Gene expression is differentially regulated in the epididymis after orchidectomy

The epididymis is the site for the transport, maturation, and storage of spermatozoa. Regulation of epididymal structure and function is highly dependent on the ipsilateral testis. At the molecular level, however, few studies have been undertaken to determine which genes are expressed in the epididymis under testicular regulation. The goal of this study was to identify genes for which expression is regulated after orchidectomy, both throughout the epididymis and in a segment-specific manner. Microarrays spotted with 474 rat cDNAs were used to examine gene expression changes over the first 7 d post orchidectomy in the initial segment, caput, corpus, and cauda epididymidis of the adult Brown Norway rat. Using k-means cluster analysis, we show that four patterns of gene expression are activated in each epididymal segment over the first week following orchidectomy. Transient up-regulation of gene expression in the epididymis after orchidectomy is described for the first time. Potential androgen-repressed genes, including Gpx-1, show increased expression in the epididymis after orchidectomy. Several glutathione-S-transferases and calcium-binding proteins decline throughout the epididymis after orchidectomy, indicating that these may be novel androgen-regulated epididymal genes. Other genes coding for metabolism-associated proteins, transporters, and alpha-1 acid glycoprotein show segment-specific regulation in the epididymis after orchidectomy. Finally, we describe the expression of the previously uncharacterized heat shock proteins, and apoptosis-associated genes in the epididymis after orchidectomy. Thus, gene expression in the epididymis is differentially affected over time after orchidectomy. These results provide novel insight into androgen-dependent and segment-specific epididymal function.     

Gene expression profiles in an hepatitis B virus transfected hepatoblastoma cell line and differentially regulated gene expression by interferon-alpha

AIM: To study interactions between hepatitis B virus (HBV) and interferon-alpha in liver- derived cells. METHODS: mRNAs were separately isolated from an HBV-transfected cell line (HepG(2)2.2.15) and its parental cell line (HepG(2)) pre- and post-interferon-alpha (IFN-alpha) treatment at 6, 24 and 48 h, followed by hybridization with a cDNA microarray filter dotted with 14 000 human genes. After hybridization and scanning of the arrays, the data were analyzed using ArrayGauge software. The microarray data were further verified by Northern blot analysis. RESULTS: Compared to HepG(2) cells, 14 genes with known functions were down-regulated 3 to 12- magnitudes, while 7 genes were up-regulated 3-13 magnitudes in HepG(2)2.2.15 cells prior to IFN-alpha treatment. After interferon-alpha treatment, the expression of four genes (vascular endothelial growth factor, tyrosine phosphate 1E, serine protein with IGF-binding motif and one gene of clathrin light chain) in HepG(2)2.2.15 were up-regulated, while one gene encoding a GTP-binding protein, two genes of interferon-induced kinases and two proto-oncogenes were further down- regulated. Interestingly, under IFN-alpha treatment, a number of differentially regulated genes were new ESTs or genes with unknown functions. CONCLUSION: The up-regulated genes in HepG(2)2.2.15 cell line suggested that under IFN-alpha treatment, these repressed cellular genes in HBV infected hepatocytes could be partially restored, while the down- regulated genes were most likely the cellular genes which could not be restored under interferon treatment. These down-regulated genes identified by microarray analysis could serve as new targets for anti-HBV drug development or for novel therapies.     

Gene expression profiles in an hepatitis B virus transfected hepatoblastoma cell line and differentially regulated gene expression by interferon-α

AIM: To study interactions between hepatitis B virus (HBV)and interferon-α in liver- derived cells.METHODS: mRNAs were separately isolated from an HBVtransfected cell line (HepG22.2.15) and its parental cell line (HepG2) pre- and post-interferon-α (IFN-α) treatment at 6,24 and 48 h, followed by hybridization with a cDNA microarray filter dotted with 14 000 human genes. After hybridization and scanning of the arrays, the data were analyzed using ArrayGauge software. The microarray data were further verified by Northern blot analysis.RESULTS: Compared to HepG2 cells, 14 genes with known functions were down-regulated 3 to 12- magnitudes, while 7genes were up-regulated 3-13 magnitudes in HepG22.2.15cells prior to IFN-α treatment. After interferon-α treatment,the expression of four genes (vascular endothelial growth factor, tyrosine phosphate 1E, serine protein with IGF-binding motif and one gene of clathrin light chain) in HepG22.2.15were up-regulated, while one gene encoding a GTP-binding protein, two genes of interferon-induced kinases and two proto-oncogenes were further down- regulated. Interestingly,under IFN-α treatment, a number of differentially regulated genes were new ESTs or genes with unknown functions.CONCLUSION: The up-regulated genes in HepG22.2.15cell line suggested that under IFN-α treatment, these repressed cellular genes in HBV infected hepatocytes could be partially restored, while the down- regulated genes were most likely the cellular genes which could not be restored under interferon treatment. These down-regulated genes identified by microarray analysis could serve as new targets for anti-HBV drug development or for novel therapies.     

Endoglin expression in blood and endothelium is differentially regulated by modular assembly of the Ets/Gata hemangioblast code

Endoglin is an accessory receptor for TGF-beta signaling and is required for normal hemangioblast, early hematopoietic, and vascular development. We have previously shown that an upstream enhancer, Eng -8, together with the promoter region, mediates robust endothelial expression yet is inactive in blood. To identify hematopoietic regulatory elements, we used array-based methods to determine chromatin accessibility across the entire locus. Subsequent transgenic analysis of candidate elements showed that an endothelial enhancer at Eng +9 when combined with an element at Eng +7 functions as a strong hemato-endothelial enhancer. Chromatin immunoprecipitation (ChIP)-chip analysis demonstrated specific binding of Ets factors to the promoter as well as to the -8, +7+9 enhancers in both blood and endothelial cells. By contrast Pu.1, an Ets factor specific to the blood lineage, and Gata2 binding was only detected in blood. Gata2 was bound only at +7 and GATA motifs were required for hematopoietic activity. This modular assembly of regulators gives blood and endothelial cells the regulatory freedom to independently fine-tune gene expression and emphasizes the role of regulatory divergence in driving functional divergence.     

Localization of hepatocyte nuclear factor‐4α in the nucleolus and nucleus is regulated by its C‐terminus

Aims/Introduction: Mutations in hepatocyte nuclear factor‐4α (HNF4α) lead to various diseases, among which C‐terminal deletions of HNF4α are exclusively responsible for maturity onset diabetes of the young 1 (MODY1). MODY is an autosomal dominant disease characterized by a primary defect in insulin response to glucose, suggesting that the C‐terminus of HNF4α is important for pancreatic β‐cell function. To clarify the role of the C‐terminus of HNF4α, changes in cellular localization and the binding ability to its regulator were examined, specifically in the region containing Q268, which deletion causes MODY1. Materials and Methods: Cellular localization of mutant HNF4α were examined in monkey kidney 7 (COS7), Chinese hamster ovary, rat insulinoma and mouse insulinoma cells, and their binding activity to other proteins were examined by fluorescence resonance energy transfer (FRET) in COS7 cells. Results: Although wild‐type HNF4α was localized in the nucleoplasm in transfected cultured cells, Q268X‐HNF4α was located predominantly in the nucleolus. Deletion analysis of the C‐terminus of HNF4α showed that the S337X‐HNF4α mutant, and other mutants with shorter amino acid sequences (S337‐K194), were mostly localized in the nucleolus. HNF4α mutants with amino acid sequences shorter than the W192X‐HNF4α mutant gradually spread to the nucleoplasm in accordance with their lengths. The A250X‐HNF4α mutant was capable of causing the accumulation of HNF4α or the small heterodimer partner (SHP), one of the HNF4α regulators, in the nucleolus. However, the R154X‐HNF4α mutant did not have binding ability to wild‐type HNF4α or SHP, and thus was seen in the nucleus. Conclusions: The C‐terminus sites might play a key role in facilitating the nucleolar and subnucleolar localization of HNF4α. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00210.x, 2012)     

Erythroid gene expression is differentially regulated by erythropoietin, haemin and delta-aminolaevulinic acid in UT-7 cells

Erythropoietin (Epo) is essential for the later stages of erythropoiesis, acting to promote cell survival and proliferation, but its role in differentiation remains to be defined. The UT-7 cell line exhibits both erythroid and megakaryocytic characteristics and can be induced to differentiate along the erythroid pathway by Epo or the megakaryocytic pathway by phorbol myristic acetate. We have compared the effects of Epo and the chemical inducers, delta-aminolaevulinic acid (delta-ALA) and haemin on the differentiation capacity of UT-7 cells. Epo alone promoted relatively early events in erythroid maturation, without significant changes in haemoglobin production or morphology. GATA-2 and c-myb were down-regulated by Epo, and GATA-2 was further down-modulated by the inducers. Conversely, SCL expression was up-regulated by Epo and further increased by haemin and delta-ALA. Epo caused an increase in the proportion of cells expressing cell surface glycophorin A (GPA) and up-regulated beta- and gamma-globin by several fold. Both haemin and delta-ALA caused a de novo increase in alpha-globin expression as well as enhancing Epo-induced beta-globin expression, leading to a marked increase in haemoglobin production. These results suggest that haemoglobin production in UT-7 cells is limited by a deficiency of erythroid-specific aminolaevulinic acid synthase (ALAS-E) activity or globin synthesis as a consequence of their immaturity as a multipotential cell line.     

小檗碱对高果糖饲养诱导胰岛素抵抗大鼠肝组织HNF-4α表达的影响

目的: 探讨小檗碱对高果糖饲养诱导胰岛素抵抗大鼠肝细胞核因子(hepatocyte nuclear factor-4α, HNF-4α)表达的影响以及其改善胰岛素抵抗的分子机制.方法:高果糖饲料喂养SD大鼠6 wk, 建立胰岛素抵抗模型; 大鼠分为4组: 正常对照组(普通饮食)、普通饮食 小檗碱处理组、高果糖饮食组及高果糖饮食 小檗碱组; 小檗碱按187.5 mg/(kg·d)灌服4 wk; 测定血糖、血清胰岛素、胰岛素抵抗指数及甘油三酯的变化; 用RT-PCR法及免疫印迹法观察肝脏HNF-4α基因及蛋白的表达.结果: 高果糖饮食组胰岛素、胰岛素抵抗指数HOMA及甘油三酯水平较正常对照组均明显升高(均P<0.01), 而高果糖饮食 小檗碱组与高果糖饮食组比较上述指标明显下降(51.62±5.68 vs 64.91±7.87, P<0.01; 12.40±1.76 vs16.06±3.32, P<0.01; 11.16±1.58 vs 14.46±2.99, P<0.05), 小檗碱可促使肝脏表达下降的HNF-4α恢复.结论:小檗碱可改善胰岛素抵抗, 其机制可能与促进HNF-4α的表达有关.     

小檗碱对HepG2细胞肝细胞核因子基因表达的影响

[目的]观察小檗碱对人肿瘤细胞株(HepG2)细胞肝细胞核因子(HNF1α、HNF1β、HNF4α、HNF6)mR-NA表达和糖代谢相关激酶作用的影响,探讨小檗碱治疗糖尿病的分子机制。[方法]对不同浓度小檗碱(0、0.1、0.3、1、3、10、30μmol/L)和1 mmol/L二甲双胍处理24 h后的HepG2细胞,采用RT-PCR方法检测其HNFs mR-NA表达,同时检测糖代谢相关激酶(葡萄糖激酶、L-丙酮酸激酶、磷酸烯醇式丙酮酸激酶)活性。[结果]与对照组比较,小檗碱能够一定程度下调HepG2细胞HNFs mRNA表达,调节肝脏葡萄糖代谢相关激酶活性。[结论]小檗碱下调HepG2细胞HNFs mRNA表达,调节肝脏葡萄糖代谢相关激酶活性,这可能是其治疗糖尿病的机制之一。     

Oxidant-induced hepatocyte injury from menadione is regulated by ERK and AP-1 signaling

Oxidative stress has been implicated as a mechanism for a variety of forms of liver injury. Although reactive oxygen species (ROS) may damage cellular macromolecules directly, oxidant-induced cell death may result from redox effects on signal transduction pathways. To understand the mechanisms of hepatocyte death from oxidative stress, the functions of the mitogen-activated protein kinases (MAPKs) were determined during oxidant-induced hepatocyte injury from menadione. Low, nontoxic, and high toxic concentrations of the superoxide generator menadione were established in the RALA255-10G rat hepatocyte cell line. Death from menadione was blocked by catalase and ebselen, indicating that death was secondary to oxidant generation and not arylation. Treatment with a nontoxic menadione concentration resulted in a brief activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). In contrast, treatment with a toxic menadione concentration induced a prolonged activation of both ERK and JNK. Chemical inhibition of ERK function sensitized RALA hepatocytes to death from previously nontoxic menadione concentrations in association with sustained JNK activation. Adenoviral expression of a dominant-negative protein for c-Jun, a downstream substrate for JNK, blocked death from menadione. The pro-apoptotic effect of c-Jun was not mediated through the mitochondrial death pathway. In conclusion, RALA hepatocyte resistance to oxidant-induced death from menadione is dependent on ERK, whereas cell death is mediated by AP-1 activation. These findings identify signaling pathways that may be therapeutic targets in the prevention or treatment of oxidant-induced liver injury.