Journal Of Receptors And Signal Transduction, 1980
Page 1. JOURNAL OF RECEPTOR RESEARCH, 1(1), 91-111 (1980) HETEROGENEITY OF ESTROGEN BINDING SITES... more Page 1. JOURNAL OF RECEPTOR RESEARCH, 1(1), 91-111 (1980) HETEROGENEITY OF ESTROGEN BINDING SITES IN MOUSE MAMMARY CANCER Cheryl S. Watson and James H. Clark* Department of Cell Biology Baylor College of Medicine Houston, Texas 77030 ...
Membrane forms of some steroid hormone receptors (mSRs) were first reported almost three decades ... more Membrane forms of some steroid hormone receptors (mSRs) were first reported almost three decades ago [(1, 2, 3),and references therein, but only recently have their identities and functions received intense focus by a growing number of laboratories. As a result, relatively little is known about the mSRs’ biochemical characteristics, molecular structure, protein targeting pathways, and the specific nature of their residence in the plasma membrane. Work conducted in our laboratory over the last 15 years, in several murine and human lymphoid cell lines, described a membrane form of the “nuclear” glucocorticoid receptor (mGR) whose level of expression is more strongly correlated with glucocorticoid (GC)-evoked lymphocytosis than is the intracellular GR (iGR) (4, 5, 6, 7, 8, 9, 10, 11, 12). This suggests that the GC-evoked signaling associated with apoptosis in lymphoid cells is initiated by a necessary mGR, and portends a great clinical importance for its measurement and manipulation in the treatment of lymphoproliferative diseases. Our studies began by demonstrating the existence of mGRs and capturing a population of cells enriched in the mGR, to perform correlative functional studies. We then more closely defined the characteristics of the mGR protein and established connections between mGR and the initiation of specific signaling cascades that terminate in apoptosis.
Evidence has accumulated for a number of years that rapid membrane-initiated steroid signaling ca... more Evidence has accumulated for a number of years that rapid membrane-initiated steroid signaling can occur (1;2) in conjunction with the binding of steroids to cellular surfaces (3). However, the identification of the class of protein which mediates this binding, and initiates the accompanying signals, has remained controversial. Our earlier collaborative studies on the membrane glucocorticoid receptors (see chapter 6) demonstrated that a monoclonal antibody (Ab) to the intracellular form of that protein could be used as a tool to identify and study an additional form of the receptor on the cell surface; the presence of this receptor could be correlated with a subset of glucocorticoid-initiated responses. Subsequently, we looked for an appropriate, rapidly estrogen-responsive cell model in which to investigate the presence and identity of a membrane estrogen receptor linked to nongenomic actions.
This paper provides a brief summary of our recent work on the heterogeneity of estradiol binding ... more This paper provides a brief summary of our recent work on the heterogeneity of estradiol binding sites in mammary tumors of the mouse and human. Mammary tumors from both species contain the classical estrogen receptor and a second site(s) which we call type II. These type II sites are found in the cytoplasmic and nuclear compartments of both tumors, and can interfere with the measurement of estrogen receptors. The function of type II sites is not known; however, an assessment of these sites in conjunction with an accurate measurement of the estrogen receptor may provide a clearer picture of the true hormone dependence of breast tumors.
Mouse kidney beta-glucuronidase is induced by androgens in a receptor-dependent fashion. Genetic ... more Mouse kidney beta-glucuronidase is induced by androgens in a receptor-dependent fashion. Genetic regulatory mutations have been described which govern this response. In mice carrying the Gus-ra allele (A/J), the induction of enzyme activity is 3-5 times greater than in animals with the Gus-rb allele (C57BL/6J). To study this hormonal and genetic control at the molecular level, we measured changes in beta-glucuronidase mRNA concentrations in these two mouse strains using cloned cDNA. The specificity of the regulation was assessed by following changes in the concentration of kidney androgen-regulated protein (KAP) mRNA, which is also under androgen control in mouse kidney. Female mice were treated with Silastic implants that released 120 micrograms testosterone/day over a 20-day time course. Induction of specific mRNA was analyzed by either Northern blot hybridization or a more quantitative assay in which renal poly(A) RNA was covalently bound to aminophenylthioether paper discs. The induction of beta-glucuronidase mRNA was about 10-fold higher in the strain carrying the Gus-ra regulatory allele, indicating that the Gus-r locus controls the beta-glucuronidase structural gene (Gus-s) at the level of mRNA accumulation. Regulation by Gus-r was specific for beta-glucuronidase mRNA as kidney androgen-regulated protein mRNA accumulation did not differ between these two strains of mice after androgen treatment.
Journal Of Receptors And Signal Transduction, 1980
Page 1. JOURNAL OF RECEPTOR RESEARCH, 1(1), 91-111 (1980) HETEROGENEITY OF ESTROGEN BINDING SITES... more Page 1. JOURNAL OF RECEPTOR RESEARCH, 1(1), 91-111 (1980) HETEROGENEITY OF ESTROGEN BINDING SITES IN MOUSE MAMMARY CANCER Cheryl S. Watson and James H. Clark* Department of Cell Biology Baylor College of Medicine Houston, Texas 77030 ...
Membrane forms of some steroid hormone receptors (mSRs) were first reported almost three decades ... more Membrane forms of some steroid hormone receptors (mSRs) were first reported almost three decades ago [(1, 2, 3),and references therein, but only recently have their identities and functions received intense focus by a growing number of laboratories. As a result, relatively little is known about the mSRs’ biochemical characteristics, molecular structure, protein targeting pathways, and the specific nature of their residence in the plasma membrane. Work conducted in our laboratory over the last 15 years, in several murine and human lymphoid cell lines, described a membrane form of the “nuclear” glucocorticoid receptor (mGR) whose level of expression is more strongly correlated with glucocorticoid (GC)-evoked lymphocytosis than is the intracellular GR (iGR) (4, 5, 6, 7, 8, 9, 10, 11, 12). This suggests that the GC-evoked signaling associated with apoptosis in lymphoid cells is initiated by a necessary mGR, and portends a great clinical importance for its measurement and manipulation in the treatment of lymphoproliferative diseases. Our studies began by demonstrating the existence of mGRs and capturing a population of cells enriched in the mGR, to perform correlative functional studies. We then more closely defined the characteristics of the mGR protein and established connections between mGR and the initiation of specific signaling cascades that terminate in apoptosis.
Evidence has accumulated for a number of years that rapid membrane-initiated steroid signaling ca... more Evidence has accumulated for a number of years that rapid membrane-initiated steroid signaling can occur (1;2) in conjunction with the binding of steroids to cellular surfaces (3). However, the identification of the class of protein which mediates this binding, and initiates the accompanying signals, has remained controversial. Our earlier collaborative studies on the membrane glucocorticoid receptors (see chapter 6) demonstrated that a monoclonal antibody (Ab) to the intracellular form of that protein could be used as a tool to identify and study an additional form of the receptor on the cell surface; the presence of this receptor could be correlated with a subset of glucocorticoid-initiated responses. Subsequently, we looked for an appropriate, rapidly estrogen-responsive cell model in which to investigate the presence and identity of a membrane estrogen receptor linked to nongenomic actions.
This paper provides a brief summary of our recent work on the heterogeneity of estradiol binding ... more This paper provides a brief summary of our recent work on the heterogeneity of estradiol binding sites in mammary tumors of the mouse and human. Mammary tumors from both species contain the classical estrogen receptor and a second site(s) which we call type II. These type II sites are found in the cytoplasmic and nuclear compartments of both tumors, and can interfere with the measurement of estrogen receptors. The function of type II sites is not known; however, an assessment of these sites in conjunction with an accurate measurement of the estrogen receptor may provide a clearer picture of the true hormone dependence of breast tumors.
Mouse kidney beta-glucuronidase is induced by androgens in a receptor-dependent fashion. Genetic ... more Mouse kidney beta-glucuronidase is induced by androgens in a receptor-dependent fashion. Genetic regulatory mutations have been described which govern this response. In mice carrying the Gus-ra allele (A/J), the induction of enzyme activity is 3-5 times greater than in animals with the Gus-rb allele (C57BL/6J). To study this hormonal and genetic control at the molecular level, we measured changes in beta-glucuronidase mRNA concentrations in these two mouse strains using cloned cDNA. The specificity of the regulation was assessed by following changes in the concentration of kidney androgen-regulated protein (KAP) mRNA, which is also under androgen control in mouse kidney. Female mice were treated with Silastic implants that released 120 micrograms testosterone/day over a 20-day time course. Induction of specific mRNA was analyzed by either Northern blot hybridization or a more quantitative assay in which renal poly(A) RNA was covalently bound to aminophenylthioether paper discs. The induction of beta-glucuronidase mRNA was about 10-fold higher in the strain carrying the Gus-ra regulatory allele, indicating that the Gus-r locus controls the beta-glucuronidase structural gene (Gus-s) at the level of mRNA accumulation. Regulation by Gus-r was specific for beta-glucuronidase mRNA as kidney androgen-regulated protein mRNA accumulation did not differ between these two strains of mice after androgen treatment.
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