Histochemical examination of cathepsin K,MMP1 and MMP2 in compressed periodontal ligament during orthodontic tooth movement in periostin deficient mice

The purpose of this study was to investigate immunolocalization of collagenolytic enzymes including cathepsin K, matrix metalloproteinase (MMP) 1 and 2 in the compressed periodontal ligament (PDL) during orthodontic tooth movement using a periostin deficient (Pn-/-) mouse model. Twelve-week-old male mice homozygous for the disrupted periostin gene and their wild type (WT) littermates were used in these experiments. The tooth movement was performed according to Waldo’s method, in which elastic bands of 0.5 mm thickness were inserted between the first and second upper molars of mice under anesthesia. At 1 and 3 days after orthodontic force application, mice were fixed with transcardial perfusion of 4 % paraformaldehyde in 0.1 M phosphate buffer (pH 7.4), and the first molars and peripheral alveolar bones were extracted for histochemical analyses. Compared with WT mice, immunolocalization of cathepsin K, MMP1 and MMP2 was significantly decreased at 1 and 3 days after orthodontic tooth movement in the compressed PDL of Pn-/- mice, although MMP1-reactivity and MMP2-reactivity decreased at different amounts. Very little cathepsin K-immunoreactivity was observed in the assessed regions of Pn-/- mice, both before and after orthodontic force application. Furthermore, Pn-/- mice showed a much wider residual PDL than WT mice. Taken together, we concluded that periostin plays an essential role in the function of collagenolytic enzymes like cathepsin K, MMP1 and MMP2 in the compressed PDL after orthodontic force application.     

Adipoparacrinology--vascular periadventitial adipose tissue (tunica adiposa) as an example

Human adipose tissue is partitioned into two large depots (subcutaneous and visceral), and many small depots associated with internal organs, e.g. heart, blood vessels, major lymph nodes, pancreas, prostate gland and ovaries. Since the adipose 'Big Bang' led to the discovery of leptin (Zhang, Proenca, Maffei, Barone, Leopold and Friedman, Nature 1994;372:425-32), adipose tissue has been seen not merely as a lipid store, but as a secretory - endocrine and paracrine - organ, particularly in the pathogenesis of a number of diseases. Accordingly, two major sub-fields of adipobiology have emerged, viz. adipoendocrinology and adipoparacrinology, the latter herein being illustrated by PAAT (periadventitial adipose tissue) in vascular walls. A long-standing paradigm holds that the vascular wall consists of three coats, tunica intima, tunica media and tunica adventitia. It is now imperative that 'to further elucidate vascular function, we should no longer, as hitherto, separate adventitia and PAAT from the vascular wall, but keep them attached and in place, and subject to thorough examination' (Chaldakov, Fiore, Ghenev, Stankulov and Aloe, Int Med J 2000;7:43-9; Chaldakov, Stankulov and Aloe, Atherosclerosis 2001;154:237-8; Chaldakov GN, Stankulov IS, Fiore M, Ghenev PI and Aloe L, Atherosclerosis 2001;159:57-66). From the available data, we propose that it is time to rethink about vascular wall composition, and suggest that the PAAT may be considered the fourth and outermost vascular coat, hence, tunica adiposa (regarding the proximal segment of coronary artery, it is the innermost part of the EAT (epicardial adipose tissue) situated around the coronary adventitia). Its significance in the pathogenesis and therapy of CMDs (cardiometabolic diseases), particularly atherosclerosis and hypertension, requires further basic, translational and clinical studies.     

慢性缺氧对大鼠肺内皮素表达的影响

本文以ＡＢＣ法和原位杂交技术,观察了慢性缺氧时大鼠肺组织内内皮素－１（ＥＴ－１）的表达情况,结果发现：①正常肺血管内皮细胞有少许ＥＴ－１样阳性染色物质呈现。②缺氧ＩＷ后,肺内ＥＴ－１含量增加,主要位于肺血管内皮细胞和支气管粘膜上皮细胞。③缺氧２Ｗ和３Ｗ后,ＥＴ１阳性免疫物质进一步增加,于肺泡细胞内也见到阳性染色。④缺氧１Ｗ后肺内ＥＴ－１ｍＲＮＡ表达增加,缺氧２Ｗ和３Ｗ后,ＥＴ－１ｍＲＮＡ的表达进一步加强。提示缺氧可刺激肺内ＥＴ－１ｍＲＮＡ的表达,慢性缺氧时肺内ＥＴ－１持续分泌增加,这可能是缺氧性肺动脉高压发生的重要因素之一。     

The roles of autophagy in development and stress responses in Arabidopsis thaliana

Autophagy is a dynamic process that involves the recycling process of the degradation of intracellular materials. Over the past decade, our molecular and physiological understanding of plant autophagy has greatly been increased. Most essential autophagic machineries are conserved from yeast to plants. The roles that autophagy-related genes (ATGs) family play in the lifecycle of the Arabidopsis are proved to be similar to that in mammal. Autophagy is activated during certain stages of development, senescence or in response to starvation, or environmental stress in Arabidopsis. In the progression of autophagy, ATGs act as central signaling regulators and could develop sophisticated mechanisms to survive when plants are suffering unfavorable environments. It will facilitate further understanding of the molecular mechanisms of autophagy in plant. In this review, we will discuss recent advances in our understanding of autophagy in Arabidopsis, areas of controversy, and highlight potential future directions in autophagy research.     

Transformation from Organo-Cr (III) to Trivalent Chromium Mineral (Guyanaite/Grimaldiite) and its Environmental Implication

Remediation of heavy-metal contamination by biomineralization has become an environmentally very important issue in the last two decades. Here we describe the transformation of amorphous organo-Cr(III) to chromium hydroxide oxide (guyanaite/grimaldiite) by hydrothermal treatment (HTT). First, glycine-Cr(III) was synthesized to serve as a simple model for exploring the conditions favoring HTT. Cell-bound Cr(III) was obtained by the reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] by Bacillus cereus. Then the reduced Cr(III) was chelated by ligands at the cell surface, forming cell-bound Cr(III). Subsequently, HTT was applied to treat cell-bound Cr(III) at different temperatures and for different lengths of time. The results showed that, by this treatment at 200°C for 7 days or at 250°C for 1 day, glycine-Cr(III) was converted to trivalent chromium mineral (guyanaite/grimaldiite), having the form of nanosheets with a length of 10～20 nm and a width of 3～5 nm under the described conditions. Cell-bound Cr(III) could also be converted to guyanaite/grimaldiite at 250°C for 9 days if it was bound by an organic compound more complex than glycine. Our finding showed that organo-Cr(III) could be transformed into minerals by an appropriate hydrothermal process, which is applicable to bioremediation of heavy-metal pollution. Our findings also suggest that organo-Cr(III) may play an important role in the biogeochemistry of chromium.     

MicroRNA-27a Negatively Modulates the Inflammatory Response in Lipopolysaccharide-Stimulated Microglia by Targeting TLR4 and IRAK4

microRNA, a family of small non-coding RNA, plays significant roles in regulating gene expression, mainly via binding to the 3′-untranslated region of target genes. Although the role of miRNA in regulating neuroinflammation via the innate immune pathway has been studied, its role in the production of inflammatory mediators during microglial activation is poorly understood. In this study, we investigated the effect of miR-27a on lipopolysaccharide (LPS)-induced microglial inflammation. miR-27a expression was found to be rapidly decreased in microglia by real-time polymerase chain reaction (real-time PCR) after LPS stimulation. Over-expression of miR-27a significantly decreased the production of inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nitric oxide (NO), whereas knockdown of miR-27a increased the expression of these inflammatory factors. We also demonstrated by loss- and gain-of-function studies that miR-27a directly suppressed the expression of toll-like receptor 4 (TLR4) and interleukin-1 receptor-associated kinase 4 (IRAK4)—a pivotal adaptor kinase in the TLR4/MyD88 signaling pathway—by directly binding their 3′-UTRs: knocking down TLR4 or IRAK4 in microglia significantly decreased TLR4 or IRAK4 expression and inhibited the downstream production of inflammatory mediators. Moreover, the inflammatory cytokines IL-6 and IL-1β were regulated by IRAK4, whereas TNF-α and NO were more dependent on TLR4 activation. Thus, miR-27a might regulate the LPS-induced production of inflammatory cytokines in microglia independently of TLR4 and IRAK4. Taken together, our results suggest that miR-27a is associated with microglial activation and the inflammatory response.     

Rational design of cationic antimicrobial peptides by the tandem of leucine-rich repeat

Antimicrobial peptides represent ancient host defense effector molecules present in organisms across the evolutionary spectrum. Lots of antimicrobial peptides were synthesized based on well-known structural motif widely existed in a variety of lives. Leucine-rich repeats (LRRs) are sequence motifs present in over 60,000 proteins identified from viruses, bacteria, and eukaryotes. To elucidate if LRR motif possesses antimicrobial potency, two peptides containing one or two LRRs were designed. The biological activity and membrane–peptide interactions of the peptides were analyzed. The results showed that the tandem of two LRRs exhibited similar antibacterial activity and significantly weaker hemolytic activity against hRBCs than the well-known membrane active peptide melittin. The peptide with one LRR was defective at antimicrobial and hemolytic activity. The peptide containing two LRRs formed α-helical structure, respectively, in the presence of membrane-mimicking environment. LRR-2 retained strong resistance to cations, heat, and some proteolytic enzymes. The blue shifts of the peptides in two lipid systems correlated positively with their biological activities. Other membrane-peptide experiments further provide the evidence that the peptide with two LRRs kills bacteria via membrane-involving mechanism. The present study increases our new understanding of well-known LRR motif in antimicrobial potency and presents a potential strategy to develop novel antibacterial agents.     

Activation of STAT3 stimulates AHSP expression in K562 cells

Studies on the chaperone proteinα-hemoglobin stabilizing protein(AHSP)reveal that abundant AHSP in erythroid cells enhance the cells’tolerance to oxidative stress imposed by excessα-hemoglobin in pathological conditions.However,the potential intracellular modulation of AHSP expression itself in response to oxidative stress is still unknown.The present study examined the effect and molecular mechanism of STAT3,an oxidative regulator,on the expression of AHSP.AHSP expression increased in K562 cells upon cytokine IL-6-induced STAT3 activation and decreased in STAT3 knock-down K562 cells.Regulation of AHSP in oxidative circumstance was then examined inα-globin-overloaded K562 cells,and real-time PCR showed strengthened expression of both AHSP and STAT3.ChIP analysis showed binding of STAT3 to AHSP promoter and binding was significantly augmented with IL6 stimulation and uponα-globin overexpression.Dual luciferase reporter assays of the wildtype and mutated SB3 element,an IL-6RE site,in the AHSP promoter in K562 cells highlighted the direct regulatory effect of STAT3 on AHSP gene.Finally,direct binding of STAT3 to SB3 site of AHSP promoter was confirmed with EMSA assays.Our work reveals an adaptive AHSP regulation mediated by the redox-sensitive STAT3 signaling pathway,and provides clues to the therapeutic strategy for AHSP enhancement.     

Nisin高产菌株的高通量筛选

【目的】乳酸链球菌素(nisin)是一种天然生物活性抗菌肽,对包括食品腐败菌和致病菌在内的许多革兰氏阳性菌具有强烈的抑制作用,而用作食品的防腐剂。本研究通过建立高通量筛选方法,实现高效快速省力的高产菌株筛选,为工业上筛选高产菌株提供研究方案。【方法】通过对Lactococcus lactis ATCC11454菌株进行紫外诱变,获得2511株突变株。利用Biomek FXP自动工作站建立96微孔板的高通量筛选方法,突变株经高通量挑选、菌种培养及菌液稀释后,加入到生长至对数中期的藤黄微球菌中,采用改进后的比浊法快速检测nisin生物活性。用此方法对突变株进行初筛、复筛后可得到nisin高产菌株,并通过摇瓶发酵评估高通量筛选方法。【结果】确定比浊法检测的条件为:nisin活性稀释在10–25 IU/m L范围内,与藤黄微球菌反应2 h后检测藤黄微球菌的菌体量(OD600)。2511株突变株经过2轮高通量筛选,最终获得约50株产量提升的菌株,对其中8株进行摇瓶精确测量,显示产量均有提高,并且其中一株产量提升了30%,成功建立了高通量筛选nisin高产菌株的方法。【结论】利用比浊检测法,在其基础上成功建立高通量筛选高产nisin菌的方法,经过初筛复筛,整个周期由1人耗时5 d即可完成2511株突变株的筛选工作。相较于传统的选育方法,高通量筛选具有快速、稳定、高效的特点,提高了筛选效率,缩短了选育周期,是工业上筛选高产nisin菌的有效手段。