Competing stress-dependent oligomerization pathways regulate self-assembly of the periplasmic protease-chaperone DegP.

DegP is an oligomeric protein with dual protease and chaperone activity that regulates protein homeostasis and virulence factor trafficking in the periplasm of gram-negative bacteria. A number of oligomeric architectures adopted by DegP are thought to facilitate its function. For example, DegP can form a "resting" hexamer when not engaged to substrates, mitigating undesired proteolysis of cellular proteins. When bound to substrate proteins or lipid membranes, DegP has been shown to populate a variety of cage- or bowl-like oligomeric states that have increased proteolytic activity. Though a number of DegP's substrate-engaged structures have been robustly characterized, detailed mechanistic information underpinning its remarkable oligomeric plasticity and the corresponding interplay between these dynamics and biological function has remained elusive. Here, we have used a combination of hydrodynamics and NMR spectroscopy methodologies in combination with cryogenic electron microscopy to shed light on the apo-DegP self-assembly mechanism. We find that, in the absence of bound substrates, DegP populates an ensemble of oligomeric states, mediated by self-assembly of trimers, that are distinct from those observed in the presence of substrate. The oligomeric distribution is sensitive to solution ionic strength and temperature and is shifted toward larger oligomeric assemblies under physiological conditions. Substrate proteins may guide DegP toward canonical cage-like structures by binding to these preorganized oligomers, leading to changes in conformation. The properties of DegP self-assembly identified here suggest that apo-DegP can rapidly shift its oligomeric distribution in order to respond to a variety of biological insults.

Improved Analysis of Cross-Linking Mass Spectrometry Data with Kojak 2.0, Advanced by Integration into the Trans-Proteomic Pipeline.

Fragmentation ion spectral analysis of chemically cross-linked proteins is an established technology in the proteomics research repertoire for determining protein interactions, spatial orientation, and structure. Here we present Kojak version 2.0, a major update to the original Kojak algorithm, which was developed to identify cross-linked peptides from fragment ion spectra using a database search approach. A substantially improved algorithm with updated scoring metrics, support for cleavable cross-linkers, and identification of cross-links between 15N-labeled homomultimers are among the newest features of Kojak 2.0 presented here. Kojak 2.0 is now integrated into the Trans-Proteomic Pipeline, enabling access to dozens of additional tools within that suite. In particular, the PeptideProphet and iProphet tools for validation of cross-links improve the sensitivity and accuracy of correct cross-link identifications at user-defined thresholds. These new features improve the versatility of the algorithm, enabling its use in a wider range of experimental designs and analysis pipelines. Kojak 2.0 remains open-source and multiplatform.

Analysis of functional surfaces on the actin nucleation promoting factor Dip1 required for Arp2/3 complex activation and endocytic actin network assembly.

Arp2/3 complex nucleates branched actin filaments that drive processes like endocytosis and lamellipodial protrusion. WISH/DIP/SPIN90 (WDS) proteins form a class of Arp2/3 complex activators or nucleation promoting factors (NPFs) that, unlike WASP family NPFs, activate Arp2/3 complex without requiring preformed actin filaments. Therefore, activation of Arp2/3 complex by WDS proteins is thought to produce the initial actin filaments that seed branching nucleation by WASP-bound Arp2/3 complexes. However, whether activation of Arp2/3 complex by WDS proteins is important for the initiation of branched actin assembly in cells has not been directly tested. Here, we used structure-based point mutations of the Schizosaccharomyces pombe WDS protein Dip1 to test the importance of its Arp2/3-activating activity in cells. Six of thirteen Dip1 mutants caused severe defects in Arp2/3 complex activation in vitro, and we found a strong correlation between the ability of mutants to activate Arp2/3 complex and to rescue endocytic actin assembly defects caused by deleting Dip1. These data support a model in which Dip1 activates Arp2/3 complex to produce actin filaments that initiate branched actin assembly at endocytic sites. Dip1 mutants that synergized with WASP in activating Arp2/3 complex in vitro showed milder defects in cells compared to those that did not, suggesting that in cells the two NPFs may coactivate Arp2/3 complex to initiate actin assembly. Finally, the mutational data reveal important complementary electrostatic contacts at the Dip1-Arp2/3 complex interface and corroborate the previously proposed wedge model, which describes how Dip1 binding triggers structural changes that activate Arp2/3 complex.

Maize metacaspases modulate the defense response mediated by the NLR protein Rp1-D21 likely by affecting its subcellular localization.

Plants usually employ resistance (R) genes to defend against the infection of pathogens, and most R genes encode intracellular nucleotide-binding, leucine-rich repeat (NLR) proteins. The recognition between R proteins and their cognate pathogens often triggers a rapid localized cell death at the pathogen infection sites, termed the hypersensitive response (HR). Metacaspases (MCs) belong to a cysteine protease family, structurally related to metazoan caspases. MCs play crucial roles in plant immunity. However, the underlying molecular mechanism and the link between MCs and NLR-mediated HR are not clear. In this study, we systematically investigated the MC gene family in maize and identified 11 ZmMCs belonging to two types. Further functional analysis showed that the type I ZmMC1 and ZmMC2, but not the type II ZmMC9, suppress the HR-inducing activity of the autoactive NLR protein Rp1-D21 and of its N-terminal coiled-coil (CCD21 ) signaling domain when transiently expressed in Nicotiana benthamiana. ZmMC1 and ZmMC2 physically associate with CCD21 in vivo. We further showed that ZmMC1 and ZmMC2, but not ZmMC9, are predominantly localized in a punctate distribution in both N. benthamiana and maize (Zea mays) protoplasts. Furthermore, the co-expression of ZmMC1 and ZmMC2 with Rp1-D21 and CCD21 causes their re-distribution from being uniformly distributed in the nucleocytoplasm to a punctate distribution co-localizing with ZmMC1 and ZmMC2. We reveal a novel role of plant MCs in modulating the NLR-mediated defense response and derive a model to explain it.

Structure of the nucleation-promoting factor SPIN90 bound to the actin filament nucleator Arp2/3 complex.

Unlike the WASP family of Arp2/3 complex activators, WISH/DIP/SPIN90 (WDS) family proteins activate actin filament nucleation by the Arp2/3 complex without the need for a preformed actin filament. This allows WDS proteins to initiate branched actin network assembly by providing seed filaments that activate WASP-bound Arp2/3 complex. Despite their important role in actin network initiation, it is unclear how WDS proteins drive the activating steps that require both WASP and pre-existing actin filaments during WASP-mediated nucleation. Here, we show that SPIN90 folds into an armadillo repeat domain that binds a surface of Arp2/3 complex distinct from the two WASP sites, straddling a hinge point that may stimulate movement of the Arp2 subunit into the activated short-pitch conformation. SPIN90 binds a surface on Arp2/3 complex that overlaps with actin filament binding, explaining how it could stimulate the same structural rearrangements in the complex as pre-existing actin filaments. By revealing how WDS proteins activate the Arp2/3 complex, these data provide a molecular foundation to understand initiation of dendritic actin networks and regulation of Arp2/3 complex by its activators.

Identification of Wiskott-Aldrich syndrome protein (WASP) binding sites on the branched actin filament nucleator Arp2/3 complex.

Arp2/3 complex nucleates branched actin filaments important for cellular motility and endocytosis. WASP family proteins are Arp2/3 complex activators that play multiple roles in branching nucleation, but little is known about the structural bases of these WASP functions, owing to an incomplete understanding of how WASP binds Arp2/3 complex. Recent data show WASP binds two sites, and biochemical and structural studies led to models in which the WASP C segment engages the barbed ends of the Arp3 and Arp2 subunits while the WASP A segment binds the back side of the complex on Arp3. However, electron microscopy reconstructions showed density for WASP inconsistent with these models on the opposite (front) side of Arp2/3 complex. Here we use chemical cross-linking and mass spectrometry (XL-MS) along with computational docking and structure-based mutational analysis to map the two WASP binding sites on the complex. Our data corroborate the barbed end and back side binding models and show one WASP binding site on Arp3, on the back side of the complex, and a second site on the bottom of the complex, spanning Arp2 and ARPC1. The XL-MS-identified cross-links rule out the front side binding model and show that the A segment of WASP binds along the bottom side of the ARPC1 subunit, instead of at the Arp2/ARPC1 interface, as suggested by FRET experiments. The identified binding sites support the Arp3 tail release model to explain WASP-mediated activating conformational changes in Arp2/3 complex and provide insight into the roles of WASP in branching nucleation.

Endothelial cell-specific anticoagulation reduces inflammation in a mouse model of acute lung injury.

Tissue factor (TF)-dependent coagulation contributes to lung inflammation and the pathogenesis of acute lung injury (ALI). In this study, we explored the roles of targeted endothelial anticoagulation in ALI using two strains of transgenic mice expressing either a membrane-tethered human tissue factor pathway inhibitor (hTFPI) or hirudin fusion protein on CD31+ cells, including vascular endothelial cells (ECs). ALI was induced by intratracheal injection of LPS, and after 24 h the expression of TF and protease-activated receptors (PARs) on EC in lungs were assessed, alongside the extent of inflammation and injury. The expression of TF and PARs on the EC in lungs was upregulated after ALI. In the two strains of transgenic mice, expression of either of hTFPI or hirudin by EC was associated with significant reduction of inflammation, as assessed by the extent of leukocyte infiltration or the levels of proinflammatory cytokines, and promoted survival after LPS-induced ALI. The beneficial outcomes were associated with inhibition of the expression of chemokine CCL2 in lung tissues. The protection observed in the CD31-TFPI-transgenic strain was abolished by injection of an anti-hTFPI antibody, but not by prior engraftment of the transgenic strains with WT bone marrow, confirming that the changes observed were a specific transgenic expression of anticoagulants by EC. These results demonstrate that the inflammation in ALI is TF and thrombin dependent, and that expression of anticoagulants by EC significantly inhibits the development of ALI via repression of leukocyte infiltration, most likely via inhibition of chemokine gradients. These data enhance our understanding of the pathology of ALI and suggest a novel therapeutic strategy for treatment.

Role and structural mechanism of WASP-triggered conformational changes in branched actin filament nucleation by Arp2/3 complex.

The Arp2/3 (Actin-related proteins 2/3) complex is activated by WASP (Wiskott-Aldrich syndrome protein) family proteins to nucleate branched actin filaments that are important for cellular motility. WASP recruits actin monomers to the complex and stimulates movement of Arp2 and Arp3 into a "short-pitch" conformation that mimics the arrangement of actin subunits within filaments. The relative contribution of these functions in Arp2/3 complex activation and the mechanism by which WASP stimulates the conformational change have been unknown. We purified budding yeast Arp2/3 complex held in or near the short-pitch conformation by an engineered covalent cross-link to determine if the WASP-induced conformational change is sufficient for activity. Remarkably, cross-linked Arp2/3 complex bypasses the need for WASP in activation and is more active than WASP-activated Arp2/3 complex. These data indicate that stimulation of the short-pitch conformation is the critical activating function of WASP and that monomer delivery is not a fundamental requirement for nucleation but is a specific requirement for WASP-mediated activation. During activation, WASP limits nucleation rates by releasing slowly from nascent branches. The cross-linked complex is inhibited by WASP's CA region, even though CA potently stimulates cross-linking, suggesting that slow WASP detachment masks the activating potential of the short-pitch conformational switch. We use structure-based mutations and WASP-Arp fusion chimeras to determine how WASP stimulates movement toward the short-pitch conformation. Our data indicate that WASP displaces the autoinhibitory Arp3 C-terminal tail from a hydrophobic groove at Arp3's barbed end to destabilize the inactive state, providing a mechanism by which WASP stimulates the short-pitch conformation and activates Arp2/3 complex.

[Spicy food intake increases the risk of overweight and obesity].

OBJECTIVE: To explore the relationship between spicy food intake and overweight or obesity in the population, and provide theoretical basis for dietary prevention of obesity. METHODS: The data of this study was collected from the cross-sectional population of China Kadoorie Biobank(CKB) in Harbin from 2004 to 2008. A cluster random sampling method was used to select 57 555 subjects aged 30-79(23 254 males and 34 301 females). Demographic information and habits information such as smoking and drinking were obtained by face-to-face questionnaires. Food frequency questionnaires were used to obtain information on various foods including spicy food intake. Physical examination was used to obtain indicators of height and weight. Logistic regression method was used to analyze the influence of spicy food intake and its interaction with predilection for meat/vegetarian diet on the risk of overweight and obesity. RESULTS: Compared with people who intake spicy foods with low frequency, the risk of overweight and obesity in people with a high frequency of intake spicy foods increased by 29%(OR=1.285, 95%CI 1.251-1.319, P<0.001) in males and 33%(OR=1.329, 95%CI 1.294-1.364, P<0.001) in females. Compared with the people who intake spicy food with a slightly intensity, the risk of overweight and obesity in males and females with a extremely intensity of intake spicy foods increased by 20%(OR=1.198, 95%CI 1.137-1.259, P=0.011) and 19%(OR=1.194, 95%CI 1.141-1.247, P=0.003), respectively. In the male population, the risk of overweight and obesity was the highest among those who preferred meat and had high frequency and degree of spicy food intake. There was an interaction between meat/vegetarian preference and spicy food intake(P<0.001). CONCLUSION: Intake spicy food can increase the risk of overweight and obesity, while reducing the intake of spicy foods and meats can be more effective in prevent overweight and obesity.

Aerosolized antibiotics for ventilator-associated pneumonia: a pairwise and Bayesian network meta-analysis.

BACKGROUND: Aerosolized antibiotics have been proposed as a novel and promising treatment option for the treatment of ventilator-associated pneumonia (VAP). However, the optimum aerosolized antibiotics for VAP remain uncertain. METHODS: We included studies from two systematic reviews and searched PubMed, EMBASE, and Cochrane databases for other studies. Eligible studies included randomized controlled trials and observational studies. Extracted data were analyzed by pairwise and network meta-analysis. RESULTS: Eight observational and eight randomized studies were identified for this analysis. By pairwise meta-analysis using intravenous antibiotics as the reference, patients treated with aerosolized antibiotics were associated with significantly higher rates of clinical recovery (risk ratio (RR) 1.21, 95% confidence interval (CI) 1.09-1.34; P = 0.001) and microbiological eradication (RR 1.42, 95% CI 1.22-1.650; P < 0.0001). There were no significant differences in the risks of mortality (RR 0.88, 95% CI 0.74-1.04; P = 0.127) or nephrotoxicity (RR 1.00, 95% CI 0.72-1.39; P = 0.995). Using network meta-analysis, clinical recovery benefits were seen only with aerosolized tobramycin and colistin (especially tobramycin), and microbiological eradication benefits were seen only with colistin. Aerosolized tobramycin was also associated with significantly lower mortality when compared with aerosolized amikacin and colistin and intravenous antibiotics. The assessment of rank probabilities indicated aerosolized tobramycin presented the greatest likelihood of having benefits for clinical recovery and mortality, and aerosolized colistin presented the best benefits for microbiological eradication. CONCLUSIONS: Aerosolized antibiotics appear to be a useful treatment for VAP with respect to clinical recovery and microbiological eradication, and do not increase mortality or nephrotoxicity risks. Our network meta-analysis in patients with VAP suggests that clinical recovery benefits are associated with aerosolized tobramycin and colistin (especially tobramycin), microbiological eradication with aerosolized colistin, and survival with aerosolized tobramycin, mostly based on observational studies. Due to the low levels of evidence, definitive recommendations cannot be made before additional, large randomized studies are carried out.

Bcl-2 inhibitors reduce steroid-insensitive airway inflammation.

BACKGROUND: Asthmatic inflammation is dominated by accumulation of either eosinophils, neutrophils, or both in the airways. Disposal of these inflammatory cells is the key to disease control. Eosinophilic airway inflammation is responsive to corticosteroid treatment, whereas neutrophilic inflammation is resistant and increases the burden of global health care. Corticosteroid-resistant neutrophilic asthma remains mechanistically poorly understood and requires novel effective therapeutic strategies. OBJECTIVE: We sought to explore the underlying mechanisms of airway inflammation persistence, as well as corticosteroid resistance, and to investigate a new strategy of effective treatment against corticosteroid-insensitive neutrophilic asthma. METHODS: Mouse models of either eosinophil-dominated or neutrophil-dominated airway inflammation were used in this study to test corticosteroid sensitivity in vivo and in vitro. We also used vav-Bcl-2 transgenic mice to confirm the importance of granulocytes apoptosis in the clearance of airway inflammation. Finally, the Bcl-2 inhibitors ABT-737 or ABT-199 were tested for their therapeutic effects against eosinophilic or neutrophilic airway inflammation and airway hyperresponsiveness. RESULTS: Overexpression of Bcl-2 protein was found to be responsible for persistence of granulocytes in bronchoalveolar lavage fluid after allergic challenge. This was important because allergen-induced airway inflammation aggravated and persisted in vav-Bcl-2 transgenic mice, in which nucleated hematopoietic cells were overexpressed with Bcl-2 and resistant to apoptosis. The Bcl-2 inhibitors ABT-737 or ABT-199 play efficient roles in alleviation of either eosinophilic or corticosteroid-resistant neutrophilic airway inflammation by inducing apoptosis of immune cells, such as eosinophils, neutrophils, TH2 cells, TH17 cells, and dendritic cells. Moreover, these inhibitors were found to be more efficient than steroids to induce granulocyte apoptosis ex vivo from patients with severe asthma. CONCLUSION: Apoptosis of inflammatory cells is essential for clearance of allergen-induced airway inflammation. The Bcl-2 inhibitors ABT-737 or ABT-199 might be promising drugs for the treatment of airway inflammation, especially for corticosteroid-insensitive neutrophilic airway inflammation.

Mitochondrial reactive oxygen species mediate the lipopolysaccharide-induced pro-inflammatory response in human gingival fibroblasts.

Although periodontal diseases are initiated by bacteria that colonize the tooth surface and gingival sulcus, the host response is believed to play an essential role in the breakdown of connective tissue and bone. Mitochondrial reactive oxygen species (mtROS) have been proposed to regulate the activation of the inflammatory response by the innate immune system. However, the role of mtROS in modulating the response of human gingival fibroblasts (HGFs) to immune stimulation by lipopolysaccharides (LPS) has yet to be fully elucidated. Here, we showed that LPS from Porphyromonas gingivalis stimulated HGFs to increase mtROS production, which could be inhibited by treatment with a mitochondrial-targeted exogenous antioxidant (mito-TEMPO) or transfection with manganese superoxide dismutase (MnSOD). A time-course study revealed that an increase in the concentration of mtROS preceded the expression of inflammatory cytokines in HGFs. Mito-TEMPO treatment or MnSOD transfection also significantly prevented the LPS-induced increase of interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α. Furthermore, suppressing LPS-induced mtROS generation inhibited the activation of p38, c-Jun N-terminal kinase, and inhibitor of nuclear factor-κB kinase, as well as the nuclear localization of nuclear factor-κB. These results demonstrate that mtROS generation is a key signaling event in the LPS-induced pro-inflammatory response of HGFs.

Porphyromonas gingivalis Infection Accelerates Atherosclerosis Mediated by Oxidative Stress and Inflammatory Responses in ApoE-/- Mice.

BACKGROUND: The periodontal pathogen Porphyromonas gingivalis (P. gingivalis) has been proven to accelerate the development of atherosclerosis in apolipoprotein E (ApoE)-deficient mice. In this study, we used an ApoE knockout (ApoE-/-) mouse model with chronic intravenous infection with P. gingivalis to investigate the possible mechanisms of P. gingivalis-induced atherosclerosis. METHODS: Eight-week-old ApoE-/- mice were randomly assigned to two groups: (a) ApoE-/- + PBS (n = 8); (b) ApoE-/- + P. gingivalis (n = 8). Both of the groups received intravenous injections 3 times per week. After 4 weeks, oxidative stress mediators in serum, heart, aorta, and liver tissues were analyzed by using histology, ELISA, realtime PCR, and Western blot. RESULTS: Development of atherosclerosis as plaque formation in the aorta has been confirmed upon P. gingivalis infection. An abnormal lipid profile was found in the serum (increased amounts of very low-density lipoprotein [vLDL] and oxidized low-density lipoprotein [oxLDL], and decreased amount of HDL) and in some organs including heart, aorta or liver (increased mRNA levels of oxidized low-density lipoprotein receptor-1 [LOX-1] or fatty acid synthase [FAS]). Meanwhile, aggravated oxidative stress (higher level of reactive oxygen species [ROS] in the serum, and increased mRNA levels of nicotinamide adenine dinucleotide phosphate oxidase [NOX]-2 and/or NOX-4 in the three organs) was observed, as well as enhanced inflammatory responses (increased expression and secretion of C-reactive protein [CRP] in the liver and serum, and increased mRNA levels of cyclooxygenase-2 [NOX-2] and/or inducible nitric oxide synthase [iNOS] in the three organs). Besides, inflammatory mediators including nuclear factor of kappa B (NF-κB) and iNOS showed increased protein levels in the three organs after P. gingivalis infection. CONCLUSIONS: These results suggest that chronic intravenous infection with P. gingivalis in ApoE-/- mice could accelerate the development of atherosclerosis, possibly associated with mediating oxidative stress as well as inflammatory responses and disturbing the lipid profile.

[Effects of Er, Cr: YSGG laser on the root surface of periodontitis and healthy teeth].

OBJECTIVE: To evaluate the effects of Er, Cr: YSGG laser on the root surface of periodontally involved teeth and healthy teeth, concerning the microstructure and the roughness. METHODS: Eight freshly extracted teeth due to severe periodontitis and eight freshly extracted teeth due to orthodontic reasons or being third molar were chosen in this study. The root surface of each tooth was divided into four areas, and received four treatment METHODS: no treatment (control group); root planing with Gracey scaler for 30 seconds; irradiation by the lower power Er, Cr: YSGG laser; irradiation by the higher power Er, Cr: YSGG laser. Four periodontally involved teeth and four healthy teeth were used for the evaluation of microstructure using scanning electron microscope (SEM). The other four periodontitis teeth and four healthy teeth were used for the evaluation of roughness (Ra value) using 3D profiler. RESULTS: Smear layer was found on the teeth scaled by Gracey scaler, while the teeth irradiated by Er, Cr: YSGG laser demonstrated a melting surface with less smear layer. In the periodontitis teeth irradiated by the higher power, opening dentinal tubules could be observed. For the periodontally involved teeth, the Ra values of groups 1 to 4 were (237.4 ± 20.0) nm, (135.7 ± 11.9) nm (P=0.01), (463.6 ± 49.3) nm (P<0.001) and (486.0 ± 59.0) nm (P<0.001) respectively. For the healthy teeth, the Ra values of groups 1 to 4 were (191.4 ± 44.5) nm, (131.6 ± 21.5) nm (P=0.482), (463.7 ± 34.6) nm (P<0.001) and (470.3 ± 121.3) nm (P<0.001) respectively. CONCLUSION: Er, Cr: YSGG laser can affect the microstructure of the cementum of the periodontitis teeth and healthy teeth. Irradiation by the Er, Cr: YSGG laser resulted in a melting surface with less smear layer and increased the roughness in the surface of root.

The Pax6 genes eyeless and twin of eyeless are required for global patterning of the ocular segment in the Tribolium embryo.

The transcription factor gene Pax6 is widely considered a master regulator of eye development in bilaterian animals. However, the existence of visual organs that develop without Pax6 input and the considerable pleiotropy of Pax6 outside the visual system dictate further studies into defining ancestral functions of this important regulator. Previous work has shown that the combinatorial knockdown of the insect Pax6 orthologs eyeless (ey) and twin of eyeless (toy) perturbs the development of the visual system but also other areas of the larval head in the red flour beetle Tribolium castaneum. To elucidate the role of Pax6 during Tribolium head development in more detail, we studied head cuticle morphology, brain anatomy, embryonic head morphogenesis, and developmental marker gene expression in combinatorial ey and toy knockdown animals. Our experiments reveal that Pax6 is broadly required for patterning the anterior embryonic head. One of the earliest detectable roles is the formation of the embryonic head lobes, which originate from within the ocular segment and give rise to large parts of the supraesophageal brain including the mushroom body, a part of the posterior head capsule cuticle, and the visual system. We present further evidence that toy continues to be required for the development of the larval eyes after formation of the embryonic head lobes in cooperation with the eye developmental transcription factor dachshund (dac). The sum of our findings suggests that Pax6 functions as a competence factor throughout the development of the insect ocular segment. Comparative evidence identifies this function as an ancestral aspect of bilaterian head development.

[Chronic periodontitis with Takayasu arteritis: a case report].

This case report concerns a 23-year-old woman with chronic periodontitis who had been previously diagnosed with Takayasu arteritis (TA). Her erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were decreased before and 3 months after non-surgical periodontal therapy with no change in her prescribed medications (ESR from 31.00 mm/h to 23.0 mm/h, CRP from 21.40 mg/L to 18.46 mm/h). Through the occasional findings, we raised a hypothetical analysis about the potential relationship between periodontitis and TA with respect to inflammatory factors, bacteria and medication. Further studies of large samples are needed to verify the findings.

Interaction of caveolin-1 with ATG12-ATG5 system suppresses autophagy in lung epithelial cells.

Autophagy plays a pivotal role in cellular homeostasis and adaptation to adverse environments, although the regulation of this process remains incompletely understood. We have recently observed that caveolin-1 (Cav-1), a major constituent of lipid rafts on plasma membrane, can regulate autophagy in cigarette smoking-induced injury of lung epithelium, although the underlying molecular mechanisms remain incompletely understood. In the present study we found that Cav-1 interacted with and regulated the expression of ATG12-ATG5, an ubiquitin-like conjugation system crucial for autophagosome formation, in lung epithelial Beas-2B cells. Deletion of Cav-1 increased basal and starvation-induced levels of ATG12-ATG5 and autophagy. Biochemical analyses revealed that Cav-1 interacted with ATG5, ATG12, and their active complex ATG12-ATG5. Overexpression of ATG5 or ATG12 increased their interactions with Cav-1, the formation of ATG12-ATG5 conjugate, and the subsequent basal levels of autophagy but resulted in decreased interactions between Cav-1 and another molecule. Knockdown of ATG12 enhanced the ATG5-Cav-1 interaction. Mutation of the Cav-1 binding motif on ATG12 disrupted their interaction and further augmented autophagy. Cav-1 also regulated the expression of ATG16L, another autophagy protein associating with the ATG12-ATG5 conjugate during autophagosome formation. Altogether these studies clearly demonstrate that Cav-1 competitively interacts with the ATG12-ATG5 system to suppress the formation and function of the latter in lung epithelial cells, thereby providing new insights into the molecular mechanisms by which Cav-1 regulates autophagy and suggesting the important function of Cav-1 in certain lung diseases via regulation of autophagy homeostasis.

[Association between chronic periodontitis and metabolic syndrome related mitochondria single nucleotide polymorphism].

OBJECTIVE: To investigate the relationship between Mitochondrial DNA(mtDNA) SNP and the severity of periodontitis. METHODS: In the study, 227 subjects in a community of Beijing received questionnaire interview, periodontal examination and biochemical laboratory examination in 2005. The designed primer was used to amplify the specific mtDNA fragments with PCR, and sequence the PCR products. Finally, the relationship between severity of chronic periodontitis and mtDNA SNP at site 10398 was analyzed. RESULTS: The number of the subjects included at mtDNA site 10398 was 227. The G allele frequency in the metabolic syndrome(MS) subjects was significantly higher than that in the non MS subjects [80(70.2%) vs. 34(29.8%),P=0.039 ]. The result of Logistic regression showed that the subjects with G allele had higher risk of MS than the subjects with A allele(OR=1.77,95%CI=1.02-3.06, P=0.042). But there was no significant relationship between the 10398 A→G SNP and severity of periodontitis. CONCLUSION: In this population, mtDNA SNP 10398 A→G may be associated with MS. However, there was no relationship between the 10398 A→G SNP and severity of chronic periodontitis.

S6K inhibition renders cardiac protection against myocardial infarction through PDK1 phosphorylation of Akt.

In the present study, we observed a rapid and robust activation of the ribosomal protein S6K (S6 kinase) provoked by MI (myocardial infarction) in mice. As activation of S6K promotes cell growth, we hypothesized that increased S6K activity contributes to pathological cardiac remodelling after MI and that suppression of S6K activation may prevent aberrant cardiac remodelling and improve cardiac function. In mice, administration of rapamycin effectively suppressed S6K activation in the heart and significantly improved cardiac function after MI. The heart weight/body weight ratio and fibrotic area were substantially reduced in rapamycin-treated mice. In rapamycin-treated mice, decreased cardiomyocyte remodelling and cell apoptosis were observed compared with vehicle-treated controls. Consistently, inhibition of S6K with PF-4708671 displayed similar protection against MI as rapamycin. Mechanistically, we observed significantly enhanced Thr308 phosphorylation and activation of Akt in rapamycin- and PF-4708671-treated hearts. Cardiomyocyte-specific deletion of PDK1 (phosphoinositide-dependent kinase 1) and Akt1/3 abolished cardioprotection after MI in the presence of rapamycin administration. These results demonstrate that S6K inhibition rendered beneficial effects on left ventricular function and alleviated adverse remodelling following MI in mice by enhancing Akt signalling, suggesting the therapeutic value of both rapamycin and PF-4708671 in treating patients following an MI.

[Periodontal status of patients with post-acute myocardial infarction].

OBJECTIVE: To evaluate the periodontal status of post-acute myocardial infarction patients, to identify whether periodontitis is associated with post-acute myocardial infarction in Chinese community population. METHODS: Case and control subjects were enrolled from a community population, the diagnose of post-acute myocardial infarction and systemic health were based on blood, electrocardiogram and ultrasound examinations by physicians. Full mouth periodontal examinations were performed in 103 post-acute myocardial infarction patients and 52 healthy subjects. Mesial-buccal and distal-lingual sites per tooth were examined. The periodontal parameters including plaque index (PLI), bleeding index (BI), probing depth (PD), attachment level (AL) and missing teeth number were recorded. Information of demographic data, behavior habits and general conditions were obtained by a questionnaire. Periodontal status were compared between case and control groups, the association between AL, PD, PLI, missing teeth and post-acute myocardial infarction was analyzed by Logistic regression. RESULTS: In post-acute myocardial infarction group, there were 83 males, 20 females, mean age was 68(41 to 84)years old, in healthy subjects there were 30 males and 22 females,mean age was 62(42 to 78) years old. There were no statistically differences between two groups in age structure, smoking condition, education status and working condition, but body mass index, total cholesterol, triglycerides and glucose in post-acute myocardial infarction group were significantly higher than that in healthy group,while high-density lipoprotein significant lower . The number of missing teeth(6.89±7.39 vs. 4.21±5.62, P=0.01), mean AL [(3.48±2.34) mm vs. (2.61±1.85) mm, P=0.02] and prevalence of severe periodontitis (44.7% vs. 32.7%, P<0.01) were significantly higher in post-acute myocardial infarction patients than that in healthy subjects. Plaque index (1.69±0.49 vs. 1.57±0.50, P=0.22), PD (2.88±1.02 vs. 2.64±0.68, P=0.09) were higher in post-acute myocardial infarction patients than that in healthy subjects, but not statistically significant. In the multivariate analysis, after adjusting sex, age, smoking, body mass index, diabetes, hypertension and serum lipid, AL≥4.00 mm was a significant risk indicator for post-acute myocardial infarction(odd ratio 4.89, 95%confidence interval 1.26 to 18.94, P=0.02). CONCLUSION: Periodontal status was worse in post-acute myocardial infarction patients than that in healthy subjects, AL≥4.00 mm was an independent risk indicator for post-acute myocardial infarction.