dll4 (p = .04) were found to independently contribute to CHD incidence, while neither Islet1 nor Fgf8 defects were found to be significant. CONCLUSIONS: Our model recapitulates the increased incidence of OFT alignment defects seen in the clinic due to PAE. The presence of a concomitant SHF genetic mutation increases the incidence of PAE-related OFT defects. An apparent synergistic interaction between PAE and the loss of DLL4-mediated Notch signaling in OFT alignment requires further analysis.

Kaempferide Prevents Photoaging of Ultraviolet-B Irradiated NIH-3T3 Cells and Mouse Skin via Regulating the Reactive Oxygen Species-Mediated Signalings.

Kaempferide (KFD) is a naturally occurring flavonoid that exists in various medicinal plants. The pharmaceutical properties of KFD, including its anti-cancer, antioxidant and anti-diabetic effects, have been noted, but the effects of KFD on photoaging and their underlying molecular mechanism have yet to be elucidated. In this study, we investigated the effects of KFD on Ultraviolet-B (UVB)-mediated photoaging processes using in vitro and in vivo photoaging model systems. The topical administration of KFD on mouse dorsal areas suppressed UVB-mediated wrinkle formation and epidermal thickening. In addition, the UVB-mediated reduction of dermal collagen content, which was estimated by Masson's trichrome staining, was recovered through KFD treatments. Furthermore, we found that UVB-induced abnormal values of procollagen type-1 (COL1A1), metalloproteinases (MMP-1a and MMP-3) and proinflammatory cytokines (IL-8, MCP-3 and IL-6) on mouse skin tissue as well as NIH-3T3 cells was recovered through KFD treatment. The administration of KFD to NIH-3T3 cells suppressed the UVB-mediated upregulation of reactive oxygen species (ROS), mitogen-activated protein kinases (MAPKs) and AKT phosphorylation. Furthermore, the treatment of ROS inhibitor restored the UVB-induced MAPKs and AKT phosphorylation as well as the abnormal expression of photoaging related genes. These findings indicate that KFD can attenuate UVB-induced ROS elevation to elicit anti-photoaging activity. Taken together, our data suggest that KFD could be developed as a potential natural anti-photoaging agent.

Mbnl1 and Mbnl2 regulate brain structural integrity in mice.

Myotonic Dystrophy Type I (DM1) patients demonstrate widespread and variable brain structural alterations whose etiology is unclear. We demonstrate that inactivation of the Muscleblind-like proteins, Mbnl1 and Mbnl2, initiates brain structural defects. 2D FSE T2w MRIs on 4-month-old Mbnl1+/-/Mbnl2-/- mice demonstrate whole-brain volume reductions, ventriculomegaly and regional gray and white matter volume reductions. Comparative MRIs on 2-month-old Mbnl1-/-, Mbnl2-/- and Mbnl1-/-/Mbnl2+/- brains show genotype-specific reductions in white and gray matter volumes. In both cohorts, white matter volume reductions predominate, with Mbnl2 loss leading to more widespread alterations than Mbnl1 loss. Hippocampal volumes are susceptible to changes in either Mbnl1 or Mbnl2 levels, where both single gene and dual depletions result in comparable volume losses. In contrast, the cortex, inter/midbrain, cerebellum and hindbrain regions show both gene and dose-specific volume decreases. Our results provide a molecular explanation for phenotype intensification in congenital DM1 and the variability in the brain structural alterations reported in DM1.

Modeling Paracrine Noncanonical Wnt Signaling In Vitro.

Noncanonical Wnt signaling regulates intracellular actin filament organization and polarized migration of progenitor cells during embryogenesis. This process requires complex and coordinated paracrine interactions between signal-sending and signal-receiving cells. Given that these interactions can occur between various types of cells from different lineages, in vivo evaluation of cell-specific defects can be challenging. The present study describes a highly reproducible method to evaluate paracrine noncanonical Wnt signaling in vitro. This protocol was designed with the ability to (1) conduct functional and molecular assessments of noncanonical Wnt signaling between any two cell types of interest; (2) dissect the role of signal-sending versus signal-receiving molecules in the noncanonical Wnt signaling pathway; and (3) perform phenotypic rescue experiments with standard molecular or pharmacologic approaches. This protocol was used to evaluate neural crest cell (NCC)-mediated noncanonical Wnt signaling in myoblasts. The presence of NCCs is associated with an increased number of phalloidin-positive cytoplasmic filopodia and lamellipodia in myoblasts and improved myoblast migration in a wound-healing assay. The Wnt5a-ROR2 axis was identified as a crucial noncanonical Wnt signaling pathway between NCC and second heart field (SHF) cardiomyoblast progenitors. In conclusion, this is a highly tractable protocol to study paracrine noncanonical Wnt signaling mechanisms in vitro.

Murine Model of Cardiac Defects Observed in Adams-Oliver Syndrome Driven by Delta-Like Ligand-4 Haploinsufficiency.

Heterozygous loss-of-function mutation in Delta-like ligand-4 (Dll4) is an important cause of Adams-Oliver syndrome (AOS). Cardiac defects, in particular outflow tract (OFT) alignment defects, are observed in about one-fourth of patients with this syndrome. The mechanism underlying this genotype-phenotype correlation has not yet been established. Dll4-mediated Notch signaling is known to play a crucial role in second heart field (SHF) progenitor cell proliferation. We hypothesized that the depletion of the SHF progenitor pool of cells due to partial loss of Dll4 is responsible for the OFT alignment defects seen in AOS. To demonstrate this, we studied Dll4 expression by murine SHF progenitor cells around E9.5, a crucial time-point in SHF biology. We used SHF-specific (Islet1-Cre) conditional knockout of Dll4 to bypass the early embryonic lethality seen in global Dll4 heterozygotes. Dll4-mediated Notch signaling is critically required for SHF proliferation such that Dll4 knockout results in a 33% reduction in proliferation and a fourfold increase in apoptosis in SHF cells, leading to a 56% decline in the size of the SHF progenitor pool. A reduction in SHF cells available for incorporation into the developing heart leads to underdevelopment of the SHF-derived right ventricle and OFT. Similar to the clinical syndrome, 32% of SHF-specific Dll4 heterozygotes demonstrate foreshortened and misaligned OFT, resulting in a double outlet right ventricle. Our murine model provides a molecular mechanism to explain the cardiac defects observed in AOS and establishes a novel clinical role for Dll4-mediated Notch signaling in SHF progenitor biology.

Delta-like ligand 4-mediated Notch signaling controls proliferation of second heart field progenitor cells by regulating Fgf8 expression.

The role played by the Notch pathway in cardiac progenitor cell biology remains to be elucidated. Delta-like ligand 4 (Dll4), the arterial-specific Notch ligand, is expressed by second heart field (SHF) progenitors at time-points that are crucial in SHF biology. Dll4-mediated Notch signaling is required for maintaining an adequate pool of SHF progenitors, such that Dll4 knockout results in a reduction in proliferation and an increase in apoptosis. A reduced SHF progenitor pool leads to an underdeveloped right ventricle (RV) and outflow tract (OFT). In its most severe form, there is severe RV hypoplasia and poorly developed OFT resulting in early embryonic lethality. In its milder form, the OFT is foreshortened and misaligned, resulting in a double outlet right ventricle. Dll4-mediated Notch signaling maintains Fgf8 expression by transcriptional regulation at the promoter level. Combined heterozygous knockout of Dll4 and Fgf8 demonstrates genetic synergy in OFT alignment. Exogenous supplemental Fgf8 rescues proliferation in Dll4 mutants in ex-vivo culture. Our results establish a novel role for Dll4-mediated Notch signaling in SHF biology. More broadly, our model provides a platform for understanding oligogenic inheritance that results in clinically relevant OFT malformations.

Muscleblind-like 3 deficit results in a spectrum of age-associated pathologies observed in myotonic dystrophy.

Myotonic dystrophy type I (DM1) exhibits distinctive disease specific phenotypes and the accelerated onset of a spectrum of age-associated pathologies. In DM1, dominant effects of expanded CUG repeats result in part from the inactivation of the muscleblind-like (MBNL) proteins. To test the role of MBNL3, we deleted Mbnl3 exon 2 (Mbnl3(ΔE2)) in mice and examined the onset of age-associated diseases over 4 to 13 months of age. Accelerated onset of glucose intolerance with elevated insulin levels, cardiac systole deficits, left ventricle hypertrophy, a predictor of a later onset of heart failure and the development of subcapsular and cortical cataracts is observed in Mbnl3(ΔE2) mice. Retention of embryonic splice isoforms in adult organs, a prominent defect in DM1, is not observed in multiple RNAs including the Insulin Receptor (Insr), Cardiac Troponin T (Tnnt2), Lim Domain Binding 3 (Ldb3) RNAs in Mbnl3(ΔE2) mice. Although rare DM1-like splice errors underlying the observed phenotypes cannot be excluded, our data in conjunction with the reported absence of alternative splice errors in embryonic muscles of a similar Mbnl3(ΔE2) mouse by RNA-seq studies, suggest that mechanisms distinct from the adult retention of embryonic splice patterns may make important contributions to the onset of age-associated pathologies in DM1.

Muscleblind-Like 1 and Muscleblind-Like 3 Depletion Synergistically Enhances Myotonia by Altering Clc-1 RNA Translation.

Loss of Muscleblind-like 1 (Mbnl1) is known to alter Clc-1 splicing to result in myotonia. Mbnl1(ΔE3/ΔE3)/Mbnl3(ΔE2) mice, depleted of Mbnl1 and Mbnl3, demonstrate a profound enhancement of myotonia and an increase in the number of muscle fibers with very low Clc-1 currents, where gClmax values approach ~ 1 mS/cm(2), with the absence of a further enhancement in Clc-1 splice errors, alterations in polyA site selection or Clc-1 localization. Significantly, Mbnl1(ΔE3/ΔE3)/Mbnl3(ΔE2) muscles demonstrate an aberrant accumulation of Clc-1 RNA on monosomes and on the first polysomes. Mbnl1 and Mbnl3 bind Clc-1 RNA and both proteins bind Hsp70 and eEF1A, with these associations being reduced in the presence of RNA. Thus binding of Mbnl1 and Mbnl3 to Clc-1 mRNA engaged with ribosomes can facilitate an increase in the local concentration of Hsp70 and eEF1A to assist Clc-1 translation. Dual depletion of Mbnl1 and Mbnl3 therefore initiates both Clc-1 splice errors and translation defects to synergistically enhance myotonia. As the HSA(LR) model for myotonic dystrophy (DM1) shows similar Clc-1 defects, this study demonstrates that both splice errors and translation defects are required for DM1 pathology to manifest. RESEARCH IN CONTEXT: Research in context: Myotonic Dystrophy type 1 (DM1) is a dominant disorder resulting from the expression of expanded CUG repeat RNA, which aberrantly sequesters and inactivates the muscleblind-like (MBNL) family of proteins. In mice, inactivation of Mbnl1 is known to alter Clc-1 splicing to result in myotonia. We demonstrate that concurrent depletion of Mbnl1 and Mbnl3 results in a synergistic enhancement of myotonia, with an increase in muscle fibers showing low chloride currents. The observed synergism results from the aberrant accumulation of Clc-1 mRNA on monosomes and the first polysomes. This translation error reflects the ability of Mbnl1 and Mbnl3 to act as adaptors that recruit Hsp70 and eEF1A to the Clc-1 mRNA engaged with ribosomes, to facilitate translation. Thus our study demonstrates that Clc-1 RNA translation defects work coordinately with Clc-1 splice errors to synergistically enhance myotonia in mice lacking Mbnl1 and Mbnl3.

Molecular marker characterization and source appointment of particulate matter and its organic aerosols.

This study was carried out to identify possible sources and to estimate their contribution to total suspended particle (TSP) organic aerosol (OA) contents. A total of 120 TSP and PM2.5 samples were collected simultaneously every third day over a one-year period in urban area of Incheon, Korea. High concentration in particulate matters (PM) and its components (NO3(-), water soluble organic compounds (WSOCs), and n-alkanoic acids) were observed during the winter season. Among the organics, n-alkanes, n-alkanoic acids, levoglucosan, and phthalates were major components. Positive matrix factorization (PMF) analysis identified seven sources of organic aerosols including combustion 1 (low molecular weight (LMW)-polycyclic aromatic hydrocarbons (PAHs)), combustion 2 (high molecular weight (HMW)-PAHs), biomass burning, vegetative detritus (n-alkane), secondary organic aerosol 1 (SOA1), secondary organic aerosol 2 (SOA2), and motor vehicles. Vegetative detritus increased during the summer season through an increase in biogenic/photochemical activity, while most of the organic sources were prominent in the winter season due to the increases in air pollutant emissions and atmospheric stability. The correlation factors were high among the main components of the organic carbon (OC) in the TSP and PM2.5. The results showed that TSP OAs had very similar characteristics to the PM2.5 OAs. SOA, combustion (PAHs), and motor vehicle were found to be important sources of carbonaceous PM in this region. Our results imply that molecular markers (MMs)-PMF model can provide useful information on the source and characteristics of PM.

Loss of muscleblind-like 1 results in cardiac pathology and persistence of embryonic splice isoforms.

Cardiac dysfunction is a prominent cause of mortality in myotonic dystrophy I (DM1), a disease where expanded CUG repeats bind and disable the muscleblind-like family of splice regulators. Deletion of muscleblind-like 1 (Mbnl1(ΔE2/ΔE2)) in 129 sv mice results in QRS, QTc widening, bundle block and STc narrowing at 2-4 months of age. With time, cardiac function deteriorates further and at 6 months, decreased R wave amplitudes, sinus node dysfunction, cardiac hypertrophy, interstitial fibrosis, multi-focal myocardial fiber death and calcification manifest. Sudden death, where no end point illness is overt, is observed at a median age of 6.5 and 4.8 months in ~67% and ~86% of male and female Mbnl1(ΔE2/ΔE2) mice, respectively. Mbnl1 depletion results in the persistence of embryonic splice isoforms in a network of cardiac RNAs, some of which have been previously implicated in DM1, regulating sodium and calcium currents, Scn5a, Junctin, Junctate, Atp2a1, Atp11a, Cacna1s, Ryr2, intra and inter cellular transport, Clta, Stx2, Tjp1, cell survival, Capn3, Sirt2, Csda, sarcomere and cytoskeleton organization and function, Trim55, Mapt, Pdlim3, Pdlim5, Sorbs1, Sorbs2, Fhod1, Spag9 and structural components of the sarcomere, Myom1, Tnnt2, Zasp. Thus this study supports a key role for Mbnl1 loss in the initiation of DM1 cardiac disease.

Linker Histone H1.2 cooperates with Cul4A and PAF1 to drive H4K31 ubiquitylation-mediated transactivation.

Increasing evidence suggests that linker histone H1 can influence distinct cellular processes by acting as a gene-specific regulator. However, the mechanistic basis underlying such H1 specificity and whether H1 acts in concert with other chromatin-altering activities remain unclear. Here, we show that one of the H1 subtypes, H1.2, stably interacts with Cul4A E3 ubiquitin ligase and PAF1 elongation complexes and that such interaction potentiates target gene transcription via induction of H4K31 ubiquitylation, H3K4me3, and H3K79me2. H1.2, Cul4A, and PAF1 are functionally cooperative because their individual knockdown results in the loss of the corresponding histone marks and the deficiency of target gene transcription. H1.2 interacts with the serine 2-phosphorylated form of RNAPII, and we argue that it recruits the Cul4A and PAF1 complexes to target genes by bridging the interaction between the Cul4A and PAF1 complexes. These data define an expanded role for H1 in regulating gene transcription and illustrate its dependence on the elongation competence of RNAPII.

Gene dysregulation by histone variant H2A.Z in bladder cancer.

BACKGROUND: The incorporation of histone variants into nucleosomes is one of the main strategies that the cell uses to regulate the structure and function of chromatin. Histone H2A.Z is an evolutionarily conserved histone H2A variant that is preferentially localized within nucleosomes at the transcriptional start site (TSS). H2A.Z reorganizes the local chromatin structure and recruits the transcriptional machinery for gene activation. High expression of H2A.Z has been reported in several types of cancers and is causally linked to genomic instability and tumorigenesis. However, it is not entirely clear how H2A.Z overexpression in cancer cells establishes aberrant chromatin states and promotes gene expression. RESULTS: Through integration of genome-wide H2A.Z ChIP-seq data with microarray data, we demonstrate that H2A.Z is enriched around the TSS of cell cycle regulatory genes in bladder cancer cells, and this enrichment is correlated with the elevated expression of cancer-promoting genes. RNAi-mediated knockdown of H2A.Z in the cancer cells causes transcriptional suppression of multiple cell cycle regulatory genes with a distinct decrease in cell proliferation. H2A.Z nucleosomes around the TSS have higher levels of H3K4me2/me3, which coincides with the recruitment of two chromatin factors, WDR5 and BPTF. The observed recruitment is functional, as the active states of H2A.Z target genes are largely erased by suppressing the expression of WDR5 or BPTF, effects resembling H2A.Z knockdown. CONCLUSIONS: We conclude that H2A.Z is overexpressed in bladder cancer cells and contributes to cancer-related transcription pathways. We also provide evidence in support of the engagement of H3K4me2/me3 and WDR5/BPTF in H2A.Z-induced cancer pathogenesis. Further studies are warranted to understand how H2A.Z overexpression contributes to the recruitment of the full repertoire of transcription machinery to target genes in bladder cancer cells.

VprBP has intrinsic kinase activity targeting histone H2A and represses gene transcription.

Histone modifications play important roles in the regulation of gene expression and chromatin organization. VprBP has been implicated in transcriptionally silent chromatin formation and cell-cycle regulation, but the molecular basis underlying such effects remains unclear. Here we report that VprBP possesses an intrinsic protein kinase activity and is capable of phosphorylating histone H2A on threonine 120 (H2AT120p) in a nucleosomal context. VprBP is localized to a large set of tumor suppressor genes and blocks their transcription, in a manner that is dependent on its kinase activity toward H2AT120. The functional significance of VprBP-mediated H2AT120p is further underscored by the fact that RNAi knockdown and small-molecule inhibition of VprBP reactivate growth regulatory genes and impede tumor growth. Our findings establish VprBP as a major kinase responsible for H2AT120p in cancer cells and suggest that VprBP inhibition could be a new strategy for the development of anticancer therapeutics.

Source apportionment of PM2.5 at the coastal area in Korea.

In this study, we analyzed the chemical composition of fine particulate matter 2.5 µm or less (PM) collected at Incheon, the coastal area in Seoul, Korea every third day from June 2009 to May 2010. Based on the analyzed chemical species in the PM samples, the sources of PM were identified using a positive matrix factorization (PMF). Nine sources of PM were determined from PMF analysis. The major sources of PM were secondary nitrate (25.4%), secondary sulfate (19.0%), motor vehicle 1 (14.8%) with a lesser contribution from industry (8.5%), motor vehicle 2 (8.2%), biomass burning (6.1%), soil (6.1%), combustion and copper production emissions (6.1%), and sea salt (5.9%). From a paired t-test, it was found that yellow sand samples were characterized as having higher contribution from soil sources (p<0.05). Furthermore, the likely source areas of PM emissions were determined using the conditional probability function (CPF) and the potential source contribution function (PSCF). CPF analysis identified the likely local sources of PM as motor vehicles and sea salt. PSCF analysis indicated that the likely source areas for secondary particles (sulfate and nitrate) were the major industrial areas in China. Finally, using the source contribution of PM and associated organic composition data, principal component analysis (PCA) was conducted to evaluate the accuracy of the PM source apportionments by PMF. The PCA analysis confirmed eight of the nine PM sources. Our result implies that the chemical composition analysis of PM data and various modeling techniques can effectively identify the potential contributing sources.

p53 requires an intact C-terminal domain for DNA binding and transactivation.

The tumor suppressor p53 plays a critical role in mediating cellular response to a wide range of environmental stresses. p53 regulates these processes mainly by acting as a short-lived DNA binding protein that stimulates transcription from numerous genes involved in cell cycle arrest, programmed cell death, and other processes. To investigate the importance of the C-terminal domain of p53, we generated a series of deletion and point mutations in this region and analyzed their effects on p53 transcription activity. Our results show that C-terminal deletion and point mutations at K320 and K382 abolish p53-mediated transcription in the context of DNA or chromatin. This defect is specific for DNA molecules because inactive mutants fail to bind a consensus p53 response element in both free DNA and nucleosomes. Chromatin immunoprecipitation assays further substantiate the importance of the p53 C-terminal domain for the targeted localization of p53 and the concomitant recruitment of p300 onto p53-responsive genes. Moreover, a synthetic peptide comprising the last 30 amino acids of p53 interacts with the N-terminal and C-terminal domains of p53 and antagonizes p53-dependent transcription. Taken together, our data reveal a functional requirement for the p53 C-terminal domain in p53 transactivation and support a working model in which the C-terminus serves as a positive regulator for N-terminal activation and central DNA binding domains.

Vpr-binding protein antagonizes p53-mediated transcription via direct interaction with H3 tail.

HIV-1 Vpr-binding protein (VprBP) has been implicated in the regulation of both DNA replication and cell cycle progression, but its precise role remains unclear. Here we report that VprBP regulates the p53-induced transcription and apoptotic pathway. VprBP is recruited to p53-responsive promoters and suppresses p53 transactivation in the absence of stress stimuli. To maintain target promoters in an inactive state, VprBP stably binds to nucleosomes by recognizing unacetylated H3 tails. Promoter-localized deacetylation of H3 tails is a prerequisite for VprBP to tether and act as a bona fide inhibitor at p53 target genes. VprBP knockdown leads to activation of p53 target genes and causes an increase in DNA damage-induced apoptosis. Moreover, phosphorylation of VprBP at serine 895 impairs the ability of VprBP to bind H3 tails and to repress p53 transactivation. Our results thus reveal a new role for VprBP in regulation of the p53 signaling pathway, as well as molecular mechanisms of cancer development related to VprBP misregulation.