Invasion of human coronary artery endothelial cells by Streptococcus mutans OMZ175

INTRODUCTION

Dissemination of oral bacteria into the bloodstream has been associated with eating, oral hygiene, and dental procedures; including tooth extraction, endodontic treatment, and periodontal surgery. Recently, studies identified Streptococcus mutans, the primary etiological agent of dental caries, as the most prevalent bacterial species found in clinical samples from patients who underwent heart valve and atheromatous plaque surgery.

METHODS

By using antibiotic protection assays, we tested the capacity of 14 strains of S. mutans to invade primary human coronary artery endothelial cells (HCAEC).

RESULTS

Serotype e strain B14 and serotype f strain OMZ175 of S. mutans were able to efficiently invade HCAEC. Among the tested strains, serotype f S. mutans OMZ175 was the most invasive, whereas strains of serotype c S. mutans, the most prevalent serotype in dental plaque, were not invasive. Based on its high invasion rate, we further investigated the invasive properties of serotype f OMZ175. Using transmission electron microscopy and antibiotic protection assays we demonstrate that S. mutans OMZ175 is capable of attaching to the HCAEC surface, entering the cells and surviving in HCAEC for at least 29 h.

DISCUSSION

Our findings highlight a potential role for S. mutans in the pathogenesis of certain cardiovascular diseases.

Transient cerebral ischemia leads to TGF-beta2 expression in Golgi apparatus organelles

Transforming growth factor2 (TGFbeta2) is a prototypic member of a large superfamily of multifunctional cytokines, and its potential mechanisms of the neuroprotective activity in ischemic stroke and subcellular compartmentalization are largely unknown. The present study investigated TGF-beta2 protein expression in hippocampal neuronal cells after transient forebrain ischemia (TFI). TFI was induced in male adult gerbils with bilateral occlusion of both common carotid arteries for 10 minutes. With immunohistochemical methods we observe the expression of TGF-beta2 and morphological alternation in Golgi appratus (GA) in different postischemic periods and sham-operation (6 hours, 1, 3 and 7 days). In addition, the subcellular localization of TGF-beta2 is determined in trans-Golgi network (TGN) by double-labeling confocal immunofluorographs with TGN38.The results showed that TGF-beta2 persistent express in the ischemic animals and it peaks at 3 days, then decreased 7 days postocclusion. No significant alterations to the GA were noted at the point of 6 hours,1 and 3 days following TFI, but there are a few neurons in which the GA lost the normal network-like configuration and its elements decreased in cortical cells from gerbils survived 7 days postocclusion. In addition, TGF-beta2 was colocalized with TGN38 in the TGN after TFI .Taken together, this result suggested that TGF-beta2 protein expression increased in neurons after ischemia, which may represent an endogenous adaptative response of the brain damage and its secretion via GA after ischemia is supposed to be beneficial for GA . Furthermore, fragmentation of GA is not common phenomenon in the ischemia, but intact GA structural of neurons is beneficial for cell survival.

Amygdala protein kinase C epsilon controls alcohol consumption

Alcoholism is a progressive disorder that involves the amygdala. Mice lacking protein kinase C epsilon (PKCepsilon) show reduced ethanol consumption, sensitivity and reward. We therefore investigated whether PKCepsilon signaling in the amygdala is involved in ethanol consumption. Local knockdown of PKCepsilon in the amygdala reduced ethanol consumption and preference in a limited-access paradigm. Further, mice that are heterozygous for the PKCepsilon allele consume less ethanol compared with wild-type mice in this paradigm. These mice have a >50% reduction in the abundance of PKCepsilon in the amygdala compared with wild-type mice. We conclude that amygdala PKCepsilon is important for ethanol consumption in mice.

Expression and hormonal regulation of IL-11Ralpha in canine uterus during early pregnancy

Embryo implantation is critical for the successful establishment of pregnancy. Interleukin-11 (IL-11) is essential for adequate decidualization in the mouse and human via binding to the specific IL-11 receptor alpha (IL-11Ralpha). But the expression and regulation of IL-11 and IL-11Ralpha in the canine endometrium remain unknown. The aim of this study was to investigate the differential expression of IL-11Ralpha in canine uterus during early pregnancy and its regulation under different conditions by in situ hybridization. Interleukin-11Ralpha mRNA was mainly localized in glandular epithelium in canine uterus. There was a low level of IL-11Ralpha expression in the glandular epithelium on days 6, 12 and 17 of pregnancy. On day 20 of pregnancy when embryo implanted, IL-11Ralpha mRNA was highly expressed in the glandular epithelium surrounding the embryo, but not in the luminal epithelium and stroma. On day 23 of pregnancy, the expression of IL-11Ralpha mRNA maintained a constant level compared with the expression of day 20 and increased on day 28 of pregnancy. During the oestrous cycle, a high level of IL-11Ralpha mRNA expression was seen in the oestrous uterus. Progesterone slightly induced the expression of IL-11Ralpha mRNA in the ovariectomized canine uterus. These results suggest that IL-11Ralpha expression is closely related to canine implantation and up-regulated by progesterone.

Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

Doppler backscattering (DBS) has been successfully used to measure the E x B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1 < or = k(perpendicular rho(s)) < or = 4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm < Delta r < 3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f or = 10 kHz) have been obtained for 0.6 < r/a < 0.95.

HSPB2/MKBP, a novel and unique member of the small heat-shock protein family

Although proteins belonging to the sHSP superfamily are diverse in sequence and size, most share characteristic features, including 1) a small molecular mass of 12-43 kDa, 2) a conserved alpha-crystallin domain of 80-100 residues, 3) formation of large oligomers, 4) a dynamic quaternary structure, and 5) induction by stress conditions and chaperone activity in suppressing protein aggregation. HSPB2/MKBP (myotonic dystrophy kinase-bind-protein) retains the structural motif of the alpha-crystallin family of HSPs but shows a unique nature compared with canonical family members, characterized by gene allocation, specific binding partners in skeletal muscle, and unique stress responsiveness. MKBP may be involved in the pathogenesis of myotonic dystrophy and contribute to the neuropathology in both Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis, Dutch type.

An animal model of human cytomegalovirus infection

To develop a rat model that allowed in vivo progressive human cytomegalovirus (HCMV) infection, allogeneic liver transplantation was performed across a rat combination of Dark Agouti (DA) to Brown Norway (BN). AD169, a well-characterized laboratory strain of HCMV, was used to establish a rat model of HCMV infection by injection of 0.4 mL (30.0 logTCID50) supernate into the rat peritoneum. Histological and blood specimens were obtained from animals sacrificed at predetermined timepoints. We performed immunohistochemical staining in liver, heart, kidney, spleen, and lung for HCMV immediate-early antigen (IE), lower matrix protein (pp65) detection in peripheral blood leukocytes, and HCMV early antigen (EA) and late antigen (LA). We compared survival rates. Our results showed positive HCMV IE and pp65 antigenemia detected in peripheral blood leukocytes in transplanted recipients from day 1 to day 30. Positive HCMV EA and LA staining cells were only detected in sections 10 days after liver transplantation, namely, in hepatocytes, mononuclear cells, bile duct epithelial cells, and endothelial cells. Successful HCMV replication was due to the combination of liver transplantation and cyclosporine (CsA) immunosuppression. Survival analysis showed no significant differences between the HCMV-infected group and HCMV-uninfected group. This new rat model of HCMV infection may be helpful to understand immune system modulation of HCMV infection.

Downregulated NM23-H1 expression is associated with intracranial invasion of nasopharyngeal carcinoma

Because the focus of nasopharyngeal carcinoma (NPC) is very close to intracranial organs, it often makes incursions into cranial cavity. Identification of intracranial invasion-associated indicators will provide potential therapeutic targets for NPC patients with intracranial invasion. In this regard, Human Xpro™ HC-plus cancer-related gene chip was utilised to screen intracranial invasion-associated genes for NPC from the biopsied primary focus tissue samples. In all, 8 upregulated and 23 downregulated genes were obtained. VEGF165 and MMP-9, the two upregulated genes, and NM23-H1, the downregulated one, were further confirmed by immunohistochemistry, quantitative real-time PCR and western blot. Invasion-associated cellular and nude mouse models were subsequently employed to study the biological properties of NM23-H1. NM23-H1 expression was significantly lower in 5-8F cells compared with that in 6-10B cells. Moreover, patch-clamp and transwell chamber were adopted to investigate the invading potential-associated biological dynamic mechanisms in the two cell lines, and Ca²⁺ current and motility were significantly elevated in 5-8F cells compared with that in 6-10B cells. Berberine, an inhibitor of Ca²⁺ current, could substantially increase the expression of NM23-H1 and decrease 5-8F cell motility. The specificity of berberine on NM23-H1 and cell motility was confirmed by RNAi assay.

Structure and acetyl-lysine recognition of the bromodomain

Histone lysine acetylation is central to epigenetic control of gene transcription. The bromodomain, found in chromatin-associated proteins and histone acetyltranferases, functions as the sole protein module known to bind acetyl-lysine motifs. Recent structural and functional analyses of bromodomains' recognition of lysine-acetylated peptides derived from major acetylation sites in histones and cellular proteins provide new insights into differences in ligand binding selectivity as well as unifying features of histone recognition by the bromodomains. These new findings highlight the functional importance of bromodomain/acetyl-lysine binding as a pivotal mechanism for regulating protein-protein interactions in histone-directed chromatin remodeling and gene transcription. These new studies also support the notion that functional diversity of a conserved bromodomain structural fold is achieved by evolutionary changes of structurally flexible amino-acid sequences in the ligand binding site such as the ZA and BC loops.

The epitope study of alpha-fodrin autoantibody in primary Sjögren's syndrome

Alpha-fodrin, an intracellular organ-specific cytoskeleton protein, was identified recently as an autoantigen associated with Sicca- and Sjögren's syndrome (SS). Identification of the antigenic determinants of alpha-fodrin is a prerequisite to developing highly sensitive and specific anti-alpha-fodrin antibodies, which provides potential means for the diagnosis of primary Sjögren's syndrome (pSS) in patients. Based on the structure and predicted antigenic sites of alpha-fodrin protein with 560 amino acids (alpha-fodrin 560), we prepared a set of overlapping recombinant protein fragments covering antigenic epitopes and synthesized a set of peptides derived from the alpha-fodrin protein. These recombinant proteins and synthesized peptides were subjected to screening with pSS patients sera, respectively. The peptide with the strongest immunoreactivity was used as antigenic peptide to define further the role of anti-alpha-fodrin-peptide antibodies in the sera of 135 patients with pSS, 48 patients with systemic lupus erythematosus (SLE), 88 patients with rheumatoid arthritis (RA) and 83 normal controls. Our data showed that the N-terminal peptide of amino acids 46-59 (N46) of alpha-fodrin 560 was the epitope with strongest antigenicity. The prevalences of anti-N46 peptide antibodies (alpha-N46PA) in patients with pSS, SLE, RA and normal controls were 78.5%, 10.4%, 21.6% and 6.0%, respectively. The sensitivity and specificity of the autoantibodies in pSS were 78.5% and 86.8%, respectively. These results suggest the alpha-N46PA which shows highest sensitivity and specificity is of significance to develop an effective diagnostic approach for pSS.

The role of EGFR trafficking in neuroblastoma

20003

Background: Signaling through growth factor receptors is important in neuroblastoma pathogenesis. Chromosome 1p36 is commonly deleted in neuroblastoma tumors and is associated with a poor prognosis. UBE4B, a gene in 1p36, has been reported mutated in high- risk neuroblastoma. We have found a direct interaction between UBE4B and hrs, a protein required for epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. We have analyzed the role of UBE4B in the EGFR pathway in neuroblastoma cell lines. Methods: The expression of UBE4B, hrs and EGFR were analyzed by quantitative Western blot in a panel of 7 human neuroblastoma cell lines (SHEP, SKNAS, SKNSH, KCNR, SY5Y, LA155N, NGP). EGFR degradation rates were determined by examining the kinetics of cellular EGFR depletion following a pulse of ligand. Results: UBE4B levels were lowest in SKNAS and highest in NGP cells. Hrs levels were lowest in SKNSH cells and higher in other cell lines. EGFR levels were lowest in NGP and KCNR and highest in SKNAS cells. UBE4B levels were correlated with known 1p deletions. EGFR degradation rates were slowest in SKNAS cells and therefore correlated with cellular UBE4B levels. The low degradation rates were correlated with high cellular levels of EGFR. Conclusions: Expression levels of UBE4B are correlated in neuroblastoma cell lines with chromosome 1p deletions. Cell lines with lower levels of UBE4B degrade EGFR at a markedly slower rate, correlated with higher cellular EGFR levels. We hypothesize that UBE4B affects cell growth by interacting with hrs, directing EGFR for degradation. In its absence the ability of a cell to sort growth factor receptors for degradation is inhibited, resulting in growth factor receptor overabundance and uncontrolled cell growth. These results support the testing of EGFR inhibitors in a future phase I trial for children with neuroblastoma.

No significant financial relationships to disclose.

Morphological alteration of Golgi apparatus and subcellular compartmentalization of TGF-beta1 in Golgi apparatus in gerbils following transient forebrain ischemia

Golgi apparatus (GA) is a very important organelle involved in the metabolism of numerous proteins. TGF-beta1 plays an important role in supporting neuronal survival after ischemic insults. Little is known, however, about the morphological alteration of GA and subcellular compartmentalization of TGF-beta1 in brain after ischemia. Therefore, our present study was designed to check for GA morphological alterations and TGF-beta1 subcellular localization. GA immunoreactivities were examined in the somatosensory cortex of gerbils after 10 min transient forebrain ischemia. Confocal Immunofluorographs of TGF-beta1 and TGN38 were also taken. Results indicated that no fragmentation of GA was found in gerbils of norm, shams and 6, 24 and 72 h postocclusion, but some of the cortical cells showed fragmentation of GA in gerbils 7 days postocclusion. TGF-beta1 was colocalized with TGN38, a marker molecule for the GA. We conclude that there was morphological alterations of GA and TGF-beta1 was present in GA in the somatosensory cortex after 10 min ischemia.