Membrane-type matrix metalloproteinase-1 expression at the site of human placentation

Human trophoblast implantation is a highly regulated process of invasion that requires action of proteolytic enzymes to degrade extracellular matrix components of the endometrium. Among these enzymes, matrix metalloproteinases (MMPs) seem to be particularly important in this degradative process. We previously showed that gelatinase A is extensively expressed in vivo in the human placenta. A new MMP, MT-MMP-1 (membrane-type matrix metalloproteinase-1), which is thought to activate progelatinase A, has recently been described. In this study, we examined the expression of MT-MMP-1, by immunohistochemistry and in situ hybridization, in human placental bed biopsies taken during the first trimester of gestation. Human first trimester intermediate trophoblasts synthesized MT-MMP-1 mRNAs and the protein. The MT-MMP-1 pattern of distribution in placental beds was similar to that of gelatinase A, suggesting a pivotal role for MT-MMP-1 in placentation, perhaps by activating progelatinase A.     

Kinetic properties of a single nucleotide binding site on chloroplast coupling factor 1 (CF1)

The kinetics of nucleotide binding to spinach chloroplast coupling factor CF1 in a fully inhibited state were investigated by stopped-flow experiments using the fluorescent trinitrophenyl analogue (NO2)3Ph-ADP. The CF1 was in a state in which two of the three binding sites on the beta subunits were irreversibly blocked with ADP, Mg2+ and fluoroaluminate, while the three binding sites on the alpha subunits were occupied by nucleotides [Garin, J., Vincon, M., Gagnon, J. & Vignais, P. V. (1994) Biochemistry 33, 3772-3777)]. Thus, it was possible to characterise a single nucleotide-binding site without superimposed nucleotide exchange or binding to an additional site. (NO2)3Ph-ADP binding to the remaining site on the third beta subunit was characterised by a high dissociation rate of 15 s(-1), leading to a very low affinity (dissociation constant higher than 150 microM). Subsequent to isolation, CF1 preparations contained two endogenously bound nucleotides. Pre-loading with ATP yielded CF1 with five tightly bound nucleotides and one free nucleotide-binding site on a beta subunit. Pre-loading with ADP, however, resulted in a CF1 preparation containing four tightly bound nucleotides and two free nucleotide binding sites. One of the two free binding sites was located on a beta subunit, while the other was probably located on an alpha subunit.     

转录因子Ets1和Ets2在小鼠睾丸组织中的表达及其意义

目的:检测Ets家族转录因子Ets1和Ets2在小鼠睾丸组织中的表达,探讨其对小鼠睾丸发育的调控及其对精原干细胞(SSCs)增殖、分化的可能影响.方法:取生后第1、5、10、15、20、25、30、35、40、50和70天的小鼠睾丸组织,对成年小鼠进行白消安10 mg·kg-1腹腔注射,分别在注射后第0、3、5、8、10和18天取睾丸组织,用半定量RT-PCR方法对比内参β-actin在对应组织内的表达水平,分析Ets1、Ets2 mRNA在睾丸组织中的相对表达量.结果:Ets1的表达量在生后第1～30天显著高于出生后第35天(P<0.05或P<0.01),之后明显降低并保持稳定;Ets2在生后第1～25天表达量显著高于第35天(P<0.05或P<0.01),之后明显下降并保持稳定.白消安处理后,Ets1的表达量于第5天降至最低,随后逐渐恢复,第9天后基本达到处理前水平并保持相对稳定,其中第5、8天表达量均显著低于处理后第0天(P<0.05或P<0.01);Ets2的表达量在白消安处理后前期变化不明显,第10天时明显降低,与第0和18天比较差异有统计学意义(P<0.05),之后缓慢回升,第18天左右恢复至处理前水平.结论:转录因子Ets1和Ets2可能对睾丸早期发育、成年精子发生的维持及精原细胞的增殖、分化具有调节作用.     

An Sp1 binding site polymorphism in the COLIA1 gene predicts osteoporotic fractures in both men and women

Genetic factors play an important role in the pathogenesis of osteoporosis, and recent studies have shown that a polymorphic Sp1 binding site in collagen type I alpha1 (COLIA1) gene is associated with bone mass and vertebral fractures in women from the U.K. Information on the predictive value of the COLIA1 Sp1 polymorphism in other populations is limited, however, and no studies have yet been performed in osteoporotic males. In view of this, we analyzed COLIA1 genotypes in relation to bone density and biochemical markers of bone turnover and the presence of osteoporotic fractures in a case-control study of Danish men and women. COLIA1 genotype was determined by polymerase chain reaction analysis of genomic DNA extracted from peripheral blood samples and related to bone mass, biochemical markers of bone turnover, and the presence of fracture in a study of 375 osteoporotic vertebral fracture patients and normal controls. There was no significant effect of COLIA1 genotype on bone mass or biochemical markers when data from the control group (n = 195) and fracture group (n = 180) were analyzed separately. However, the genotype distribution was significantly different in the fracture cases compared with age-matched controls (chi2 = 16.48, n = 249,p = 0.0003) due mainly to over-representation of the ss genotype in the fracture patients (14.3% vs. 1.4%), equivalent to an odds ratio for vertebral fracture of 11.83 (95% confidence interval 2.64-52.97) in those with the ss genotype. Similar differences in genotype distribution between osteoporotic patients and controls were observed in both men (chi2 = 11.52, n = 95, p = 0.0032, OR = 2.04) and women (chi2 = 6.90, n = 154, p = 0.032, OR = 1.37). In keeping with the above, logistic regression analysis showed that the ss genotype was an independent predictor of osteoporotic fracture (p = 0.028). This study confirms that the COLIA1 Sp1 polymorphism is significantly associated with osteoporotic vertebral fractures. The association is seen in both men and women, and the effect on fracture risk appears to be partly independent of bone mineral density. Our results raise the possibility that genotyping at the Sp1 site could be of clinical value in identifying individuals at risk of osteoporotic fractures in both genders.     

Effects of phosphate neutralization on the shape of the AP-1 transcription factor binding site in duplex DNA

Previous electrophoretic experiments suggest that the AP-1 site in duplex DNA bends in response to the pattern of amino acid charges distal to the basic region in bound bZIP proteins. The extent and direction of apparent DNA bending are consistent with the prediction that DNA will collapse locally upon asymmetric phosphate charge neutralization. To prove that asymmetric phosphate neutralization could produce the observed degree of DNA bending, the present experiments partially substitute anionic phosphate diesters in the AP-1 site with various numbers of neutral methylphosphonate linkages. DNA bending is induced toward the neutralized face of DNA. The degree of DNA bending induced by methylphosphonate substitution (approximately 3.5 degrees per neutralized phosphate) is comparable to that induced by GCN4 variants carrying increasing numbers of additional basic amino acids. It is plausible, therefore, that asymmetric phosphate neutralization is the cause of DNA bending in such complexes.     

A H1 hemagglutinin of a human influenza A virus with a carbohydrate-modulated receptor binding site and an unusual cleavage site

Two receptor binding variants of the influenza virus A/Tübingen/12/85 (H1N1) were separated by their different plaque formation in MDCK cells. Hemagglutination of variant I was restricted to red blood cells of guinea pigs, whereas variant II also hemagglutinated chicken cells. The variants differed also in their ability to bind to alpha 2,6-linked sialic acid. Evidence is presented that this difference is determined by a complex carbohydrate side chain at asparagine131 near the receptor binding site which is absent in variant II. With both variants, the arginine found at the cleavage site of all other human isolates analyzed so far was replaced by lysine.     

Clinical significance of matrix metalloproteinase-9 and tissue inhibitor of matrix metalloproteinase-1 in peripheral blood of patients with gastric carcinoma

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in peripheral blood were measured in 54 patients with gastric carcinoma; 46 were primary and 8 were recurrent cases. There were no significant associations between MMP-9 concentrations and clinicopathological factors. TIMP-1 levels were significantly increased in advanced and recurrent cases, and in cases with peritoneal dissemination and lymph node metastasis, suggesting that TIMP-1 concentration in the peripheral blood could be a new tumor marker for the recurrence of gastric carcinoma.     

Excitotoxic brain lesion modifies binding to a USF binding site acting as a negative regulatory element in the Protease nexin-1 promoter

This paper demonstrates that epidermal cells in culture produce an activity which can increase the frequency of Ia+ epidermal Langerhans cells (LC). This was achieved by treating mice topically with a mixture containing supernatant derived from primary culture of murine epidermis (ES) and a synthetic corticosteroid, triamcinolone acetonide (TAC). The presence of the supernatant in the mixture partially protected the Ia+ LC from depletion by the steroid. The Ia+ LC frequency increasing activity was measured as the difference between the Ia+ LC frequency due to treatment with steroid mixed with supernatant and the Ia+ LC frequency due to treatment with steroid mixed with negative control medium. The mean frequency of Ia+ LC in epidermis treated with TAC mixed with ES was 606(SD 43) cells/mm2, as compared with 486 (SD 68) cells/mm2 in the epidermis treated with TAC mixed with control medium. The activity appeared to be caused by (a) proteinaceous factor(s). A fraction of ES which was retained above a > or = 10 KDa molecular weight cut-off membrane was capable of partially protecting Ia+ LC frequency from TAC depletion. Supernatants from cultured lymph nodes, dermis as well as the squamous cell carcinoma lines T7 and T79, but not the human osteosarcoma cell-line 143B, also contained similar activities. We demonstrate that GM-CSF also increased the number of Ia+ epidermal LC when applied topically to mouse skin in this system. Therefore, using this Ia+ LC frequency modulation system, we propose that GM-CSF is one example of a cytokine which may be involved in the regulation of Ia+ LC numbers in epidermis and that epidermal cells produce factors which can increase the number of Ia+ LC.