Regulatory elements can be essential for maintaining broad chromatin organization and cell viability.

Increasing evidence shows that promoters and enhancers could be related to 3D chromatin structure, thus affecting cellular functions. Except for their roles in forming canonical chromatin loops, promoters and enhancers have not been well studied regarding the maintenance of broad chromatin organization. Here, we focused on the active promoters/enhancers predicted to form many 3D contacts with other active promoters/enhancers (referred to as hotspots) and identified dozens of loci essential for cell growth and survival through CRISPR screening. We found that the deletion of an essential hotspot could lead to changes in broad chromatin organization and the expression of distal genes. We showed that the essentiality of hotspots does not result from their association with individual genes that are essential for cell viability but rather from their association with multiple dysregulated non-essential genes to synergistically impact cell fitness.

Correlation between Graphitic Carbon and Elemental Carbon in Diesel Particulate Matter in Workplace Atmospheres.

We investigated the suitability of the graphitic carbon (GC) content of diesel particulate matter (DPM), measured using Raman spectroscopy, as a surrogate measure of elemental carbon (EC) determined by thermal optical analysis. The Raman spectra in the range of 800-1800 cm-1 (including the D mode at ∼1322 cm-1 and the G mode at ∼1595 cm-1) were used for GC identification and quantification. Comparison of the Raman spectra for two certified DPM standards (NIST SRM 1650 and SRM 2975), two types of diesel engine exhaust soot, and three types of DPM-enriched workplace aerosols show that the uncertainty of GC quantification based on the D peak height, G peak height, and the total peak area below D and G peaks was about 6.0, 6.7, and 6.9%, respectively. The low uncertainty for different aerosol types suggested possible use of GC as a surrogate measure of EC in workplace atmospheres. A calibration curve was constructed using two laboratory-aerosolized DPM standards to describe the relationship between GC measured by a portable Raman spectrometer and the EC concentration determined by NIOSH Method 5040. The calibration curve was then applied to determine GC-based estimates of the EC contents of diesel engine exhaust samples from two vehicles and seven air samples collected at a hydraulic fracturing worksite. The GC-EC estimates obtained through Raman measurements agreed well with those found by NIOSH Method 5040 for the same samples at EC filter loadings below 2.86 µg/cm2. The study shows that using an appropriate sample collection method that avoids high filter mass loadings, onsite measurement of GC by a portable or hand-held Raman spectrometer can provide a useful indicator of EC in workplace aerosol.

Associations of hematological and biochemical markers with intracranial atherosclerotic stenosis in stroke-free populations: A systematic review and meta-analysis of observational studies.

BACKGROUND AND AIMS: Intracranial atherosclerotic stenosis (ICAS) is an important cause of ischemic stroke and transient ischemic attack. We aimed to synthesize relevant evidence on the associations of hematological and biochemical markers with ICAS in stroke-free populations. METHODS AND RESULTS: We searched MEDLINE and EMBASE for articles reporting associations of hematological and biochemical markers with ICAS presence in stroke-free populations. Weighted mean difference (WMD) and 95% confidence interval (CI) for each biomarker were pooled using fixed- or random-effects models. Among 32 studies included in the systematic review, 23 studies (48,326 subjects) with 22 biomarkers were meta-analyzed. Compared with subjects without ICAS, those with ICAS had significantly higher white blood cell (4118 subjects, WMD 0.28 per 109/L, 95% CI 0.01-0.56), neutrophil (4326 subjects, WMD 0.24 per 109/L, 0.10-0.38), neutrophil/lymphocyte ratio (4326 subjects, WMD 0.16, 0.07-0.26), low-density lipoprotein (28,606 subjects, WMD 0.12 mmol/L, 0.05-0.19), non-high-density lipoprotein (3671 subjects, WMD 0.17 mmol/L, 0.08-0.25), C-reactive protein (CRP; 5355 subjects, WMD 0.06 mg/dL, 0.04-0.07), high-sensitivity CRP (9383 subjects, WMD 0.07 mg/dL, 0.01-0.13), uric acid (5966 subjects, WMD 17.91 µmol/L, 11.16-24.66), creatinine (5731 subjects, WMD 4.03 µmol/L, 0.77-7.29), and homocysteine (7053 subjects, WMD 2.25 µmol/L, 1.02-3.48), but lower lymphocyte (4326 subjects, WMD -0.12 per 109/L, -0.19--0.04). Sensitivity analyses showed similar results. CONCLUSIONS: Several hematological and biochemical markers easily accessible were associated with ICAS presence in stroke-free populations. This can facilitate early identification of subjects at a high risk of ICAS, who may benefit from ICAS screening and prevention. PROSPERO REGISTRATION NUMBER: CRD42021247990.

lncRNA Helf promotes hepatic inflammation and fibrosis by interacting with PTBP1 to facilitate PIK3R5 mRNA stabilization.

BACKGROUND: Hepatic fibrosis is a common consequence of chronic liver diseases without approved antifibrotic therapies. Long noncoding RNAs (lncRNAs) play an important role in various pathophysiological processes. However, the functions of certain lncRNAs involved in mediating the antifibrotic role remain largely unclear. METHODS: The RNA level of lnc-High Expressed in Liver Fibrosis (Helf) was detected in both mouse and human fibrotic livers. Furthermore, lnc-Helf-silenced mice were treated with carbon tetrachloride (CCl4) or bile duct ligation (BDL) to investigate the function of lnc-Helf in liver fibrosis. RESULTS: We found that lnc-Helf has significantly higher expression in human and mouse fibrotic livers as well as M1 polarized hepatic macrophages (HMs) and activated hepatic stellate cells (HSCs). In vivo studies showed that silencing lnc-Helf by AAV8 vector alleviates CCl4- and BDL-induced hepatic inflammation and fibrosis. Furthermore, in vitro experiments revealed that lnc-Helf promotes HSCs activation and proliferation, as well as HMs M1 polarization and proliferation in the absence or presence of cytokine stimulation. Mechanistically, our data illustrated that lnc-Helf interacts with RNA binding protein PTBP1 to promote its interaction with PIK3R5 mRNA, resulting in increased stability and activating the AKT pathway, thus promoting HSCs and HMs activation and proliferation, which augments hepatic inflammation and fibrosis. CONCLUSION: Our results unveil a lnc-Helf/PTBP1/PIK3R5/AKT feedforward, amplifying signaling that exacerbates the process of hepatic inflammation and fibrosis, thus providing a possible therapeutic strategy for hepatic fibrosis.

NAP1-Related Protein 1 (NRP1) has multiple interaction modes for chaperoning histones H2A-H2B.

Nucleosome Assembly Protein 1 (NAP1) family proteins are evolutionarily conserved histone chaperones that play important roles in diverse biological processes. In this study, we determined the crystal structure of Arabidopsis NAP1-Related Protein 1 (NRP1) complexed with H2A-H2B and uncovered a previously unknown interaction mechanism in histone chaperoning. Both in vitro binding and in vivo plant rescue assays proved that interaction mediated by the N-terminal α-helix (αN) domain is essential for NRP1 function. In addition, the C-terminal acidic domain (CTAD) of NRP1 binds to H2A-H2B through a conserved mode similar to other histone chaperones. We further extended previous knowledge of the NAP1-conserved earmuff domain by mapping the amino acids of NRP1 involved in association with H2A-H2B. Finally, we showed that H2A-H2B interactions mediated by αN, earmuff, and CTAD domains are all required for the effective chaperone activity of NRP1. Collectively, our results reveal multiple interaction modes of a NAP1 family histone chaperone and shed light on how histone chaperones shield H2A-H2B from nonspecific interaction with DNA.

Bibliometric analysis of post-traumatic growth after childbirth.

AIM: To make a bibliometric analysis on post-traumatic growth (PTG) after childbirth. METHODS: The topic advanced search strategy extracted the information from the Web of Science Core Collection. Descriptive statistics were performed using Excel, and bibliometric analysis was performed using VOSviewer. RESULTS: A total of 362 publications were published in 199 journals were obtained in the WoSCC from 1999 to 2022. Postpartum post-traumatic growth is in a trend of fluctuating growth, and the United States (N = 156) and Bar-Ilan University (N = 22) were the top contributing countries and institutions, respectively. Research hotspots mainly focus on theoretical models of PTG, postpartum post-traumatic stress disorder (PTSD) as a predictor of PTG, facilitators of PTG, and the relationship between mother-infant attachment and PTG. CONCLUSION: This bibliometric study provides a comprehensive overview of the current state of research on PTG after childbirth, an area that has received considerable scholarly attention in recent years. However, research on post-traumatic growth after childbirth is lacking, and further research is needed.

LncRNA Airn maintains LSEC differentiation to alleviate liver fibrosis via the KLF2-eNOS-sGC pathway.

BACKGROUND: Long noncoding RNAs (lncRNAs) have emerged as important regulators in a variety of human diseases. The dysregulation of liver sinusoidal endothelial cell (LSEC) phenotype is a critical early event in the fibrotic process. However, the biological function of lncRNAs in LSEC still remains unclear. METHODS: The expression level of lncRNA Airn was evaluated in both human fibrotic livers and serums, as well as mouse fibrotic livers. Gain- and loss-of-function experiments were performed to detect the effect of Airn on LSEC differentiation and hepatic stellate cell (HSC) activation in liver fibrosis. Furthermore, RIP, RNA pull-down-immunoblotting, and ChIP experiments were performed to explore the underlying mechanisms of Airn. RESULTS: We have identified Airn was significantly upregulated in liver tissues and LSEC of carbon tetrachloride (CCl4)-induced liver fibrosis mouse model. Moreover, the expression of AIRN in fibrotic human liver tissues and serums was remarkably increased compared with healthy controls. In vivo studies showed that Airn deficiency aggravated CCl4- and bile duct ligation (BDL)-induced liver fibrosis, while Airn over-expression by AAV8 alleviated CCl4-induced liver fibrosis. Furthermore, we revealed that Airn maintained LSEC differentiation in vivo and in vitro. Additionally, Airn inhibited HSC activation indirectly by regulating LSEC differentiation and promoted hepatocyte (HC) proliferation by increasing paracrine secretion of Wnt2a and HGF from LSEC. Mechanistically, Airn interacted with EZH2 to maintain LSEC differentiation through KLF2-eNOS-sGC pathway, thereby maintaining HSC quiescence and promoting HC proliferation. CONCLUSIONS: Our work identified that Airn is beneficial to liver fibrosis by maintaining LSEC differentiation and might be a serum biomarker for liver fibrogenesis.

HOP1 and HOP2 are involved in salt tolerance by facilitating the brassinosteroid-related nucleo-cytoplasmic partitioning of the HSP90-BIN2 complex.

The co-chaperone heat shock protein (HSP)70-HSP90 organizing protein (HOP) is involved in plant thermotolerance. However, its function in plant salinity tolerance was not yet studied. We found that Arabidopsis HOP1 and HOP2 play critical roles in salt tolerance by affecting the nucleo-cytoplasmic partitioning of HSP90 and brassinosteroid-insensitive 2 (BIN2). A hop1/2 double mutant was hypersensitive to salt-stress. Interestingly, this sensitivity was remedied by exogenous brassinolide application, while the application of brassinazole impeded growth of both wild-type (WT) and hop1/2 plants under normal and salt stress conditions. This suggested that the insufficient brassinosteroid (BR) content was responsible for the salt-sensitivity of hop1/2. After WT was transferred to salt stress conditions, HOP1/2, BIN2 and HSP90 accumulated in the nucleus, brassinazole-resistant 1 (BZR1) was phosphorylated and accumulated in the cytoplasm, and BR content significantly increased. This initial response resulted in dephosphorylation of BZR1 and BR response. This dynamic regulation of BR content was impeded in salt-stressed hop1/2. Thus, we propose that HOP1 and HOP2 are involved in salt tolerance by affecting BR signalling.

Small vessel disease burden may not portend unfavorable outcome after thrombectomy for acute large vessel occlusion.

OBJECTIVES: We aimed to investigate the correlation between an overall cerebral small vessel disease (CSVD) burden and outcomes after endovascular treatment (EVT) for patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). METHODS: In a multicenter registry study, we enrolled patients with EVT for anterior-circulation LVO-stroke. In 3.0-T MR imaging, we assessed 4 CSVD imaging markers, lacunes, white matter hyperintensities, cerebral microbleeds, and enlarged perivascular spaces, each assigned a score of 0 or 1 and summed up to an overall CSVD burden score of 0-4. We dichotomized the overall CSVD severity as none to mild (score 0-2) and moderate to severe (3-4). Primary outcome was 90-day functional dependence or death (modified Rankin Scale (mRS) 3-6). Secondary outcomes included increase in NIH Stroke Scale ≥ 4 within 24 h (early neurological deterioration (END)) and within 7 days, symptomatic intracranial hemorrhage, 90-day mRS 2-6, and 90-day mortality. RESULTS: Among 311 patients (63.0% male; mean age 65.1 ± 12.7 years), 260 (83.6%) had none-to-mild and 51 (16.4%) had moderate-to-severe overall CSVD burden. Moderate-to-severe CSVD burden was not significantly associated with the primary outcome (47.1% versus 45.4%; p > 0.05 in univariate and multivariate logistic regression), or the secondary outcomes except for a higher risk of END (11.8% versus 3.1%; p < 0.05 in multivariate analyses). Sensitivity analyses with 0-1 versus 2-4 of the CSVD burden score, and the score as an ordinal variable, showed similar results. CONCLUSIONS: An overall moderate-to-severe CSVD burden was not associated with 90-day functional dependence or death, after EVT for anterior-circulation LVO. TRIAL REGISTRATION: ChiCTR1900022154 KEY POINTS: • Moderate-to-severe cerebral small vessel disease burden on MRI should not be an exclusion indicator in determining the eligibility of an acute ischemic stroke patient for endovascular treatment.

Two Structurally Similar Co5 Cluster-Based Metal-Organic Frameworks Containing Open Metal Sites for Efficient C2H2/CO2 Separation.

To reasonably design and synthesize metal-organic frameworks (MOFs) with high stability and excellent adsorption/separation performance, the pore configuration and functional sites are very important. Here, we report two structurally similar cluster-based MOFs using a pyridine-modified low-symmetry ligand [H4L = 2,6-bis(2',5'-dicarboxyphenyl)pyridine], [(NH2Me2)2][Co5(L)2(OCH3)2(µ3-OH)2·2DMF]·2DMF·2H2O (1) and [Co5(L)2(µ3-OH)2(H2O)2]·2H2O·4DMF (2). The structures of 1 and 2 are built from Co5 clusters, which have one-dimensional open channels, but their microporous environments are different due to the different ways in which ligands bind to the metals. Both MOFs have extremely high chemical stabilities over a wide pH range (2-12). The two MOFs have similar adsorption capacities of C2H2 (144.0 cm3 g-1 for 1 and 141.3 cm3 g-1 for 2), but 1 has a higher C2H2/CO2 selectivity of 3.5 under ambient conditions. The difference in gas adsorption and separation between the two MOFs has been compared by a breakthrough experiment and theoretical calculation, and the influence of the microporous environment on the gas adsorption and separation performance of MOFs has been further studied.

LncRNA-Airn alleviates acute liver injury by inhibiting hepatocyte apoptosis via the NF-κB signaling pathway.

Acute liver injury is a common and serious syndrome caused by multiple factors and unclear pathogenesis. If the injury persists, liver injury can lead to cirrhosis and liver failure and ultimately results in the development of liver cancer. Emerging evidence has indicated that long noncoding RNAs (lncRNAs) play an important role in the development of liver injury. However, the role of antisense Igf2r RNA (Airn) in acute liver injury and its underlying mechanism remain largely unclear. In this study, we show that Airn is upregulated in liver tissue and primary hepatocytes from an acute liver injury mouse model. Consistently, Airn is also overexpressed in serum samples of patients with acute-on-chronic liver failure and is negatively correlated with the Model for End-Stage Liver Disease (MELD) score. Moreover, gene knockout and rescue assays reveal that Airn alleviates CCl 4-induced liver injury by inhibiting hepatocyte apoptosis and oxidative stress in vivo. Further investigation reveals that Airn decreases H 2O 2-induced hepatocyte apoptosis in vitro. Mechanistically, we reveal that Airn represses CCl 4- and H 2O 2-induced enhancement of phosphorylation of p65 and IκBα, suggesting that Airn inhibits hepatocyte apoptosis by inactivating the NF-κB pathway. In conclusion, our results demonstrate that Airn can alleviate acute liver injury by inhibiting hepatocyte apoptosis via inactivating the NF-κB signaling pathway, and Airn could be a potential biomarker for acute liver injury.

Influencing Factors of Horizontal Movement Distance of Bodies in High Falling Deaths.

OBJECTIVES: To explore the influencing factors of the horizontal distance of bodies in the high falling scene and the feasibility of inferring the falling mode based on it. METHODS: A total of 614 high falling deaths and 15 cases of corpse dumping from high altitudes were collected. The relationship between the horizontal distance and the falling height, as well as the sex, age and manner of death (suicide, accident and corpse dumping) were observed. RESULTS: The horizontal distance increased with the increase of falling height, and the difference among the height groups was statistically significant. The horizontal distance decreased with the increase of the age of the deceased, in each height group, the difference between the group over 60 years old and other age groups was statistically significant (P<0.05). The horizontal distance of male deceased was (1.99±0.27) m, which was greater than that of female deceased (1.88±0.19) m, and the difference was statistically significant in partial height groups (P<0.05). Roof falls had a greater horizontal movement distance than window falls. Except for the >20-30 m group, there was no significant difference in horizontal distance between suicide high falls and accidental high falls in other height groups. CONCLUSIONS: The horizontal distance is affected by the falling height, the sex and age of the victim, and the spatial characteristics of the falling starting point.

Hesperidin alleviates bupivacaine anesthesia-induced neurotoxicity in SH-SY5Y cells by regulating apoptosis and oxidative damage.

Local anesthetic with bupivacaine (BV) administration may cause severe neurotoxicity and neurological complications in developing neurons. Any substances that can mitigate the toxic effects of BV are of great importance in surgical procedures and pain management. The present study attempted to investigate if hesperidin (HN) could inhibit or prevent BV-induced neurotoxicity in SH-SY5Y cells. Exposure of BV at 5 mM resulted in a significant decrease of cell viability and a remarkable increase of lactate dehydrogenase release via the induction of apoptosis and production of reactive oxygen species. Moreover, a loss of mitochondrial membrane potential, decreased Bcl-2 protein expression, as well as increased expression of cytoplasmic cytochrome c, Bax, and cleaved caspase-3 protein was also observed in BV-stimulated SH-SY5Y cells. In addition, BV stimulation impaired the balance of oxidation-reduction and inflammation system, as evidenced by the increased malondialdehyde content, decreased superoxide dismutase and catalase activity, and reduced level of reduced glutathione, interleukin-6 (IL-6), IL-1ß, and tumor necrosis factor-α. However, these iatrogenic changes were all reversed by the HN (5, 10, and 20 µM) supplement for 48 h in a concentration-dependent manner. In conclusion, HN can protect SH-SY5Y cells against BV-stimulated neurotoxicity via the inhibition of apoptosis, oxidative stress, and inflammation response. The present findings suggested that HN may be an effective alternative agent to inhibit or prevent BV-induced neurotoxicity in human patients.

Relationship between small dense low-density lipoprotein cholesterol with carotid plaque in Chinese individuals with abnormal carotid artery intima-media thickness.

AIM: To investigate the relationship of small dense low-density lipoprotein cholesterol (sdLDL-C) to carotid artery intima-media thickness (CA-IMT) and carotid plaque (CAP) in Chinese general population, and to evaluate whether sdLDL-C could be an independent risk factor for individuals with subclinical atherosclerosis. METHODS: A total of 729 subjects were randomly collected from consecutive individuals from April 2019 to April 2020 for an annual health checkup. CA-IMT > 1.0 mm was defined as abnormal IMT. Plaque stability was measured by ultrasound examination based on the property of the echo. And sdLDL-C levels were detected by LipoPrint system. Multivariate logistic regression analysis was performed to identify factors associated with CA-IMT and carotid plaque. RESULTS: The abnormal IMT group had significantly higher sdLDL-C levels than control group (p < 0.0001). And sdLDL-C levels were significantly positively correlated with IMT value (r = 0.1396, p = 0.0021) and presence of carotid plaque (r = 0.14, p = 0.002) in the subjects with abnormal IMT. In addition, subjects with higher levels of sdLDL-C (r = 0.11, p = 0.035) tended to have unstable CAP. After adjustment for age, gender and blood glucose, sdLDL-C level was an independent risk factor of the presence of CAP (OR = 1.59, 95% CI: 1.02-1.83, p = 0.034) in subjects with abnormal IMT. CONCLUSION: SdLDL-C is an independent risk factor of the occurrence of CAP in the Chinese subjects with abnormal IMT. Our findings provide supporting evidence that sdLDL-C might be an alternative way to predict CVD in early stage.

Identification of DNA motifs that regulate DNA methylation.

DNA methylation is an important epigenetic mark but how its locus-specificity is decided in relation to DNA sequence is not fully understood. Here, we have analyzed 34 diverse whole-genome bisulfite sequencing datasets in human and identified 313 motifs, including 92 and 221 associated with methylation (methylation motifs, MMs) and unmethylation (unmethylation motifs, UMs), respectively. The functionality of these motifs is supported by multiple lines of evidence. First, the methylation levels at the MM and UM motifs are respectively higher and lower than the genomic background. Second, these motifs are enriched at the binding sites of methylation modifying enzymes including DNMT3A and TET1, indicating their possible roles of recruiting these enzymes. Third, these motifs significantly overlap with "somatic QTLs" (quantitative trait loci) of methylation and expression. Fourth, disruption of these motifs by mutation is associated with significantly altered methylation level of the CpGs in the neighbor regions. Furthermore, these motifs together with somatic mutations are predictive of cancer subtypes and patient survival. We revealed some of these motifs were also associated with histone modifications, suggesting a possible interplay between the two types of epigenetic modifications. We also found some motifs form feed forward loops to contribute to DNA methylation dynamics.

Ribonuclease activity of MARF1 controls oocyte RNA homeostasis and genome integrity in mice.

Producing normal eggs for fertilization and species propagation requires completion of meiosis and protection of the genome from the ravages of retrotransposons. Mutation of Marf1 (meiosis regulator and mRNA stability factor 1) results in defects in both these key processes in mouse oocytes and thus in infertility. MARF1 was predicted to have ribonuclease activity, but the structural basis for the function of MARF1 and the contribution of its putative ribonuclease domain to the mutant oocyte phenotype was unknown. Therefore, we resolved the crystal structures of key domains of MARF1 and demonstrated by biochemical and mutagenic analyses that the ribonuclease activity of MARF1 controls oocyte meiotic progression and retrotransposon surveillance. The N-terminal NYN domain of MARF1 resembles the nuclease domains of Vpa0982, T4 RNase H, and MCPIP1 and contains four conserved aspartate residues, D178, D215, D246, and D272. The C-terminal LOTUS domain of MARF1 adopts a winged helix-turn-helix fold and binds ssRNA and dsRNA. Purified MARF1 cleaved ssRNAs in vitro, but this cleavage activity was abolished by mutations of conserved aspartates in its NYN domain and truncation of the LOTUS domain. Furthermore, a point mutation in the D272 residue in vivo caused a female-only infertile phenotype in mice, with failure of meiotic resumption and elevation of Line1 and Iap retrotransposon transcripts and DNA double-strand breaks in oocytes. Therefore, the ribonuclease activity of MARF1 controls oocyte meiosis and genome integrity. This activity depends upon conserved aspartic residues in the catalytic NYN domain and the RNA-binding activity of the LOTUS domain.

LncRNA Meg8 suppresses activation of hepatic stellate cells and epithelial-mesenchymal transition of hepatocytes via the Notch pathway.

Long non-coding RNAs (lncRNAs) play an important role in various physiological and pathological processes. However, the biological role of lncRNA Meg8 in liver fibrosis is largely unknown. In this study, we found that Meg8 was over-expressed in activated hepatic stellate cells (HSCs), injured hepatocytes (HCs) and fibrotic livers. Furthermore, we revealed that Meg8 suppressed the expression of the pro-fibrogenic and proliferation genes in activated HSCs. In addition, silencing Meg8 significantly inhibited the expression of the epithelial markers, while noticeably promoted the expression of the mesenchymal markers in primary HCs and AML12 cells. Mechanistically, we demonstrated that Meg8 suppressed HSCs activation and epithelial-mesenchymal transition (EMT) of HCs through inhibiting the Notch pathway. In conclusion, our findings indicate that Meg8 may serve as a novel protective molecule and a potential therapeutic target of liver fibrosis.

The Histone Chaperone NRP1 Interacts with WEREWOLF to Activate GLABRA2 in Arabidopsis Root Hair Development.

NUCLEOSOME ASSEMBLY PROTEIN1 (NAP1) defines an evolutionarily conserved family of histone chaperones and loss of function of the Arabidopsis thaliana NAP1 family genes NAP1-RELATED PROTEIN1 (NRP1) and NRP2 causes abnormal root hair formation. Yet, the underlying molecular mechanisms remain unclear. Here, we show that NRP1 interacts with the transcription factor WEREWOLF (WER) in vitro and in vivo and enriches at the GLABRA2 (GL2) promoter in a WER-dependent manner. Crystallographic analysis indicates that NRP1 forms a dimer via its N-terminal α-helix. Mutants of NRP1 that either disrupt the α-helix dimerization or remove the C-terminal acidic tail, impair its binding to histones and WER and concomitantly lead to failure to activate GL2 transcription and to rescue the nrp1-1 nrp2-1 mutant phenotype. Our results further demonstrate that WER-dependent enrichment of NRP1 at the GL2 promoter is involved in local histone eviction and nucleosome loss in vivo. Biochemical competition assays imply that the association between NRP1 and histones may counteract the inhibitory effect of histones on the WER-DNA interaction. Collectively, our study provides important insight into the molecular mechanisms by which histone chaperones are recruited to target chromatin via interaction with a gene-specific transcription factor to moderate chromatin structure for proper root hair development.

Unique 5'-P recognition and basis for dG:dGTP misincorporation of ASFV DNA polymerase X.

African swine fever virus (ASFV) can cause highly lethal disease in pigs and is becoming a global threat. ASFV DNA Polymerase X (AsfvPolX) is the most distinctive DNA polymerase identified to date; it lacks two DNA-binding domains (the thumb domain and 8-KD domain) conserved in the homologous proteins. AsfvPolX catalyzes the gap-filling reaction during the DNA repair process of the ASFV virus genome; it is highly error prone and plays an important role during the strategic mutagenesis of the viral genome. The structural basis underlying the natural substrate binding and the most frequent dG:dGTP misincorporation of AsfvPolX remain poorly understood. Here, we report eight AsfvPolX complex structures; our structures demonstrate that AsfvPolX has one unique 5'-phosphate (5'-P) binding pocket, which can favor the productive catalytic complex assembly and enhance the dGTP misincorporation efficiency. In combination with mutagenesis and in vitro catalytic assays, our study also reveals the functional roles of the platform His115-Arg127 and the hydrophobic residues Val120 and Leu123 in dG:dGTP misincorporation and can provide information for rational drug design to help combat ASFV in the future.

Structural Tuning and Pore Modulation of Three Cu(II)-Organic Frameworks: Enhancement of Stability and Functionality.

Through use of an irregular pentacarboxylate ligand, 2,2'-(pyridine-2,6-diyl)diterephthalic acid (H4L), two Cu(II)-based metal-organic frameworks, {[(Me2NH2)0.5][Cu0.75(L)0.5(DMA)0.375]·H2O}n (1) and {[Cu4(L)2(H2O)4]·4DMF·8H2O}n (2), have been synthesized. A structural analysis demonstrates that 1 is a 2D layer and 2 shows a 3D framework, which exhibit hopeful possibilities for the selective separations of C2H2/CH4 and CO2/CH4. To enhance the adsorption properties, 5-amino-1H-tetrazole (HAT) has been introduced in the synthesis system, and a new framework, {[Cu4(L)2(ATZ)2(H2O)]·5DMF·5H2O}n (3), has been obtained. 3 is a 3D framework. Especially, 3 is constructed from multiple SBUs and displays an unusual (3,4,6)-connected topology. Furthermore, especially 3 performs better than 1 and 2 in terms of uptake capacity as well as adsorption selectivity, which might be ascribed to the more proper pore space of 3.