Synthetic robust perfect adaptation achieved by negative feedback coupling with linear weak positive feedback

Unlike their natural counterparts, synthetic genetic circuits are usually fragile in the face of environmental perturbations and genetic mutations. Several theoretical robust genetic circuits have been designed, but their performance under real-world conditions has not yet been carefully evaluated. Here, we designed and synthesized a new robust perfect adaptation circuit composed of two-node negative feedback coupling with linear positive feedback on the buffer node. As a key feature, the linear positive feedback was fine-tuned to evaluate its necessity. We found that the desired function was robustly achieved when genetic parameters were varied by systematically perturbing all interacting parts within the topology, and the necessity of the completeness of the topological structures was evaluated by destroying key circuit features. Furthermore, different environmental perturbances were imposed onto the circuit by changing growth rates, carbon metabolic strategies and even chassis cells, and the designed perfect adaptation function was still achieved under all conditions. The successful design of a robust perfect adaptation circuit indicated that the top-down design strategy is capable of predictably guiding bottom-up engineering for robust genetic circuits. This robust adaptation circuit could be integrated as a motif into more complex circuits to robustly implement more sophisticated and critical biological functions.     

Paclitaxel treatment enhances lymphatic metastasis of B16F10 melanoma cells via CCL21/CCR7 axis

Chemotherapeutic drugs have been successfully used to treat several cancers, including melanoma. However, metastasis occasionally occurs after chemotherapy. Here, we reported that paclitaxel (PTX) treatment for B16F10 tumour in mice led to an enhanced lymphatic metastasis of the melanoma cells, although a significant inhibition of tumour growth at the injection site was observed. Further study demonstrated that PTX upregulated the expression of C-C chemokine receptor type 7 (CCR7) in B16F10 cells, enhancing their migration through the activation of JNK and p38 signalling pathways. Loss of CCR7 or blockade of C-C motif chemokine ligand 21 (CCL21)/CCR7 axis abolished the pro-migration effect of PTX on B16F10 melanoma cells. Importantly, combination of PTX and CCR7 mAb could simultaneously delay the tumour growth and reduce the lymphatic metastasis in B16F10 melanoma. The blockade of CCL21/CCR7 axis may collectively serve as a strategy for lymphatic metastasis in some melanoma after chemotherapy.     

新疆多年生小麦族植物染色体数的观察

本文对1987年采集于新疆的多年生小麦族(Triticeae Dum. )属种进行了细胞学观察。该地区多年生小麦族各属种的染色体数目变化范围是从2n=14到2n=84,前者主要存在于大麦属(Hordeum)、新麦草属(Psathyrostachys),而后者全部集中于赖草属(Leymus).其中染色体数目为2n=28和2n=42的频率最高,主要存在于鹅冠草属(Roegneria)和披碱草属(Elymus)。Roegneria gobicola, Roegneria kuqaensis, Roegneria tahelacona, Roegneria zhoasuensis的染色体数为首次报道。     

Stearoyl-CoA Desaturase-1 dependent lipid droplets accumulation in cancer-associated fibroblasts facilitates the progression of lung cancer

Rationale: Cancer-associated fibroblasts (CAFs) are the main components in the tumor microenvironment (TME) and facilitate lung cancer progression. Studies have reported that metabolic reprogramming can regulate the function of CAFs, especially abnormal lipid metabolism. Lipid droplets (LDs) are ubiquitous organelles that store neutral lipids and have a crucial role in lipid metabolism. However, little is known about the synthesis and functions of LDs in lung CAFs.Methods: TetO-EGFR^L858R; CCSP-rtTA transgenic mouse model was used to establish a spontaneous pulmonary tumor model and investigate the accumulation of LDs in CAFs. The effect of LDs accumulation on the phenotype change of fibroblasts was estimated in vitro using mouse fibroblast cell lines. RNA sequencing, Western blotting, RT-PCR, and DNA-pull down were performed to determine the mechanism of LDs synthesis in fibroblasts.Results: We found that LDs were enriched in lung CAFs and induced the pro-tumoral phenotype of CAFs with increased expression of α-smooth muscle actin (α-SMA) and Collagen alpha-2 (I) chain (COL1A2). As the main regulator, hypoxia-inducible factor-1α (HIF-1α) was highly expressed in activated fibroblasts and increased the content of LDs. RNA-sequencing results showed that Stearoyl-CoA Desaturase1 (SCD1) was a downstream gene of HIF-1α, which upregulated the number of LDs in fibroblasts. Importantly, SCD1 inhibition reduced the growth of lung tumors, which was correlated with LDs decrease in CAFs. Analysis of human lung adenocarcinoma tissue chip revealed that CAFs with a high level of SCD1 were positively correlated with the expression of HIF-1α and poor survival in lung cancer patients.Conclusions: The HIF-1α/SCD1 axis regulates the accumulation of LDs in CAFs, which might represent a novel target for lung cancer therapy.     

TMP195 Exerts Antitumor Effects on Colorectal Cancer by Promoting M1 Macrophages Polarization

Studies have shown that epigenetic enzymes such as histone deacetylase (HDAC) are closely related to cancers and that several HDAC inhibitors exert antitumor effects. Studies have further suggested that class IIa HDAC inhibitors are related to immune functions, including immune responses and the expression of chemokines and complement pathway components. TMP195, a selective class IIa HDAC inhibitor, has been reported to be effective against breast cancer. However, the role and mechanism of TMP195 in colorectal cancer remain unknown. In this study, we found that TMP195 significantly reduced the tumor burden in two mouse models of colitis-associated colorectal cancer (CAC) and subcutaneous tumor. Mechanistically, TMP195 decreased the proportion of total macrophages but increased the proportion of M1 macrophages by promoting polarization, resulting in the increased release of inflammatory cytokines. TMP195 had no direct effect on the proliferation of colorectal cancer cells, and its antitumor effect on the colorectal cancer disappeared when macrophages were partly depleted by clodronate liposomes. In addition, TMP195 enhanced the efficacy of PD-1 blockade. The present study revealed that the combination of TMP195 and PD-1 blockade may provide a therapeutic strategy for colorectal cancer.     

PINOCYTOSIS IN ROOT CAP CELLS EXPOSED TO URANYL SALTS

In cap cells of intact plant roots exposed to 1mM uranyl for 30 min or less, uranyl crystals were found only in cell walls and in secretory products which had been extruded from the protoplast. In roots exposed for 10–20 hr to 0.1mm uranyl, packets of uranyl crystals bound to secretory products were found within the protoplasts of those exterior cells which contained accumulations of secretory products between the cell wall and protoplast. Although the evidence indicated that these packets of crystals entered the protoplast pinocytotically, results with these specialized exterior cells did not apply to the vast majority of root cap cells in which, after prolonged exposure to 0.1mm uranyl, crystals were concentrated in vacuoles. In roots exposed to 1 or 5mm uranyl for 1 hr, the plasmalemma of interior cap cells was much thicker (13.1 nm) than normal (8.2 nm), and many invaginations and vesicular structures were found near the protoplast surface. Crystals were confined to cell walls except for a few found in vesicles with thickened membranes. Serial sections indicated that most vesicular structures with thickened membranes were in contact with the cell wall, but a few, including some which contained uranyl crystals, were within the protoplast. These results provide evidence of pinocytotic activity in intact plant cells exposed to a toxic heavy metal.     

Expression of maize Adh1 intron mutants in tobacco nuclei

In vivo and in vitro gene transfer experiments have suggested that the elements mediating intron recognition differ in mammalian, yeast and plant nuclei. Differences in the sequence dependencies, which also exist between dicotyledonous and monocotyledonous nuclei, have prevented some monocot introns from being spliced in dicot nuclei. To locate elements which modulate efficient recognition of introns in dicot nuclei, the maize Adh1 gene has been expressed in full-length and single intron constructs in Nicotiana benthamiana nuclei using an autonomously replicating plant expression vector. Quantitative PCR-Southern analyses indicate that the inefficient splicing of the maize Adh1 intron 1 (57% AU) in these dicot nuclei can be dramatically enhanced by increasing the degree of U1 snRNA complementarity at the 5′ splice site. This indicates that the 5′ splice site plays a significant role in defining the splicing efficiency of an intron in dicot nuclei and that, most importantly, the remainder of this monocot intron contains no elements which inhibit its accurate recognition in dicot nuclei. Deletions in intron 3 (66% AU) which effectively move the 3′ boundary between AU-rich intron and GC-rich exon sequences strongly activate a cryptic upstream splice site; those which do not reposition this boundary activate a downstream cryptic splice site. This suggests that 3′ splice site selection in dicot nuclei is extremely flexible and not dependent on strict sequence requirements but rather on the transition points between introns and exons. Our results are consistent with a model in which potential splice sites are selected if they are located upstream (5′ splice site) or downstream (3′ splice site) of AU transition points and not if they are embedded within AU-rich sequences.     

Quadruple therapy with vonoprazan 20 mg daily as a first-line treatment for Helicobacter pylori infection: A single-center,open-label,noninferiority, randomized controlled trial

Background

Although vonoprazan has been proven to be a highly potent drug for Helicobacter pylori eradication, there have been no randomized trials comparing the effectiveness of regimens containing vonoprazan 20 mg daily with alternative standard strategies. We aimed to assess the efficacy, tolerance, and cost-effectiveness of quadruple therapy with vonoprazan 20 mg daily as a first-line therapy for H. pylori eradication.

Materials and Methods

We conducted a single-center, open-label, noninferiority, randomized controlled study in Zhejiang, China. Treatment-naive H. pylori-positive participants (n = 234) were randomly assigned to three groups in a 1:1:1 ratio: vonoprazan 20 mg daily with amoxicillin 1000 mg, furazolidone 100 mg and colloidal bismuth 200 mg each given twice a day for 10 days (V10) or 14 days (V14), or esomeprazole 20 mg with amoxicillin 1000 mg, furazolidone 100 mg and colloidal bismuth 200 mg each given twice a day for 14 days (E14). The primary endpoint was the eradication rates in each group. The secondary endpoints were the incidence of adverse events (AEs) and compliance.

Results

The eradication rates in the V10, V14 and E14 groups were 96.2% (89.2–99.2%), 94.9% (87.4–98.6%), and 93.6% (85.7–97.9%) in the intention-to-treat analysis, and 98.6% (92.7–100.0%), 97.4% (90.8–99.7%), and 94.8% (87.2–98.6%) in the per-protocol analysis, respectively. Quadruple therapy with vonoprazan 20 mg daily was noninferior to the esomeprazole-based regimen (Farrington and Manning test: margin 10%, significance level 2.5%). The adverse event rates were 12.8% versus 3.8% versus 6.4% in the V10, V14, and E14 groups, respectively. All regimens were well tolerated without significant differences (p = 0.096). The cost-effectiveness ratio was 1.32, 1.88, and 3.06 for the V10, V14, and E14 groups in the intention-to-treat analysis, respectively. (NCT04907747).

Conclusions

Vonoprazan (20 mg daily) was as effective as esomeprazole (20 mg twice a day) in quadruple therapies for the eradication of H. pylori, was more economical, and was well tolerated. In addition, the 10-day regimen of vonoprazan (20 mg daily) was comparable to the 14-day regimen.