Recent progress in hormone research最新文献

Gene expression was evaluated in clones of the acute lymphoblastic leukemic cell line CEM that were sensitive or resistant to apoptosis evoked by the glucocorticoid, dexamethasone (Dex). Founding clones CEM-C7 (glucocorticoid sensitive) and CEM-C1 (glucocorticoid resistant) were subcloned to maximize uniformity of each population studied. Among subclones of C1, our original pseudodiploid clone of glucocorticoid-resistant cells, we found a high proportion of hyperploid clones. Most C1 subclones were glucocorticoid resistant but two C1 subclones were found to be revertants to glucocorticoid sensitivity. Glucocorticoid receptor content of the C1 subclones varied almost 5-fold but higher quantity of receptors did not guarantee steroid sensitivity. Gene expression analysis was carried out on microchips containing representations for approximately 12,600 human genes. When a group of four subclones from C1 (three glucocorticoid-resistant and one glucocorticoid-sensitive revertant) were compared with the glucocorticoid-sensitive subclone CEM-C7-14 for basal gene expression, the four C1 subclones clustered closely and far from C7-14. Thus, basal gene expression in the C1 subclones differed for a large number of genes from that in the C7 subclone. Reversion to glucocorticoid sensitivity did not cause a major shift in basal gene expression to a more C7-like state. Three clones (one revertant glucocorticoid sensitive from C1 subclone, one C7 sensitive subclone, and one C1 glucocorticoid-resistant subclone) were compared for the genes regulated by treatment for 20 hours with 10(-6)M Dex. This interval brings the cells to a point just before the onset of apoptosis. We tested the hypothesis that a distinctive set of genes would be regulated in the glucocorticoid-sensitive clones. This proved to be so. In three experiments, at our chosen levels of discrimination, 39 genes were consistently induced > or = 2.5-fold and 21 genes were consistently reduced > or = 2-fold in glucocorticoid-sensitive clones but not in the glucocorticoid-resistant clone. The glucocorticoid-resistant clone showed induction or reduction of 88 genes different from those regulated in the glucocorticoid-sensitive clones. These data support our hypothesis and further show that the glucocorticoid-resistant clone is capable of responding to steroid but with a different set of genes. We propose that a general metabolic switch accounts for the alteration.

Pituitary gland development is controlled by signals that guide expression of specific combinations of transcription factors that dictate serial determination and differentiation events. One class of factors is paired-like homeodomain factors. Two that have been investigated are the repressor Hex1/Rpx and activator prophet of Pit-1 (Prop-1), which exert selective roles during pituitary development. The opposing actions of these factors provide one aspect of pituitary organogenesis.

We have undertaken a high-throughput analysis to identify targets of glucocorticoid regulation in P1798 murine T-lymphoma cells. G1/S-arrested cultures were treated for 8 hours with 0.1 microM dexamethasone (dex) in the presence and absence of 1 microg/ml cycloheximide. Untreated cultures and cultures exposed to cycloheximide alone were prepared as controls. RNA was isolated and gene expression analyzed using Affymetrix MG-U74A oligonucleotide arrays (Gene Chips). Three independent experiments were performed. The data were analyzed using a variety of statistical and analytical approaches in order to identify primary transcriptional targets of the glucocorticoid receptor. We identified 44 genes that increase by > 2-fold in both dex-treated and dex + cycloheximide-treated cultures (relative to control and cycloheximide-treated cultures) in three replicate experiments. Statistical analysis of control data indicate that the probability that a given probeset would, as a result of random error, increase > 2-fold both in the presence and absence of cycloheximide in two independent experiments is approximately 7 x 10(-9). We have retrieved from the Celera mouse genomic sequence 8 kb of promoter sequence, spanning 4 kb either side of the 5'-end of the cDNA from eight of the induced genes. These sequences were analyzed for potential glucocorticoid receptor binding sites. Five of these genes contain the sequence ACAnnnTGTnCT within 4 kb of the presumptive transcriptional start site. Eight control genes were selected at random and analyzed for the sequence ACAnnnTGTnCT. Two control genes had such sequences within 4 kb of the transcriptional start site.

Statistical methods for analyzing data from DNA microarray experiments are reviewed. Specifically, we discuss common experimental setups, methods for data reduction and clustering, and analysis of time-course experiments. While early microarray studies focused mainly on the basic methodological and technical aspects of DNA arrays, emphasis has shifted to biological, medical, and clinical applications. We mention several of these and present results from our recent research as illustrative examples. New developments in this ever-growing field are outlined.

Chronically elevated luteinizing hormone (LH) induces significant pathology in the LHbetaCTP transgenic mouse model, which uses the bovine gonadotropin alpha (alpha)-subunit promoter to direct transgene expression specifically to gonadotropes in the anterior pituitary. Previously, it was shown that female LHbetaCTP mice are infertile due to anovulation, develop granulosa cell tumors, and undergo precocious puberty from elevated LH and steroid hormones that fail to completely repress the alpha-subunit promoter. This chapter will discuss recent studies that further elucidate the impact of chronically elevated LH on diverse physiological systems. Granulosa cell tumors induced by elevated LH are strain dependent and prevented when transgenics are treated with human chorionic gonadotropin (hCG) surges. A granulosa cell tumor-associated transcriptome is generated, revealing several possible gene candidates for ovarian granulosa cell tumorigenesis. Primordial follicles in LHbetaCTP transgenics become depleted and oocytes exhibit increased rates of meiotic segregation defects, although meiotic competency is acquired normally. Anovulation can be rescued in transgenics by superovulation, though pregnancy fails at midgestation due to maternal factors. Uterine receptivity defects prevent implantation of normal embryos following induction of pseuodpregnancy. Transgenics develop Cushing-like adrenocortical hyperfunction with increased corticosterone production following induction of adrenal LH receptor expression. Elevated LH acts as a tumor promoter in the gonads and the adrenal gland, when expressed in conjunction with the inhibin-alpha SV40 transgene. Finally, chronic elevated LH promotes mammary tumorigenesis. The understanding of multiple clinical pathologies--including ovarian cancer, perimenopausal reproductive aging, premature ovarian failure, polycystic ovarian syndrome, Cushing's syndrome, and breast cancer--may be enhanced through further study of this useful transgenic mouse model.