A proteome-wide visual screen identifies fission yeast proteins localizing to DNA double-strand breaks

DNA double-strand breaks (DSBs) are a major threat to genome integrity. Proteins involved in DNA damage checkpoint signaling and DSB repair often relocalize and concentrate at DSBs. Here, we used an ORFeome library of the fission yeast Schizosaccharomyces pombe to systematically identify proteins targeted to DSBs. We found 51 proteins that, when expressed from a strong exogenous promoter on the ORFeome plasmids, were able to form a distinct nuclear focus at an HO endonuclease-induced DSB. The majority of these proteins have known connections to DNA damage response, but few have been visualized at a specific DSB before. Among the screen hits, 37 can be detected at DSBs when expressed from native promoters. We classified them according to the focus emergence timing of the endogenously tagged proteins. Eight of these 37 proteins are yet unnamed. We named these eight proteins DNA-break-localizing proteins (Dbls) and performed preliminary functional analysis on two of them, Dbl1 (SPCC2H8.05c) and Dbl2 (SPCC553.01c). We found that Dbl1 and Dbl2 contribute to the normal DSB targeting of checkpoint protein Rad26 (homolog of human ATRIP) and DNA repair helicase Fml1 (homolog of human FANCM), respectively. As the first proteome-wide inventory of DSB-localizing proteins, our screen result will be a useful resource for understanding the mechanisms of eukaryotic DSB response.     

Optical Curtain Effect: Extraordinary Optical Transmission Enhanced by Antireflection

In this paper, we employ an antireflective coating which comprises inverted π-shaped metallic grooves to manipulate the behaviour of a transverse-magnetic (TM)-polarised plane wave transmitted through a periodic nanoslit array. At normal incidence, such scheme cannot only retain the optical curtain effect in the output region but also generate the extraordinary transmission of light through the nanoslits with the total transmission efficiency as high as 90 %. Besides, we show that the spatially invariant field distribution in the output region as well as the field distribution of resonant modes around the inverted π-shaped grooves can be reproduced immaculately when the system is excited by an array of point sources beneath the inverted π-shaped grooves. Furthermore, we investigate the influence of centre groove and side-corners of the inverted π-shaped grooves on suppressing the reflection of light, respectively. Based on our work, it shows promising potential in applications of enhancing the extraction efficiency as well as controlling the beaming pattern of light emitting diodes.     

Carbon–Nitrogen Interaction Modulates Plant Growth and Expression of Metabolic Genes in Rice

Carbon (C) and nitrogen (N) interact to coordinate their metabolism in achieving C:N homeostasis in all cellular organisms. Plant shoots and roots take up C and N, respectively, and the coordinated C and N assimilation is essential for normal plant growth and development. In this study, rice was used as a model system for the investigation of molecular mechanisms underlying C–N interactions and coordination in cereal species. We investigated the growth response of rice seedlings to a wide range of exogenous C:N availabilities and established balanced exogenous C:N that was optimal for rice seedling growth. To assess correlations between the modulation of plant growth and the regulation of metabolic gene expression by C:N availabilities, we examined the expression of PEPC, PK, NR, GS, and GOGAT in rice seedlings treated with four C:N availabilities: low C/low N, low C/high N, high C/low N, and high C/high N. It was found that their expression was subjected to complex regulation by C:N availabilities. Our results demonstrate that growth of shoot and root rice seedlings is regulated by C–N interaction and growth modulations are associated with changes in metabolic gene expression. Our findings suggest that rice is a useful model system for the investigation of regulation mechanisms responsible for C–N interaction and coordination in plants.     

Arbuscular mycorrhizal fungi associated with vegetation and soil parameters under rest grazing management in a desert steppe ecosystem

The impact of rest grazing on arbuscular mycorrhizal fungi (AMF) and the interactions of AMF with vegetation and soil parameters under rest grazing condition were investigated between spring and late summer in a desert steppe ecosystem with different grazing managements (rest grazing with different lengths of resting period, banned or continuous grazing) in Inner Mongolia, China. AMF diversity and colonization, vegetation biomass, soil properties and soil phosphatase activity were examined. In rest grazing areas of 60 days, AMF spore number and diversity index at a 0–10 cm soil depth as well as vesicular and hyphal colonization rates were higher compared with other grazing treatments. In addition, soil organic matter and total N contents were highest and soil alkaline phosphatase was most active under 60-day rest grazing. In August and September, these areas also had the highest amount of aboveground vegetation. The results indicated that resting grazing for an appropriate period of time in spring has a positive effect on AMF sporulation, colonization and diversity, and that under rest grazing conditions, AMF parameters are positively correlated with some soil characteristics.     

SHBG Is an Important Factor in Stemness Induction of Cells by DHT In Vitro and Associated with Poor Clinical Features of Prostate Carcinomas

Androgen plays a vital role in prostate cancer development. However, it is not clear whether androgens influence stem-like properties of prostate cancer, a feature important for prostate cancer progression. In this study, we show that upon DHT treatment in vitro, prostate cancer cell lines LNCaP and PC-3 were revealed with higher clonogenic potential and higher expression levels of stemness related factors CD44, CD90, Oct3/4 and Nanog. Moreover, sex hormone binding globulin (SHBG) was also simultaneously upregulated in these cells. When the SHBG gene was blocked by SHBG siRNA knock-down, the induction of Oct3/4, Nanog, CD44 and CD90 by DHT was also correspondingly blocked in these cells. Immunohistochemical evaluation of clinical samples disclosed weakly positive, and areas negative for SHBG expression in the benign prostate tissues, while most of the prostate carcinomas were strongly positive for SHBG. In addition, higher levels of SHBG expression were significantly associated with higher Gleason score, more seminal vesicle invasions and lymph node metastases. Collectively, our results show a role of SHBG in upregulating stemness of prostate cancer cells upon DHT exposure in vitro, and SHBG expression in prostate cancer samples is significantly associated with poor clinicopathological features, indicating a role of SHBG in prostate cancer progression.     

Sex Hormone-Binding Globulin (SHBG) Expression in Ovarian Carcinomas and Its Clinicopathological Associations

Sex hormone-binding globulin (SHBG) is known as a carrier protein. It is classically thought to be mainly synthesized in the liver and then secreted into the circulating system, where it binds to sex steroids with a high affinity and modulates the bio-availability of the hormones. Other organs known to produce SHBG include brain, uterus, testis, prostate, breast and ovary, and the local expressed SHBG may play an important role in tumor development. However, SHBG expression status and its clinicopathological significance in ovarian cancer cells are not reported yet. In our present study, we examined and found the variable SHBG expression in four ovarian cancer cell lines (OV-90, OVCAR-3, SKOV-3 and ES-2) by immunocytochemistry and Western blotting. We then extended our study to 248 ovarian carcinoma samples, which were collected at The Norwegian Radium Hospital, Oslo University Hospital with complete clinical information, and discovered that SHBG was variably expressed in these ovarian carcinomas. Higher level of SHBG expression was significantly associated with more aggressive histological subtype (p = 0.022), higher FIGO stage (p = 0.018) and higher histological grade (grade of differentiation, p = 0.020), although association between SHBG expression and OS/PFS was not observed. Our results demonstrate that ovarian cancer cells produce SHBG and higher SHBG expression in ovarian carcinoma is associated with unfavorable clinicopathological features.     

Physiological Responses and Evaluation of Effects of BMI,Smoking and Drinking in High Altitude Acclimatization: A Cohort Study in Chinese Han Young Males

High altitude acclimatization is a series of physiological responses taking places when subjects go to altitude. Many factors could influence these processes, such as altitude, ascending speed and individual characteristics. In this study, based on a repeated measurement design of three sequential measurements at baseline, acute phase and chronic phase, we evaluated the effect of BMI, smoking and drinking on a number of physiological responses in high altitude acclimatization by using mixed model and partial least square path model on a sample of 755 Han Chinese young males. We found that subjects with higher BMI responses were reluctant to hypoxia. The effect of smoking was not significant at acute phase. But at chronic phase, red blood cell volume increased less while respiratory function increased more for smoking subjects compared with nonsmokers. For drinking subjects, red blood cell volume increased less than nondrinkers at both acute and chronic phases, while blood pressures increased more than nondrinkers at acute phase and respiratory function, red blood cell volume and oxygen saturation increased more than nondrinkers at chronic phase. The heavy and long-term effect of smoking, drinking and other factors in high altitude acclimatization needed to be further studied.     

A Study Assessing the Association of Glycated Hemoglobin A1C (HbA1C) Associated Variants with HbA1C,Chronic Kidney Disease and Diabetic Retinopathy in Populations of Asian Ancestry

Glycated hemoglobin A_1C (HbA_1C) level is used as a diagnostic marker for diabetes mellitus and a predictor of diabetes associated complications. Genome-wide association studies have identified genetic variants associated with HbA_1C level. Most of these studies have been conducted in populations of European ancestry. Here we report the findings from a meta-analysis of genome-wide association studies of HbA_1C levels in 6,682 non-diabetic subjects of Chinese, Malay and South Asian ancestries. We also sought to examine the associations between HbA_1C associated SNPs and microvascular complications associated with diabetes mellitus, namely chronic kidney disease and retinopathy. A cluster of 6 SNPs on chromosome 17 showed an association with HbA_1C which achieved genome-wide significance in the Malays but not in Chinese and Asian Indians. No other variants achieved genome-wide significance in the individual studies or in the meta-analysis. When we investigated the reproducibility of the findings that emerged from the European studies, six loci out of fifteen were found to be associated with HbA_1C with effect sizes similar to those reported in the populations of European ancestry and P-value ≤ 0.05. No convincing associations with chronic kidney disease and retinopathy were identified in this study.     

The Identification of CD163 Expressing Phagocytic Chondrocytes in Joint Cartilage and Its Novel Scavenger Role in Cartilage Degradation

Background

Cartilage degradation is a typical characteristic of arthritis. This study examined whether there was a subset of phagocytic chondrocytes that expressed the specific macrophage marker, CD163, and investigated their role in cartilage degradation.

Methods

Cartilage from the knee and temporomandibular joints of Sprague-Dawley rats was harvested. Cartilage degradation was experimentally-induced in rat temporomandibular joints, using published biomechanical dental methods. The expression levels of CD163 and inflammatory factors within cartilage, and the ability of CD163⁺ chondrocytes to conduct phagocytosis were investigated. Cartilage from the knees of patients with osteoarthritis and normal cartilage from knee amputations was also investigated.

Results

In the experimentally-induced degrading cartilage from temporomandibular joints, phagocytes were capable of engulfing neighboring apoptotic and necrotic cells, and the levels of CD163, TNF-α and MMPs were all increased (P<0.05). However, the levels of ACP-1, NO and ROS, which relate to cellular digestion capability were unchanged (P>0.05). CD163⁺ chondrocytes were found in the cartilage mid-zone of temporomandibular joints and knee from healthy, three-week old rats. Furthermore, an increased number of CD163⁺ chondrocytes with enhanced phagocytic activity were present in Col-II⁺ chondrocytes isolated from the degraded cartilage of temporomandibular joints in the eight-week experimental group compared with their age-matched controls. Increased number with enhanced phagocytic activity of CD163⁺ chondrocytes were also found in isolated Col-II⁺ chondrocytes stimulated with TNF-α (P<0.05). Mid-zone distribution of CD163⁺ cells accompanied with increased expression of CD163 and TNF-α were further confirmed in the isolated Col-II⁺ chondrocytes from the knee cartilage of human patients with osteoarthritis, in contrast to the controls (both P<0.05).

Conclusions

An increased number of CD163⁺ chondrocytes with enhanced phagocytic activity were discovered within degraded joint cartilage, indicating a role in eliminating degraded tissues. Targeting these cells provides a new strategy for the treatment of arthritis.