1: Brain Res. 2004 Jun 4;1010(1-2):35-44. Estradiol enhances light-induced expression of transcription factors in the SCN. Abizaid A, Mezei G, Horvath TL. Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT 06510, USA. The suprachiasmatic nucleus of the hypothalamus (SCN) is the master clock that regulates circadian and seasonal rhythms. Among these, the SCN regulates the phasic release of hormones and provides for the timing of the preovulatory luteinizing hormone (LH) surge necessary for ovulation in females. There is little evidence, however, of sex hormone effects on mechanisms underlying SCN function. This study examined the effects of exogenous administration of estradiol on the light-induced expression of transcription factors in the SCN of female rats. Ovariectomized (OVX) female rats were given estradiol or cholesterol implants and perfused 48 h later. Half of the animals were sacrificed 1 h after the regular onset of light within the colony. The rest had the lights go on 2 h prior to the regular time and perfused 1 h later. Collected brains were sliced and sets of SCN sections were processed for immunoreactivity (ir) detecting the Fos, pCREB, egr-1, CREB binding protein (CBP), and calbindin-D (28K) proteins. Following quantification, statistical analyses demonstrated that estradiol enhanced Fos and p-CREB-ir in the SCN of females that experienced a 2-h phase advance. The phase advance also enhanced calbindin and egr-1-ir, but the expression of these proteins was not affected by estradiol. These results demonstrate that estradiol enhances the levels of transcription factors that precede the expression of clock gene proteins in the SCN in response to advances in the onset of environmental light. These data support the hypothesis that steroid hormones play an important role in the fine tuning of the clock in the face of environmental changes in daylight. Copyright 2004 Elsevier B.V. PMID: 15126115 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 2: Ai Zheng. 2004 Feb;23(2):150-4. [Study of gene expression difference in lung carcinogenesis by cDNA microarray] [Article in Chinese] Peng ZM, Tang FQ, Wu ES. Department of Respiratory Medicine,Second Xiangya Hospital, Central South University, Changsha, Hunan, PR China. zaimeipg@hotmail.com BACKGROUND & OBJECTIVE: Lung cancer is a kind of disease with high incidence and mortality, however its molecular mechanism is not clear yet. This study was designed to investigate gene expression differences among lung cancer tissues, lung paracancerous tissues,matched peripheral normal lung tissues and the metastases of lymph nodes, and to seek the relatively high expressed genes in lung carcinoma tissues, providing possible theoretical basis for early diagnosis and treatment of pulmonary carcinoma. METHODS: Fresh lung cancer tissue, lung paracancerous tissue, matched normal lung tissue and metastases of lymph nodes were deep-frozen in liquid nitrogen; their total RNA were extracted for reversed transcription cDNA probes, which were labeled and subsequently used to hybridize with cDNA microarray with 588 genes. Different gene expression profiles were obtained by analyzing the integrated density (ID) of spot images on the X-ray. RESULTS: In lung cancer tissues, 40 genes were detected to be differentially expressed, 36 of which such as early growth response protein 1 (EGR1), secreted apoptosis related protein 1 (SARP1) were upregulated while the others such as myeloid cell leukemia protein 1 (MCL1) were downregulated. The upregulated genes were mainly oncogene/suppressor gene, cell cycle regulatory gene, growth factors and apoptosis-related genes. In lung paracancerous tissues, 33 genes had different expression, 20 of which such as matrix metalloproteinase-9 (MMP-9) were upregulated, and the other 13 such as MCL1,endothelin 2 (ET2) were downregulated. In metastases of lymph nodes, there were 21 genes found to be differently expressed, 15 of which such as CD40 receptor-associated factor 1 (CRAF1) were downregulated while the rest were upregulated, and the upregulated genes (6 in 15) were mainly the genes associated with adhesion molecules, matrix metalloproteinases and collagen. CONCLUSION: EGR1, SARP1, NDKA, etc. may be the key genes in pulmonary carcinogenesis course. At the same time, MMP9, thrombospondin 2 (TSP2), etc.may play an important role in pulmonary cancer metastasis and infiltration. PMID: 14960233 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Biol Chem. 2001 Jun;382(6):891-902. Biological activity of mammalian transcriptional repressors. Thiel G, Lietz M, Bach K, Guethlein L, Cibelli G. Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical School, Homburg, Germany. Research on the regulation of transcription in mammals has focused in recent years mainly on the mechanism of transcriptional activation. However, transcriptional repression mediated by repressor proteins is a common regulatory mechanism in mammals and might play an important role in many biological processes. To understand the molecular mechanism of transcriptional repression, the activity of eight mammalian repressors or repressor domains was investigated using a set of model promoters in combination with two different transcriptional detection methods. The repressors studied were: REST, the thyroid hormone receptors alpha and beta, the zinc finger protein NK10 containing a 'kruppel-associated box' (KRAB), repressor domains derived from the proteins Egr-1, Oct2A and Dr1 and the repressor/activator protein YY1. Here we show that the repressor domains of REST, Egr-1, the thyroid hormone receptors alpha< and beta and NK10 were transferable to a heterologous DNA-binding domain and repressed transcription from proximal and distal positions. Moreover, these repressor domains also blocked the activity of a strong viral enhancer in a 'remote position'. Thus, these domains are 'general' transcriptional repressor domains. The 'kruppel-associated box' was the most powerful repressor domain tested. In contrast, the repressor domains derived from Oct2A and Dr1 were inactive when fused to a heterologous DNA-binding domain. The repressor domain of YY1 exhibited transcriptional repression activity only in one of the transcriptional assay systems. The recruitment of histone deacetylases to the proximity of the basal transcriptional apparatus was recently discussed as a mechanism for some mammalian transcriptional repressor proteins. Here we show here that histone deacetylase 2, targeted to the reporter gene via DNA-protein interaction, functions as a transcriptional repressor protein regardless of the location of its binding site within the transcription unit. PMID: 11501753 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Brain Res Mol Brain Res. 1997 Aug;48(1):73-86. Daily variation of CNS gene expression in nocturnal vs. diurnal rodents and in the developing rat brain. O'Hara BF, Watson FL, Andretic R, Wiler SW, Young KA, Bitting L, Heller HC, Kilduff TS. Center for Sleep and Circadian Neurobiology, Department of Biological Sciences, Stanford University, CA 94305, USA. Expression of c-fos has been shown to vary throughout the brain over the course of the 24-h day. The magnitude of these changes appear to be similar in a light:dark (LD) cycle or in constant dark (DD). To further examine whether the diurnal and circadian changes in c-fos and other immediate-early gene (IEG) expression in brain are related to waking behaviors such as locomotor activity, we conducted three experiments using Northern analysis. First, we compared IEG expression in nocturnal vs. diurnally active species. Second, we investigated IEG expression in a hibernating species during its active and inactive phases. Third, we examined the development of IEG expression in the young post-natal rat. As a comparison to results obtained in extra-SCN brain regions, we also examined IEG and vasopressin expression in the SCN itself across the circadian cycle. Animals maintained under a 12:12-h LD cycle were sacrificed in the morning (10:00-11:00 h, ZT2-ZT3) or night (22:00-23:00 h, ZT14-ZT15) or at the corresponding circadian times (CT) when kept in DD. Rats sacrificed in the morning always showed lower c-fos expression than at night in all brain areas examined while the reverse pattern was seen in squirrels under both LD and DD conditions, suggesting a direct correlation between c-fos message and activity. The cerebellum displayed the greatest magnitude change between morning and night (often reaching 10-fold). Among other IEGs examined, the expression of NGFI-A and junB are similar to c-fos, but of lesser magnitude, whereas c-jun appears to be invariant in the rat but is increased during the active phase in squirrels. During the hibernation season, squirrels have lower levels of c-fos consistent with their low levels of activity even during their euthermic interbout periods. c-fos expression in the cerebellum and rest of brain of 1-week-old rats sacrificed at ZT3 and ZT15 showed low levels at both timepoints whereas 2- and 3-week-old animals had higher levels at night as do adults. Among other IEGs, junB and NGFI-A again were similar to c-fos while c-jun and junD were more constant. Our observations support the idea of a diurnal rhythm of IEG expression in the CNS that is related to waking behaviors. Among IEGs, c-fos exhibits the greatest daily variation in expression. PMID: 9379853 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------