LAMPs and ABH histo-blood group antigens in granulation tissue

Endothelial cells are major participants in angiogenic processes accompanying wound repair. The functions of ABH histo-blood group antigens (HBGAs) and lysosome-associated membrane proteins LAMP-1 and LAMP-2 in endothelial cells of granulation tissue are currently unkown. Here we hypothesize that HBGAs and LAMPs enrich the phenotypic characteristics of endothelial cells and might be implicated in the plasticity of granulation tissue. Immunohistochemistry revealed permanent expression of HBGAs in the cytoplasm of endothelial cells of all sprouting capillaries regardless of the organ examined. A modulation in both the localization and the intensity of the signal for LAMPs was observed. Interestingly, LAMP-1 showed a more intensive staining compared to LAMP-2. LAMP-1 was found in the cytoplasm, as well as on plasma membranes of endothelial cells. We present the first comparative immunohistochemical study of the expression of HBGA and LAMPs in endothelial cells of granulation tissue. Novel evidence for modulating LAMP reactivity is reported. Our results suggest that both glycoconjugates might contribute to the process of neoangiogenesis and tissue remodeling in wound healing.     

Cytokeratin expression in normal human thymus at different ages

Subsets of thymic epithellal cells were examined Immuno-histochemically to determine whether or not their pheno-types change during thymic growth and at early involution in terms of cytokeratin (CK) expression. Five monoclonal antibodies specific for CK4, CK8, CK13, CK18 and CK19 were used and applied for 16 neonatal, three Infantile and one adult thymus speeimen, which had been obtained at autopsy, that were normal macroscopically and microscopicaily. CK4, CK8, CK13, CK18 and CK19 were expressed simultaneously in the cortex, medulla and subcapsular area with the exception of CK4, which showed expression on the adult thymus. Light and electron microscopy showed that CK8 and CK19 expression was overlapped. Thus, It was thought that CK8 and CK19 formed complexes in the cytoplasm of thymic epithelial cells. The Immunoreactivity to CK4, CK13 and CK18 were attenuated or disappeared In the subcapsular area during the early involution stage. Interestingly, two patterns of CK18 expression were observed in the neonatal and Infantile thymus tissues, which Indicated that the thymic microenvironment was changeable even under normal conditions.     

陈旧性坐骨神经缺损对大鼠腓肠肌组织蛋白含量及泛素表达的影响

目的：了解陈旧性坐骨神经缺损后肌肉萎缩过程中蛋白质降解的机制。方法：用SD大鼠建立坐骨神经缺损模型,切断大鼠右侧坐骨神经,形成10 mm缺损。测定术后1、2、3、4、6、9及12个月腓肠肌肌总蛋白的含量;免疫组化法观察组织中泛素的表达变化;Western印迹法测定组织中泛素蛋白的表达水平。结果：坐骨神经缺损后腓肠肌肌总蛋白含量随缺损时间延长呈进行性下降;正常腓肠肌组织中泛素呈低表达,随缺损时间延长泛素表达水平增强,持续到9个月,随后呈下调趋势。结论：陈旧性坐骨神经缺损后腓肠肌蛋白的降解、肌总蛋白量下降及肌萎缩可能和泛素-蛋白酶体途径有关。     

泛素羧基端水解酶L1在人类疾病发生发展中的调控作用

泛素-蛋白酶系统(ubiquitin proteasome system,UPS)在细胞分裂、细胞信号转导以及细胞程序死亡的过程中起到非常重要的作用.此系统主要是靠泛素化酶和去泛素化酶来实施对于目的蛋白的快速精确调控.其中,泛素羧基端水解酶L1 (ubiquitin carboxy-terminal hydrolase L1,UCH-L1)是去泛素化酶家族中的一个重要的分子,是由223个氨基酸组成的一类半胱氨酸水解酶,通过识另和裂解目标蛋白上羧基末端第76位甘氨酸,可把泛素分子从目标蛋白的多聚泛素化链上切割下来,阻止目标蛋白被UPS系统降解,从而对目标蛋白的降解代谢负向调控.由此而产生游离的泛素单体,则进一步循环参与下一个目标蛋白的泛素化代谢.UCH-L1是一个多功能的分子,除了去泛素化酶功能,还有稳定泛素单体,泛素连接酶及参与细胞骨架蛋白调控,细胞微管形成等多功能作用.     

Modulation of ABH histo-blood group antigen expression in normal and myasthenic human thymus

The role of ABH histo-blood group antigens (HBGA) in intercellular communication during normal and pathological processes is still uncertain. The present work investigates the expression of ABH HBGA in epithelial cells and lymphocytes in normal thymus, and characterizes the modulation of their immunoreactivity during myasthenic transformation. Immunohistochemistry and immunoelectron microscopy were applied on normal young thymus and on myasthenia gravis-associated thymomas and thymic hyperplasias. The Hassall's corpuscules in the thymus of young individuals were homogeneously stained for HBGA, while in hyperplastic glands only their central part was positive. Stromal epithelial cells permanently expressed HBGA in all tissue samples. In thymomas, mainly the lymphocytes in close proximity to antigen expressing epithelial cells were positive, while in the hyperplastic gland the most intensely stained lymphocytes were those within Hassall's corpuscules. Novel evidence for modulation of ABH antigen reactivity in normal and myasthenic human thymus is presented. It suggests that HBGA might participate in the regulation of the cross-talk in the thymocyte microenvironment throughout the ontogeny, as well as during the myasthenic transformation.     

Onset of promiscuous gene expression in murine fetal thymus organ culture

T-cell differentiation and induction of tolerance to self-antigens occurs mainly in the thymus. Thymic stromal cells, specifically medullary thymic epithelial cells, express a diverse set of genes encoding parenchymal organ-specific proteins. This phenomenon has been termed promiscuous gene expression (PGE) and has been implicated in preventing organ-specific autoimmunity by inducing T-cell tolerance to self antigens. Early thymopoiesis and the critical factors involved in T-cell differentiation can be reproduced in vitro by murine fetal thymus organ culture (FTOC), which mimics the natural thymic microenvironment. To evaluate the occurrence of PGE in FTOC, gene expression profiling during in vitro thymic development in BALB/c mice was performed using a set of nylon cDNA microarrays containing 9216 sequences. The statistical analysis of the microarray data (sam program) revealed the temporal repression and induction of 57 parenchymal and seven lymphoid organ-specific genes. Most of the genes analysed are repressed during early thymic development (15-17 days post-coitum). The expression of the autoimmune regulator (AIRE) gene at 16 days post-coitum marks the onset of PGE. This precedes the induction of parenchymal organ genes during the late developmental phase at 20 days post-coitum. The mechanism of T-cell tolerance induction begins during fetal development and continues into adulthood. Our findings are significant because they show a fine demarcation of PGE onset, which plays a central role in induction of T-cell tolerance.     

The Differential Profiling of Ubiquitin‐Proteasome and Autophagy Systems in Different Tissues before the Onset of Huntington's Disease Models

Huntington's disease (HD) is a genetic and neurodegenerative disease, leading to motor and cognitive dysfunction in HD patients. At cellular level, this disease is caused by the accumulation of mutant huntingtin (HTT) in different cells, and finally results in the dysfunction of different cells. To clean these mutant proteins, ubiquitin‐proteasome system (UPS) and autophagy system are two critical pathways in the brain; however, little is known in other peripheral tissues. As mutant HTT affects different tissues progressively and might influence the UPS and autophagy pathways at early stages, we attempted to examine two clearance systems in HD models before the onset. Here, in vitro results showed that the accumulation of UPS signals with time was observed obviously in neuroblastoma and kidney cells, not in other cells. In HD transgenic mice, we observed the impairment of UPS, but not autophagy, over time in the cortex and striatum. In heart and muscle tissues, disturbance of autophagy was observed, whereas dysfunction of UPS was displayed in liver and lung. These results suggest that two protein clearance pathways are disturbed differentially in different tissues before the onset of HD, and enhancement of protein clearance at early stages might provide a potential stratagem to alleviate the progression of HD.     

人胸腺内Ghrelin的免疫组织化学定位

目的:观察Ghrelin在人胸腺的定位与分布,为深入探讨胸腺内Ghrelin的功能意义提供实验依据。方法:采用特异性抗Ghrelin血清,用免疫组织化学ABC法观察人胸腺内Ghrelin的定位与分布。结果:Ghrelin免疫反应阳性细胞在胸腺内分布广泛。胸腺皮质浅层的Ghrelin阳性细胞呈巨噬细胞形态特点;而皮髓质交界区有大量上皮性网状细胞呈Ghrelin免疫反应阳性;胸腺髓质内Ghrelin阳性信号主要定位于树突状细胞和上皮性网状细胞;胸腺小体呈Ghrelin免疫反应强阳性。结论:胸腺内Ghrelin分布广泛,定位于胸腺巨噬细胞、上皮性网状细胞、树突状细胞和胸腺小体。Ghrelin可能参与胸腺细胞分化和成熟的调节。     

Immunohistochemical localization of ubiquitin cross-reactive protein in human tissues

Ubiquitin cross-reactive protein (UCRP) is an interferon-inducible ubiquitin homologue which is constitutively present in cells and can be conjugated to other proteins. Using a characterized polyclonal antiserum to UCRP, immunohistochemical localization of UCRP was performed on paraffin-processed normal human tissues and in human tissues known to contain ubiquitinated intracellular inclusions. The antibody to UCRP immunostained lymphoid cells, striated and smooth muscle, several epithelia, and neurons. The level of staining varied greatly between tissues but was in a consistent punctate pattern. Localization to neuromuscular junctions and striations is similar to that described for antisera to ubiquitin-protein conjugates. Inclusion bodies characterized by immunoreactivity to anti-ubiquitin were not detected by the antibody to UCRP. Importantly, because UCRP may also be detected by antisera to conjugated ubiquitin, future studies on the distribution of ubiquitin in tissue sections must now take account of possible cross-reactivity with UCRP.     

Manipulation of ubiquitin/SUMO pathways in human herpesviruses infection

Post‐translational modification of proteins with ubiquitin/small ubiquitin‐like modifier (SUMO) molecules triggers multiple signaling pathways that are critical for many aspects of cellular physiology. Given that viruses hijack the biosynthetic and degradative systems of their host, it is not surprising that viruses encode proteins to manipulate the host's cellular machinery for ubiquitin/SUMO modification at multiple levels. Infection with a herpesvirus, among the most ubiquitous human DNA viruses, has been linked to many human diseases, including cancers. The interplay between human herpesviruses and the ubiquitylation/SUMOylation modification system has been extensively investigated in the past decade. In this review, we present an overview of recent advances to address how the ubiquitin/SUMO–modified system alters the latency and lytic replication of herpesvirus and how herpesviruses usurp the ubiquitin/SUMO pathways against the host's intrinsic and innate immune response to favor their pathogenesis.     

UCH‐L1 expression of podocytes in diseased glomeruli and in vitro

Ubiquitin C‐terminal hydrolase‐L1 (UCH‐L1), an important member of de‐ubiquitination enzyme families involved in the ubiquitin–proteasome pathway, is expressed mainly in neural and reproductive systems as well as in some tumours. Recently, expression of UCH‐L1 has been discovered in parietal epithelial cells of Bowman's capsules and some tubular epithelia in the kidney. However, whether UCH‐L1 is expressed in the capillary tufts of the glomeruli has not yet become clear. In this study, we used immunohistochemistry, double immunofluorescence labelling, immunoelectron microscopy in kidney biopsy tissues and western blot in cultured rat podocytes to investigate the expression of UCH‐L1 and the regulation of this expression in podocytes. The results demonstrated that UCH‐L1 was expressed in podocytes and its expression was significantly higher in acute proliferative glomerulonephritis (APGN), lupus nephritis (LN), membranous glomerulonephritis (MGN) and IgA nephropathy than that in focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), minor abnormality and normal kidney tissues (p < 0.05). In in vitro experiments, western blot showed that UCH‐L1 expression significantly increased in the two groups of podocytes co‐cultured with mesangial cells exposed to ATS 50 µl/ml and ATS 50 µl/ml with normal human serum 30 µl/ml, respectively (p < 0.05), while the other groups treated with TGFβ1 1 ng/ml, TNFα 10 ng/ml or IL‐1 10 ng/ml had little rise of UCH‐L1 expression, with no statistical significance compared with normal control (p > 0.05). Further tests indicated that the percentage of PCNA‐positive podocytes in LN, APGN and IgA nephropathy was significantly higher than that in MCD, FSGS and normal control (p < 0.05). These data show for the first time that podocytes do express UCH‐L1 and that its expression can be increased in these immunocomplex‐mediated nephrites. The immune injury is a main cause for stimulating podocytes to express UCH‐L1. The expression of UCH‐L1 may be associated with the regeneration of podocytes as a repair response to immunocomplex‐mediated injury. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.