Betaine homocysteine methyltransferase (BHMT) as a specific and sensitive blood marker for acute liver injury.

We developed a high-performance ELISA assay and measured serum BHMT levels in healthy individuals and patients with acute liver injury (ALI). The detection range of this ELISA assay was from 1.56 to 100 ng/ml. BHMT levels are significantly higher in ALI groups. In the healthy group (n = 244), the median value (interquartile range, IQR 0-56.40) was 1.83 ng/ml. In the ALI group (n = 42), the median value of BHMT was 748.48 ng/ml (IQR, 0-51095.92). ROC curve analysis demonstrated good sensitivity (0.86) and specificity (0.98). In addition, in five ALI cases with time course samples available, BHMT and ALT both followed the "rise and fall" temporal pattern with the disease progression. However, the slopes of BHMT curves were steeper than ALT curves. And in three out of the five cases, BHMT levels peaked 1 day earlier than ALT levels be a sensitive marker with good prognostic value.

Generation of neutralizing monoclonal antibodies against Enterovirus 71 using synthetic peptides.

Enterovirus 71 (EV71) has led to recent outbreaks of hand, foot and mouth disease (HFMD) in China, resulting in high mortality. In this study, several monoclonal antibodies were generated by immunizing mice with two synthetic peptides, SP55 and SP70, containing amino acids 163-177 and 208-222 of VP1. The specificities of the anti-EV71 peptide monoclonal antibodies were confirmed by Western blot analysis and immunocytochemistry against EV71 virus. Most importantly, we have identified a monoclonal antibody, clone 22A12, which shows strong neutralizing activity against EV71 in an in vitro neutralization assay. Because there is no vaccine available and treatment is very limited, mouse anti-EV71 monoclonal antibody, clone 22A12, could be a promising candidate to be humanized and used for treatment of EV71 infection.

Targeted disruption of Smad4 in mouse epidermis results in failure of hair follicle cycling and formation of skin tumors.

Smad4 is the common mediator of transforming growth factor-beta (TGF-beta) superfamily signaling, which functions in diverse developmental processes in mammals. To study the role of Smad4 in skin development, a keratinocyte-specific null mutant of Smad4 (Smad4(co/co);K5-Cre) was generated in mice using the Cre-loxP system. The Smad4-mutant mice exhibited progressive alopecia as a result of the mutant hair follicles failing to undergo programmed regression. Sonic hedgehog (Shh) was only detected in Smad4-mutant hair follicles at the catagen stage. Seventy percent of Smad4(co/co); K5-Cre mice developed spontaneous tumors within 12 months of birth. c-Myc and cyclin D1 were up-regulated whereas p21 and p27 expressions were decreased, which correlated with the epidermal hyperplasia in Smad4 mutants. Interestingly, coordinated deletion of the Smad4 and PTEN genes resulted in accelerated hair loss and skin tumor formation, suggesting that Smad4 and PTEN act synergistically to regulate epidermal proliferation and differentiation. All of our data indicate that Smad4 is essential for catagen induction and acts as a critical suppressor in skin tumorigenesis.

[SMAD3 inhibits the expression of MMP-2 in mouse embryonic fibroblasts].

SMAD3 is one of the receptor-activated SMADs which are important in TGF-beta signal transduction. Smad3-null mice show accelerated cutaneous wound healing compared with wild-type mice. In this work, we investigated the functions and the mechanism of Smad3-mediated TGF-beta signal on matrix metaloproteinase-2 (MMP-2) in mouse fibroblast. We found that MMP-2 at wound bed was expressed earlier in Smad3-null mice than that in wild type and heterozygotes. In the sera of wounding mice, the activity of MMP-2 was also remarkably higher in Smad3-null mice than that in the other two. The embryonic fibroblasts were separated from Smad3 knockout mice to test the function of Smad3 in modulating the expression of MMP-2. The results showed that the expression and activity of MMP-2 in Smad3-null fibroblasts were higher than those in wild type cells. TGF-beta1 could increase the MMP-2 activities in both Smad3 mutant and wild type fibroblasts. The expression and activity of MMP-2 were inhibited by over expression of SMAD3 in Smad3-null fibroblasts, while the expression and activity of MMP-2 were increased by over expression of anti-sense Smad3 in wild type cells. All these results showed that SMAD3 inhibited the expression of MMP-2 in mouse embryonic fibroblasts.

Mutation analysis of the Smad3 gene in human osteoarthritis.

Osteoarthritis (OA) is the most common joint disease worldwide. Recent studies have shown that targeted disruption of Smad3 in mouse results in OA. To reveal the possible association between the Smad3 gene mutation and human OA, we employed polymerase chain reaction-single strand conformation polymorphism and sequencing to screen mutations in all nine exons of the Smad3 gene in 32 patients with knee OA and 50 patients with only bone fracture. A missense mutation of the Smad3 gene was found in one patient. The single base mutation located in the linker region of the SMAD3 protein was A --> T change in the position 2 of codon 197 and resulted in an asparagine to isoleucine amino-acid substitution. The expressions of matrix metalloproteinase 2 (MMP-2) and MMP-9 in sera of the patient carrying the mutation were higher than other OA patients and controls. This is the first report showing that the Smad3 gene mutations could be associated with the pathogenesis of human OA.

[Establishment of keratinocyte-specific Cre recombinase transgenic mice].

A keratinocyte-specific Cre transgenic construct (pK5-Cre) containing the keratin 5 promoter, Cre recombinase gene and polyA of human growth hormone gene was generated. The 4.2 kb DNA fragment of K5-Cre-hGH was introduced into 720 fertilized zygotes by microinjection. 695 injected eggs were implanted into the oviduct of 29 female mice respectively, from which 48 off-spring were obtained. Twelve mice carrying the transgene were identified by genotyping, and the integration efficiency is 25%. The K5-Cre transgenic mice were crossed with Smad4 conditional gene targeting mice to check the tissue-specific expression of the Cre recombinase and the Cre mediated recombination in multiple tissues. The results showed that the Cre recombinase was expressed in skin tissue only and successfully mediated the recombination between the loxP sites in vivo.