Development of an Escherichia coli whole cell biocatalyst for the production of hyperoside

Biotechnology Letters - To produce high concentrations of hyperoside from quercetin using recombinant Escherichia coli with in situ regeneration of UDP-galactose. Sucrose synthase from Glycine max...     

Recombinant jurkat cells (HMGN2-T cells) secrete cytokines and inhibit the growth of tumor cells

Journal of Molecular Histology - High Mobility Group Chromosomal Protein N2 (HMGN2) can recognize tumor cells and enhance the anti-tumor effect of immune cells. This study aimed to establish a...     

The IL-6–STAT3 axis mediates a reciprocal crosstalk between cancer-derived mesenchymal stem cells and neutrophils to synergistically prompt gastric cancer progression

Emerging evidence indicate that mesenchymal stem cells (MSCs) affect tumor progression by reshaping the tumor microenvironment. Neutrophils are essential component of the tumor microenvironment and are critically involved in cancer progression. Whether the phenotype and function of neutrophils is influenced by MSCs is not well understood. Herein, we investigated the interaction between neutrophils and gastric cancer-derived MSCs (GC-MSCs) and explored the biological role of this interaction. We found that GC-MSCs induced the chemotaxis of neutrophils and protected them from spontaneous apoptosis. Neutrophils were activated by the conditioned medium from GC-MSCs with increased expression of IL-8, TNFα, CCL2, and oncostatin M (OSM). GC-MSCs-primed neutrophils augmented the migration of gastric cancer cells in a cell contact-dependent manner but had minimal effect on gastric cancer cell proliferation. In addition, GC-MSCs-primed neutrophils prompted endothelial cells to form tube-like structure in vitro. We demonstrated that GC-MSCs stimulated the activation of STAT3 and ERK1/2 pathways in neutrophils, which was essential for the functions of activated neutrophils. We further revealed that GC-MSCs-derived IL-6 was responsible for the protection and activation of neutrophils. In turn, GC-MSCs-primed neutrophils induced the differentiation of normal MSCs into cancer-associated fibroblasts (CAFs). Collectively, our results suggest that GC-MSCs regulate the chemotaxis, survival, activation, and function of neutrophils in gastric cancer via an IL-6–STAT3–ERK1/2 signaling cascade. The reciprocal interaction between GC-MSCs and neutrophils presents a novel mechanism for the role of MSCs in remodeling cancer niche and provides a potential target for gastric cancer therapy.Accumulating evidence suggest that neutrophils are critical for cancer initiation and progression.^{1, 2} The increased presence of intratumoral neutrophils has been linked to a poorer prognosis for patients with renal cancer, hepatocellular carcinoma (HCC), melanoma, head and neck squamous cell carcinoma (HNSCC), pancreatic cancer, colorectal carcinoma, and gastric adenocarcinoma.³ Recent studies using murine tumor models or involving cancer patients have suggested an important functional role of neutrophils during tumor progression.^{4, 5, 6, 7} Neutrophils-derived factors promote genetic mutations leading to tumorigenesis or promote tumor cell proliferation,⁸ migration, and invasion.^{9, 10} Neutrophils have also been demonstrated to induce tumor vascularization by the production of pro-angiogenic factors^{11, 12}The infiltration of neutrophils into tumors has been shown to be mediated by factors produced by both tumor and stromal cells. Recent reports suggest that tumor cells actively modulate the functions of neutrophils. Tumor-derived CXCL5 modulates the chemotaxis of neutrophils, which in turn enhances the migration and invasion of human HCC cells.¹³ HNSCC cells-derived MIF induces the recruitment and activation of neutrophils through a p38-dependent manner.^{14, 15} Neutrophils respond to hyaluronan fragments in tumor supernatants via PI3K/Akt signaling, leading to prolonged survival and stimulating effect on HCC cell motility.¹⁶ Kuang et al.¹⁷ suggest that IL-17 promotes the migration of neutrophils into HCC through epithelial cell-derived CXC chemokines, resulting in increased MMP-9 production and angiogenesis at invading tumor edge However, much less is known about the role of stromal cells in modulating the phenotype and function of neutrophils in cancer thus far.Cancer-associated fibroblasts (CAFs) have a key role in cancer mainly through secretion of soluble factors, as growth factors or inflammatory mediators, as well as production of extracellular matrix proteins and their proteases. These activated fibroblasts are involved in creating a niche for cancer cells, promoting their proliferation, motility and chemoresistance. Activated fibroblasts express several mesenchymal markers such as α-smooth muscle actin (α-SMA), fibroblast activation protein (FAP), and vimentin. CAFs actively participate in reciprocal interaction with tumor cells and with other cell types in the microenvironment, contributing to a tumor-permissive niche and promoting tumor progression.Mesenchymal stem cells (MSCs) are adult stromal cells with self-renewal and pluripotent differentiation abilities. MSCs can be mobilized from bone marrow to the site of damage, respond to the local microenvironment, and exert wound repair and tissue regeneration functions upon injury and inflammation conditions.¹⁸ MSCs have been considered as one of the major components of the tumor stroma and are believed to be the precursors of CAFs.^{19, 20} We have previously demonstrated that human bone marrow MSCs prompt tumor growth in vivo.²¹ In addition, we have recently isolated MSCs-like cells from the gastric cancer tissues (GC) and the adjacent normal tissues (GCN) and shown that the gastric cancer-derived MSCs (GC-MSCs) possess the properties of CAFs.^{22, 23} As tumor-derived MSCs are often exposed to distinct inflammatory cells and factors in the tumor microenvironment, they may acquire novel functions that are not present in normal MSCs, and these unique functions may have a role in reshaping the tumor microenvironment and ultimately affect tumor progression. As neutrophils are key mediators of tumor progression and tumor angiogenesis, it is likely that an intense interaction may exist between the tumor-derived MSCs and tumor-infiltrating neutrophils.The emerging roles of CAFs in cancer immunoeditting led us to investigate whether GC-MSCs are able to regulate the phenotype and function of neutrophils in gastric cancer. We have shown that there is a reciprocal interaction between GC-MSCs and neutrophils. GC-MSCs enhanced the chemotaxis of peripheral blood-derived neutrophils and protected them from spontaneous apoptosis. GC-MSCs induced the activation of neutrophils to highly express IL-8, CCL2, TNFα, and oncostatin M (OSM), leading to the increase of gastric cancer cell migration and angiogenesis in vitro. GC-MSCs exerted this effect through the IL-6–STAT3–ERK1/2 signaling axis, and blockade of the IL-6–IL-6R interaction or pharmacological inhibition of STAT3 and ERK1/2 activation abrogated this role. In turn, GC-MSCs-activated neutrophils could trigger the CAF differentiation of normal MSCs. Therefore, these results establish a bi-directional interaction between GC-MSCs and neutrophils that may be critically involved in the progression of gastric cancer.     

El Tor型霍乱弧菌及其细胞壁缺陷型分子遗传学背景的研究

El Tor 型霍乱弧菌(以下简称 El Tor 弧菌)可以在人工培养条件下长期存活。当微环境改变时可形成细胞壁有不同程度缺陷的菌株如抗噬菌体突变株或 L 型菌株。我们以 DNA 酶切图谱和 El Tor 弧菌溶血素、神经氨酸酶基因探针杂交图谱为参数对 El Tor 弧菌的野生型及其细胞壁缺陷型变异株在遗传背景上进行了比较分析研究。结果提示细胞壁缺陷型菌株与其野生型在DNA 水平上高度同源。此外,文中还介绍了一种从 L 型菌株中制备 DNA 的方法。     

Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta.

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.     

藏山羊KLF8基因克隆及组织表达分析

本试验旨在获得藏山羊KLF8基因序列,并分析其生物学特征,同时阐明该基因在不同组织中的表达情况。利用RT-PCR技术克隆藏山羊KLF8基因序列,利用实时荧光定量PCR (quantitative real-time PCR,qPCR)检测其在藏山羊各个组织中的表达丰度。结果表明,获得藏山羊KLF8基因序列1 069 bp,其中包含CDS区1 008 bp,5'UTR序列28 bp和3'UTR序列33 bp,共编码335个氨基酸,为不稳定亲水碱性蛋白。KLF8基因在藏山羊的肺脏组织中表达水平最高,极显著高于其他组织(p<0.01)。本研究为进一步阐明KLF8基因在藏山羊中的生物学功能提供了依据。     

Proline fed to intact soybean plants influences acetylene reducing activity and content and metabolism of proline in bacteroids

Supplying l-proline to the root system of intact soybean (Glycine max [L.] Merr.) plants stimulated acetylene reducing activity to the same extent as did supplying succinate. Feeding l-proline also caused an increase in bacteroid proline dehydrogenase activity that was highly correlated with the increase in acetylene-reducing activity. Twenty-four hours after irrigating with l-proline, endogenous proline content had increased in host cell cytoplasm and bacteroids, about three- and eightfold, respectively. In bacteroids, proline concentration was calculated to be at least 3.5 millimolar. In experiments in which [U-¹⁴C]l-proline was supplied to uprooted, intact plants incubated in aerated solution, ¹⁴C-labeled products of proline metabolism, as well as [¹⁴C]proline itself, accumulated in both host cells and bacteroids. When plants were incubated in aerated solutions containing [5-³H]l-proline, ³H-labeled proline was found in host cells and bacteroids. [³H] Pyrroline-5-carboxylate was found in bacteroids, but not host cells, after a 2-hour incubation in [5-³H]l-proline. When [U-¹⁴C]l-proline was supplied for 24 hours, a significant amount of [¹⁴C] pyrroline-5-carboxylate was found in the host cells, in contrast with the results from the shorter incubation in [5-³H]proline, although the amount in the host cells was only about half the quantity found in the bacteroids. Taken as a whole, these results indicate that proline crosses both plant and bacterial membranes under the in vivo experimental conditions utilized and are consistent with a significant role for proline as an energy source in support of bacteroid functioning. In spite of the increase in acetylene-reducing activity when proline was supplied to the root system of intact plants, proline application did not rescue stemgirdled plants from loss of acetylene-reducing activity, although succinate application did. This suggests a nonphloem route for succinate, but not proline, from roots to nodules.