Genome Sequence of Clostridium tunisiense TJ,Isolated from Drain Sediment from a Pesticide Factory

Clostridium tunisiense is a Gram-positive, obligate anaerobe that was first isolated in an anaerobic evironment under eutrophication. Here we report the first genome sequence of the Clostridium tunisiense TJ isolated from drain sediment of a pesticide factory in Tianjin, China. The genome is of great importance for both basic and application research.     

Systems Mapping for Hematopoietic Progenitor Cell Heterogeneity

Cells with the same genotype growing under the same conditions can show different phenotypes, which is known as “population heterogeneity”. The heterogeneity of hematopoietic progenitor cells has an effect on their differentiation potential and lineage choices. However, the genetic mechanisms governing population heterogeneity remain unclear. Here, we present a statistical model for mapping the quantitative trait locus (QTL) that affects hematopoietic cell heterogeneity. This strategy, termed systems mapping, integrates a system of differential equations into the framework for systems mapping, allowing hypotheses regarding the interplay between genetic actions and cell heterogeneity to be tested. A simulation approach based on cell heterogeneity dynamics has been designed to test the statistical properties of the model. This model not only considers the traditional QTLs, but also indicates the methylated QTLs that can illustrate non-genetic individual differences. It has significant implications for probing the molecular, genetic and epigenetic mechanisms of hematopoietic progenitor cell heterogeneity.     

Surface hydrolysis of sphingomyelin by the outer membrane protein Rv0888 supports replication of Mycobacterium tuberculosis in macrophages

Sphingomyelinases secreted by pathogenic bacteria play important roles in host–pathogen interactions ranging from interfering with phagocytosis and oxidative burst to iron acquisition. This study shows that the Mtb protein Rv0888 possesses potent sphingomyelinase activity cleaving sphingomyelin, a major lipid in eukaryotic cells, into ceramide and phosphocholine, which are then utilized by Mtb as carbon, nitrogen and phosphorus sources, respectively. An Mtb rv0888 deletion mutant did not grow on sphingomyelin as a sole carbon source anymore and replicated poorly in macrophages indicating that Mtb utilizes sphingomyelin during infection. Rv0888 is an unusual membrane protein with a surface‐exposed C‐terminal sphingomyelinase domain and a putative N‐terminal channel domain that mediated glucose and phosphocholine uptake across the outer membrane in an M. smegmatis porin mutant. Hence, we propose to name Rv0888 as SpmT (sp hingomyelinase of M ycobacterium t uberculosis). Erythrocyte membranes contain up to 27% sphingomyelin. The finding that Rv0888 accounts for half of Mtb's hemolytic activity is consistent with its sphingomyelinase activity and the observation that Rv0888 levels are increased in the presence of erythrocytes and sphingomyelin by 5‐ and 100‐fold, respectively. Thus, Rv0888 is a novel outer membrane protein that enables Mtb to utilize sphingomyelin as a source of several essential nutrients during intracellular growth.     

Elastin overexpression by cell-based gene therapy preserves matrix and prevents cardiac dilation

After a myocardial infarction, thinning and expansion of the fibrotic scar contribute to progressive heart failure. The loss of elastin is a major contributor to adverse extracellular matrix remodelling of the infarcted heart, and restoration of the elastic properties of the infarct region can prevent ventricular dysfunction. We implanted cells genetically modified to overexpress elastin to re‐establish the elastic properties of the infarcted myocardium and prevent cardiac failure. A full‐length human elastin cDNA was cloned, subcloned into an adenoviral vector and then transduced into rat bone marrow stromal cells (BMSCs). In vitro studies showed that BMSCs expressed the elastin protein, which was deposited into the extracellular matrix. Transduced BMSCs were injected into the infarcted myocardium of adult rats. Control groups received either BMSCs transduced with the green fluorescent protein gene or medium alone. Elastin deposition in the infarcted myocardium was associated with preservation of myocardial tissue structural integrity (by birefringence of polarized light; P < 0.05 versus controls). As a result, infarct scar thickness and diastolic compliance were maintained and infarct expansion was prevented (P < 0.05 versus controls). Over a 9‐week period, rats implanted with BMSCs demonstrated better cardiac function than medium controls; however, rats receiving BMSCs overexpressing elastin showed the greatest functional improvement (P < 0.01). Overexpression of elastin in the infarcted heart preserved the elastic structure of the extracellular matrix, which, in turn, preserved diastolic function, prevented ventricular dilation and preserved cardiac function. This cell‐based gene therapy provides a new approach to cardiac regeneration.     

Inhibition of CLIC4 enhances autophagy and triggers mitochondrial and ER stress-induced apoptosis in human glioma U251 cells under starvation

CLIC4/mtCLIC, a chloride intracellular channel protein, localizes to mitochondria, endoplasmic reticulum (ER), nucleus and cytoplasm, and participates in the apoptotic response to stress. Apoptosis and autophagy, the main types of the programmed cell death, seem interconnected under certain stress conditions. However, the role of CLIC4 in autophagy regulation has yet to be determined. In this study, we demonstrate upregulation and nuclear translocation of the CLIC4 protein following starvation in U251 cells. CLIC4 siRNA transfection enhanced autophagy with increased LC3-II protein and puncta accumulation in U251 cells under starvation conditions. In that condition, the interaction of the 14-3-3 epsilon isoform with CLIC4 was abolished and resulted in Beclin 1 overactivation, which further activated autophagy. Moreover, inhibiting the expression of CLIC4 triggered both mitochondrial apoptosis involved in Bax/Bcl-2 and cytochrome c release under starvation and endoplasmic reticulum stress-induced apoptosis with CHOP and caspase-4 upregulation. These results demonstrate that CLIC4 nuclear translocation is an integral part of the cellular response to starvation. Inhibiting the expression of CLIC4 enhances autophagy and contributes to mitochondrial and ER stress-induced apoptosis under starvation.     

DHP-Derivative and Low Oxygen Tension Effectively Induces Human Adipose Stromal Cell Reprogramming

Background and Methods

In this study, we utilized a combination of low oxygen tension and a novel anti-oxidant, 4-(3,4-dihydroxy-phenyl)-derivative (DHP-d) to directly induce adipose tissue stromal cells (ATSC) to de-differentiate into more primitive stem cells. De-differentiated ATSCs was overexpress stemness genes, Rex-1, Oct-4, Sox-2, and Nanog. Additionally, demethylation of the regulatory regions of Rex-1, stemnesses, and HIF1α and scavenging of reactive oxygen species were finally resulted in an improved stem cell behavior of de-differentiate ATSC (de-ATSC). Proliferation activity of ATSCs after dedifferentiation was induced by REX1, Oct4, and JAK/STAT3 directly or indirectly. De-ATSCs showed increased migration activity that mediated by P38/JUNK and ERK phosphorylation. Moreover, regenerative efficacy of de-ATSC engrafted spinal cord-injured rats and chemical-induced diabetes animals were significantly restored their functions.

Conclusions/Significance

Our stem cell remodeling system may provide a good model which would provide insight into the molecular mechanisms underlying ATSC proliferation and transdifferentiation. Also, these multipotent stem cells can be harvested may provide us with a valuable reservoir of primitive and autologous stem cells for use in a broad spectrum of regenerative cell-based disease therapy.     

Structure of the ribosome associating GTPase HflX

The HflX‐family is a widely distributed but poorly characterized family of translation factor‐related guanosine triphosphatases (GTPases) that interact with the large ribosomal subunit. This study describes the crystal structure of HflX from Sulfolobus solfataricus solved to 2.0‐Å resolution in apo‐ and GDP‐bound forms. The enzyme displays a two‐domain architecture with a novel “HflX domain” at the N‐terminus, and a classical G‐domain at the C‐terminus. The HflX domain is composed of a four‐stranded parallel β‐sheet flanked by two α‐helices on either side, and an anti‐parallel coiled coil of two long α‐helices that lead to the G‐domain. The cleft between the two domains accommodates the nucleotide binding site as well as the switch II region, which mediates interactions between the two domains. Conformational changes of the switch regions are therefore anticipated to reposition the HflX‐domain upon GTP‐binding. Slow GTPase activity has been confirmed, with an HflX domain deletion mutant exhibiting a 24‐fold enhanced turnover rate, suggesting a regulatory role for the HflX domain. The conserved positively charged surface patches of the HflX‐domain may mediate interaction with the large ribosomal subunit. The present study provides a structural basis to uncover the functional role of this GTPases family whose function is largely unknown. Proteins 2010. © 2009 Wiley‐Liss, Inc.     

Asymmetric reduction of ketopantolactone using a strictly (<Emphasis Type="Italic">R</Emphasis>)-stereoselective carbonyl reductase through efficient NADPH regeneration and the substrate constant-feeding strategy

Objectives

To characterize a recombinant carbonyl reductase from Saccharomyces cerevisiae (SceCPR1) and explore its use in asymmetric synthesis of (R)-pantolactone [(R)-PL].

Results

The NADPH-dependent SceCPR1 exhibited strict (R)-enantioselectivity and high activity in the asymmetric reduction of ketopantolactone (KPL) to (R)-PL. Escherichia coli, coexpressing SceCPR1 and glucose dehydrogenase from Exiguobacterium sibiricum (EsGDH), was constructed to fulfill efficient NADPH regeneration. During the whole-cell catalyzed asymmetric reduction of KPL, the spontaneous hydrolysis of KPL significantly affected the yield of (R)-PL, which was effectively alleviated by the employment of the substrate constant-feeding strategy. The established whole-cell bioreduction for 6 h afforded 458 mM (R)-PL with the enantiomeric excess value of >99.9% and the yield of 91.6%.

Conclusions

Escherichia coli coexpressing SceCPR1 and EsGDH efficiently catalyzed the asymmetric synthesis of (R)-PL through the substrate constant-feeding strategy.

     

Stretchable Lithium‐Ion Batteries Enabled by Device‐Scaled Wavy Structure and Elastic‐Sticky Separator

Fast developments and substantial achievements have been shaping the field of wearable electronic devices, resulting in the persistent requirement for stretchable lithium‐ion batteries (LIBs). Despite recent progress in stretchable electrodes, stretching full batteries, including electrodes, separator, and sealing material, remains a great challenge. Here, a simple design concept for stretchable LIBs via a wavy structure at the full battery device scale is reported. All components including the package are capable of being reversibly stretched by folding the entire pouch cell into a wavy shape with polydimethylsiloxane filled in each valley region. In addition, the stretchable, sticky, and porous polyurethane/poly(vinylidene fluoride) membrane is adopted as a separator for the first time, which can maintain intimate contact between electrodes and separator to continuously secure ion pathway under dynamic state. Commercial cathode, anode, and package can be utilized in this rationally designed wavy battery to enable stretchability. The results indicate good electrochemical performances and long‐term stability at repeatable release–stretch cycles. A high areal capacity of 3.6 mA h cm^?2 and energy density of up to 172 W h L^?1 can be achieved for the wavy battery. The promising results of the cost‐effective wavy battery with high stretchability shed light on the development of stretchable energy storages.