[Effects of MMPs inhibitors on microleakage with wet bonding technique].

PURPOSE: To observe the effects of matrix metalloproteinases(MMPs) inhibitors on microleakage with wet bonding technique. METHODS: Twenty-seven premolars were randomly assigned to 3 groups. Class Ⅴ cavities were prepared in the neck of the teeth and treated with distilled water, 2% chlorhexidine (CHX) or 2% monocycline (MI) for 60 seconds. Resin was used to restore the prepared cavities following application of luting agent. Samples in each group were soaked for 1 h with 10% NaClO and then 2 layers of nail polish were applied, followed by treatment with 50wt% ammoniated silver nitrate (ASN), and developing solution in turn. Each tooth was sectioned longitudinally to 1~2 mm slices and examined with stereo microscope and scanning electron microscope (SEM). The data were analyzed with SPSS 16.0 software package for Wilcoxon rank sum test. RESULTS: There was varied microleakage at the margin. The difference was significant between group CHX and control group, between group MI and control group; However, there was no significant difference between group CHX and group MI. CONCLUSIONS: MMPs inhibitor can reduce microleakage with wet bonding technique.

[Evaluation of the effect for ffh gene silencing on the aciduricity of fluoride resistant Streptococcus mutans].

PURPOSE: To analyze the effect of ffh gene silencing on the aciduricity of fluoride resistant Streptococcus mutans in vitro. METHODS: By using electroporation, UA159-FR was transformed and combined with targeted site of ffh gene sequence, and the best piece of siRNA for fluoride resistant Streptococcus mutans was screened. In different values of pH of BHI, they were cultured for 24 hours with UA159-FR respectively, and then centrifugated to determine the pH and OD600. SPSS17.0 software package was used to analyze the data. RESULTS: The aciduricity of UA159-FR had significant differences compared with ffh gene silencing for UA159-FR in δpH (P<0.05), and the former was higher than the latter. At pH=3.5-5.0, P<0.01; at pH=5.5-7.5, P<0.05. Significant differences were noted in OD600 and their growth tendency were similar. CONCLUSIONS: The aciduricity of fluoride resistant Streptococcus mutans has significant effect when the ffh gene is silenced.

Overexpression of myofibrillogenesis regulator-1 aggravates cardiac hypertrophy induced by angiotensin II in mice.

Myofibrillogenesis regulator-1 (MR-1) augments cardiomyocytes hypertrophy induced by angiotensin II (Ang II) in vitro. However, its roles in cardiac hypertrophy in vivo remain unknown. Here, we investigate whether MR-1 can promote cardiac hypertrophy induced by Ang II in vivo and elucidate the molecular mechanisms of MR-1 on cardiac hypertrophy. We used a model of Ang II-induced cardiac hypertrophy by infusion of Ang II in female mice. In wild-type mice subjected to the Ang II infusion, cardiac hypertrophy developed after 2 weeks. In mice overexpressing human MR-1 (transgenic), however, cardiac hypertrophy was significantly greater than in wild-type mice as estimated by heart weight:body weight ratio, cardiomyocyte area, and echocardiographic measurements, as well as cardiac atrial natriuretic peptide and B-type natriuretic peptide mRNA and protein levels. Our further results showed that cardiac inflammation and fibrosis observed in wild-type Ang II mice were augmented in transgenic Ang II mice. Importantly, increased nuclear factor kappaB activation was significantly increased higher in transgenic mice compared with wild-type mice after 2 weeks of Ang II infusion. In vitro experiments also revealed that overexpression of MR-1 enhanced Ang II-induced nuclear factor kappaB activation, whereas downregulation of MR-1 blocked it in cardiac myocytes. In conclusion, our results suggest that MR-1 plays an aggravative role in the development of cardiac hypertrophy via activation of the nuclear factor kappaB signaling pathway.

[Cloning of mMR-1 gene and expression in Pichia pastoris systems].

hMR-1 (Homo Myofibrillogenesis Regulator 1, AF417001) is a novel homo gene, which was firstly cloned in our laboratory. The former studies revealed that hMR-1 is a transmembrane protein which shows protein interaction with sarcomeric proteins like myomesin I, myosin regulatory light chain, alpha-enolase and some cell regulator proteins such as eukaryotic translation initiation factor3 subunit 5 (eIF3S5) and etc. In this work, we focused on cloning the homologous gene of hMR-1 from mouse C57BL/6J and exploring its expression using Pichia pastoris yeast system. Two pairs of primers were synthesized according to the hMR-1 gene homologous sequence on mouse genome chromosome 1. The mouse MR-1 gene (mMR-1) was cloned by PCR following the first round RT-PCR from mouse C57BL/6J spleen total RNA. Sequence analysis verified that mMR-1 gene and amino acids sequence showed 90.4% and 90.1% identity with hMR-1, respectively. The prediction of hydrophobic transmembrane structure of mMR-1 suggested it is also a transmembrane protein. The mMR-1 Pichia pastoris expression vector pPIC9-mMR-1 was constructed by fusion of the flanking mMR-1 ORF in the pPIC9 plasmid. After linearization of pPIC9-mMR-1 with Sal I, the 8.5kb DNA fragment was transformed into Pichia pastoris GS115 strain by electroporation. GS115/Mut+ pPIC9-mMR-1 transformants were selected on minimal methanol medium. Integration of mMR-1 gene into the yeast genome in the recombinants was verified by PCR from the transformants total DNA. The mMR-1 protein was expressed by induction under the concentration of 0.5 % methanol. The specific induced protein of 25 kD molecular mass in SDS-PAGE was confirmed to be the mMR-1 protein by Western blot rsing hMR-1 polyclonal antibody. The expression level of this recombinant mMR-1 protein was about 50 mg/L. The successful expression of mMR-1 in the Pichia pastoris GS115 will facilitate the further functional analysis of the novel gene MR-1 in animal model.

[Expression of a human myofibrillogenesis regulator 1 gene in E. coli and its immunogenicity].

OBJECTIVE: To study the expression of human myofibrillogenesis regulator 1 (MR-1) gene in E. coli and obtain the MR-1 protein and its antibody for further investigation of its biological function. METHODS: Expression vectors pGEX-5X-1, pET30a (+), and pET24a (+), as well as host strain E. coli BL21 (DE3) and BL21-CodonPlus (DE3) -RIL were used for expression of MR-1. MR-1 N-terminal with GST or T7-tag or C-terminal with His-tag, separately, or N terminal with T7-tag and C terminal with His-tag, simultaneously, were fused in plasmids pGEX-5X-1, pET30a (+) , and pET24a (+). The expressed MR-1-T protein, separated and purified by preparative SDS-PAGE, was applied to immunize the rabbits. The titer of the antibody was assayed by ELISA and its immunogenicity was tested by Western blot with pcDNA3/MR-1 transfected human breast cancer cell MCF7. RESULTS: The MR-1 protein was successfully expressed as inclusion body by fusing its N-terminal with T7-tag in E. coli BL21-CodonPlus (DE3) -RIL. MR-1 protein was purified by electro-elution from SDS-PAGE gel. Using this purified protein, polyclonal antibody in rabbit against MR-1 was essentially generated. ELISA and Western blot showed the titer of this antibody was about 1:10(5) with high immunogenicity. CONCLUSIONS: The N-terminal fusion tag is the most important mechanism for MR-1 expression. The polyclonal antibody of the generated MR-1 protein in E. coli may be applied for its further biological function studies.

Characterization of MR-1, a novel myofibrillogenesis regulator in human muscle.

The actin-myosin contractile apparatus consists of several thick filament and thin filament proteins. Specific regulatory mechanisms are involved in this highly ordered process. In this paper, we reported the identification and characterization of a novel myofibrillogenesis regulator, MR-1. The MR-1 gene was cloned from human skeletal muscle cDNA library by using a strategy that involves EST data base searching, PCR and RACE. The MR-1 gene is located on human chromosome 2q35 and encodes a 142 aa protein. Northern blot revealed that the mRNA level of MR-1 was highest in the skeletal muscle and certain level of MR-1 expression was also observed in heart, liver and kidney. Immunohistochemical assay confirmed that the MR-1 protein existed in human myocardial myofibrils. It was found by yeast two-hybrid screening and confirmed by in vitro binding assay that MR-1 could interact with sarcomeric proteins, such as myosin regulatory light chain, myomesin 1 and beta-enolase. These studies suggested that MR-1 might play a regulatory role in the muscle cell and it was worth investigating further.