Epigenetic modifier trichostatin A enhanced osteogenic differentiation of mesenchymal stem cells by inhibiting NF-κB (p65) DNA binding and promoted periodontal repair in rats

We wished to evaluate whether epigenetic modifiers have a beneficial effect on treating experimental periodontitis and mechanisms for regulating the cell fate of mesenchymal stem cells (MSCs) in inflammatory microenvironments. We isolated MSCs from healthy and inflamed gingival tissues to investigate whether trichostatin A (TSA) could improve osteogenic differentiation and resolve inflammation in vitro. The tissue regenerative potentials were evaluated when treated with a temperature-dependent, chitosan-scaffold-encapsulated TSA, in a rat model of periodontitis. After induction with the conditioned medium, TSA treatment increased the osteogenic differentiation potential of inflamed MSCs and healthy MSCs. In addition, interleukin-6 and interleukin-8 levels in supernatants were significantly decreased after TSA treatment. Moreover, TSA promoted osteogenic differentiation by inhibiting nuclear factor-κB (p65) DNA binding in MSCs. In rats with experimental periodontitis, 7 weeks after local injections of chitosan-scaffold-encapsulated TSA, histology and microcomputed tomography showed a significant increase in alveolar bone volume and less inflammatory infiltration compared with vehicle-treated rats. The concentrations of interferon-γ and interleukin-6 were significantly decreased in the gingival crevicular fluid after TSA treatment. This study demonstrated that TSA had anti-inflammatory properties and could promote periodontal tissue repair, which indicated that epigenetic modifiers hold promise as a potential therapeutic option for periodontal tissue repair.     

p120-catenin suppresses proliferation and tumor growth of oral squamous cell carcinoma via inhibiting nuclear phospholipase C-γ1 signaling

p120-catenin (p120) serves as a stabilizer of the calcium-dependent cadherin-catenin complex and loss of p120 expression has been observed in several types of human cancers. The p120-dependent E-cadherin-β-catenin complex has been shown to mediate calcium-induced keratinocyte differentiation via inducing activation of plasma membrane phospholipase C-γ1 (PLC-γ1). On the other hand, PLC-γ1 has been shown to interact with phosphatidylinositol 3-kinase enhancer in the nucleus and plays a critical role in epidermal growth factor-induced proliferation of oral squamous cell carcinoma (OSCC) cells. To determine whether p120 suppresses OSCC proliferation and tumor growth via inhibiting PLC-γ1, we examined effects of p120 knockdown or p120 and PLC-γ1 double knockdown on proliferation of cultured OSCC cells and tumor growth in xenograft OSCC in mice. The results showed that knockdown of p120 reduced levels of PLC-γ1 in the plasma membrane and increased levels of PLC-γ1 and its signaling in the nucleus in OSCC cells and OSCC cell proliferation as well as xenograft OSCC tumor growth. However, double knockdown of p120 and PLC-γ1 or knockdown of PLC-γ1 alone did not have any effect. Immunohistochemical analysis of OSCC tissue from patients showed a lower expression level of p120 and a higher expression level of PLC-γ1 compared with that of adjacent noncancerous tissue. These data indicate that p120 suppresses OSCC cell proliferation and tumor growth by inhibiting signaling mediated by nuclear PLC-γ1.     

黑果枸杞不同组织内生细菌群落多样性

【目的】黑果枸杞是我国荒漠区特有的药用盐生植物,本研究分析了黑果枸杞不同组织中内生细菌群落多样性特征及分布规律。【方法】应用Illumina MiSeq高通量测序技术对黑果枸杞内生细菌的16S rRNAV5-V7区域序列进行测定,并分析群落组成、多样性及功能等生物学信息。【结果】黑果枸杞不同组织内生细菌群落多样性及功能均有较大的差异。花、叶、果、茎和根产生的OTUs分别是182、173、119、187和254,群落多样性表现为根花果、茎叶。从门水平上看,变形菌门是优势菌门,在不同组织中均有分布,花、叶、果、茎和根中的相对丰度分别为87.66%、41.51%、81.76%、97.67%和61.85%。在属水平上显示内生细菌的分布表现出器官差异性。花部能够准确分类的优势菌属为沙雷氏菌属和不动杆菌属,相对丰度分别为11.57%和8.55%。叶部为红球菌属和慢生根瘤菌属,相对丰度分别为29.68%和5.53%。果实中为泛菌属、红球菌属和沙雷氏菌属,相对丰度分别为23.12%、5.52%和4.29%。茎部为沙雷氏菌属和假单胞菌属,相对丰度分别为12.03%和17.71%。根部为盐单胞菌属、Fodinicurvata和Lipingzhangella,相对丰度分别为24.18%、5.16%和4.86%。在不同组织中分布较广的盐单胞菌、沙雷氏菌、不动杆菌、红球菌、泛菌等菌属均具有较高耐盐性和促生、生防、降解有机污染物及抗氧化等功能。PICRUSt功能预测分析显示,黑果枸杞组织中内生细菌功能中涉及丰富的多糖、萜类和酮类、酶及维他命等次生代谢产物的生物合成。【结论】黑果枸杞内生细菌具有丰富的群落和功能多样性,拥有多种益生功能性状,也含有多个与人和植物体代谢相关的功能信息。不同组织优势菌属和功能信息各有不同,其中根部的内生细菌物种最丰富,花部和茎部参与各种代谢调控的细菌丰度最高。此外,不同组织中还含有大量未知种属的微生物类群,这些都为内生细菌功能利用和挖掘新的有益微生物资源提供广阔的发展空间。     

马里亚纳海沟可培养水生细菌的多样性

【目的】马里亚纳海沟是地球表面最深的海沟,环境极端多样,如高压、低温及无光,拥有独特的微生物资源。本研究旨在探究马里亚纳海沟不同深度水生细菌形态特征并挖掘可培养细菌资源。【方法】采集马里亚纳海沟7个层位海水(2–8727 m),利用原子力显微镜与扫描电镜观察水生微生物的形态特征;采用2种常规培养基(1/5×2216E和1/30×2216E)及6种选择性培养基(有机碳氮组合),结合切向流与高压富集培养进行水生细菌分离与鉴定。【结果】从不同深度水样中发现多种大小不一的细菌类群(130 nm–1.5μm),以球菌和杆菌为主。在表层水体中常见颗粒附着的细菌,在深层水体中常见自由游动的细菌。共鉴定365株可培养水生细菌,隶属于3个门、31个属与56个种。γ-变形菌纲(Gammaproteobacteria)是绝对优势类群(占据可培养细菌总数的62.7%),相对丰度在深层水体中高于浅层。交替单胞菌属(Alteromonas,21.8%)和亚硫酸杆菌属(Sulfitobacter,19.1%)是主要优势属,在浅层水体中占绝对优势。稀释的2216E与氨基酸培养基对海杆菌属的选择性更好,葡萄糖-甘露糖培养基与牛磺酸-乙醇酸培养基对稀有细菌的选择性更好。7株菌(5种)是潜在的新型细菌。此外,通过切向流富集培养与压力筛选培养分别分离得到70株(22属)可通过0.22-μm细菌(0.22-μm-passable bacteria)与33株(8属)耐压细菌。【结论】马里亚纳海沟不同深度水样中不同营养利用型细菌、可通过0.22-μm细菌与耐压细菌及其形态均具有丰富的多样性。本研究所获得的不同类型的细菌菌株为研究细菌在马里亚纳海沟中生物地球化学功能及其营养类型差异和高压适应机制奠定了菌株基础。     

地毯草黄单胞菌双组分系统VgrS-VgrR基因敲除及表型筛选

【目的】研究地毯草黄单胞菌双组分系统VgrS-VgrR与致病性的关系,为木薯细菌性病害的高效防控提供分子生物学证据。【方法】采用同源重组方法构建vgrS和vgrR的插入失活突变体,用可移动的cosmid载体p HM1构建互补菌株。检测突变体的致病性、细菌游动性、胞外酶、胞外多糖的变化,观察细菌对H_2O_2和金属离子胁迫的反应。【结果】相比野生型菌株,vgrS和vgrR突变体接种寄主植物木薯后致病力显著降低,突变体的游动性减少、蛋白酶活性减弱、H_2O_2耐受性降低,在高浓度金属离子Fe²⁺、Fe³⁺、Cu²⁺、Ni²⁺、Zn²⁺、Co²⁺的胁迫条件下菌体生长显著减弱。然而,vgrS和vgrR突变体的胞外多糖含量显著升高,分别是野生型的2.14和1.89倍。【结论】阐明了VgrS-VgrR系统在细菌致病过程中发挥的重要作用,为鉴定VgrS-VgrR调控机制提供线索,为药物筛选提供靶向目标。     

Are cultured human myotubes far from home?

Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent a model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system are that the most relevant genetic background is available for the investigation of human disease (as opposed to rodent cell cultures), the extracellular environment can be precisely controlled and the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor. Limitations in differentiation status (fiber type) of the cells and energy metabolism can be improved by proper treatment, such as electrical pulse stimulation to mimic exercise. This review focuses on the way that human myotubes can be employed as a tool for studying metabolism in skeletal muscles, with special attention to changes in muscle energy metabolism in obesity and type 2 diabetes.     

Human serum albumin from recombinant DNA technology: Challenges and strategies

Background

As the most abundant protein in the blood, human serum albumin (HSA) plays an important role in maintaining plasma oncotic pressure and fluid balance between the body's compartments. HSA is thus widely used in the clinic to treat diseases. However, the shortage of and safety issues arising from using plasma HSA (pHSA) underscore the importance of recombinant HSA (rHSA) as a promising substitute for pHSA.

Scope of review

Here, we review the production of rHSA, from expression to downstream processing, and highlight the scalability and cost-effectiveness of the two main expression platforms. We also discuss the biosafety of commercially available pharmaceutical rHSA with respect to impurities and contaminants, followed by an analysis of recent progress in preclinical and clinical trials. We emphasise the challenges of producing pharmaceutical-grade rHSA.

Major conclusions

rHSA can be highly expressed in various hosts and seems to be identical to pHSA. rHSA generated from yeast appears to be as efficient and safe as pHSA in a series of preclinical and clinical trials, whereas rHSA from rice seeds exhibits great potential for more cost-effective production. Cost-effective products with no adverse effects will likely play a vital role in future human therapeutics.

General significance

Our understanding of pharmaceutical-grade rHSA production has improved with respect to expression hosts, biochemical properties, downstream processing, and the detection and removal of impurities. However, due to the large dosages required for clinical applications, the production of sufficient quantities of rHSA still presents challenges. This article is part of a Special Issue entitled Serum Albumin.     

Dissecting the in vivo assembly of the 30S ribosomal subunit reveals the role of RimM and general features of the assembly process

Ribosome biogenesis is a tightly regulated, multi-stepped process. The assembly of ribosomal subunits is a central step of the complex biogenesis process, involving nearly 30 protein factors in vivo in bacteria. Although the assembly process has been extensively studied in vitro for over 40 years, very limited information is known for the in vivo process and specific roles of assembly factors. Such an example is ribosome maturation factor M (RimM), a factor involved in the late-stage assembly of the 30S subunit. Here, we combined quantitative mass spectrometry and cryo-electron microscopy to characterize the in vivo 30S assembly intermediates isolated from mutant Escherichia coli strains with genes for assembly factors deleted. Our compositional and structural data show that the assembly of the 3′-domain of the 30S subunit is severely delayed in these intermediates, featured with highly underrepresented 3′-domain proteins and large conformational difference compared with the mature 30S subunit. Further analysis indicates that RimM functions not only to promote the assembly of a few 3′-domain proteins but also to stabilize the rRNA tertiary structure. More importantly, this study reveals intriguing similarities and dissimilarities between the in vitro and the in vivo assembly pathways, suggesting that they are in general similar but with subtle differences.     

Stimulation of σ1-receptor restores abnormal mitochondrial Ca mobilization and ATP production following cardiac hypertrophy

Background

We previously reported that the σ₁-receptor (σ₁R) is down-regulated following cardiac hypertrophy and dysfunction in transverse aortic constriction (TAC) mice. Here we address how σ₁R stimulation with the selective σ₁R agonist SA4503 restores hypertrophy-induced cardiac dysfunction through σ₁R localized in the sarcoplasmic reticulum (SR).

Methods

We first confirmed anti-hypertrophic effects of SA4503 (0.1–1 μM) in cultured cardiomyocytes exposed to angiotensin II (Ang II). Then, to confirm the ameliorative effects of σ₁R stimulation in vivo, we administered SA4503 (1.0 mg/kg) and the σ₁R antagonist NE-100 (1.0 mg/kg) orally to TAC mice for 4 weeks (once daily).

Results

σ₁R stimulation with SA4503 significantly inhibited Ang II-induced cardiomyocyte hypertrophy. Ang II exposure for 72 h impaired phenylephrine (PE)-induced Ca^2 + mobilization from the SR into both the cytosol and mitochondria. Treatment of cardiomyocytes with SA4503 largely restored PE-induced Ca^2 + mobilization into mitochondria. Exposure of cardiomyocytes to Ang II for 72 h decreased basal ATP content and PE-induced ATP production concomitant with reduced mitochondrial size, while SA4503 treatment completely restored ATP production and mitochondrial size. Pretreatment with NE-100 or siRNA abolished these effects. Chronic SA4503 administration also significantly attenuated myocardial hypertrophy and restored ATP production in TAC mice. SA4503 administration also decreased hypertrophy-induced impairments in LV contractile function.

Conclusions

σ₁R stimulation with the specific agonist SA4503 ameliorates cardiac hypertrophy and dysfunction by restoring both mitochondrial Ca^2 + mobilization and ATP production via σ₁R stimulation.

General significance

Our observations suggest that σ₁R stimulation represents a new therapeutic strategy to rescue the heart from hypertrophic dysfunction.