Hepatic Snai1 and Snai2 promote liver regeneration and suppress liver fibrosis in mice

Liver injury stimulates hepatocyte replication and hepatic stellate cell (HSC) activation, thereby driving liver regeneration. Aberrant HSC activation induces liver fibrosis. However, mechanisms underlying liver regeneration and fibrosis remain poorly understood. Here, we identify hepatic Snai1 and Snai2 as important transcriptional regulators for liver regeneration and fibrosis. Partial hepatectomy or CCl4 treatment increases occupancies of Snai1 and Snai2 on cyclin A2 and D1 promoters in the liver. Snai1 and Snai2 in turn increase promoter H3K27 acetylation and cyclin A2/D1 expressions. Hepatocyte-specific deletion of both Snai1 and Snai2, but not one alone, suppresses liver cyclin A2/D1 expression and regenerative hepatocyte proliferation after hepatectomy or CCl4 treatments but augments CCl4-stimulated HSC activation and liver fibrosis. Conversely, Snai2 overexpression in the liver enhances hepatocyte replication and suppresses liver fibrosis after CCl4 treatment. These results suggest that hepatic Snai1 and Snai2 directly promote, via histone modifications, reparative hepatocyte replication and indirectly inhibit liver fibrosis.

Minimally Invasive Delivery of Percutaneous Ablation Agent via Magnetic Colloidal Hydrogel Injection for Treatment of Hepatocellular Carcinoma

Percutaneous thermotherapy, a minimally invasive operational procedure, is employed in the ablation of deep tumor lesions by means of target-delivering heat. Conventional thermal ablation methods, such as radiofrequency or microwave ablation, to a certain extent, are subjected to extended ablation time as well as biosafety risks of unwanted overheating. Given its effectiveness and safety, percutaneous thermotherapy gains a fresh perspective, thanks to magnetic hyperthermia. In this respect, an injectable- and magnetic-hydrogel-construct-based thermal ablation agent is likely to be a candidate for the aforementioned clinical translation. Adopting a simple and environment-friendly strategy, a magnetic colloidal hydrogel injection is introduced by a binary system comprising super-paramagnetic Fe3O4 nanoparticles and gelatin nanoparticles. The colloidal hydrogel constructs, unlike conventional bulk hydrogel, can be easily extruded through a percutaneous needle and then self-heal in a reversible manner owing to the unique electrostatic cross-linking. The introduction of magnetic building blocks is exhibited with a rapid magnetothermal response to an alternating magnetic field. Such hydrogel injection is capable of generating heat without limitation of deep penetration. The materials achieve outstanding therapeutic results in mouse and rabbit models. These findings constitute a new class of locoregional interventional thermal therapies with minimal collateral damages.

Long-term efficacy and safety of baricitinib in patients with severe alopecia areata: 104-week results from BRAVE-AA1 and BRAVE-AA2

BACKGROUND

Efficacy of the Janus kinase (JAK) inhibitor baricitinib for severe alopecia areata (AA) continuously increased over 52 weeks in two Phase 3 trials. There are limited long-term data on JAK inhibitors in AA.

OBJECTIVES

To evaluate efficacy and safety of baricitinib for severe AA through 104 weeks of continuous therapy.

METHODS

Integrated data from the BRAVE-AA1 and BRAVE-AA2 Phase 3 trials included adults with Severity of Alopecia Tool (SALT) scores ≥50 (≥50% scalp hair loss) randomized to and continuously treated with 2-mg or 4-mg baricitinib through Week 104. Patients who qualified to remain on continuous treatment included subjects who achieved SALT score ≤20 at Week 52 (Week-52 responders; 2-mg: N = 65; 4-mg: N = 129) and baricitinib 4-mg-treated patients who had SALT score >20 at Week 52 but achieved SALT score ≤20 at prior visit(s) and/or had significant improvement in eyebrow or eyelash hair growth relative to baseline by Week 52 (Week-52 mixed responders; N = 110). Week-104 outcomes included the proportion of patients achieving SALT score ≤20 (≤20% scalp hair loss). Data were censored after treatment discontinuation.

RESULTS

Among baricitinib 4-mg-treated and baricitinib 2-mg-treated Week-52 responders, 90.7% and 89.2%, respectively, maintained SALT score ≤20 at Week 104. Among Week-52 mixed responders, 39.1% reached SALT score ≤20 by Week 104. Continued improvement in eyebrow and eyelash regrowth was observed across groups. The most frequent treatment-emergent adverse events were COVID-19, upper respiratory tract infection, headache, nasopharyngitis, acne, urinary tract infection and creatine phosphokinase increase.

CONCLUSIONS

Baricitinib demonstrated a high level of maintenance of efficacy over 104 weeks in patients with severe AA. Efficacy increased in Week-52 mixed responders, illustrating that long-term treatment is necessary to observe maximum benefit in some patients. No new safety signals were observed.

miR-30e-5p regulates leukemia stem cell self-renewal through the Cyb561/ROS signaling pathway

Leukemia stem cells (LSC) represent a crucial and rare subset of cells present in acute myeloid leukemia (AML); they play a pivotal role in the initiation, maintenance, and relapse of this disease. Targeting LSC holds great promise for preventing AML relapse and improving long-term outcomes. However the precise molecular mechanisms governing LSC self-renewal are still poorly understood. Here, we present compelling evidence that the expression of miR-30e-5p, a potential tumor-suppressive microRNA, is significantly lower in AML samples than in healthy bone marrow samples. Forced expression of miR- 30e effectively inhibits leukemogenesis, impairs LSC self-renewal, and delays leukemia progression. Mechanistically, Cyb561 acts as a direct target of miR-30e-5p in LSC, and its deficiency restricts the self-renewal of LSC by activating reactive oxygen series signaling and markedly prolongs recipients' survival. Moreover, genetic or pharmacological overexpression of miR-30e-5p or knockdown of Cyb561 suppresses the growth of human AML cells. In conclusion, our findings establish the crucial role of the miR-30e-5p/Cyb561/ROS axis in finely regulating LSC self-renewal, highlighting Cyb561 as a potential therapeutic target for LSC-directed therapies.

LepRb+ cell-specific deletion of Slug mitigates obesity and nonalcoholic fatty liver disease in mice

Leptin exerts its biological actions by activating the long-form leptin receptor (LepRb). LepRb signaling impairment and leptin resistance are believed to cause obesity. The transcription factor Slug - also known as Snai2 - recruits epigenetic modifiers and regulates gene expression by an epigenetic mechanism; however, its epigenetic action has not been explored in leptin resistance. Here, we uncover a proobesity function of neuronal Slug. Hypothalamic Slug was upregulated in obese mice. LepRb+ cell-specific Slug-knockout (SlugΔLepRb) mice were resistant to diet-induced obesity, type 2 diabetes, and liver steatosis and experienced decreased food intake and increased fat thermogenesis. Leptin stimulated hypothalamic Stat3 phosphorylation and weight loss to a markedly higher level in SlugΔLepRb than in Slugfl/fl mice, even before their body weight divergence. Conversely, hypothalamic LepRb+ neuron-specific overexpression of Slug, mediated by AAV-hSyn-DIO-Slug transduction, induced leptin resistance, obesity, and metabolic disorders in mice on a chow diet. At the genomic level, Slug bound to and repressed the LepRb promoter, thereby inhibiting LepRb transcription. Consistently, Slug deficiency decreased methylation of LepRb promoter H3K27, a repressive epigenetic mark, and increased LepRb mRNA levels in the hypothalamus. Collectively, these results unravel what we believe to be a previously unrecognized hypothalamic neuronal Slug/epigenetic reprogramming/leptin resistance axis that promotes energy imbalance, obesity, and metabolic disease.

[Transmission characteristics and risk factors of household COVID-19 clusters caused by 2019-nCoV Omicron variant in Tianjin]

Objective: To understand the transmission characteristics and risk factors of household COVID-19 clusters caused by 2019-nCoV Omicron variant in Tianjin and provide evidence for COVID-19 prevention and control. Methods: Field epidemiological method was used to investigate the epidemiological characteristics of COVID-19 cases, and descriptive analysis was used to describe the epidemiological information. Results: A total of 430 cases were reported in this epidemic in Tianjin, in which 409 cases were included in this study. Among these cases, 70.90% (290/409) occurred in families. The family secondary attack rate was 33.64% The family secondary attack rate in age group 12-17 years (13.79%) was significantly lower than that in age group 18-49 years (36.48%), the OR was 0.378 (95%CI: 0.170-0.840). The logistic regression analysis showed that compared with centralized quarantine, the OR of the index cases found in closed-off/controlled areas and in home quarantine were 2.951 (95%CI:1.322-6.586) and 2.287 (95%CI:1.164-4.495), respectively, compared with the cases without sore throat, the OR of the index cases with sore throat was 3.003 (95%CI: 1.576-5.720), and compared with cases in families without completed COVID-19 vaccinations in all members, the OR of the cases in families with completed COVID-19 vaccinations in all members was 0.268 (95%CI: 0.132-0.552). Conclusions: The risk of household transmission of infection with Omicron variant was high. Detecting the index case in closed-off/controlled areas or in home quarantine and sore throat in index cases were the risk factors of the household transmission, completed COVID-19 vaccination was the protective factor.

[Clinical features and treatment efficacy of infantile renal tumors: a multicenter retrospective study]

Objective: To further understand the clinical features, treatment efficacy and risk factors for poor prognosis in infantile-onset renal tumors. Methods: Clinical data of 45 cases of infantile-onset renal tumors from June 2011 to November 2019 in Peking University First Hospital, Beijing Children's Hospital, Beijing Tongren Hospital and Beijing Shijitan Hospital were analyzed retrospectively. The clinical features were summarized and the prognoses were evaluated. Multi-disciplinary diagnosis and treatment was used, including surgery, chemotherapy and radiotherapy. Kaplan-Meier analysis was used to calculate the overall survival rate and the event-free survival rate, while the chi-square test was used to analyze the risk factors for poor prognosis. Results: Among 45 patients, 24 were males and 21 females. The age of onset was 7 (ranged 3-11) months, and the length of tumor at initial diagnosis was 9.7 (ranged 4.9-25.0)cm. The International Society of Pediatric Oncology (SIOP) staging: 5 cases (11%) were in stage Ⅰ, 22 cases in stage Ⅱ (49%), 8 cases in stage Ⅲ (18%), 6 cases in stage Ⅳ (13%), and 4 cases in stage Ⅴ (9%). Risk groups included 5 cases (11%) in the low-risk group, 22 cases (49%) in the intermediate-risk group, and 18 cases (40%) in the high-risk group. Forty-four cases (98%) did not receive preoperative biopsy, 26 cases (58%) received preoperative chemotherapy, 39 cases (87%) received postoperative chemotherapy, and 2 cases (4%) received three-dimensional conformal radiotherapy. The 5-year overall survival rate was (83±7)%, and the 5-year event-free survival rate was (76±8)%. Hematuria as the first symptom (3/8 vs. 83% (30/36), χ²=7.005, P=0.024), tumor long diameter≤8 cm (5/11 vs. 85% (28/33), χ²=5.606, P=0.027) and high-risk pathological group (7/18 vs.100% (26/26), χ²=21.928, P<0.01) were risk factors for poor prognosis of children with renal tumors in this group. Conclusion: The prognosis of children with infantile-onset renal tumors is fairly well, nevertheless the prognosis is poor in patients with hematuria as the first symptom and in high-risk pathological group.

Hepatic Slug epigenetically promotes liver lipogenesis, fatty liver disease, and type 2 diabetes

De novo lipogenesis is tightly regulated by insulin and nutritional signals to maintain metabolic homeostasis. Excessive lipogenesis induces lipotoxicity, leading to nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes. Genetic lipogenic programs have been extensively investigated, but epigenetic regulation of lipogenesis is poorly understood. Here, we identified Slug as an important epigenetic regulator of lipogenesis. Hepatic Slug levels were markedly upregulated in mice by either feeding or insulin treatment. In primary hepatocytes, insulin stimulation increased Slug expression, stability, and interactions with epigenetic enzyme lysine-specific demethylase-1 (Lsd1). Slug bound to the fatty acid synthase (Fasn) promoter where Slug-associated Lsd1 catalyzed H3K9 demethylation, thereby stimulating Fasn expression and lipogenesis. Ablation of Slug blunted insulin-stimulated lipogenesis. Conversely, overexpression of Slug, but not a Lsd1 binding-defective Slug mutant, stimulated Fasn expression and lipogenesis. Lsd1 inhibitor treatment also blocked Slug-stimulated lipogenesis. Remarkably, hepatocyte-specific deletion of Slug inhibited the hepatic lipogenic program and protected against obesity-associated NAFLD, insulin resistance, and glucose intolerance in mice. Conversely, liver-restricted overexpression of Slug, but not the Lsd1 binding-defective Slug mutant, had the opposite effects. These results unveil an insulin/Slug/Lsd1/H3K9 demethylation lipogenic pathway that promotes NAFLD and type 2 diabetes.

[Seroepidemiological survey and influencing factors of hepatitis E virus infection among key occupational population in Tianjin]

Objective: To evaluate the infection rate and influencing factors of hepatitis E virus (HEV) among key occupational population in Tianjin, so as to help occupational population to carry out HEV prevention and control. Methods: A combination of stratified random sampling and convenience sampling was carried out for the study in Tianjin in June 2019. The livestock and poultry-related farming workers, slaughtering workers, selling workers, doctors, farmers, seafood sellers, sewage pipeline workers as the key occupational population groups (1036 person) , and non key occupational population as the control group (200 person) , cross-sectional surveys were conducted in the groups. Enzyme-linked immunosorbent assay (ELISA) was used to detect the serum IgG and IgM antibodies to HEV, and logistic regression model was used to analyze the influencing factors of HEV infection. Results: The positive rate of anti-HEV IgG in key occupational group was 26.45% (274/1036) , which was higher than that in control group of 14.50% (29/200) (χ(2)=13.41, P<0.01) . The occupations with the highest positive rate of anti-HEV IgG were livestock (swine) , breeding and slaughtering workers, all of which reached 33.96% (18/53) . The difference in infection rates between different occupations was statistically significant (χ(2)=22.57, P<0.01) . Multivariate logistic regression analysis showed that the longer working years, high frequency of eating out (3-5, ≥6 times/week) , drinking raw water, eating under-cooked pork or pig liver, and low frequency of washing hands were risk factors for HEV infection in occupational population (P<0.05) . But the high education is a protective factor for HEV infection (P<0.05) . Conclusion: There is a high positive rate of anti-HEV IgG in key occupational population in Tianjin. It is necessary to strengthen the monitoring, publicity and education of the high-risk population, pay attention to personal and dietary hygiene.

Carcinogenesis of Male Oral Submucous Fibrosis Alters Salivary Microbiomes

Most oral squamous cell carcinoma (OSCC) tumors arise from oral premalignant lesions. Oral submucous fibrosis (OSF), usually occurring in male chewers of betel quid, is a premalignant stromal disease characterized by a high malignant transformation rate and high prevalence. Although a relationship between the inhabited microbiome and carcinogenesis has been proposed, no detailed information regarding the oral microbiome of patients with OSF exists; the changes of the salivary microbiome during cancer formation remain unclear. This study compared the salivary microbiomes of male patients with OSCC and a predisposing OSF background (OSCC-OSF group) and those with OSF only (OSF group). The results of high-throughput sequencing of the bacterial 16S rRNA gene indicated that OSF-related carcinogenesis and smoking status significantly contributed to phylogenetic composition variations in the salivary microbiome, leading to considerable reductions in species richness and phylogenetic diversity. The microbiome profile of OSF-related malignancy was associated with increased microbial stochastic fluctuation, which dominated the salivary microbiome assembly and caused species co-occurrence network collapse. Artificial intelligence selection algorithms consistently identified 5 key species in the OSCC-OSF group: Porphyromonas catoniae, Prevotella multisaccharivorax, Prevotella sp. HMT-300, Mitsuokella sp. HMT-131, and Treponema sp. HMT-927. Robust accuracy in predicting oral carcinogenesis was obtained with our exploratory and validation data sets. In functional analysis, the microbiome of the OSCC-OSF group had greater potential for S-adenosyl-l-methionine and norspermidine synthesis but lower potential for l-ornithine and pyrimidine deoxyribonucleotide synthesis and formaldehyde metabolism. These findings indicated that the salivary microbiome plays important roles in modulating microbial metabolites during oral carcinogenesis. In conclusion, our results provided new insights into salivary microbiome alterations during the malignant transformation of OSF.

[Investigation and analysis on characteristics of a cluster of COVID-19 associated with exposure in a department store in Tianjin]

Objective: To describe the epidemiological characteristics of a cluster of COVID-19 cases reported in Baodi district of Tianjin as of 18 February, 2020, which might be associated with the exposure in a local department store, and provide suggestions for prevention and control strategy development. Methods: The basic characteristics, time and area distributions, clinical manifestations, epidemiological history and transmission mode of the COVID-19 cases associated with the department store exposure were analyzed. Results: A total of 40 COVID-19 cases were associated with the department store exposure, accounting for 75.47% of the total confirmed cases (53 cases) reported in Baodi district. The cases were mainly at the age of 60 years or older (35.00%) and farmers (40.00%). The main clinical manifestations included fever (95.00%), cough (35.00%), and diarrhea (15.00%). The proportion of confirmed severe cases was 32.50%. The incidence curve showed that the incidence peak occurred on 31 January, 2020. Among the 40 cases, 6(15.00%) were department store employees, 19 (47.50%) were customers and 15 (37.50%) were close contacts (secondary cases). The first case occurred on 21 January, 2020, this case was a department store employee who had a purchasing history at whole sale markets in other provinces and cities before the onset, and 3 employees were still on duty after symptom onsets. The median of the incubation period of customer cases was 6 days, and the median of the interval between onset and medical treatment of customer cases was 7 days. Conclusion: This was a cluster epidemic of COVID-19, which might be associated with the exposure in the department store. By now, the current prevention and control measures have achieved satisfied effects.

Inhibition of Slug effectively targets leukemia stem cells via the Slc13a3/ROS signaling pathway

Leukemia stem cells (LSCs) are the rare populations of acute myeloid leukemia (AML) cells that are able to initiate, maintain, and propagate AML. Targeting LSCs is a promising approach for preventing AML relapse and improving long-term outcomes. While Slug, a zinc-finger transcription repressor, negatively regulates the self-renewal of normal hematopoietic stem cells, its functions in AML are still unknown. We report here that Slug promotes leukemogenesis and its loss impairs LSC self-renewal and delays leukemia progression. Mechanistically, Slc13a3, a direct target of Slug in LSCs, restricts the self-renewal of LSCs and markedly prolongs recipient survival. Genetic or pharmacological inhibition of SLUG or forced expression of Slc13a3 suppresses the growth of human AML cells. In conclusion, our studies demonstrate that Slug differentially regulates self-renewal of LSCs and normal HSCs, and both Slug and Slc13a3 are potential therapeutic targets of LSCs.

The transcription factor Slug represses p16Ink4a and regulates murine muscle stem cell aging

Activation of the p16^Ink4a-associated senescence pathway during aging breaks muscle homeostasis and causes degenerative muscle disease by irreversibly dampening satellite cell (SC) self-renewal capacity. Here, we report that the zinc-finger transcription factor Slug is highly expressed in quiescent SCs of mice and functions as a direct transcriptional repressor of p16^Ink4a. Loss of Slug promotes derepression of p16^Ink4a in SCs and accelerates the entry of SCs into a fully senescent state upon damage-induced stress. p16^Ink4a depletion partially rescues defects in Slug-deficient SCs. Furthermore, reduced Slug expression is accompanied by p16^Ink4a accumulation in aged SCs. Slug overexpression ameliorates aged muscle regeneration by enhancing SC self-renewal through active repression of p16^Ink4a transcription. Our results identify a cell-autonomous mechanism underlying functional defects of SCs at advanced age. As p16^Ink4a dysregulation is the chief cause for regenerative defects of human geriatric SCs, these findings highlight Slug as a potential therapeutic target for aging-associated degenerative muscle disease.

Muscle regeneration depends on self-renewal of muscle stem cells but how this is regulated on aging is unclear. Here, the authors identify Slug as regulating p16^Ink4a in quiescent muscle stem cells, and when Slug expression reduces in aged stem cells, p16^Ink4a accumulates, causing regenerative defects.

Femtosecond laser-induced size reduction and emission quantum yield enhancement of colloidal silicon nanocrystals: effect of laser ablation time

Colloidal silicon (Si) nanocrystals (NCs) with different sizes were successfully prepared by femtosecond laser ablation under different laser ablation time (LAT). The mean size decreases from 4.23 to 1.42 nm by increasing the LAT from 30 to 120 min. In combination with structural characterization, temperature-dependent photoluminescence (PL), time-resolved PL and PL excitation spectra, we attribute room-temperature blue emissions peaked at 405 and 430 nm to the radiative recombination of electron-hole pairs via the oxygen-deficient centers related to Si-C-H₂ and Si-O-Si bonds of colloidal Si NCs prepared in 1-octene, respectively. In particular, the measured PL quantum yield of colloidal Si NCs has been enhanced significantly from 23.6% to 55.8% by prolonging the LAT from 30 to 120 min.

Correlation between luminescence and structural evolution of colloidal silicon nanocrystals synthesized under different laser fluences

We present a detailed investigation of the structural evolution and photoluminescence (PL) properties of colloidal silicon (Si) nanocrystals (NCs) synthesized through femtosecond laser ablation at different laser fluences. It is shown that the mean size of colloidal Si NCs increases from ∼0.97-2.37 nm when increasing laser fluence from 1.0-2.5 mJ cm^-2. On the basis of structural characterization, temperature-dependent PL, time-resolved PL, and PL excitation spectra, we identify that the size-dependent spectral shift of violet emission is attributed to the quantum confinement effect. The localized excitons' radiative recombination via the oxygen-related surface states on the surface of the colloidal Si NCs is employed to explain the origin of the blue emission.

Application of TALE-Based Approach for Dissecting Functional MicroRNA-302/367 in Cellular Reprogramming

MicroRNAs are small 18-24 nt single-stranded noncoding RNA molecules involved in many biological processes, including stemness maintenance and cellular reprogramming. Current methods used in loss-of-function studies of microRNAs have several limitations. Here, we describe a new approach for dissecting miR-302/367 functions by transcription activator-like effectors (TALEs), which are natural effector proteins secreted by Xanthomonas and Ralstonia bacteria. Knockdown of the miR-302/367 cluster uses the Kruppel-associated box repressor domain fused with specific TALEs designed to bind the miR-302/367 cluster promoter. Knockout of the miR-302/367 cluster uses two pairs of TALE nucleases (TALENs) to delete the miR-302/367 cluster in human primary cells. Together, both TALE-based transcriptional repressor and TALENs are two promising approaches for loss-of-function studies of microRNA cluster in human primary cells.

[Prevalence of hepatitis C in Tianjin, China and related risk factors]

Objective: To investigate the prevalence of hepatitis C in Tianjin, China and major risk factors, and to provide a theoretical basis for the development of scientific prevention and control strategies for hepatitis C. Methods: The monitoring system of notifiable infectious diseases was used to establish the database of hepatitis C cases reported from 2004 to 2014 in Tianjin. With reference to the results of serological surveillance and special case-control investigation, a statistical analysis was performed to investigate the epidemiological characteristics and prevalence of hepatitis C in Tianjin, as well as related risk factors. Results: The report rate of hepatitis C in Tianjin showed a decreasing trend from 2004 to 2014(χ ² = 150.018, P < 0.01). The group aged 60 years had the highest report rate(9.09/100000), and there were significant differences between this group and other groups(χ ² = 2540.887, P < 0.01). The six urban districts in Tianjin had the highest report rate(6.54/100000), and there were significant differences between this area and other areas. The multivariate logistic regression analysis showed that a history of surgery(χ ² = 12.57, P < 0.01), blood transfusion and blood products(χ ² = 36.67, P < 0.01), hemodialysis(χ ² = 4.62, P < 0.01), and intravenous drug use(χ ² = 12.92, P < 0.01)were major risk factors for hepatitis C. Conclusion: The epidemic situation of hepatitis C in Tianjin tends to decrease in recent years. Although there is no effective vaccine for hepatitis C, it still can be prevented and treated. The most effective interventions for hepatitis C include strengthening health education and raising the awareness rate of hepatitis C in the whole population, as well as early detection, diagnosis, and treatment.

Selective Expansion of Skeletal Muscle Stem Cells from Bulk Muscle Cells in Soft Three-Dimensional Fibrin Gel

Muscle stem cells (MuSCs) exhibit robust myogenic potential in vivo, thus providing a promising curative treatment for muscle disorders. Ex vivo expansion of adult MuSCs is highly desired to achieve a therapeutic cell dose because of their scarcity in limited muscle biopsies. Sorting of pure MuSCs is generally required for all the current culture systems. Here we developed a soft three‐dimensional (3D) salmon fibrin gel culture system that can selectively expand mouse MuSCs from bulk skeletal muscle preparations without cell sorting and faithfully maintain their regenerative capacity in culture. Our study established a novel platform for convenient ex vivo expansion of MuSCs, thus greatly advancing stem cell‐based therapies for various muscle disorders. Stem Cells Translational Medicine2017;6:1412–1423

A novel slug-containing negative-feedback loop regulates SCF/c-Kit-mediated hematopoietic stem cell self-renewal

The stem cell factor (SCF)/c-Kit pathway has crucial roles in controlling hematopoietic stem cell (HSC) renewal. However, little is known about the intracellular regulation of the SCF/c-Kit pathway in HSCs. We report here that Slug, a zinc-finger transcription repressor, functions as a direct transcriptional repressor of c-Kit in HSCs. Conversely, SCF/c-Kit signaling positively regulates Slug through downstream c-Myc and FoxM1 transcription factors. Intriguingly, c-Kit expression is induced by SCF/c-Kit signaling in Slug-deficient HSCs. The balance between Slug and c-Kit is critical for maintaining HSC repopulating potential in vivo. Together, our studies demonstrate that Slug functions in a novel negative-feedback regulatory loop in the SCF/c-Kit signaling pathway in HSCs.

Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution

We present a detailed investigation into the origin of blue emission from colloidal silicon (Si) nanocrystals (NCs) fabricated by femtosecond laser ablation of Si powder in 1-hexene. High resolution transmission electron microscopy and Raman spectroscopy observations confirm that Si NCs with average size 2.7 nm are produced and well dispersed in 1-hexene. Fourier transform infrared spectrum and x-ray photoelectron spectra have been employed to reveal the passivation of Si NCs surfaces with organic molecules. On the basis of the structural characterization, UV-visible absorption, temperature-dependent photoluminescence (PL), time-resolved PL, and PL excitation spectra investigations, we deduce that room-temperature blue luminescence from colloidal Si NCs originates from the following two processes: (i) under illumination, excitons first form within colloidal Si NCs by direct transition at the X or Γ (Γ25 → Γ'2) point; (ii) and then some trapped excitons migrate to the surfaces of colloidal Si NCs and further recombine via the surface states associated with the Si-C or Si-C-H2 bonds.

Zfp281 Coordinates Opposing Functions of Tet1 and Tet2 in Pluripotent States

Pluripotency is increasingly recognized as a spectrum of cell states defined by their growth conditions. Although naive and primed pluripotency states have been characterized molecularly, our understanding of events regulating state acquisition is wanting. Here, we performed comparative RNA sequencing of mouse embryonic stem cells (ESCs) and defined a pluripotent cell fate (PCF) gene signature associated with acquisition of naive and primed pluripotency. We identify Zfp281 as a key transcriptional regulator for primed pluripotency that also functions as a barrier toward achieving naive pluripotency in both mouse and human ESCs. Mechanistically, Zfp281 interacts with Tet1, but not Tet2, and its direct transcriptional target, miR-302/367, to negatively regulate Tet2 expression to establish and maintain primed pluripotency. Conversely, ectopic Tet2 alone, but not Tet1, efficiently reprograms primed cells toward naive pluripotency. Our study reveals a molecular circuitry in which opposing functions of Tet1 and Tet2 control acquisition of alternative pluripotent states.

[Investigation of renal corticomedullary differentiation with age-related change on non-contrast-enhanced MRI]

OBJECTIVE

To evaluate the relationship between renal corticomedullary differentiation, renal cortical thickness and age-related changes with non-contrast-enhanced steady-state free precession(SSFP) magnetic resonance imaging (MRI) and spatially selective inversion recovery(IR) pulse technology as well as its applied value .

METHODS

A total of 76 healthy volunteers had been recruited from August 2014 to June 2015 in First Hospital of China Medical University.All volunteers were divided into three groups: 2-40 years old, 41-60 years old, 61-80 years old. All 76 volunteers underwent non-contrast-enhanced steady-state free precession(SSFP) 3.0 T MRI scan using variable inversion times (TIs)(TI=1 000, 1 100, 1 200, 1 300, 1 400, 1 500, 1 600, 1 700 ms). The renal corticomedullary differentiation was observed and the signal intensity of renal cortex and medulla were measured respectively as well in order to calculate renal corticomedullary contrast ratio. Besides, renal cortical thickness and renal size were measured.

RESULTS

All 76 volunteers were successfully performed all the sequences of MRI scan, including 152 useful imaging of kidney in total. The renal corticomedullary differentiation was clearly shown in all subjects. There was negative correlation between the optimal inversion time(TI) and age(r=-0.65, P<0.01). Similarly, negative correlation was observed between renal corticomedullary contrast ratio and age(r=-0.35, P<0.01). The mean renal cortical thickness of all subjects was (5.33±0.71)mm and there were statistically significant difference among those different groups, which was negative-related with age(r=-0.79, P<0.01). There was no statistically significant difference between sexuality and renal cortical thickness.Additionally, renal cortical thickness had no statistically significant difference in both sides of kidneys.

CONCLUSION

The renal corticomedullary differentiation is depicted clearly by means of non-contrast-enhanced steady-state free precession MRI with spatially selective inversion recovery pulse technology. The optimal inversion time decreases along with the increase of age. In the meanwhile, the renal cortical thickness could be measured truthfully and accurately.

SLUG is a direct transcriptional repressor of PTEN tumor suppressor

BACKGROUND

PTEN/AKT signaling plays a key role in prostate cancer development and maintenance of prostate cancer stem cells. How other oncogenes or tumor suppressors interact with this pathway remain to be elucidated. SLUG is an zinc finger transcription factor of the Snail superfamily, and it promotes cancer metastasis and determines the mammary stem cell state.

METHODS

SLUG was overexpressed in cells by retroviral vector and knockdown of SLUG and PTEN was mediated by shRNAs-expressing lentiviruses. Expression level of SLUG and PTEN was examined by Western blot, RT-PCR, and qPCR analyses. PTEN promoter activity was measured by luciferase reporter assay. ChIP assay was used to measure the binding between SLUG and the PTEN promoter in vivo.

RESULT

We showed that overexpression of SLUG decreased expression of PTEN tumor repressor in prostate cancer cell lines 22RV1 and DU145; conversely, knockdown of SLUG expression elevated PTEN expresson at both protein and RNA level in these cells. We demonstrated that SLUG overexpression inhibits PTEN promoter activity through the proximal promoter region in prostate cancer cells. By ChIP assay, we confirmed that SLUG directly binds to the PTEN promoter region covering the E-box sites. We also showed that Slug deficiency leads to an increased expression of PTEN in mouse embryo fibroblasts and prostate tissues. Importantly, we found that overexpression of SLUG increases drug resistance of DU145 prostate cancer cell line and knockdown of SLUG by shRNA sensitizes DU145 cell line to chemotherapeutic drugs. We further demonstrated that PTEN knockdown converts drug sensitivity of DU145 cells expressing SLUG shRNA to anticancer drugs.

CONCLUSION

We provide compelling evidence showing that PTEN is a direct functional target of SLUG. Our findings offer new insight in the regulation of the PTEN/AKT pathway and provide a molecular basis for potential targeted therapies of prostate cancer Prostate 75:907-916, 2015. © 2015 Wiley Periodicals, Inc.

The adsorption behavior of U(VI) on granite

The effects of pH, counter ions and temperature on the adsorption of U(VI) on Beishan granite (BsG) were investigated in the presence and absence of fulvic acid (FA) and humic acid (HA). The adsorption edge of U(VI) on BsG suggested that U(VI) adsorption was mainly controlled by ion exchange and outer-sphere complexation at low pH, whereas inner-sphere complex was the dominant adsorption species in the pH range of 4.0-9.0. Above pH 9.0, Na2U2O7 might play an important role in the rise of U(VI) adsorption again. Counter ions such as Cl(-), SO4(2-) and PO4(3-) can provoke U(VI) adsorption on BsG to some extent, which was directly correlated to the complexing ability of U(VI)-ligand. More noticeably, the large enhancement of U(VI) adsorption in the presence of phosphate can be attributed to the ternary complex formation (BsG-PO4-UO2), precipitation ((UO2)3(PO4)2(s)) and secondary phase (Na-autunite). Both FA and HA can slightly increase U(VI) adsorption at low pH, whereas they strongly inhibited U(VI) adsorption at high pH range. Artificial synthesized granite (AsG) prepared in the laboratory is impossible to use as an analogue of natural granite because of the large difference in the adsorption and surface properties.

Sodium butyrate facilitates reprogramming by derepressing OCT4 transactivity at the promoter of embryonic stem cell-specific miR-302/367 cluster

Small-molecule inhibitors and microRNAs (miRNAs) are two newly emerging classes of tools for optimizing induced pluripotent stem cell (iPSC) generation. We report here that sodium butyrate (NaB), a small-molecule inhibitor of histone deacetylases (HDACs), upregulates transcriptional levels of the miR-302/367 cluster by enhancing Oct4 transcriptional activity at the miR-302/367 cluster promoter. NaB does not affect the OCT4 DNA-binding domain; instead it enhances transactivity of the OCT4 transactivation domains. We elucidate that OCT4 transcriptional activity is usually dampened by its associated HDACs in cells and can be derepressed by NaB by impairing the interaction between Oct4 and HDACs, which leads to an elevated expression of the miR-302/367 cluster. Our new findings suggest a novel molecular mechanism for NaB in promoting somatic cell reprogramming via the miR-302/367 cluster.

Dissecting the roles of miR-302/367 cluster in cellular reprogramming using TALE-based repressor and TALEN

MicroRNAs are important gene regulators involved in many biological processes, including stemness maintenance and cellular reprogramming. Current methods used in loss-of-function studies of microRNAs mainly include locked nucleic acid (LNA) oligonucleotides and miRZip inhibitors, which have several limitations. Due to their unique gene structures and small sizes, there is no efficient or simple strategy to knock down or knock out microRNAs or whole microRNA clusters. Here, we demonstrate knockdown of the miR-302/367 cluster by using the Kruppel-associated box repressor domain fused with specific transcription activator-like effectors (TALEs) designed to bind the miR-302/367 cluster promoter. We also designed two pairs of TALE nucleases (TALENs) to efficiently delete the miR-302/367 cluster in primary human fibroblasts and determined that knockout of the miR-302/367 cluster completely blocked induced pluripotent stem cell (iPSC) generation. Together, our results demonstrate that TALE-based transcriptional repressor and TALENs are two promising approaches for loss-of-function studies of microRNA clusters in somatic cells and pluripotent stem cells.

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TALE-KRAB repressor is an efficient approach to knock down microRNA clusters

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A vector was constructed for assembly of TALE-KRAB using the Golden Gate TALLEN2.0

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TALENs efficiently knock out the miR-302/367 cluster in primary human fibroblasts

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Knockout of the miR-302/367 cluster blocks iPSC generation in HFFs

MYBL2 is a sub-haploinsufficient tumor suppressor gene in myeloid malignancy

A common deleted region (CDR) in both myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) affects the long arm of chromosome 20 and has been predicted to harbor a tumor suppressor gene. Here we show that MYBL2, a gene within the 20q CDR, is expressed at sharply reduced levels in CD34+ cells from most MDS cases (65%; n = 26), whether or not they harbor 20q abnormalities. In a murine competitive reconstitution model, Mybl2 knockdown by RNAi to 20-30% of normal levels in multipotent hematopoietic progenitors resulted in clonal dominance of these 'sub-haploinsufficient' cells, which was reflected in all blood cell lineages. By 6 months post-transplantation, the reconstituted mice had developed a clonal myeloproliferative/myelodysplastic disorder originating from the cells with aberrantly reduced Mybl2 expression. We conclude that downregulation of MYBL2 activity below levels predicted by classical haploinsufficiency underlies the clonal expansion of hematopoietic progenitors in a large fraction of human myeloid malignancies. DOI:http://dx.doi.org/10.7554/eLife.00825.001.

Sodium butyrate promotes generation of human induced pluripotent stem cells through induction of the miR302/367 cluster

Small molecules (SM) can greatly enhance the efficiency of induced pluripotent stem (iPS) cell generation, but the mechanisms by which they act have not been fully explored. We show here that an SM cocktail (NaB, PD03259, and SB431542) significantly promotes iPS cell generation from human fibroblasts, and NaB is more potent than the other two common histone deacetylase inhibitors (valproic acid and Trichostatin A) in promoting cellular reprogramming. Our data indicate that the SM cocktail substantially upregulates the miR302/367 cluster expression by increasing the stability and transcriptional level of this microRNA (miRNA) cluster in a manner dependent on the four defined transcription factors (TFs). Among the four TFs, Oct4 in particular appears to be required for the induction of the miR302/367 cluster by the SM cocktail. We also found that NaB alone can enhance the TFs-dependent upregulation of the miR302/367 cluster. Using a promoter reporter assay, we show that the SM cocktail remarkably enhanced the transcriptional activity of the four TFs in the miR302/367 promoter. Notably, attenuation of miRNA302/367 using a miRZip impairs the ability of the SM cocktail in promoting reprogramming. Collectively, these findings suggest that the SM cocktail promotes reprogramming at least partly through the induction of the miR302/367 cluster expression. Further insights into this process may pave the way for the generation of iPS cells using only SM cocktails.

Effect of MWCNTs on Gastric Emptying in Mice

After making model of gastric functional disorder (FD), part of model mice were injected intravenously (i.v.) with oxide multi-walled carbon nanotubes (oMWCNTs) to investigate effect of carbon nanotubes on gastric emptying. The results showed that NO content in stomach, compared with model group, was decreased significantly and close to normal level post-injection with oMWCNTs (500 and 800 μg/mouse). In contrast to FD or normal groups, the content of acetylcholine (Ach) in stomach was increased obviously in injection group with 500 or 800 μg/mouse of oMWCNTs. The kinetic curve of emptying was fitted to calculate gastric motility factor k; the results showed that the k of injection group was much higher than FD and normal. In other words, the gastric motility of FD mice was enhanced via injection with oMWCNTs. In certain dosage, oMWCNTs could improve gastric emptying and motility.

SLUG promotes prostate cancer cell migration and invasion via CXCR4/CXCL12 axis

Background

SLUG is a zinc-finger transcription factor of the Snail/Slug zinc-finger family that plays a role in migration and invasion of tumor cells. Mechanisms by which SLUG promotes migration and invasion in prostate cancers remain elusive.

Methods

Expression level of CXCR4 and CXCL12 was examined by Western blot, RT-PCR, and qPCR analyses. Forced expression of SLUG was mediated by retroviruses, and SLUG and CXCL12 was downregulated by shRNAs-expressing lentiviruses. Migration and invasion of prostate cancer were measured by scratch-wound assay and invasion assay, respectively.

Research

We demonstrated that forced expression of SLUG elevated CXCR4 and CXCL12 expression in human prostate cancer cell lines PC3, DU145, 22RV1, and LNCaP; conversely, reduced expression of SLUG by shRNA downregulated CXCR4 and CXCL12 expression at RNA and protein levels in prostate cancer cells. Furthermore, ectopic expression of SLUG increased MMP9 expression and activity in PC3, 22RV1, and DU-145 cells, and SLUG knockdown by shRNA downregulated MMP9 expression. We showed that CXCL12 is required for SLUG-mediated MMP9 expression in prostate cancer cells. Moreover, we found that migration and invasion of prostate cancer cells was increased by ectopic expression of SLUG and decreased by SLUG knockdown. Notably, knockdown of CXCL12 by shRNA impaired SLUG-mediated migration and invasion in prostate cancer cells. Lastly, our data suggest that CXCL12 and SLUG regulate migration and invasion of prostate cancer cells independent of cell growth.

Conclusion

We provide the first compelling evidence that upregulation of autocrine CXCL12 is a major mechanism underlying SLUG-mediated migration and invasion of prostate cancer cells. Our findings suggest that CXCL12 is a therapeutic target for prostate cancer metastasis.

Efficient generation of fully reprogrammed human iPS cells via polycistronic retroviral vector and a new cocktail of chemical compounds

Direct reprogramming of human somatic cells into induced pluripotent stem (iPS) cells by defined transcription factors (TFs) provides great potential for regenerative medicine and biomedical research. This procedure has many challenges, including low reprogramming efficiency, many partially reprogrammed colonies, somatic coding mutations in the genome, etc. Here, we describe a simple approach for generating fully reprogrammed human iPS cells by using a single polycistronic retroviral vector expressing four human TFs in a single open reading frame (ORF), combined with a cocktail containing three small molecules (Sodium butyrate, SB431542, and PD0325901). Our results demonstrate that human iPS cells generated by this approach express human ES cells markers and exhibit pluripotency demonstrated by their abilities to differentiate into the three germ layers in vitro and in vivo. Notably, this approach not only provides a much faster reprogramming process but also significantly diminishes partially reprogrammed iPS cell colonies, thus facilitating efficient isolation of desired fully reprogrammed iPS cell colonies.

Bcl-xL enhances single-cell survival and expansion of human embryonic stem cells without affecting self-renewal

Robust expansion and genetic manipulation of human embryonic stem cells (hESCs) and induced-pluripotent stem (iPS) cells are limited by poor cell survival after enzymatic dissociation into single cells. Although inhibition of apoptosis is implicated for the single-cell survival of hESCs, the protective role of attenuation of apoptosis in hESC survival has not been elucidated. Bcl-xL is one of several anti-apoptotic proteins, which are members of the Bcl-2 family of proteins. Using an inducible system, we ectopically expressed Bcl-xL gene in hESCs, and found a significant increase of hESC colonies in the single-cell suspension cultures. Overexpression of Bcl-xL in hESCs decreased apoptotic caspase-3(+) cells, suggesting attenuation of apoptosis in hESCs. Without altering the kinetics of pluripotent gene expression, the efficiency to generate embryoid bodies (EBs) in vitro and the formation of teratoma in vivo were significantly increased in Bcl-xL-overexpressing hESCs after single-cell dissociation. Interestingly, the number and size of hESC colonies from cluster cultures were not affected by Bcl-xL overexpression. Several genes of extracellular matrix and adhesion molecules were upregulated by Bcl-xL in hESCs without single-cell dissociation, suggesting that Bcl-xL regulates adhesion molecular expression independent of cell dissociation. In addition, the gene expressions of FAS and several TNF signaling mediators were downregulated by Bcl-xL. These data support a model in which Bcl-xL promotes cell survival and increases cloning efficiency of dissociated hESCs without altering hESC self-renewal by i) attenuation of apoptosis, and ii) upregulation of adhesion molecules to facilitate cell-cell or cell-matrix interactions.

Endothelial cells regulate cardiomyocyte development from embryonic stem cells

The molecules and environment that direct pluripotent stem cell differentiation into cardiomyocytes are largely unknown. Here, we determined a critical role of receptor tyrosine kinase, EphB4, in regulating cardiomyocyte generation from embryonic stem (ES) cells through endothelial cells. The number of spontaneous contracting cardiomyocytes, and the expression of cardiac-specific genes, including alpha-MHC and MLC-2V, was significantly decreased in EphB4-null ES cells. EphB4 was expressed in endothelial cells underneath contracting cardiomyocytes, but not in cardiomyocytes. Angiogenic inhibitors, including endostatin and angiostatin, inhibited endothelial cell differentiation and diminished cardiomyogenesis in ES cells. Generation of functional cardiomyocytes and the expression of cardiac-specific genes were significantly enhanced by co-culture of ES cells with human endothelial cells. Furthermore, the defects of cardiomyocyte differentiation in EphB4-deficient ES cells were rescued by human endothelial cells. For the first time, our study demonstrated that endothelial cells play an essential role in facilitating cardiomyocyte differentiation from pluripotent stem cells. EphB4 signaling is a critical component of the endothelial niche to regulate regeneration of cardiomyocytes.

Slug inhibits proliferation of human prostate cancer cells via downregulation of cyclin D1 expression

BACKGROUND

Slug is a transcription factor of the Snail/Slug zinc-finger family and is implicated in metastasis of tumors, but its role in cell proliferation of prostate cancers is unclear.

METHODS

Expression level of Slug and other genes was examined by Western blot, RT-PCR, and QPCR analyses. The forced expression of Slug was mediated by retroviruses and adenoviruses. Slug was downregulated by shRNA. Cell growth was measured by the MTT assay and the quick cell proliferation assay.

RESULTS

Here, we demonstrated that Slug expression is elevated in mouse prostate tumors, and human prostate cancer cell lines LNCaP, PC-3, and 22RV1. Forced expression of Slug-inhibited proliferation of prostate cancer cells PC-3 and DU-145. Conversely, reduced expression of Slug by shRNA promoted growth of PC-3 cancer cells. Consistent with these data, we found that forced expression of Slug in prostate cancer cells led to G1 cell-cycle arrest. Furthermore, ectopic expression of Slug decreased cyclin D1 expression in both PC-3 and DU-145 cells, and knockdown of Slug by shRNA upregulated cyclin D1 expression in these cancer cells. In addition, we demonstrated that ectopic expression of cyclin D1 relieved Slug-mediated inhibition of proliferation of prostate cancer cells.

CONCLUSIONS

We provide the first compelling evidence that Slug is a negative regulator of proliferation of prostate cancer cells. Our findings in this study are distinct from the previously reported role of Slug as a promoter for tumor metastasis, and suggest that Slug is a prognostic marker and potential therapeutic target.

BMP4 regulates vascular progenitor development in human embryonic stem cells through a Smad-dependent pathway

The signals that direct pluripotent stem cell differentiation into lineage-specific cells remain largely unknown. Here, we investigated the roles of BMP on vascular progenitor development from human embryonic stem cells (hESCs). In a serum-free condition, hESCs sequentially differentiated into CD34+CD31-, CD34+CD31+, and then CD34-CD31+ cells during vascular cell development. CD34+CD31+ cells contained vascular progenitor population that gives rise to endothelial cells and smooth muscle cells. BMP4 promoted hESC differentiation into CD34+CD31+ cells at an early stage. In contrast, TGFbeta suppressed BMP4-induced CD34+CD31+ cell development, and promoted CD34+CD31- cells that failed to give rise to either endothelial or smooth muscle cells. The BMP-Smad inhibitor, dorsomorphin, inhibited phosphorylation of Smad1/5/8, and blocked hESC differentiation to CD34+CD31+ progenitor cells, suggesting that BMP Smad-dependent signaling is critical for CD34+CD31+ vascular progenitor development. Our findings provide new insight into how pluripotent hESCs differentiate into vascular cells.

Gene-delivery systems for iPS cell generation

IMPORTANCE OF THE FIELD

Induced pluripotent stem (iPS) cells offer extraordinary promise for regenerative medicine applications, and provide new opportunities for use in disease modeling, drug screening and drug toxicology. AREAS COVED IN THIS REVIEW: iPS cell technology is still in its infancy. In this review article, we present a comprehensive survey of reprogramming approaches focusing on gene-delivery systems used for generation of iPS cells from somatic cells, categorize gene-delivery vectors, and discuss their advantages and limitations for somatic cell reprogramming. We include pertinent literature published between 2006 and the present.

WHAT THE READER WILL GAIN

Although iPS cell technology has been improved via the use of various gene-delivery vectors, it still suffers from either low reprogramming efficiency or too many genomic modification steps. Extensive work is still required to improve current vectors or explore new vectors for effectively reprogramming human somatic cells into iPS cells, with or without minimal genomic modification steps.

TAKE HOME MESSAGE

A single non-integrating reprogramming vector system with high reprogramming efficiency is probably essential for generation of clinically translatable human iPS cells.

Sorption of Eu(III) on attapulgite studied by batch, XPS, and EXAFS techniques

The effects of pH, ionic strength, and temperature on sorption of Eu(III) on attapulgite were investigated in the presence and absence of fulvic acid (FA) and humic acid (HA). The results indicated that the sorption of Eu(III) on attapulgite was strongly dependent on pH and ionic strength, and independent of temperature. In the presence of FA/HA, Eu(III) sorption was enhanced at pH < 4, decreased at pH range of 4-6, and then increased again at pH > 7. The X-ray photoelectron spectroscopy (XPS) analysis suggested that the sorption of Eu(III) might be expressed as is identical to X3Eu0, is identical to S(w)OHEu3+, and is identical to SOEu-OOC-/HA in the ternary Eu/HN/attapulgite system. The extended X-ray absorption fine structure (EXAFS) analysis of Eu-HA complexes indicated that the distances of d(Eu-O) decreased from 2.415 to 2.360 angstroms with increasing pH from 1.76 to 9.50, whereas the coordination number (N) decreased from approximately 9.94 to approximately 8.56. Different complexation species were also found for the different addition sequences of HA and Eu(III) to attapulgite suspension. The results are important to understand the influence of humic substances on Eu(III) behavior in the natural environment.

Generation of iPS cells using defined factors linked via the self-cleaving 2A sequences in a single open reading frame

Generation of induced pluripotent stem (iPS) cells from somatic cells has been achieved successfully by simultaneous viral transduction of defined reprogramming transcription factors (TFs). However, the process requires multiple viral vectors for gene delivery. As a result, generated iPS cells harbor numerous viral integration sites in their genomes. This can increase the probability of gene mutagenesis and genomic instability, and present significant barriers to both research and clinical application studies of iPS cells. In this paper, we present a simple lentivirus reprogramming system in which defined factors are fused in-frame into a single open reading frame (ORF) via self-cleaving 2A sequences. A GFP marker is placed downstream of the transgene to enable tracking of transgene expression. We demonstrate that this polycistronic expression system efficiently generates iPS cells. The generated iPS cells have normal karyotypes and are similar to mouse embryonic stem cells in morphology and gene expression. Moreover, they can differentiate into cell types of the three embryonic germ layers in both in vitro and in vivo assays. Remarkably, most of these iPS cells only harbor a single copy of viral vector. This system provides a valuable tool for generation of iPS cells, and our data suggest that the balance of expression of transduced reprogramming TFs in each cell is essential for the reprogramming process. More importantly, when delivered by non-integrating gene-delivery systems, this re-engineered single ORF will facilitate efficient generation of human iPS cells free of genetic modifications.

Chromosome 5q deletion and epigenetic suppression of the gene encoding α-catenin (CTNNA1) in myeloid cell transformation

Interstitial loss of all or part of the long arm of chromosome 5, or del(5q), is a frequent clonal chromosomal abnormality in human myelodysplastic syndrome (MDS, a preleukemic disorder) and acute myeloid leukemia (AML), and is thought to contribute to the pathogenesis of these diseases by deleting one or more tumor-suppressor genes. Although a major commonly deleted region (CDR) has been delineated on chromosome band 5q31.1 (refs. 3-7), attempts to identify tumor suppressors within this band have been unsuccessful. We focused our analysis of gene expression on RNA from primitive leukemia-initiating cells, which harbor 5q deletions, and analyzed 12 genes within the CDR that are expressed by normal hematopoietic stem cells. Here we show that the gene encoding alpha-catenin (CTNNA1) is expressed at a much lower level in leukemia-initiating stem cells from individuals with AML or MDS with a 5q deletion than in individuals with MDS or AML lacking a 5q deletion or in normal hematopoietic stem cells. Analysis of HL-60 cells, a myeloid leukemia line with deletion of the 5q31 region, showed that the CTNNA1 promoter of the retained allele is suppressed by both methylation and histone deacetylation. Restoration of CTNNA1 expression in HL-60 cells resulted in reduced proliferation and apoptotic cell death. Thus, loss of expression of the alpha-catenin tumor suppressor in hematopoietic stem cells may provide a growth advantage that contributes to human MDS or AML with del(5q).

Slug antagonizes p53-mediated apoptosis of hematopoietic progenitors by repressing puma

In response to DNA damage, the p53 tumor suppressor can elicit either apoptosis or cell-cycle arrest and repair, but how this critical decision is made in specific cell types remains largely undefined. We investigated the mechanism by which the transcriptional repressor Slug specifically rescues hematopoietic progenitor cells from lethal doses of gamma radiation. We show that Slug is transcriptionally induced by p53 upon irradiation and then protects the damaged cell from apoptosis by directly repressing p53-mediated transcription of puma, a key BH3-only antagonist of the antiapoptotic Bcl-2 proteins. We established the physiologic significance of Slug-mediated repression of puma by demonstrating that mice deficient in both genes survive doses of total-body irradiation that lethally deplete hematopoietic progenitor populations in mice lacking only slug. Thus, Slug functions downstream of p53 in developing blood cells as a critical switch that prevents their apoptosis by antagonizing the trans-activation of puma by p53.

Langerhans cell histiocytosis patients have HLA Cw7 and DR4 types associated with specific clinical presentations and no increased frequency in polymorphisms of the tumor necrosis factor alpha promoter

BACKGROUND

Current theory on the etiology of Langerhans cell histiocytosis (LCH), formerly Histiocytosis-X, is that abnormality(ies) of the immune system are responsible for dysregulation of Langerhans cells (LC) in patients' lesions. Among the known abnormalities in LCH patients are increased amounts of tumor necrosis factor alpha (TNF-alpha) and other cytokines in the lesions.

PROCEDURE

We investigated the human leukocyte antigen (HLA) phenotypes of 29 patients and 37 healthy family members to determine if any haplotypes segregate with the presence or locations of the disease. The lymphocyte subsets for 22 patients and 11 family members were also determined.

RESULTS

Patients with single bone, multiple bone, or multi-system LCH had different relative proportions of HLA types. Patients presenting with single bone disease had an especially high frequency of the DR4 type. In this patient group, every Caucasian patient had either Cw7 or DR4. Lymphopenia was documented in patients who had been off therapy as well as those who only had surgical curetage of their lesions. Family members also had low numbers of T lymphocytes. There were fewer mutations of the TNF-alpha promoter in patients than in the general population.

CONCLUSIONS

Although there is an increased percentage of LCH patients with DR4 and/or Cw7 there was also an increased prevalence of this antigen as well as lymphopenia among unaffected family members. Additional genetic and/or environmental factors are necessary to explain this association. TNF-alpha promoter mutations are not responsible for the increased production of this cytokine.

Enhanced PCE dechlorination by biobarrier systems under different redox conditions

The industrial solvent tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to evaluate the (1) feasibility of enhancing PCE biodegradation using cane molasses and sludge cakes as the primary substrates under methanogenic and iron reducing conditions, and (2) potential of installation a sludge cake/cane molasses biobarrier to clean up PCE-contaminated aquifers. The biodegradability of sludge cake (from secondary wastewater treatment system) and cane molasses was tested using bioavailability experiments. Results show that biodegradable materials were released from sludge cake/cane molasses and utilized by microbial consortia. Based on the chemical oxygen demand (COD) tests, approximately 28 and 248 mg of biodegradable COD can be released from 1g of sludge cake and 1g of cane molasses under anaerobic conditions, which have the potential to convert 70 and 620 mg of PCE to ethylene (ETH), respectively. Reductive dechlorination was evaluated using microcosms containing primary substrates (sludge cake/cane molasses) and inocula (aquifer sediments). Results indicate that sludge cake and cane molasses can serve as the diffusion sources of primary substrates, and enhance the reductive dechlorination of PCE under methanogenic processes. However, results from this study were not sufficient enough to show that reductive dechlorination of PCE would occur under iron-reducing conditions. This indicates that more studies need to be performed to further evaluate the role of iron reduction on the PCE dechlorination. Results reveal that it is feasible and applicable to install a sludge cake or cane molasses biobarrier to clean up PCE contaminated aquifers. From an engineering point of view, the sludge cake/cane molasses biobarrier has the potential to become an environmentally and economically acceptable technology for PCE bioremediation.

Promyelocytic leukemia protein sensitizes tumor necrosis factor alpha-induced apoptosis by inhibiting the NF-kappaB survival pathway

The promyelocytic leukemia protein (PML) is a growth/tumor suppressor essential for induction of apoptosis by diverse apoptotic stimuli. The mechanism by which PML regulates cell death remains unclear. In this study we found that ectopic expression of PML potentiates cell death by apoptosis in the tumor necrosis factor alpha (TNFalpha)-resistant cell line U2OS and other cell lines. Treatment with TNFalpha significantly sensitized these cells to apoptosis in a p53-independent manner. PML/TNFalpha-induced cell death is associated with DNA fragmentation, activation of caspase-3, -7, and -8, and degradation of DNA fragmentation factor/inhibitor of CAD. PML/TNFalpha-induced cell death could be blocked by the caspase-8 inhibitors CrmA and c-FLIP but not by Bcl-2. These findings indicate that this cell death event is initiated through the death receptor-dependent apoptosis pathway. PML is a transcriptional repressor of NF-kappaB by interacting with RelA/p65 and prevents its binding to the cognate enhancer through the C terminus. Coimmunoprecipitation and double-color immunofluorescence staining demonstrated that PML physically interacts with RelA/p65 in vivo and the two proteins colocalized at the endogenous levels. Overexpression of NF-kappaB rescued cell death induced by PML/TNFalpha. Furthermore, PML(-/-) mouse embryo fibroblasts are more resistant to TNFalpha-induced apoptosis. Together this study defines a novel mechanism by which PML induces apoptosis through repression of the NF-kappaB survival pathway.

The promyelocytic leukemia protein represses A20-mediated transcription

The promyelocytic leukemia (PML) protein is a tumor suppressor that is disrupted by the chromosomal translocation t(15;17), a consistent cytogenetic feature of acute promyelocytic leukemia. A role of PML in multiple pathways of apoptosis was conclusively demonstrated using PML(-/-) animal and cell culture models. In a previous study, we found that PML sensitizes tumor necrosis factor-induced apoptosis in tumor necrosis factor (TNF)-resistant U2OS cells. This finding helped to explain the mechanism of PML-induced apoptosis. The zinc finger protein A20 is a target gene of NF kappa B inducible by TNF alpha, and it is a potent inhibitor of TNF-induced apoptosis. In the this study, we demonstrated that PML is a transcriptional repressor of the A20 promoter and that PML represses A20 expression induced by TNF alpha. We showed that PML inhibits A20 transactivation through the NF kappa B site by interfering with its binding to the promoter. We also showed that stable overexpression of A20 inhibits apoptosis and caspase activation induced by PML/TNF alpha. The results of this study suggest that A20 is a downstream target of PML-induced apoptosis and supports a role of A20 in modulating cell death induced by PML/TNF alpha in TNF-resistant cells.

Promyelocytic leukemia protein PML inhibits Nur77-mediated transcription through specific functional interactions

The promyelocytic leukemia protein PML is a tumor and growth suppressor and plays an important role in a multiple pathways of apoptosis and regulation of cell cycle progression. Our previous studies and others also documented a role of PML in transcriptional regulation through its association with transcription coactivator CBP and transcription corepressor HDAC. Here, we showed that PML is a potent transcriptional repressor of Nur77, an orphan receptor and a member of the steroid receptor superfamily of proteins. We found that PML represses Nur77-mediated transactivation through a physical and functional interaction between the two proteins. PML interacts with Nur-77 in vitro in a GST-pull down assay and in vivo by coimmunoprecipitation assay. PML/Nur77 colocalized in vivo in a double immunofluorescent staining and confocal microscopic analysis. Our study further showed that the coiled-coil domain of PML interacts with the DNA-binding domain of Nur77 (amino acids 267-332). Electrophoretic mobility shift assay demonstrated that PML interferes with Nur77 DNA binding in a dose-dependent manner. This study indicates that PML interacts with the DNA-binding domain of Nur77 and represses transcription by preventing it from binding to the target promoter. This study supports a role of PML/Nur77 interaction in regulating cell growth and apoptosis.

QT interval effects of cisapride in the clinical setting

PURPOSE

The clinical effect of cisapride on QT intervals was prospectively studied.

SUBJECTS

Consecutive adult patients were recruited in whom cisapride was indicated for gastroesophogeal reflux, gastric ulcer, duodenal ulcer, diabetic gastroparesis or chronic constipation refractory to laxatives. Exclusion criteria included disorders and medications affecting cardiac conduction, electrolyte homeostasis, drug clearance and membrane stability.

METHODS

Seventy-five patients were included and followed at 1 to 2 week intervals. Patients took cisapride 5 mg thrice daily for 1 to 4 weeks (lower dose stage), followed by 10 mg thrice daily for another 1 to 4 weeks (higher dose stage). Twelve-lead ECGs were performed before commencing cisapride (group B), at completion of the lower dose stage (group L) and at completion of the higher dose stage (group H).

RESULTS

No patients experienced presyncope or syncope. Seventeen patients failing to comply, and 7 complaining of abdominal discomfort or diarrhea were excluded, leaving 51 participants. Group H's corrected QT interval (QTc) was longer than group B's by 13+/-15 ms (P<0.001), and longer than group L's by 7+/-11 ms (P<0.001). Group L's QTc was longer than group B's by 7+/-21 ms (P<0.05). QT dispersion did not differ significantly among groups. Neither torsade de pointe nor ventricular tachycardia were noted in Holter monitoring of 33 patients during the higher dose stage.

CONCLUSION

cisapride dose-dependently prolongs the QT interval. Further study is needed to examine the arrhythmogenicity of cisapride in higher doses and for longer durations.

Involvement of p-15(INK4b) and p-16(INK4a) gene expression in saikosaponin a and TPA-induced growth inhibition of HepG2 cells

Saikosaponin a, a purified ingredient of Chinese herb with known antitumor activity, can inhibit cell growth and DNA synthesis of hepatoma cell line HepG2. Both mRNA and protein of the CDK inhibitor p-16(INK4a) and p-15(INK4b) in HepG2 were greatly induced by saikosaponin a while that of p-21(CIP), p-27(KIP) and other cell cycle related genes were not. In addition, reduced phosphorylation of RB protein is observed in saikosaponin a-treated HepG2. Staurosporin, one of the PKC inhibitors, significantly prevented the saikosaponin a induced growth inhibition suggesting PKC pathway be involved. On the other hand, the phorbol ester tumor promoter TPA (12-O-Tetredecanolyphorbol 13-acetate) also inhibited HepG2 growth and specifically induced p-16(INK4a) and p-15(INK4b) mRNA expression. The results suggest that both saikosaponin a and TPA-induced HepG2 growth inhibition are associated with p-15(INK4a) and p-16(INK4b) gene expression and might be mediated by PKC signaling pathway.

The growth suppressor PML represses transcription by functionally and physically interacting with histone deacetylases

The growth suppressor promyelocytic leukemia protein (PML) is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL). PML plays a key role in multiple pathways of apoptosis and regulates cell cycle progression. The present study demonstrates that PML represses transcription by functionally and physically interacting with histone deacetylase (HDAC). Transcriptional repression mediated by PML can be inhibited by trichostatin A, a specific inhibitor of HDAC. PML coimmunoprecipitates a significant level of HDAC activity in several cell lines. PML is associated with HDAC in vivo and directly interacts with HDAC in vitro. The fusion protein PML-RARalpha encoded by the t(15;17) breakpoint interacts with HDAC poorly. PML interacts with all three isoforms of HDAC through specific domains, and its expression deacetylates histone H3 in vivo. Together, the results of our study show that PML modulates histone deacetylation and that loss of this function in APL alters chromatin remodeling and gene expression. This event may contribute to the development of leukemia.