Primate gastrulation and early organogenesis at single-cell resolution.

Our understanding of human early development is severely hampered by limited access to embryonic tissues. Due to their close evolutionary relationship with humans, nonhuman primates are often used as surrogates to understand human development but currently suffer from a lack of in vivo datasets, especially from gastrulation to early organogenesis during which the major embryonic cell types are dynamically specified. To fill this gap, we collected six Carnegie stage 8-11 cynomolgus monkey (Macaca fascicularis) embryos and performed in-depth transcriptomic analyses of 56,636 single cells. Our analyses show transcriptomic features of major perigastrulation cell types, which help shed light on morphogenetic events including primitive streak development, somitogenesis, gut tube formation, neural tube patterning and neural crest differentiation in primates. In addition, comparative analyses with mouse embryos and human embryoids uncovered conserved and divergent features of perigastrulation development across species-for example, species-specific dependency on Hippo signalling during presomitic mesoderm differentiation-and provide an initial assessment of relevant stem cell models of human early organogenesis. This comprehensive single-cell transcriptome atlas not only fills the knowledge gap in the nonhuman primate research field but also serves as an invaluable resource for understanding human embryogenesis and developmental disorders.

Monomeric Far-red and Near-infrared Fluorescent Biliproteins of Ultrahigh Brightness.

Far-red and near-infrared fluorescent proteins have regions of maximum transmission in most tissues and can be widely used as fluorescent biomarkers. We report that fluorescent phycobiliproteins originating from the phycobilisome core subunit ApcF2 can covalently bind biliverdin, named BDFPs. To further improve BDFPs, we conducted a series of studies. Firstly, we mutated K53Q and T144A of BDFPs to increase their effective brightness up to 190 % in vivo. Secondly, by homochromatic tandem fusion of high-brightness BDFPs to achieve monomerization, which increases the effective brightness by up to 180 % in vivo, and can effectively improve the labeling effect. By combining the above two approaches, the brightness of the tandem BDFPs was much improved compared with that of the previously reported fluorescent proteins in a similar spectral range. The tandem BDFPs were expressed stably while maintaining fluorescence in mammalian cells and Caenorhabditis elegans. They were also photostable and resistant to high temperature, low pH, and chemical denaturation. The tandem BDFPs advantages were proved in applications as biomarkers for imaging in super-resolution microscopy.

Circulating C-reactive protein increases lung cancer risk: Results from a prospective cohort of UK Biobank.

Chronic inflammation has been associated with the development of lung cancer. In this study, we examined the association between C-reactive protein (CRP) and lung cancer in a prospective cohort study and used Mendelian randomization (MR) to clarify the causality. We included 420 977 participants from the UK Biobank (UKB) in the analyses; 1892 thereof were diagnosed with lung cancer during the follow-up. Hazards ratios (HRs) of CRP concentrations were estimated by Cox proportional hazard models and two approaches of MR analysis were performed. Besides, we added CRP concentrations to epidemiological model of lung cancer to evaluate its prediagnostic role through time-dependent receiver operating characteristic curve analysis. Elevated CRP levels were associated with a 22% increased lung cancer risk per 1 SD increase (HR = 1.22, 95% confidence interval [CI] = 1.18-1.26). Positive associations were observed in small cell lung cancer (HR = 1.21, 95% CI = 1.10-1.33), lung adenocarcinoma (HR = 1.17, 95% CI = 1.11-1.23) and lung squamous cell carcinoma (HR = 1.22, 95% CI = 1.14-1.31). No genetical association of circulating CRP levels and lung cancer risk was observed in MR analysis. When added to a risk model of lung cancer, CRP improved the performance of model as long as 8 years among current smokers (basic model: C-statistic = 0.78 [95% CI = 0.75-0.80]; CRP model: C-statistic = 0.79 [95% CI = 0.76-0.81]; Pnonadjusted  = .003, Padjusted  = .014). Our results did not support the causal association of circulating CRP with lung cancer risk. However, circulating CRP could be a prediagnostic marker of lung cancer as long as 8 years in advance for current smokers.

New Far-Red and Near-Infrared Fluorescent Phycobiliproteins with Excellent Brightness and Photostability.

Far-red and near-infrared fluorescent proteins can be used as fluorescence biomarkers in the region of maximal transmission of most tissues and facilitate multiplexing. Recently, we reported the generation and properties of far-red and near-infrared fluorescent phycobiliproteins, termed BeiDou Fluorescent Proteins (BDFPs), which can covalently bind the more readily accessible biliverdin. Far-red BDFPs maximally fluoresce at ∼670 nm, while near-infrared BDFPs fluoresce at ∼710 nm. In this work, we molecularly evolved BDFPs as follows: (a) mutations L58Q, S68R and M81K of BDFPs, which can maximally enhance the effective brightness in vivo by 350 %; (b) minimization and monomerization of far-red BDFPs 2.1, 2.2, 2.3, and near-infrared BDFPs 2.4, 2.5 and 2.6. These newly developed BDFPs are remarkably brighter than the formerly reported far-red and near-infrared fluorescent proteins. Their advantages are demonstrated by biolabeling in mammalian cells using super-resolution microscopy.

Functional characterization and clinical significance of super-enhancers in lung adenocarcinoma.

Super-enhancers (SEs) are important transcriptional regulators in tumorigenesis; however, the functional characterization and clinical significance of SEs in lung adenocarcinoma (LUAD) remain unclear. By using H3K27ac ChIP-seq data of two LUAD cell lines and eight lung tissues, we detected 1045 cancer-specific and 5032 normal-specific SEs. Compared to normal-specific SEs, cancer-specific SEs have different regulatory mechanisms where associated target genes were enriched in critical tumor-related pathways and tended to be regulated by transcription factors of Fos Proto-Oncogene, AP-1 Transcription Factor Subunit and Jun Proto-Oncogene, AP-1 Transcription Factor Subunit families. By using expression data of 513 LUAD and 57 adjacent samples from The Cancer Genome Atlas and 80 tumor-normal paired LUAD samples from the Nanjing Lung Cancer Cohort study, we performed differential expression analysis of target genes for SEs and defined 243 crucial SEs. Unsupervised clustering of crucial SEs revealed two subtypes with different levels of genomic aberrations (i.e., mutation and copy number alteration) and clinical outcomes (progression-free interval: p = 0.030; disease-free interval: p = 0.047). In addition, patients with adverse clinical outcomes were more sensitive to three small molecule inhibitors (bortezomib, doxorubicin, and etoposide), and their targets (PSMB5 and TOP2A) also have elevated expression levels among these patients. Taken together, our findings provided a comprehensive characterization of SEs in LUAD and emphasized their clinical significance in LUAD therapy.

Air Pollution, Genetic Factors, and the Risk of Lung Cancer: A Prospective Study in the UK Biobank.

Rationale: Both genetic and environmental factors contribute to lung cancer, but the degree to which air pollution modifies the impact of genetic susceptibility on lung cancer remains unknown. Objectives: To investigate whether air pollution and genetic factors jointly contribute to incident lung cancer. Methods: We analyzed data from 455,974 participants (53% women) without previous cancer at baseline in the UK Biobank. The concentrations of particulate matter (PM) (PM ⩽2.5 µm in aerodynamic diameter [PM2.5], coarse PM between 2.5 µm and 10 µm in aerodynamic diameter [PMcoarse], and PM ⩽10 µm in aerodynamic diameter [PM10]), nitrogen dioxide (NO2), and nitrogen oxides (NOx) were estimated by using land-use regression models, and the association between air pollutants and incident lung cancer was investigated by using a Cox proportional hazard model. Furthermore, we constructed a polygenic risk score and evaluated whether air pollutants modified the effect of genetic susceptibility on the development of lung cancer. Measurements and Main Results: The results showed significant associations between the risk of lung cancer and PM2.5 (hazard ratio [HR], 1.63; 95% confidence interval [CI], 1.33-2.01; per 5 µg/m3), PM10 (HR, 1.53; 95% CI, 1.20-1.96; per 10 µg/m3), NO2 (HR, 1.10; 95% CI, 1.05-1.15; per 10 µg/m3), and NOx (HR, 1.13; 95% CI, 1.07-1.18; per 20 µg/m3). There were additive interactions between air pollutants and the genetic risk. Compared with participants with low genetic risk and low air pollution exposure, those with high air pollution exposure and high genetic risk had the highest risk of lung cancer (PM2.5: HR, 1.71; 95% CI, 1.45-2.02; PM10: HR, 1.77; 95% CI, 1.50-2.10; NO2: HR, 1.77; 95% CI, 1.42-2.22; NOx: HR, 1.67; 95% CI, 1.43-1.95). Conclusions: Long-term exposure to air pollution may increase the risk of lung cancer, especially in those with high genetic risk.

Genome-wide gene-smoking interaction study identified novel susceptibility loci for non-small cell lung cancer in Chinese populations.

Gene-smoking interactions play important roles in the development of non-small cell lung cancer (NSCLC). To identify single-nucleotide polymorphisms (SNPs) that modify the association of smoking behavior with NSCLC risk, we conducted a genome-wide gene-smoking interaction study in Chinese populations. The genome-wide interaction analysis between SNPs and smoking status (ever- versus never-smokers) was carried out using genome-wide association studies of NSCLC, which included 13 327 cases and 13 328 controls. Stratified analysis by histological subtypes was also conducted. We used a genome-wide significance threshold of 5 × 10-8 for identifying significant gene-smoking interactions and 1 × 10-6 for identifying suggestive results. Functional annotation was performed to identify potential functional SNPs and target genes. We identified three novel loci with significant or suggestive gene-smoking interaction. For NSCLC, the interaction between rs2746087 (20q11.23) and smoking status reached genome-wide significance threshold [odds ratio (OR) = 0.63, 95% confidence interval (CI): 0.54-0.74, P = 3.31 × 10-8], and the interaction between rs11912498 (22q12.1) and smoking status reached suggestive significance threshold (OR = 0.72, 95% CI: 0.63-0.82, P = 8.10 × 10-7). Stratified analysis by histological subtypes identified suggestive interactions between rs459724 (5q11.2) and smoking status (OR = 0.61, 95% CI: 0.51-0.73, P = 7.55 × 10-8) in the risk of lung squamous cell carcinoma. Functional annotation indicated that both classic and novel biological processes, including nicotine addiction and airway clearance, may modulate the susceptibility to NSCLC. These novel loci provide new insights into the biological mechanisms underlying NSCLC risk. Independent replication in large-scale studies is needed and experimental studies are warranted to functionally validate these associations.

PLAC8, a new marker for human interstitial extravillous trophoblast cells, promotes their invasion and migration.

Proper differentiation of trophoblast cells in the human placenta is a prerequisite for a successful pregnancy, and dysregulation of this process may lead to malignant pregnancy outcomes, such as preeclampsia. Finding specific markers for different types of trophoblast cells is essential for understanding trophoblast differentiation. Here, we report that placenta-specific protein 8 (PLAC8) is specifically expressed in the interstitial extravillous trophoblast cells (iEVTs) on the fetomaternal interface. Using model systems, including placental villi-decidua co-culture, iEVTs induction by using primary trophoblast cells or explants, etc., we found that PLAC8 promotes invasion and migration of iEVTs. Mechanistically, time-lapse imaging, GTPase activity assay, co-immunoprecipitation and RNA-seq studies show that PLAC8 increases the Cdc42 and Rac1 activities, and further induces the formation of filopodia at the leading edge of the migratory trophoblast cells. More interestingly, PLAC8 is significantly upregulated under hypoxia and expression of PLAC8 is higher in iEVTs from preeclamptic placentas when compared with those from the normal control placentas. Together, PLAC8 is a new marker for iEVTs and plays an important role in promoting trophoblast invasion and migration.

Tracing the origin of the placental trophoblast cells in mouse embryo development†.

The placenta, which originates from the trophectoderm (TE), is the first organ to form during mammalian embryogenesis. Recent studies based on bioinformatics analysis have revealed that heterogeneous gene expression initiates cell-fate decisions and directs two distinct cell fates by modulating the balance of pluripotency and differentiation as early as the four-cell stage. However, direct developmental evidence to support this is still lacking. To address at which stage the cell fate of the TE and inner cell mass (ICM) is determined, in this study, we administered a microinjection of Cre mRNA into a single blastomere of the mTmG mouse at different cleavage stages before implantation to examine the distributions of the descendants of the single-labeled cell in the mouse fetus and the placenta at E12.5. We found that the descendants of the labeled cells at the two-cell stage contributed to both the placenta and the fetus. Notably, the derivatives of the labeled cells at the four-cell stage fell into three categories: (1) distributed in both embryonic and extraembryonic lineages, (2) distributed only in mouse placental trophoblast layers, or (3) distributed only in the lineage derived from the ICM. In addition, these results fell in line with single-cell studies focusing on gene expression patterns that characterize particular lineages within the blastocyst. In conclusion, this study shows that the four-cell blastomeres differ in their individual developmental properties insofar as they contribute to either or both the ICM and trophoblast fate.

Very Bright Phycoerythrobilin Chromophore for Fluorescence Biolabeling.

Biliproteins have extended the spectral range of fluorescent proteins into the far-red (FR) and near-infrared (NIR) regions. These FR and NIR fluorescent proteins are suitable for the bioimaging of mammalian tissues and are indispensable for multiplex labeling. Their application, however, presents considerable challenges in increasing their brightness, while maintaining emission in FR regions and oligomerization of monomers. Two fluorescent biliprotein triads, termed BDFP1.2/1.6:3.3:1.2/1.6, are reported. In mammalian cells, these triads not only have extremely high brightness in the FR region, but also have monomeric oligomerization. The BDFP1.2 and BDFP1.6 domains covalently bind to biliverdin, which is accessible in most cells. The BDFP3.3 domain noncovalently binds phycoerythrobilin that is added externally. A new method of replacing phycoerythrobilin with proteolytically digested BDFP3.3 facilitates this labeling. BDFP3.3 has a very high fluorescence quantum yield of 66 %, with maximal absorbance at λ=608 nm and fluorescence at λ=619 nm. In BDFP1.2/1.6:3.3:1.2/1.6, the excitation energy that is absorbed in the red region by phycoerythrobilin in the BDFP3.3 domain is transferred to biliverdin in the two BDFP1.2 or BDFP1.6 domains and fluoresces at λ≈670 nm. The combination of BDFP3.3 and BDFP1.2/1.6:3.3:1.2/1.6 can realize dual-color labeling. Labeling various proteins by fusion to these new fluorescent biliproteins is demonstrated in prokaryotic and mammalian cells.