安德罗斯坦代谢产物与核受体CAR-beta结合并使其失活
B M Forman1, I Tzameli, H S Choi
1The City of Hope National Medical Center, Duarte, California 91010, USA. bforman@gte.net
Nature
|October 23, 1998
概括
构成性安德罗斯坦受体-β (CAR-β) 活性被特定的安德罗斯坦类固醇抑制. 这些类固醇作为反向激动剂,逆转CAR-β.
科学领域:
- 分子内分泌学分子内分泌学
- 类固醇信号通道的信号通道
- 核受体研究 核受体研究
背景情况:
- 孤儿受体CAR-beta (构成性安德罗斯坦受体-β) 与视网膜X受体形成异构体.
- 构成性地激活基因转录的CAR-β独立于连接体结合.
- 经典的核受体通常需要连接物结合来进行转录激活.
研究的目的:
- 调查CAR-beta构成活动背后的机制.
- 为了确定调节CAR-β活性的潜在配体.
- 描述已识别的连接体的性质及其作用机制.
主要方法:
- 选潜在的CAR-β的配体.
- 评估已识别的类固醇对CAR-β的构成性转录活性的影响.
- 评估类固醇相互作用的立体特异性.
- 分析类固醇对CAR-β异体化,DNA结合和协活性剂招募/释放的影响.
主要成果:
- 安德罗斯坦诺和安德罗斯坦诺被确定为CAR-beta构成性活性的抑制剂.
- 抑制作用是立体特异性的,需要3alpha-hydroxy,5alpha-减少的安德罗斯坦结构.
- 这些安德罗斯坦不会影响异构或DNA结合,但会促进CAR-beta的联合激活剂释放.
结论:
- 卡尔-β功能通过连接体独立的协同激活剂招募.
- 特定的安德罗斯坦作为天然存在的CAR-beta的逆激动剂.
- 这定义了一个新的类固醇信号通路,反对传统的核受体机制.
相关概念视频
Intracellular Hormone Receptors
Lipid-soluble hormones diffuse across the plasma and nuclear membrane of target cells to bind to their specific intracellular receptors. These receptors act as transcription factors that regulate gene expression and protein synthesis in the target cell
Internal Receptors
Many cellular signals are hydrophilic and therefore cannot pass through the plasma membrane. However, small or hydrophobic signaling molecules can cross the hydrophobic core of the plasma membrane and bind to internal, or intracellular, receptors that reside within the cell. Many mammalian steroid hormones use this mechanism of cell signaling, as does nitric oxide (NO) gas.
Types of Receptors: Internal Receptors
Many cellular signals are hydrophilic and cannot pass through the plasma membrane. However, small or hydrophobic signaling molecules can cross the hydrophobic core of the plasma membrane and bind intracellular receptors that reside within the cell cytoplasm or nucleus. Many mammalian steroid hormones and nitric oxide (NO) gas use this cell signaling mechanism.
Similar to membrane-bound receptors, the binding of a ligand to the intracellular receptor of causes a conformational change in the...
Similar to membrane-bound receptors, the binding of a ligand to the intracellular receptor of causes a conformational change in the...
GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
Transducer Mechanism: Nuclear Receptors
Nuclear receptors, or NRs, are unique transcription factors that regulate gene transcription and affect the cellular pathways involved in reproduction, development, or metabolism. Their ability to be stimulated by small lipophilic ligands and control vital cellular processes makes them ideal drug targets. Nearly 10-15% of currently prescribed drugs target these receptors.
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
Adrenergic Receptors: β Subtype
β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...


