细胞外基质黏附分子表达与成釉细胞瘤生物学特性的关系

 【目的】探讨细胞外基质黏附分子层粘连蛋白（LN）和纤黏连蛋白（FN）与成釉细胞瘤复发和侵袭的关系。【方法】采用免疫组织化学LABC方法检测28例成釉细胞瘤组织中LN和FN的表达。【结果】在28例成釉细胞瘤中，LN和FN在基底膜的阳性表达率分别为46．4％和39．3％，复发性成釉细胞瘤LN和FN在基底膜的阳性表达率明显低于原发性成釉细胞瘤（P〈0．01）。LN和FN的表达形式相似，阳性着色部位均位于基底膜及部分肿瘤细胞的胞浆，在基底膜连续着色的部位，靠近基底膜的肿瘤外周细胞胞浆染色较强，中央内层细胞胞浆染色弱或无，而在基底膜着色缺失的部位，靠近基底膜的肿瘤外周细胞胞浆染色弱或缺失。【结论】LN和FN在基底膜表达缺失与成釉细胞瘤的复发密切相关，可能是成釉细胞瘤局部侵袭的机制之一。     

Ultrastructural Characterization of Mesenchymal and Epithelial Cells Co-Cultured from Human Dental Root Apical Explants

Previous studies have shown the role of cell-cell and cell-matrix interactions in the differentiation of the specific secretory cells of the tooth. In order to elucidate the mechanisms implicated in root dentin formation, we developed a co-culture system of human pulpal mesenchymal and epithelial root sheath cells. Root tips of premolars were cultured in Eagle's basal Medium supplemented with fetal calf serum, ascorbic acid, antibiotics and, for some of them, with sodium β-glycerophosphate. After 60 days of culture, cells were prepared for light and electron microscopy. Three main cell types were observed: (1) polygonal mesenchymal cells showing a functional polarity and producing a dense network of tactoid collagenous fibers. The latter had a specific circular organization that delimited small lacunae around the cells and mineralized in the presence of β-glycerophosphate; (2) spindle-shaped mesenchymal cells mainly localized inside epithelial-mesenchymal knots and synthesizing an abundant collagenous matrix; and (3) epithelial cells lying on the plastic culture dish, on the dense collagenous matrix, or on spindle-shaped cells. Epithelial cells deposited a structured basement membrane when they were lying on the plastic culture dish or on spindle-shaped cells. On the contrary, no basement membrane was found when epithelial cells were overlying the dense collagenous network. Immunoelectron microscopic analysis of type IV collagen and laminin indicated that these two specific basement membrane components were produced by all cell types. These results show that the co-culture system should be valuable for (1) studying the in vitro formation of human dental root hard tissues, (2) characterizing cell-cell and cell-matrix interactions implicated in dental basement membrane production, and (3) isolating populations of cells implicated in dental root formation.     

Review: Lutheran/B-CAM: A Laminin Receptor on Red Blood Cells and in Various Tissues

The Lutheran blood group glycoprotein (Lu), also known as basal cell adhesion molecule (B-CAM), is a transmembrane receptor with five immunoglobulin-like domains in its extracellular region; it is therefore classified as a member of the immunoglobulin (Ig) gene family. Lu/B-CAM is observed not only on red blood cells, but also on a subset of muscle and epithelial cells in various tissues. Recently, several groups have reported that Lu/B-CAM is a novel receptor for laminin α5. The laminin α5 chain is a component of the laminin-511 (α5β1γ1), -521 (α5β2γ1), and -523 (α5β2γ3) heterotrimers and is expressed throughout the mammalian body. We also have shown that Lu/B-CAM is co-localized with laminin α5 in various tissues. Although the biological role of Lu/B-CAM remains unclear, the specific binding of Lu/B-CAM to laminin α5 suggests that it plays an important role in developmental and physiological processes. It also is necessary to investigate further the interaction between Lu/B-CAM and laminin α5 in pathological processes, including sickle cell disease and cancer.     

肝病患者LN,PCⅢ,Ⅳ-C及PLD变化的意义

目的探讨慢性肝病患者血清LN，PCⅢ，Ⅳ－C及PLD变化的临床意义．方法慢性肝病患者99例，其中慢性HBV感染30例，肝硬变40例，肝癌29例及正常对照30例进行研究.血清LN，PCⅢ及Ⅳ－C含量用放射免疫测定，血清PLD采用生化比色法测定.结果肝硬变及肝癌患者血清LN，PCⅢ，Ⅳ－C，PLD均显著高于正常组及慢性HBV感染织（P均＜0．01），慢性HBV感染织PCⅢ也较正常组为高（P＜0．01），肝硬变患者血清PCⅢ，Ⅳ－C含量较肝癌组增高（P＜0.05）．肝硬变组各指标单项检测阳性率为PCⅢ＞LN＞Ⅳ－C＞PLD，联合检测以PCⅢ＋LN阳性率为高.肝硬变、肝癌与HBV感染单项指标检测结果存在部分重叠．结论LN，PC-Ⅲ，Ⅳ－C及PLD检测有助于肝硬变患者的临床诊断及慢性HBV感染的趋势判断；PCⅢ＋LN联合检测可提高肝硬变诊断的特异性．     

Biocompatibility evaluation of emulsion electrospun nanofibers using osteoblasts for bone tissue engineering

Emulsion electrospinning is an advanced technique to fabricate core-shell structured nanofibrous scaffolds, with great potential for drug encapsulation. Incorporation of dual factors hydroxyapatite (HA) and laminin, respectively, within the shell and core of nanofibers through emulsion electrospinning might be of advantageous in supporting the adhesion, proliferation, and maturation of cells instead of single factor-encapsulated nanofibers. We fabricated poly(L-lactic acid-co-?-caprolactone) (PLCL)/hydroxyapaptite (PLCL/HA), PLCL/laminin (PLCL/Lam), and PLCL/hydroxyapatite/laminin (PLCL/HA/Lam) scaffolds with fiber diameter of 388?±?35, 388?±?81, and 379?±?57?nm, respectively, by emulsion electrospinning. The elastic modulus of the prepared scaffolds ranged from 22.7–37.0?MPa. The osteoblast proliferation on PLCL/HA/Lam scaffolds, determined on day 21, was found 10.4% and 12.0% higher than the cell proliferation on PLCL/Lam or PLCL/HA scaffold, respectively. Cell maturation determined on day 14, by alkaline phosphatase (ALP) activity, was significantly higher on PLCL/HA/Lam scaffolds than the ALP activity on PLCL/HA and PLCL/Lam scaffolds (p???0.05). Results of the energy dispersive X-ray studies carried out on day 28 also showed higher calcium deposition by cells seeded on PLCL/HA/Lam scaffolds. Osteoblasts were found to adhere, proliferate, and mature actively on PLCL/HA/Lam nanofibers with enhanced cell proliferation, ALP activity, bone protein expression, and mineral deposition. Based on the results, we can conclude that laminin and HA individually played roles in osteoblast proliferation and maturation, and the synergistic function of both factors within the novel emulsion electrospun PLCL/HA/Lam nanofibers enhanced the functionality of osteoblasts, confirming their potential application in bone tissue regeneration.     

Potentiation of the ligand-binding activity of integrin alpha3beta1 via association with tetraspanin CD151

CD151, one of the tetraspanins, forms a stable complex with integrin alpha3beta1, the major laminin receptor on the cell surface. We found that 8C3, an anti-CD151 mAb obtained by screening for reactivity with integrin alpha3beta1-CD151 complexes, was capable of dissociating CD151 from integrin alpha3beta1, thereby allowing us to deplete CD151 from purified integrin alpha3beta1-CD151 complexes. The CD151-free integrin alpha3beta1 thus obtained showed a significant reduction in its ability to bind to laminin-10/11, a high-affinity ligand for integrin alpha3beta1, with a concomitant reduction in its reactivity with mAb AG89, which recognizes activated beta1-containing integrins. These results raised the possibility that the association of integrin alpha3beta1 with CD151 potentiates the ligand-binding activity of the integrin through sustaining its activated conformation. In support of this possibility, the ligand-binding activity was restored when CD151-free integrin alpha3beta1 was reassociated with purified CD151. 8C3-induced dissociation of CD151 from integrin alpha3beta1 was also demonstrated on the surface of living cells by fluorescent resonance energy transfer imaging, accompanied by a concomitant reduction in the cell adhesion to laminin-10/11-coated substrates. CD151 knock-down by RNA interference also resulted in a reduction in the adhesive activity of the cells. Taken together, these results indicate that CD151 association modulates the ligand-binding activity of integrin alpha3beta1 through stabilizing its activated conformation not only with purified proteins but also in a physiological context.     

ROLE of exercise in maintaining the integrity of the neuromuscular junction

Physical activity plays an important role in preventing chronic disease in adults and the elderly. Exercise has beneficial effects on the nervous system, including at the neuromuscular junction (NMJ). Exercise causes hypertrophy of NMJs and improves recovery from peripheral nerve injuries, whereas decreased physical activity causes degenerative changes in NMJs. Recent studies have begun to elucidate molecular mechanisms underlying the beneficial effects of exercise. These mechanisms involve Bassoon, neuregulin‐1, peroxisome proliferator–activated receptor gamma coactivator 1α, insulin‐like growth factor‐1, glial cell line–derived neurotrophic factor, neurotrophin 4, Homer, and nuclear factor of activated T cells c1. For example, NMJ denervation and active zone decreases have been observed in aged NMJs, but these age‐dependent degenerative changes can be ameliorated by exercise. In this review we assess the effects of exercise on the maintenance and regeneration of NMJs and highlight recent insights into the molecular mechanisms underlying these exercise effects. Muscle Nerve 49 :315–324, 2014     

Differential expression of matrilysin-1 (MMP-7), 92 kD gelatinase (MMP-9), and metalloelastase (MMP-12) in oral verrucous and squamous cell cancer

Squamous cell carcinoma (SCC) of the oral cavity is a highly invasive tumour of stratified squamous epithelium that spreads through degradation of the basement membrane (BM) and extracellular matrix (ECM). There are currently no reliable tissue or serum markers to predict whether the tumour has metastasized at the time of diagnosis. Verrucous carcinoma (VC) of the oral cavity is a rare low-grade variant of oral SCC that penetrates into the subepithelial connective tissue. Many matrix metalloproteinases (MMPs), such as MMP-1, -2, -7, -9, -13, and -14, as well as integrin receptors have been implicated in cancer invasion. Integrin alphavbeta6 is induced in SCC and appears to be involved in up-regulation of MMP-9 expression by oral keratinocytes and promotion of their migration. The aim of this study was to investigate whether the pattern of MMP expression or that of alphavbeta6 integrin contributes to the differences in the biological behaviour of oral SCC and VC. The results show that the less aggressive nature of oral VC may be connected to its MMP expression profile. Typically, VCs were devoid of epithelial MMP-3, -7, -9, -12 and -13 expression, compared with SCCs. MMP-19 was expressed by epithelial keratinocytes in hyperproliferative areas of verrucous hyperplasia, VC, and SCC, but was absent in the invasive cancer cell nests of SCC. MMP-26 was expressed by hyperproliferative keratinocytes in VC as well as by invasive cancer cells in SCCs. MMP-10 was expressed widely in the epithelium of all SCC specimens. alphavbeta6 integrin expression was also detected in some cases of epithelial hyperplasia but was significantly more abundant in cancers at the invasive front. The absence of MMP-7, -9 and -12 from epithelial cells may serve as a good prognostic marker of non-invasive oral carcinoma. Blocking the activity of invasion-specific MMPs or alphavbeta6 integrin might offer novel therapeutic modalities in early-stage oral carcinoma.