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Progesterone induction of metallothionein-IIA gene expression 总被引:8,自引:0,他引:8
E P Slater A C Cato M Karin J D Baxter M Beato 《Molecular endocrinology (Baltimore, Md.)》1988,2(6):485-491
Expression of the metallothionein gene is known to be induced by glucocorticoids in a variety of cells. Here we show that in human cell lines containing functional progesterone receptors, the endogenous metallothionein-IIA (hMTIIA) gene is inducible by the synthetic progestins R5020 and medroxy-progesterone acetate. That this effect reflects a direct interaction with the metallothionein gene is supported by our finding that the partially purified progesterone receptor binds to the promoter region of the gene in vitro. The limits of the DNase I footprint and the guanine residues protected in methylation studies with the progesterone receptor are similar to those previously described for the glucocorticoid receptor. Thus, the hormone regulatory element of the human metallothionein-IIA gene can mediate regulation by both glucocorticoids and progestins, as does the hormone regulatory element of mouse mammary tumor virus. 相似文献
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Metabolic and ultrastructural response to glucose of two eurytrophic bacteria isolated from seawater at different enriching concentrations. 总被引:4,自引:3,他引:1 下载免费PDF全文
Two marine bacteria, an Acinetobacter sp. (strain GO1) and a vibrio sp. (strain G1), were isolated by extinction dilution and maintained in natural seawater supplemented with nitrogen, phosphorus, and glucose at 0.01 and 10 mg of glucose carbon per liter above ambient monosaccharide concentrations, respectively. After 3 days in unsupplemented natural seawater, growth in batch culture with glucose supplements was determined by changes in cell numbers and glucose concentration. The exponential growth of the Acinetobacter strain with added glucose was indistinguishable from that in natural seawater alone, whereas that of the Vibrio strain was more rapid in the presence of glucose supplements, suggesting that the Acinetobacter strain preferred the natural organic matter in seawater as a carbon source. The ultrastructure for both isolates was unaffected by glucose supplements during exponential growth, but there were marked changes in stationary-phase cells. The Vibrio strain formed polyphosphate at 10 mg of glucose carbon per liter, whereas poly-beta-hydroxybutyrate formation occurred at 100 mg and became excessive at 1,000 mg, disrupting the cells. In contrast, the Acinetobacter strain elongated at 100 and 1,000 mg of glucose carbon per liter but failed to show poly-beta-hydroxybutyrate formation. The diversity of responses shown here would not have been detected with a single concentration of substrate, often used in the literature to characterize both pure and natural populations of marine bacteria. 相似文献
225.
Molecular changes associated with induction of cell death in a human T-cell leukaemia line: putative nucleases identified as histones 总被引:1,自引:0,他引:1
G D Baxter P J Smith M F Lavin 《Biochemical and biophysical research communications》1989,162(1):30-37
Following treatment of the human T-cell leukaemia line, CEM-C7, with the glucocorticoid, dexamethasone, a rapid decrease in viability occurred after 40 h which coincided with fragmentation of DNA in these cells. A similar pattern of DNA fragmentation was observed when these cells were gamma-irradiated or treated with cycloheximide. Distinct morphological changes occurred after treatment, indicating a form of cell death, regulated from within, termed apoptosis. A set of nuclear proteins ranging in size from 10-18 kDa appeared by 40 h following treatment with dexamethasone. Treatment of cells with gamma-irradiation or cycloheximide also produced the same protein pattern. This set of proteins, and a doublet approximately 55 kDa in size, had apparent nuclease activity which was not observed in untreated cells. However, protein microsequencing of these bands in the 10-18 kDa region revealed that they were histone proteins. These results cast doubt on a recent report which provided evidence that these proteins were induced nucleases. 相似文献
226.
A targeting sequence for dense secretory granules resides in the active renin protein moiety of human preprorenin 总被引:6,自引:0,他引:6
Human renin plays an important role in blood pressure homeostasis and is secreted in a regulated manner from the juxtaglomerular apparatus of the kidney in response to various physiological stimuli. Many aspects of the regulated release of renin (including accurate processing of prorenin to renin, subcellular targeting of renin to dense secretory granules, and regulated release of active renin) can be reproduced in mouse pituitary AtT-20 cells transfected with a human preprorenin expression vector. Using protein engineering, we have attempted to define the roles of various structures in prorenin that affect its production and trafficking to dense core secretory granules, resulting in its activation and regulated secretion. Replacement of the native signal peptide of human preprorenin with that of a constitutively secreted protein (immunoglobulin M) had no apparent effect on either the constitutive secretion of prorenin or the regulated secretion of active renin in transfected AtT-20 cells. Removal of the pro segment resulted in a marked reduction in total renin secretion, but did not prevent renin from entering the regulated secretory pathway. Single or combined mutations in the two glycosylation sites of human renin did not prevent its regulated secretion; however, the complete elimination of glycosylation resulted in a significant increase in the ratio of renin/prorenin secreted by the transfected cells. Thus, these results suggest that 1) at least one of the sequences that target human renin to dense secretory granules lies within the protein moiety of active renin; 2) the presence of the pro segment is important for efficient prorenin and renin production; and 3) glycosylation can quantitatively affect the proportion of active renin secreted. 相似文献
227.
Several aspects of the social system of spider monkeys remain poorly understood in spite of previous studies of their behavior.
Our work investigates sex differences of adultAteles geoffroyi to develop a better understanding of their social organization. A six-month field study of this species in Guatemala showed
that adult males were both more aggressive and more socially cohesive than females, as well as more territorial. Adult females
were more vocal, more submissive, more nonsocial, and more dispersed than adult males. Males were more likely to associate
affinitively with other males than with females, and to direct their aggressive behaviors at females rather than males. Spider
monkey society was found to be sex-segregated; males traveling and interacting in all-male subgroups, while females travel
alone or with offspring.
These findings are used, in conjunction with other evidence, to draw inferences about the dynamics of theAteles social system, and to derive an explanation for the evolution of spider monkey social organization. The frugivorous diet
ofAteles is linked to the dispersion females and to the cohesion of related adult males, who form cooperative territorial groups,
in which the low level of male-male competition is related to the absence of sexual dimorphism. Spider monkeys provide an
illuminating contrast to the general primate model, derived from Old World monkeys, which links sexual dimorphism in size
to sex differences in behavior, and ultimately to sexual selection. 相似文献
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