Overexpression of ubiquitin carboxyl-terminal hydrolase L1 arrests spermatogenesis in transgenic mice

Ubiquitin carboxyl-terminal hydrolase 1 (UCH-L1) can be detected in mouse testicular germ cells, mainly spermatogonia and somatic Sertoli cells, but its physiological role is unknown. We show that transgenic (Tg) mice overexpressing EF1alpha promoter-driven UCH-L1 in the testis are sterile due to a block during spermatogenesis at an early stage (pachytene) of meiosis. Interestingly, almost all spermatogonia and Sertoli cells expressing excess UCH-L1, but little PCNA (proliferating cell nuclear antigen), showed no morphological signs of apoptosis or TUNEL-positive staining. Rather, germ cell apoptosis was mainly detected in primary spermatocytes having weak or negative UCH-L1 expression but strong PCNA expression. These data suggest that overexpression of UCH-L1 affects spermatogenesis during meiosis and, in particular, induces apoptosis in primary spermatocytes. In addition to results of caspases-3 upregulation and Bcl-2 downregulation, excess UCH-L1 influenced the distribution of PCNA, suggesting a specific role for UCH-L1 in the processes of mitotic proliferation and differentiation of spermatogonial stem cells during spermatogenesis.     

The Fas/FasL system is a possible regulator of germ cell apoptosis in the testis of Torpedo marmorata

The role played by the Fas/FasL system in the activation of apoptosis during the spermatogenesis of the spotted ray Torpedo marmorata was investigated. By immunohistochemical and western blot techniques it was demonstrated that the Fas/FasL system is amply represented during spermatogenesis of T. marmorata and it could act both via a paracrine and autocrine route: paracrine at the level of immature and mature cysts, autocrine only in mature cysts.     

人脑星形细胞瘤中p53，Fas／FasL的表达及其与凋亡关系的研究

目的：探讨细胞凋亡在星形细胞瘤中的作用及其与p53、Fas和Fas配体（Fas ligand,FasL）的关系。方法：对43例星形细胞瘤的标本分别进行HE染色,TUNEL及免疫组化分别标记p53,Fas和FasL。结果：高级别肿瘤和低级别肿瘤间的凋亡无显著差异（P〉0．05）。高级别星形细胞瘤的p53,Fas和FasL的表达均显著高于低级别肿瘤（P均〈0．05）。结论：突变型p53可作为评价星形细胞瘤生物学行为的参考指标。与低级别星形细胞瘤相比,高级别肿瘤中的细胞凋亡受到了抑制,且Fas与FasL的过表达对细胞凋亡可产生明显影响。     

人脑星形细胞瘤中p53，Fas/FasL 的表达及其与凋亡关系的研究

目的:探讨细胞凋亡在星形细胞瘤中的作用及其与p53、Fas和Fas配体(Fas ligand,FasL)的关系。方法:对43例星形细胞瘤的标本分别进行HE染色,TUNEL及免疫组化分别标记p53,Fas和FasL。结果:高级别肿瘤和低级别肿瘤间的凋亡无显著差异(P>0.05)。高级别星形细胞瘤的p53,Fas和FasL的表达均显著高于低级别肿瘤(P均<0.05)。结论:突变型p53可作为评价星形细胞瘤生物学行为的参考指标。与低级别星形细胞瘤相比,高级别肿瘤中的细胞凋亡受到了抑制,且Fas与FasL的过表达对细胞凋亡可产生明显影响。     

牙龈卟啉单胞菌诱导T淋巴细胞活化、凋亡的体外研究

目的检测牙龈卟啉单胞菌对人外周血中T淋巴细胞活化及凋亡的作用,并检测Fas/FasL在牙龈卟啉单胞菌(Porphyrom onas gingivalis,Pg)诱导的T淋巴细胞凋亡中的表达。方法选取10例全身及牙周组织健康受试者,分离外周血中T淋巴细胞,在有/无Pg情况下培养0~96 h,用荧光探针(Annexin V-FITC、PI、CD69)及特殊的单克隆抗体(Fas、FasL)进行标记,并进行流式细胞仪检测。结果 CD69+淋巴细胞+Pg组Annexin V+/PI-细胞百分数在各个时间点上都明显高于T淋巴细胞+Pg组(P0.01)。Fas和FasL的表达量明显上调。用抗Fas单克隆抗体阻滞Fas-FasL相互作用导致T细胞凋亡的明显减少,百分比为(20.56±2.43)%,未加抗体的为(50.41±2.68)%。但残余的细胞凋亡活动与阴性对照相比仍高。结论 Pg能够诱导人外周血中T淋巴细胞活化,并且能够通过活化促进其凋亡,Pg诱导T淋巴细胞凋亡主要通过Fas-FasL途径,并具有时间依赖性。     

雷公藤甲素对病毒性心肌炎细胞凋亡及Fas/FasL 蛋白表达的研究

目的:研究雷公藤甲素对柯萨奇病毒B3病毒(CVB3)感染的病毒性心肌炎小鼠心肌细胞凋亡和Fas/FasL蛋白表达的抑制作用,探讨TP治疗病毒性心肌炎的作用机制。方法:将Balb/c小鼠随机分成4组作为动物模型,分别为对照组、模型组、利巴韦林组和TP组。对照组腹腔注射生理盐水,其余三组腹腔注射CVB3,利巴韦林组和TP组小鼠分别予以相应的药物治疗后,测定各组小鼠存活率及心肌病变积分,采用末端转移酶标记技术(TUNEL法)检测小鼠心肌细胞凋亡,免疫组化法检测Fas/FasL蛋白阳性表达。结果:空白对照组心肌无病变,利巴韦林组、TP组与模型组相比有显著性差异(P<0.01)。正常组鲜见心肌细胞凋亡,模型组细胞凋亡率较正常组显著增加(P<0.01),治疗组利巴韦林组和TP组凋亡率比模型组明显降低(P<0.05,P<0.01)。模型组Fas/FasL表达比正常组显著增多(P<0.01),治疗组利巴韦林组和TP组较模型组显著降低(P<0.01)。结论:雷公藤甲素具有通过抑制Fas/FasL蛋白的表达,减缓心肌细胞凋亡,达到抑制病毒性心肌炎从而保护心肌细胞的作用。     

Proliferative inhibition, cell-cycle dysregulation, and induction of apoptosis by ursolic acid in human non-small cell lung cancer A549 cells

Ursolic acid (UA) is a pentacyclic triterpene compound isolated from many types of medicinal plants and is present in human diet. It has been reported to possess a wide range of pharmacological properties, and is one of the most promising chemopreventive agents for cancer. Here, we report that UA inhibits the cell proliferation of human lung cancer cell line A549 and provide a molecular understanding of this effect. The results showed that UA blocked cell cycle progression in the G1 phase that was associated with a marked decrease in the protein expression of cyclin D1, D2, and E and their activating partner cdk2, 4, and 6 with concomitant induction of p21/WAF1. This accumulation of p21/WAF1 might be through a p53-dependent manner. Further, UA treatment also resulted in the triggering of apoptosis as determined by DNA fragmentation assay. This effect was found to correlate with the up-regulation of Fas/APO-1, Fas ligand, and Bax, and down-regulation of NF-kappaB, Bcl-2, and Bcl-XL. Taken together, our study indicated that UA might be a potential chemopreventive agent for lung cancer.     

Enhancement of germ cell apoptosis induced by ethanol in transgenic mice overexpressing Fas Ligand

It was suggested that chronic ethanol exposure could result in testicular germ cell apoptosis, but the mechanism is still unclear. In the present study, we use a model of transgenic mice ubiquitously overexpressing human FasL to investigate whether Fas ligand plays a role in ethanol-induced testicular germ cell apoptosis. Both wild-type (WT) mice and transgenic (TG) mice were treated with acute ethanol (20% v/v) by introperitoneal injection for five times. After ethanol injection, WT mice displayed up-regulation of Fas ligand in the testes, which was shown by FITCconjugated flow cytometry and western blotting. Moreover, TG mice exhibited significantly more apoptotic germcells than WT mice did after ethanol injection, which was demonstrated by DNA fragmentation, PI staining flowcytometry and TUNEL staining. In addition, histopathological examination revealed that degenerative changes ofepithelial component of the tubules occurred in FasL overexpressing transgenic mice while testicular morphologywas normal in wild-type mice after acute ethanol exposure, suggesting FasL expression determines the sensitivity of testes to ethanol in mice. In summary, we provide the direct evidences that Fas ligand mediates the apoptosis of testicular germ cells induced by acute ethanol using FasL transgenic mice.     

Boar proacrosin expressed in spermatids of transgenic mice does not reach the acrosome and disrupts spermatogenesis

Transgenic mice that express boar proacrosin were produced to examine mechanisms for targeting hydrolytic enzymes to the acrosome. A 2.3 kb transgene was constructed by ligating the cDNA for boar preproacrosin with the mouse protamine 2 promoter region. Six founder mice that incorporated the transgene were identified by polymerase chain reaction and Southern blot analysis. Northern blots indicated that the two male founders (Ac.2 and Ac.5) and male progeny from three female founders (Ac.3, Ac.4, Ac.6) expressed the transgene mRNA in testis, but not in somatic tissues. In these transgenic animals boar proacrosin was detected by immunohistochemistry in condensing spermatids, but was not localized in the acrosome. This acrosomal targeting defect of the transgene product may result from its delayed expression during the later steps of haploid differentiation. Furthermore, both male founders and all Ac.4 and Ac.6 males were infertile, as determined by multipe matings for at least 2 months. Ac.3 males were either infertile or rarely transmitted the transgene to their offspring The infertile males mated, produced copulatory plugs, and had seminal vesicle weights and testosterone levels within the normal range. However, they produced significantly fewer spermatozoa and had lower testis weights than controls. Although the mitotic and meiotic phases of spermatogenesis appeared normal by histological criteria, condensing spermatids were missing from most tubules, and multinucleated cells were present in the lumen of seminiferous tubules and in the epididymis. We hypothesize that boar proacrosin which fails to reach the acrosome is activated in these transgenic mice, and that its proteolytic activity disrupts spermatogenesis during spermatid formation. © 1996 Wiley-Liss, Inc.     

Spontaneous hepatic fibrosis in transgenic mice overexpressing PDGF-A

Platelet derived growth factor (PDGF) plays a central role in repair mechanisms after acute and chronic tissue damage. To further evaluate the role of PDGF-A in liver fibrogenesis in vivo, we generated transgenic mice with hepatocyte-specific overexpression of PDGF-A using the CRP-gene promoter. Transgenic but not wildtype mice showed expression of PDGF-A mRNA in the liver. Hepatic PDGF-A overexpression was accompanied by a significant increase in hepatic procollagen III mRNA expression as well as TGF-beta1 expression. Liver histology showed increased deposition of extracellular matrix in transgenic but not in wildtype mice. PDGF-A-transgenic mice showed positive sinusoidal staining for alpha-SMA indicating an activation of hepatic stellate cells. Since the profibrogenic effect of PDGF-A was accompanied by increased TGF-beta1 protein concentration in the liver of transgenic mice, it can be postulated that PDGF-A upregulates expression of TGF-beta1 which is a strong activator of hepatic stellate cells. Thus, these results point towards a fibrosis induction by PDGF-A via the TGF-beta1 signalling pathway. In conclusion, expression and functional analysis of PDGF-A in the liver of transgenic mice suggest a relevant profibrogenic role of PDGF-A via TGF-beta1 induction. Counteracting PDGF-A may therefore be one of the effects of tyrosine kinase inhibitors which showed protective effects in animal models of liver fibrosis.     

SP600125, a selective JNK inhibitor, protects ischemic renal injury via suppressing the extrinsic pathways of apoptosis

Accumulating evidence suggests that c-Jun N-terminal kinase (JNK) signaling pathway plays a critical role in renal ischemia/reperfusion injury. However, the downstream mechanism that accounts for the proapoptotic actions of JNK during renal ischemia/reperfusion has not been elucidated. We report that SP600125, a potent, cell-permeable, selective, and reversible inhibitor of c-Jun N-terminal kinase (JNK), potently decreased renal epithelial tubular cell apoptosis induced by renal ischemia/reperfusion via suppression of the extrinsic pathway. This corresponds to the decrease in JNK phosphorylation at 20 min and c-Jun phosphorylation (Ser63/73) at 3 h after renal ischemia. Additionally, SP600125 attenuated the increased expression of FasL induced by ischemia/reperfusion at 3 h. The administration of SP600125 prior to ischemia was also protective. Thus, our findings imply that SP600125 can inhibit the activation of the JNK-c-Jun-FasL pathway and protect renal tubular epithelial cells against ischemia/reperfusion-induced apoptosis. Taken together, these results indicate that targeting the JNK pathway provides a promising therapeutic approach for renal ischemia/reperfusion injury.     

Abnormal sperm development in pcd 3J-/- mice: the importance of Agtpbp1 in spermatogenesis

Homozygous Purkinje cell degeneration (pcd) mutant males exhibit abnormal sperm development. Microscopic examination of the testes from pcd(3J)-/- mice at postnatal days 12, 15, 18 and 60 revealed histological differences, in comparison to wild-type mice, which were evident by day 18. Greatly reduced numbers of spermatocytes and spermatids were found in the adult testes, and apoptotic cells were identified among the differentiating germ cells after day 15. Our immunohistological analysis using an antihuman AGTPBP1 antibody showed that AGTPBP1 was expressed in spermatogenic cells between late stage primary spermatocytes and round spermatids. A global gene expression analysis from the testes of pcd(3J)-/- mice showed that expression of cyclin B3 and de-ubiquitinating enzymes USP2 and USP9y was altered by >1.5-fold compared to the expression levels in the wild-type. Our results suggest that the pcd mutant mice have defects in spermatogenesis that begin with the pachytene spermatocyte stage and continue through subsequent stages. Thus, Agtpbp1, the gene responsible for the pcd phenotype, plays an important role in spermatogenesis and is important for survival of germ cells at spermatocytes stage onward.