Tuning the Interface Stability of Nickel-Rich NCM Cathode Against Aggressive Structural Collapse via the Synergistic Effect of Additives.

Nickel-rich layered oxides are envisaged as one of the most promising alternative cathode materials for lithium-ion batteries, considering their capabilities to achieve ultrahigh energy density at an affordable cost. Nonetheless, with increasing Ni content in the cathodes comes a severe extent of Ni4+ redox side reactions on the interface, leading to fast capacity decay and structural stability fading over extended cycles. Herein, dual additives of bis(vinylsulfonyl)methane (BVM) and lithium difluorophosphate (LiDFP) are adopted to synergistically generate the F-, P-, and S-rich passivation layer on the cathode, and the Ni4+ activity and dissolution at high voltage are restricted. The sulfur-rich layer formed by the polymerization of BVM, combined with the Li3PO4 and LiF phases derived from LiDFP, alleviates the problems of increased impedance, cracks, and an irreversible H2-H3 phase transition. Consequently, the Ni-rich LiNixM1-xO2 (x > 0.95) button half-cell cycled in LiDFP + BVM electrolyte exhibits a significant discharging capacity of 181.4 mAh g-1 at 1 C (1 C = 200 mA g-1) with retention of 83.7% after 100 cycles, surpassing the performance of the commercial electrolyte (160.7 mAh g-1) with retention of 53.3%. Remarkably, the NCM95||graphite pouch cell exhibits a remarkable capacity retention of 95.5% after 200 cycles. This work inspires the rational design of electrolyte additives for ultrahigh-energy batteries with nickel-rich layered oxide cathodes.

A comprehensive meta-analysis of risk factors associated with osteosarcopenic obesity: a closer look at gender, lifestyle and comorbidities.

This study reviewed the risk factors of Osteosarcopenic obesity (OSO), a condition linking weak bones, muscle loss, and obesity. Notable associations were found with female gender, physical inactivity, hypertension, and frailty. Recognizing these early can aid targeted prevention, emphasizing further research for improved understanding and strategies. PURPOSE: Osteosarcopenic obesity (OSO) represents a confluence of osteopenia/osteoporosis, sarcopenia, and obesity, contributing to increased morbidity and mortality risks. Despite escalating prevalence, its risk factors remain under-explored, necessitating this comprehensive systematic review and meta-analysis. METHODS: A diligent search of PubMed, Scopus, and Cochrane databases was conducted for pertinent studies until June 2023. The random-effects model was employed to compute pooled odds ratios (ORs) and 95% confidence intervals (CIs), scrutinizing various risk factors like age, gender, lifestyle factors, and common comorbidities. RESULTS: Our meta-analysis incorporated 21 studies comprising 178,546 participants. We identified significant associations between OSO and factors such as female gender (OR 1.756, 95% CI 1.081 to 2.858), physical inactivity (OR 1.562, 95% CI 1.127-2.165), and hypertension (OR 1.482, 95% CI 1.207-1.821). Conversely, smoking (OR 0.854, 95% CI 0.672-1.084), alcohol consumption (OR 0.703, 95% CI 0.372-1.328), and dyslipidemia (OR 1.345, 95% CI 0.982-1.841) showed no significant associations. Remarkable heterogeneity was observed across studies, indicating considerable variation in effect sizes. Notably, OSO was strongly associated with frailty (OR 6.091; 95% CI 3.576-10.375). CONCLUSIONS: Our study underscored the substantial role of female gender, physical inactivity, and hypertension in the development of OSO, whilst suggesting a strong link between OSO and frailty. These findings emphasize the importance of early risk factor identification and targeted interventions in these groups. Further research is warranted to decode the complex pathophysiological interplay and devise effective prevention and management strategies.

Emission enhanced fluorometric biosensor by functionalized carbon polymer dots for glutathione detection in human real samples and molecular logic gate operation.

Glutathione (GSH), an active peptide, plays pivotal roles in many physiological processes and detection of GSH inside of human body is of great importance for the playing of its biological effects. Here silver-phosphorus co-doped carbonized polymer dots (Ag@PCPDs) were prepared via solvothermal treatment of citric acid and phytic acid in the presence of Ag+ for GSH determination. The physicochemical and optical performance of the Ag@PCPDs were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR), X-ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), fluorescence spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy analyses. The prepared Ag@PCPDs have outstanding water solubility with high monodispersity (7.81 ± 0.31 nm) and exhibited excellent optical properties with excitation-dependent emission, high photostability, pH, and ionic strength tolerance. An optimized excitation at 358 nm, the Ag@PCPDs showed strong photoluminescent (PL) emission at 456 nm with a PL quantum yield (QYs) of 15.6%. Furthermore, the Ag@PCPDs were used as a PL sensing platform for detection GSH in a linear range of 0-200 µM with a low limit of detection at 0.68 µM. In addition, the proposed system can construct molecular logic gates with GSH and Fe3+ ions as the chemical inputs and PL emissions as the output. And the Ag@PCPDs were successfully used for GSH determination in real samples resulting in high sensitivity and satisfactory recoveries (92.81--107.45%). More importantly, the Ag@PCPDs showed low cytotoxicity at 500 µg/mL and superior cell imaging capability in HeLa cells, which offer a new path for detection and categorization of GSH in biomedical applications.

Sarcopenic obesity by the ESPEN/EASO criteria for predicting mortality in advanced non-small cell lung cancer.

BACKGROUND: The European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO) recently released the first international consensus on the diagnostic criteria for sarcopenic obesity (SO), which recommended skeletal muscle mass adjusted for body weight (SMM/W) to determine low muscle mass. SMM adjusted for body mass index (SMM/BMI) appeared to be better associated with physical performance than SMM/W. Thus, we modified the ESPEN/EASO criteria by using SMM/BMI. We aimed (1) to evaluate the agreement of the ESPEN/EASO-defined SO (SOESPEN) and the modified ESPEN/EASO-defined SO (SOESPEN-M) with other commonly used SO definitions, and (2) to compare different SO definitions for predicting mortality in a prospective cohort with advanced non-small cell lung cancer (NSCLC). METHODS: This prospective study included patients with advanced NSCLC. We defined SO according to five different diagnostic criteria: SOESPEN, SOESPEN-M, Asian Working Group for Sarcopenia (AWGS)-determined sarcopenia with BMI-determined obesity (SOAWGS), computed tomography-derived sarcopenia with BMI-determined obesity (SOCT), and fat mass to fat-free mass ratio >0.8 (SOFM). The outcome was all-cause mortality. RESULTS: Of the 639 participants (mean age 58.6 years, 229 women) we studied, 488 (76.4%) died during the median follow-up period of 25 months. SMM/BMI was significantly lower in the death group than in the survivor group (men: p = 0.001, women: p < 0.001), but SMM/W was not. Only 3 (0.47%) participants met all five SO diagnostic criteria. SOESPEN showed an excellent agreement with SOESPEN-M (Cohen's kappa = 0.896), a moderate agreement with SOAWGS (Cohen's kappa = 0.415), but poor agreements with SOCT and SOFM (Cohen's kappa = 0.078 and 0.092, respectively). After full adjustment for potential confounders, SOESPEN (HR 1.54, 95% CI 1.26-1.89), SOESPEN-M (HR 1.56, 95% CI 1.26-1.92), and SOAWGS (HR 1.43, 95% CI 1.14-1.78) were significantly associated with mortality. However, SOCT (HR 1.17, 95% CI 0.87-1.58) and SOFM (HR 1.15, 95% CI 0.90-1.46) showed no significant association with mortality. CONCLUSIONS: SOESPEN showed an excellent agreement with SOESPEN-M, a moderate agreement with SOAWGS, but poor agreements with SOCT and SOFM. SOESPEN, SOESPEN-M, and SOAWGS were independent prognostic factors for mortality in our study population, but SOCT and SOFM were not. Although SMM/BMI was better associated with survival than SMM/W, SOESPEN-M did not show an advantage in predicting survival over SOESPEN.

Kae1 of Saccharomyces cerevisiae KEOPS complex possesses ADP/GDP nucleotidase activity.

The KEOPS complex is an evolutionarily conserved protein complex in all three domains of life (Bacteria, Archaea, and Eukarya). In budding yeast Saccharomyces cerevisiae, the KEOPS complex (ScKEOPS) consists of five subunits, which are Kae1, Bud32, Cgi121, Pcc1, and Gon7. The KEOPS complex is an ATPase and is required for tRNA N6-threonylcarbamoyladenosine modification, telomere length maintenance, and efficient DNA repair. Here, recombinant ScKEOPS full complex and Kae1-Pcc1-Gon7 and Bud32-Cgi121 subcomplexes were purified and their biochemical activities were examined. KEOPS was observed to have ATPase and GTPase activities, which are predominantly attributed to the Bud32 subunit, as catalytically dead Bud32, but not catalytically dead Kae1, largely eliminated the ATPase/GTPase activity of KEOPS. In addition, KEOPS could hydrolyze ADP to adenosine or GDP to guanosine, and produce PPi, indicating that KEOPS is an ADP/GDP nucleotidase. Further mutagenesis characterization of Bud32 and Kae1 subunits revealed that Kae1, but not Bud32, is responsible for the ADP/GDP nucleotidase activity. In addition, the Kae1V309D mutant exhibited decreased ADP/GDP nucleotidase activity in vitro and shortened telomeres in vivo, but showed only a limited defect in t6A modification, suggesting that the ADP/GDP nucleotidase activity of KEOPS contributes to telomere length regulation.

Swc4 positively regulates telomere length independently of its roles in NuA4 and SWR1 complexes.

Telomeres at the ends of eukaryotic chromosomes are essential for genome integrality and stability. In order to identify genes that sustain telomere maintenance independently of telomerase recruitment, we have exploited the phenotype of over-long telomeres in the cells that express Cdc13-Est2 fusion protein, and examined 195 strains, in which individual non-essential gene deletion causes telomere shortening. We have identified 24 genes whose deletion results in dramatic failure of Cdc13-Est2 function, including those encoding components of telomerase, Yku, KEOPS and NMD complexes, as well as quite a few whose functions are not obvious in telomerase activity regulation. We have characterized Swc4, a shared subunit of histone acetyltransferase NuA4 and chromatin remodeling SWR1 (SWR1-C) complexes, in telomere length regulation. Deletion of SWC4, but not other non-essential subunits of either NuA4 or SWR1-C, causes significant telomere shortening. Consistently, simultaneous disassembly of NuA4 and SWR1-C does not affect telomere length. Interestingly, inactivation of Swc4 in telomerase null cells accelerates both telomere shortening and senescence rates. Swc4 associates with telomeric DNA in vivo, suggesting a direct role of Swc4 at telomeres. Taken together, our work reveals a distinct role of Swc4 in telomere length regulation, separable from its canonical roles in both NuA4 and SWR1-C.

Opportunistic Infection in Hospitalised Patients with Inflammatory Bowel Disease.

OBJECTIVE: To investigate the incidence, clinical features, and risk factors of opportunistic infections in elderly patients with inflammatory bowel disease (IBD). STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Department of Digestive and Geriatrics Center, Sichuan University West China Hospital, China between January 2012 and January 2019. METHODOLOGY: Patients (≥18 years) with IBD were enrolled in this study. Clinical data from the infected elderly group (age ≥60 years), non-infected elderly group (age ≥60 years) and infected adult group (age: 18-59 years) were compared. Logistic regression analysis was used for risk factors associated with opportunistic infection. RESULTS:  A total of 8.9% (307/3,456) of patients with IBD had opportunistic infection. The opportunistic infection rate of elderly group was 16.5% (80/485), which was significantly higher than that of adult group (7.6%, 227/2,971, p <0.05). Compared with infected adult group or non-infected elderly group, infected elderly group had less fever and leukocytosis, but more hypoproteinemia and several activities (p <0.05). Cytomegalovirus and Epstein-Barr virus were the most common agents in elderly group and adult group, respectively. Multiple episodes (three or more) were more common in infected elderly group; the time of opportunistic infections was associated with systemic inflammatory reaction syndrome (SIRS, p <0.05). Logistic regression analysis showed that age ≥60 years, corticosteroids, immunosuppressive and biological agents were risk factors for opportunistic infections in patients with IBD. CONCLUSION: Hospitalised elderly IBD patients, receiving corticosteroids, immunosuppressive, and biological agents, are at higher risk for infection. The symptoms of opportunistic infections in elderly patients are atypical, but they are prone to multiple infections with poor prognosis. Key Words: Elderly patients, Inflammatory bowel disease, Opportunistic infection, Systemic inflammation reaction syndrome.

Single-Atom Iron as Lithiophilic Site To Minimize Lithium Nucleation Overpotential for Stable Lithium Metal Full Battery.

High lithium nucleation overpotential on a lithiophobic matrix results in uncontrollable growth of lithium dendrites and thus restricts the wide application of lithium-metal batteries. Herein, the single-atom iron in a N-doped carbon matrix (FeSA-N-C) is first reported as a lithiophilic site to minimize Li nucleation overpotential from 18.6 mV to a very low value of 0.8 mV. Molecular dynamics simulations quantitatively confirmed the excellent affinity between Li ions and FeSA-N-C in the atomic level. Induced by the homogeneously distributed FeSA-N in the carbon substrate, uniform and stable metallic Li plating/stripping behaviors are realized and lithium dendrite growth is greatly suppressed. The proposed strategy of using single-atom iron as a lithiophilic site to minimize lithium nucleation overpotential opens a promising avenue for solving intrinsic problems of Li-metal-based batteries.

MicroRNA 375 modulates hyperglycemia-induced enteric glial cell apoptosis and Diabetes-induced gastrointestinal dysfunction by targeting Pdk1 and repressing PI3K/Akt pathway.

Diabetic neuropathy can damage systemic nervous system, including alteration of enteric nervous system and subsequent gastrointestinal dysfunction. The effect of diabetes on enteric glia cell (EGC) is not clear. We investigated the effect of diabetes and hyperglycemia on EGC, and the role of microRNA375 in modulating EGC survival in vivo and in vitro. Streptozotocin-induced diabetic mice were intraperitoneally injected with microRNA375 inhibitor or its negative control. EGC was transfected with microRNA375 inhibitor or its mimic. Diabetes mice with gastrointestinal dysfunction showed increased apoptosis of EGC (no difference in cell numbers) and gene expression of micorRNA375 in the myenteric plexus. Hyperglycemia triggered apoptosis of EGC in vitro with decreased expression of Pdk1 and p-Akt, but increased expression of micorRNA375. MicorRNA375 mimic induced apoptosis of EGC in vitro with repressed Pdk1and p-Akt. MicorRNA375 inhibitor could both prevent hyperglycemia-induced apoptosis of EGC in vitro and diabetes-induced gastrointestinal dysfunction in vivo. Our results suggest that diabetes-induced gastrointestinal dysfunction is related to increased apoptosis of EGC in the myenteric plexus. Hyperglycemia can increase the expression of microRNA375 and damage EGC survival through PI3K/Akt pathway. MicroRNA375 specific inhibition can prevent hyperglycemia induced EGC damage and diabetes-induced gastrointestinal dysfunction.

Yeast KEOPS complex regulates telomere length independently of its t6A modification function.

In Saccharomyces cerevisiae, the highly conserved Sua5 and KEOPS complex (including five subunits Kae1, Bud32, Cgi121, Pcc1 and Gon7) catalyze a universal tRNA modification, namely N6-threonylcarbamoyladenosine (t6A), and regulate telomere replication and recombination. However, whether telomere regulation function of Sua5 and KEOPS complex depends on the t6A modification activity remains unclear. Here we show that Sua5 and KEOPS regulate telomere length in the same genetic pathway. Interestingly, the telomere length regulation by KEOPS is independent of its t6A biosynthesis activity. Cytoplasmic overexpression of Qri7, a functional counterpart of KEOPS in mitochondria, restores cytosolic tRNA t6A modification and cell growth, but is not sufficient to rescue telomere length in the KEOPS mutant kae1Δ cells, indicating that a t6A modification-independent function is responsible for the telomere regulation. The results of our in vitro biochemical and in vivo genetic assays suggest that telomerase RNA TLC1 might not be modified by Sua5 and KEOPS. Moreover, deletion of KEOPS subunits results in a dramatic reduction of telomeric G-overhang, suggesting that KEOPS regulates telomere length by promoting G-overhang generation. These findings support a model in which KEOPS regulates telomere replication independently of its function on tRNA modification.

Quercetin Inhibits LPS-Induced Inflammation and ox-LDL-Induced Lipid Deposition.

Aberrant activation of inflammation and excess accumulation of lipids play crucial role in the occurrence and progression of atherosclerosis (AS). Quercetin (QCT) has been tested effectively to cure AS. It is widely distributed in plant foods and has been proved to have potential antioxidative and anticancer activities. However, the underlying molecular mechanisms of OCT in AS are not completely understood. In the present study, we stimulated murine RAW264.7 cells with lipopolysaccharide (LPS) or oxidized low-density lipoproteins (ox-LDL) to mimic the development of AS. The data show that QCT treatment leads to an obvious decrease of multiple inflammatory cytokines in transcript level, including interleukin (IL)-1α, IL-1ß, IL-2, IL-10, macrophage chemoattractant protein-1 (MCP-1), and cyclooxygenase-2 (COX-2) induced by LPS. Moreover, expressions of other factors that contribute to the AS development, such as matrix metalloproteinase-1 (MMP-1) and suppressor of cytokine signaling 3 (SOCS3) induced by LPS are also downregulated by QCT. Furthermore, we found that QCT suppressed LPS-induced the phosphorylation of STAT3. Meanwhile, QCT could ameliorate lipid deposition and overproduction of reactive oxygen species induced by ox-LDL, and block the expression of lectin-like oxidized LDL receptor-1 (LOX-1) in cultured macrophages. Taken together, our data reveal that QCT has obvious anti-inflammatory and antioxidant virtues and could be a therapeutic agent for the prevention and treatment of AS.

Core-Shell Coating Silicon Anode Interfaces with Coordination Complex for Stable Lithium-Ion Batteries.

In situ core-shell coating was used to improve the electrochemical performance of Si-based anodes with polypyrrole-Fe coordination complex. The vast functional groups in the organometallic coordination complex easily formed hydrogen bonds when in situ modifying commercial Si nanoparticles. The incorporation of polypyrrole-Fe resulted in the conformal conductive coating surrounding each Si nanoparticle, not only providing good electrical connection to the particles but also promoting the formation of a stable solid-electrolyte-interface layer on the Si electrode surface, enhancing the cycling properties. As an anode material for Li-ion batteries, modified silicon powders exhibited high reversible capacity (3567 mAh/g at 0.3 A/g), good rate property (549.12 mAh/g at 12 A/g), and excellent cycling performance (reversible capacity of 1500 mAh/g after 800 cycles at 1.2 A/g). The constructed novel concept of core-shell coating Si particles presented a promising route for facile and large-scale production of Si-based anodes for extremely durable Li-ion batteries, which provided a wide range of applications in the field of energy storage of the renewable energy derived from the solar energy, hydropower, tidal energy, and geothermal heat.

On-chip supercapacitors with ultrahigh volumetric performance based on electrochemically co-deposited CuO/polypyrrole nanosheet arrays.

We introduce a new method for fabricating unique on-chip supercapacitors based on CuO/polypyrrole core/shell nanosheet arrays by means of direct electrochemical co-deposition on interdigital-like electrodes. The prepared all-solid-state device demonstrates exceptionally high specific capacitance of 1275.5 F cm(-3) (∼40 times larger than that of CuO-only supercapacitors) and high-energy-density of 28.35 mWh cm(-3), which are both significantly greater than other solid-state supercapacitors. More importantly, the device maintains approximately 100% capacity retention at 2.5 A cm(-3) after 3000 cycles. The in situ co-deposition of CuO/polypyrrole nanosheets on interdigital substrate enables effective charge transport, electrode fabrication integrity, and device integration. Because of their high energy, power density, and stable cycling stability, these newly developed on-chip supercapacitors permit fast, reliable applications in portable and miniaturized electronic devices.

Recent transcription-induced histone H3 lysine 4 (H3K4) methylation inhibits gene reactivation.

Recent transcription of GAL genes transiently leaves an H3K4 methylation mark at their promoters, providing an epigenetic memory for the recent transcriptional activity. However, the physiological significance of this mark is enigmatic. In our study, we show that the transient H3K4 di- and trimethylation at recently transcribed GAL1 inhibited the reinduction of GAL1. The H3K4 methylation functioned by recruiting the Isw1 ATPase onto GAL1 and thereby limiting the action of RNA polymerase II during GAL1 reactivation. Strikingly, the H3K4 methylation was also observed at the promoters of inositol- and fatty acid-responsive genes after recent transcription and played a negative role in their reinduction. Taken together, our data present a new mechanism by which H3K4 methylation regulates gene transcription.

Reprogramming of ovine adult fibroblasts to pluripotency via drug-inducible expression of defined factors.

Reprogramming of somatic cells in the enucleated egg made Dolly, the sheep, the first successfully cloned mammal in 1996. However, the mechanism of sheep somatic cell reprogramming has not yet been addressed. Moreover, sheep embryonic stem (ES) cells are still not available, which limits the generation of precise gene-modified sheep. In this study, we report that sheep somatic cells can be directly reprogrammed to induced pluripotent stem (iPS) cells using defined factors (Oct4, Sox2, c-Myc, Klf4, Nanog, Lin28, SV40 large T and hTERT). Our observations indicated that somatic cells from sheep are more difficult to reprogram than somatic cells from other species, in which iPS cells have been reported. We demonstrated that sheep iPS cells express ES cell markers, including alkaline phosphatase, Oct4, Nanog, Sox2, Rex1, stage-specific embryonic antigen-1, TRA-1-60, TRA-1-81 and E-cadherin. Sheep iPS cells exhibited normal karyotypes and were able to differentiate into all three germ layers both in vitro and in teratomas. Our study may help to reveal the mechanism of somatic cell reprogramming in sheep and provide a platform to explore the culture conditions for sheep ES cells. Moreover, sheep iPS cells may be directly used to generate precise gene-modified sheep.

SWR1 complex poises heterochromatin boundaries for antisilencing activity propagation.

In eukaryotes, chromosomal processes are usually modulated through chromatin-modifying complexes that are dynamically targeted to specific regions of chromatin. In this study, we show that the chromatin-remodeling complex SWR1 (SWR1-C) uses a distinct strategy to regulate heterochromatin spreading. Swr1 binds in a stable manner near heterochromatin to prepare specific chromosomal regions for H2A.Z deposition, which can be triggered by NuA4-mediated acetylation of histone H4. We also demonstrate through experiments with Swc4, a module shared by NuA4 and SWR1-C, that the coupled actions of NuA4 and SWR1-C lead to the efficient incorporation of H2A.Z into chromatin and thereby synergize heterochromatin boundary activity. Our results support a model where SWR1-C resides at the heterochromatin boundary to maintain and amplify antisilencing activity of histone H4 acetylation through incorporating H2A.Z into chromatin.

Yeast telomerase subunit Est1p has guanine quadruplex-promoting activity that is required for telomere elongation.

Telomeres are eukaryotic protein-DNA complexes found at the ends of linear chromosomes that are essential for maintaining genome integrity and are implicated in cellular aging and cancer. The guanine (G)-rich strand of telomeric DNA, usually elongated by the telomerase reverse transcriptase, can form a higher-order structure known as a G-quadruplex in vitro and in vivo. Several factors that promote or resolve G-quadruplexes have been identified, but the functional importance of these structures for telomere maintenance is not well understood. Here we show that the yeast telomerase subunit Est1p, known to be involved in telomerase recruitment to telomeres, can convert single-stranded telomeric G-rich DNA into a G-quadruplex structure in vitro in a Mg(2+)-dependent manner. Cells carrying Est1p mutants deficient in G-quadruplex formation in vitro showed gradual telomere shortening and cellular senescence, indicating a positive regulatory role for G-quadruplex in the maintenance of telomere length.

Immortalization of normal human cytotrophoblast cells by reconstitution of telomeric reverse transcriptase activity.

Placental trophoblast cells are unique endocrine cells that play vital roles during the processes of embryonic implantation and placentation. However, research into the function of human trophoblast has been largely restrained mainly due to a lack of adequate cell models. A normal placenta-origin cytotrophoblast cell line (NPC) was previously established by our group, but these cells showed replicating senescence after 50 population doublings (PDs). In this study, the human telomerase catalytic subunit gene (htert) was transferred into B6 strain of NPC cells, and strains with reconstituted telomerase activity (B6Tert) were established. It was shown that B6Tert-1 cells produce various biomarkers of normal extravillous cytotrophoblasts during the early weeks of gestation. Meanwhile, the cell invasiveness was inhibited by transforming growth factor beta (TGFbeta). However, their ability to form syncytium was relatively low when stimulated with fetal calf serum (FCS). The cells maintained normal cell growth properties and failed to elicit tumours in nude mice. They proliferated continuously with no signs of senescence until the final count at 210 PDs. The growth rate of B6Tert-1 cells was increased when compared with the parental cells, which results, at least partly, from facilitating release of the G1/S checkpoint during the cell-cycle regulation. This is the first report of immortalizing human normal cytotrophoblast (CTB) cells by activation of telomerase activity. The cells will provide an ideal in vitro model for the study of human extravillous trophoblast (EVT) functions and consequently the mechanisms of embryonic implantation and placentation.

Characterization of ATPase activity of recombinant human Pif1.

Saccharomyces cerevisiae Pif1p helicase is the founding member of the Pif1 subfamily that is conserved from yeast to human. The potential human homolog of the yeast PIF1 gene has been cloned from the cDNA library of the Hek293 cell line. Here, we described a purification procedure of glutathione S-transferase (GST)-fused N terminal truncated human Pif1 protein (hPif1deltaN) from yeast and characterized the enzymatic kinetics of its ATP hydrolysis activity. The ATPase activity of human Pif1 is dependent on divalent cation, such as Mg2+, Ca2+ and single-stranded DNA. Km for ATP for the ATPase activity is approximately 200 microM. As the ATPase activity is essential for hPif1's helicase activity, these results will facilitate the further investigation on hPif1.

The human Pif1 helicase, a potential Escherichia coli RecD homologue, inhibits telomerase activity.

Telomeres, the protein-DNA complexes at the ends of eukaryotic chromosomes, are essential for chromosome stability, and their maintenance is achieved by the specialized reverse transcriptase activity of telomerase or the homologous recombination pathway in most eukaryotes. Here, we identified a human helicase, hPif1 that inhibits telomerase activity. The primary sequence and biochemical analysis suggest that hPif1 is a potential homologue of Escherichia coli RecD, an ATP-dependent 5' to 3' DNA helicase. Ectopic expression of wild-type, but not the ATPase/helicase-deficient hPif1, causes telomere shortening in HT1080 cells. hPif1 reduces telomerase processivity and unwinds DNA/RNA duplex in vitro. hPif1 preferentially binds telomeric DNA in vitro and in vivo. We propose that the mechanism of hPif1's inhibition on telomerase involves unwinding of the DNA/RNA duplex formed by telomerase RNA and telomeric DNA, and RecD homologues in eukaryotes may have evolved gaining additional functions.