Structure/Activity Elements of the Multifunctional Protein, GMEB-1

Kaul, Sunil C.; Simons, S. Stoney

doi:10.1074/jbc.m202311200

Cited by 18 publications

(21 citation statements)

References 61 publications

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“…To identify the domain(s) of TIF2/GRIP1 that are required for this modulation, we now use an abbreviated assay in which increases in the activity of a subsaturating concentration of steroid, expressed as percent of maximal induction by saturating concentrations of agonist, have been shown to be diagnostic of a left shift in the doseresponse curve to lower EC 50 values (20,21,42,43). The main advantage of this abbreviated assay is that it requires many fewer samples to reach the same conclusion.…”

Section: Minimum Domain Of Coactivator Tif2/grip1 For Modulation Of Gmentioning

confidence: 99%

Modulation of Induction Properties of Glucocorticoid Receptor-Agonist and -Antagonist Complexes by Coactivators Involves Binding to Receptors but Is Independent of Ability of Coactivators to Augment Transactivation

He¹,

Szapary²,

Simons

2002

Journal of Biological Chemistry

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Coactivators such as TIF2 and SRC-1 modulate the positioning of the dose-response curve for agonistbound glucocorticoid receptors (GRs) and the partial agonist activity of antiglucocorticoid complexes. These properties of coactivators differ from their initially defined activities of binding to, and increasing the total levels of transactivation by, agonist-bound steroid receptors. We now report that constructs of TIF2 and SRC-1 lacking the two activation domains (AD1 and AD2) have significantly less ability to increase transactivation but retain most of the activity for modulating the dose-response curve and partial agonist activity. Mammalian two-hybrid experiments show that the minimum TIF2 segment with modulatory activity (TIF2.4) does not interact with p300, CREB-binding protein, or PCAF, which also modulates GR activities. DRIP150 and DRIP205 have been implicated in coactivator actions but are unable to modulate GR activities. The absence of synergism by PCAF or DRIP150 with SRC-1 or TIF2, respectively, further suggests that these other factors are not involved. The ability of a TIF2.4 fragment (i.e. TIF2.37), which is not known to interact with proteins, to block the actions of TIF2.4 suggests that an unidentified binder mediates the modulatory activity of TIF2. Pull-down experiments with GST/TIF2.4 demonstrate a direct interaction of TIF2 with GR in a hormone-dependent fashion that requires the receptor interaction domains of TIF2 and is equally robust with agonists and most antiglucocorticoids. These observations, which are confirmed in mammalian two-hybrid assays, suggest that the capacity of coactivators such as TIF2 to modulate the partial agonist activity of antisteroids is mediated by the binding of coactivators to GR-antagonist complexes. In conclusion, the modulatory activity of coactivators with GR-agonist and -antagonist complexes is mechanistically distinct from the ability of coactivators to augment the total levels of transactivation and appears to involve the binding to both GR-steroid complexes and an unidentified TIF2-associated factor(s).

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Section: Minimum Domain Of Coactivator Tif2/grip1 For Modulation Of Gmentioning

confidence: 99%

Modulation of Induction Properties of Glucocorticoid Receptor-Agonist and -Antagonist Complexes by Coactivators Involves Binding to Receptors but Is Independent of Ability of Coactivators to Augment Transactivation

He¹,

Szapary²,

Simons

2002

Journal of Biological Chemistry

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“…However, the amino acid sequence 412-563 in GMEB1 is sufficient for the expression of intrinsic transactivation activity (37). In the present study, we demonstrated that the C terminus 373-563 containing the transactivation domain is critical for interactions with procaspase, sug- gesting that this C terminus may function as both a transcriptional factor and a procaspase inhibitor through binding.…”

Section: Discussionmentioning

confidence: 57%

Glucocorticoid Modulatory Element-binding Protein 1 Binds to Initiator Procaspases and Inhibits Ischemia-induced Apoptosis and Neuronal Injury

Tsuruma

Nakagawa

Morimoto

et al. 2006

Journal of Biological Chemistry

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Caspases are divided into two classes: initiator caspases, which include caspase-8 and -9 and possess long prodomains, and effector caspases, which include caspase-3 and -7 and possess short prodomains. Recently, we demonstrated that glucocorticoid modulatory element-binding protein 1 (GMEB1) interacts with the prodomain of procaspase-2, thereby disrupting its autoactivation and the induction of apoptosis. Here we show that GMEB1 is also capable of binding to procaspase-8 and -9. GMEB1 attenuated the Fas-mediated activation of these caspases and the subsequent apoptosis. The knockdown of endogenous GMEB1 using RNA interference revealed that cells with decreased GMEB1 expression are more sensitive to stress and undergo accelerated apoptosis. Transgenic mice expressing a neurospecific GMEB1 had smaller cerebral infarcts and less brain swelling than wildtype mice in response to transient focal ischemia. These results suggest that GMEB1 is an endogenous regulator that selectively binds to initiator procaspases and inhibits caspase-induced apoptosis.Human caspases are the primary executioners of apoptosis and are divided into two classes, initiators and effectors. The effector caspases, which include caspase-3 and -7, possess short prodomains. The initiator caspases, which include caspase-8 and -9, possess long prodomains that consist of interaction domains essential for their activation. In response to the binding of ligands to death receptors, such as Fas, the adaptor protein FADD 3 and procaspase-8 are recruited to the activated receptor and are incorporated into a death-inducing signaling complex (DISC) (1). The interaction between FADD and procaspase-8 is mediated by the death effector domains (DED) of both proteins (2-4). A second molecule of procaspase-8 then binds to the complex, thus facilitating the autocatalytic activation of caspase-8.Procaspase-9 is activated by a variety of internal and external death stimuli that promote cytochrome c release from mitochondria. In the cytosol, cytochrome c binds the adaptor protein Apaf-1 in a dATPdependent fashion. The binding of cytochrome c and dATP induces a conformational change in Apaf-1 that allows it to associate with procaspase-9 via their respective caspase recruitment domains (CARD) (5, 6). The oligomerization of these procaspases while associated with these specific adapter molecules leads to autoactivation of the caspases (7). The enzymatic activation of initiator caspases leads to proteolytic activation of downstream effector caspases, the subsequent caspase-dependent cleavage of many vital proteins, and ultimately to programmed cell death. Thus, the regulation of initiator caspases is critical in determining whether a cell lives or dies.Caspases are synthesized in the cell as inactive precursors (procaspases), and their activation is strictly controlled by a variety of regulatory proteins, including Bcl-2, heat-shock proteins (HSPs), and the inhibitor of apoptosis (IAP) family of proteins (8 -13). Recently, we showed that glucocorticoid modulatory element...

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“…First, as shown in Figure 3, repression requires the SP100B SAND domain, which functions as a DNA binding domain in the AIRE, NUDR, DEAF-1, and GMEB-1 proteins, all of which are transcriptional regulators [Gross and McGinnis, 1996;Huggenvik et al, 1998;Kumar et al, 2001;Chen et al, 2002]. A highly conserved KDWK or KNWK sequence occurs at the protein:DNA interface in the SAND domain of each of these proteins.…”

Section: Discussionmentioning

confidence: 98%

SP100B is a repressor of gene expression

Wilcox¹,

Sheriff²,

Isaac³

et al. 2005

J of Cellular Biochemistry

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Mammalian cell nuclei exhibit discrete sites where specific proteins characteristically localize. PML nuclear bodies (PML NBs) (nuclear domain 10s (ND10s)) are the primary localization site for the promyelocytic leukemia (PML) protein and the SP100 autoantigen. The observations that some PML and SP100 isoforms can function as transcriptional regulators, that both the size and number of PML bodies increase in response to interferon treatment, and that many mammalian viruses encode proteins that mediate disruption of PML bodies suggest that these sites suppress viral infection, perhaps by repressing viral gene expression. We hypothesized that a component of PML NBs functions as a repressor of gene expression. To test this hypothesis, we characterized the effect of PML or SP100 isoforms on expression of transfected reporter genes. PML-I, PML-VI, and SP100A did not repress reporter gene expression. In contrast, SP100B repressed reporter gene expression, especially under conditions in which the reporter gene expression was elevated by a viral transactivator or addition of trichostatin A to the culture medium. The SP100B DNA binding domain was required for repression. SP100B had no detectable effect on the amount, methylation pattern, or topological form of plasmid DNA in the nuclei of transfected cells. The demonstrated repressive activity of SP100B supports the hypothesis that SP100B is a component of an innate immune response that represses expression of ectopic DNA.

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Structure/Activity Elements of the Multifunctional Protein, GMEB-1

Cited by 18 publications

References 61 publications

Modulation of Induction Properties of Glucocorticoid Receptor-Agonist and -Antagonist Complexes by Coactivators Involves Binding to Receptors but Is Independent of Ability of Coactivators to Augment Transactivation

Modulation of Induction Properties of Glucocorticoid Receptor-Agonist and -Antagonist Complexes by Coactivators Involves Binding to Receptors but Is Independent of Ability of Coactivators to Augment Transactivation

Glucocorticoid Modulatory Element-binding Protein 1 Binds to Initiator Procaspases and Inhibits Ischemia-induced Apoptosis and Neuronal Injury

SP100B is a repressor of gene expression

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