胰岛素如何通过 PI3K-AKT 通路让葡萄糖转运体 GLUT4 转移到细胞膜？
How does insulin use the PI3K-AKT pathway to move the glucose transporter GLUT4 to the plasma membrane?
胰岛素结合受体后使其自身酪氨酸磷酸化并招募 IRS 蛋白，活化 I 类 PI3K 生成磷脂 PIP3；PIP3 招募 PDK1 与 AKT2 到膜并使 AKT2 被磷酸化激活。AKT2 磷酸化 RabGAP 蛋白 TBC1D4（AS160），解除其对 Rab8a、Rab10 的抑制，使储存 GLUT4 的囊泡沿细胞骨架移动、停靠并与质膜融合，膜上转运体密度上升数倍。肌肉与脂肪组织中该环节的缺陷是胰岛素抵抗的核心表现之一。
Insulin binding triggers receptor autophosphorylation and recruitment of IRS proteins, activating class I PI3K to generate the lipid PIP3, which brings PDK1 and AKT2 to the membrane where AKT2 is phosphorylated and activated. AKT2 phosphorylates the RabGAP protein TBC1D4, also called AS160, releasing inhibition of Rab8a and Rab10 so that GLUT4 storage vesicles traffic along the cytoskeleton, tether and fuse with the plasma membrane, raising surface transporter density several-fold. Defects at this step in muscle and adipose tissue are a core feature of insulin resistance.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Lemmon MA, Schlessinger J. Cell signaling by receptor tyrosine kinases. Cell (2010) 141:1117-1134
Lemmon MA, Schlessinger J. Cell signaling by receptor tyrosine kinases. Cell (2010) 141:1117-1134
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1016/j.cell.2010.06.011
#GLUT4 #PI3K-AKT #囊泡转运 #胰岛素抵抗
糖皮质激素在同一组织中既可抗炎又可导致代谢损害，其分子机制如何解释这种双面性？
Glucocorticoids can be anti-inflammatory yet metabolically harmful in the same tissue; how is this dual action explained molecularly?
糖皮质激素受体激活后可通过两种模式作用：以二聚体形式结合糖皮质激素反应元件直接反式激活基因，包括糖异生酶 PEPCK 与 G6Pase，从而升高血糖并促进肌肉蛋白分解；也可以单体形式与 NF-κB、AP-1 等炎症转录因子相互抑制，实现抗炎的反式阻遏。此外还存在不依赖转录的快速非基因组作用。抗炎与代谢副作用共用同一受体但依赖不同的作用模式，这是研发选择性受体调节剂以分离两类效应的理论依据。
The activated glucocorticoid receptor works in two modes: as a dimer it binds glucocorticoid response elements and transactivates genes including the gluconeogenic enzymes PEPCK and G6Pase, raising blood glucose and promoting muscle protein breakdown; as a monomer it mutually inhibits inflammatory transcription factors such as NF-kappaB and AP-1, producing anti-inflammatory transrepression. Rapid non-genomic actions add a third layer. Because both benefit and metabolic harm run through one receptor but different modes, selective receptor modulators aim to dissociate the two.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Sapolsky, Romero & Munck,《How Do Glucocorticoids Influence Stress Responses? Integrating Permissive, Suppressive, Stimulatory, and Preparative Actions》,Endocrine Reviews 21, 55-89,2000 (DOI: 10.1210/edrv.21.1.0389)
Sapolsky, Romero & Munck, 'How Do Glucocorticoids Influence Stress Responses? Integrating Permissive, Suppressive, Stimulatory, and Preparative Actions', Endocrine Reviews 21, 55-89, 2000, DOI: 10.1210/edrv.21.1.0389
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1210/edrv.21.1.0389
#糖皮质激素受体 #反式阻遏 #糖异生 #抗炎机制
既然瘦素能抑制食欲，为什么给多数肥胖者补充瘦素并不能减重？
If leptin suppresses appetite, why does giving leptin fail to reduce weight in most obese people?
瘦素由脂肪组织按脂肪量分泌，作用于下丘脑弓状核的 POMC 与 AgRP 神经元来降低摄食并提高能量消耗。多数肥胖者血清瘦素本已升高，却存在瘦素抵抗：血脑屏障转运饱和、下丘脑内质网应激与炎症、以及 SOCS3 和 PTP1B 等负调控分子上调，使受体后信号 JAK2-STAT3 通路反应迟钝。因此外源补充瘦素无效，只有先天性瘦素缺乏的罕见患者补充后疗效显著。
Leptin is secreted by adipose tissue in proportion to fat mass and acts on POMC and AgRP neurons in the hypothalamic arcuate nucleus to reduce intake and raise energy expenditure. Most obese individuals already have high circulating leptin but are leptin resistant: transport across the blood-brain barrier saturates, hypothalamic endoplasmic reticulum stress and inflammation develop, and negative regulators such as SOCS3 and PTP1B blunt post-receptor JAK2-STAT3 signalling. Exogenous leptin therefore adds little, and dramatic responses are seen only in rare congenital leptin deficiency.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Friedman JM. Leptin and the endocrine control of energy balance. Nature Metabolism (2019) 1:754-764
Friedman JM. Leptin and the endocrine control of energy balance. Nature Metabolism (2019) 1:754-764
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1038/s42255-019-0095-y
#瘦素 #瘦素抵抗 #下丘脑 #能量平衡
胰岛素与胰高血糖素如何配合把血糖维持在狭窄范围内？
How do insulin and glucagon cooperate to keep blood glucose within a narrow range?
餐后血糖升高时胰岛 β 细胞分泌胰岛素，促进肌肉和脂肪组织的葡萄糖转运体 GLUT4 转位、加速糖原合成并抑制肝糖异生与脂解。血糖下降时 α 细胞分泌胰高血糖素，通过 cAMP 与蛋白激酶 A 激活肝糖原分解和糖异生，把葡萄糖释放回血液。两种激素互为拮抗又彼此调节，构成典型的双向负反馈系统；其失衡分别对应糖尿病的高血糖和降糖治疗中的低血糖风险。
After a meal, rising glucose prompts pancreatic beta cells to release insulin, which triggers GLUT4 translocation in muscle and fat, accelerates glycogen synthesis and suppresses hepatic gluconeogenesis and lipolysis. When glucose falls, alpha cells secrete glucagon, which acts through cAMP and protein kinase A to activate hepatic glycogenolysis and gluconeogenesis and return glucose to the blood. The two hormones antagonize and mutually regulate each other in a bidirectional negative-feedback loop whose failure produces the hyperglycaemia of diabetes and the hypoglycaemia risk of glucose-lowering therapy.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Saltiel AR, Kahn CR. Insulin signalling and the regulation of glucose and lipid metabolism. Nature (2001) 414:799-806
Saltiel AR, Kahn CR. Insulin signalling and the regulation of glucose and lipid metabolism. Nature (2001) 414:799-806
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1038/414799a
#胰岛素 #胰高血糖素 #血糖稳态 #糖原代谢
甲状腺分泌的主要是 T4，为什么真正发挥作用的却是 T3？
The thyroid secretes mainly T4, so why is T3 the hormone that actually acts on tissues?
甲状腺分泌的激素约九成是四碘甲状腺原氨酸 T4，它更像是循环中的前体和储备库，半衰期约一周。外周组织中的脱碘酶 D1 和 D2 将 T4 脱去一个碘原子生成三碘甲状腺原氨酸 T3，后者与核内甲状腺激素受体的亲和力高出约十倍，是主要活性形式；D3 则把 T4 和 T3 转化为无活性产物。这种局部脱碘调控让不同组织可以在血浆激素水平相近时，各自调整细胞内的实际激素活性。
About nine-tenths of thyroid output is thyroxine, T4, which behaves as a circulating reservoir with a half-life of roughly one week. Peripheral deiodinases D1 and D2 remove one iodine to generate triiodothyronine, T3, which binds nuclear thyroid hormone receptors about ten times more tightly and is the main active form, while D3 inactivates both T4 and T3. Local deiodination therefore lets individual tissues tune their intracellular hormone activity even when plasma levels are similar.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiological Reviews (2014) 94:355-382
Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiological Reviews (2014) 94:355-382
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1152/physrev.00030.2013
#甲状腺激素 #T4与T3 #脱碘酶 #代谢调控
什么是内分泌干扰物，它们通过哪些方式扰乱激素系统？
What are endocrine-disrupting chemicals and by what routes do they perturb hormone systems?
内分泌干扰物是能干扰激素合成、分泌、运输、结合或代谢的外源化学物质，常见来源包括部分增塑剂、农药和工业副产物。它们可作为激素受体的激动剂或拮抗剂，也可抑制类固醇合成酶、改变激素结合蛋白或影响受体表达水平。其效应常呈非单调的剂量反应关系，且在胚胎和青春期等发育窗口暴露的影响最为持久，这也是相关风险评估难度较大的原因。
Endocrine-disrupting chemicals are exogenous substances that interfere with hormone synthesis, secretion, transport, binding or metabolism, and common sources include certain plasticizers, pesticides and industrial by-products. They can act as receptor agonists or antagonists, inhibit steroidogenic enzymes, alter hormone-binding proteins or change receptor expression. Their dose-response curves are often non-monotonic and exposure during developmental windows such as gestation and puberty has the most lasting effects, which makes risk assessment particularly difficult.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Urry 等,《Campbell Biology》第11版,Pearson,2017
L. A. Urry et al., Campbell Biology, 11th ed., Pearson, 2017
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-13-409341-3 (11th ed., Pearson)
#内分泌干扰物 #受体拮抗 #发育窗口 #剂量反应
下丘脑-垂体-肾上腺轴是如何组织应激反应的？
How does the hypothalamic-pituitary-adrenal axis organize the stress response?
应激刺激使下丘脑室旁核释放促肾上腺皮质激素释放激素，促使垂体前叶分泌促肾上腺皮质激素，再驱动肾上腺皮质合成糖皮质激素。糖皮质激素动员糖异生、抑制部分免疫和生殖功能，把能量导向应急需求，并通过作用于垂体、下丘脑和海马的受体实施负反馈关闭该轴。若应激持续，负反馈效率下降，长期高皮质醇会带来代谢、心血管和认知方面的累积负担。
A stressor drives the paraventricular nucleus of the hypothalamus to release corticotropin-releasing hormone, which triggers pituitary secretion of adrenocorticotropic hormone and in turn adrenal synthesis of glucocorticoids. Glucocorticoids mobilize gluconeogenesis and dampen some immune and reproductive functions, redirecting energy to the emergency, while acting on receptors in pituitary, hypothalamus and hippocampus to switch the axis off by negative feedback. Under chronic stress this feedback becomes less efficient, and sustained high cortisol imposes cumulative metabolic, cardiovascular and cognitive costs.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
McEwen,《Physiology and Neurobiology of Stress and Adaptation: Central Role of the Brain》,Physiological Reviews,2007 (DOI: 10.1152/physrev.00041.2006)
McEwen, 'Physiology and Neurobiology of Stress and Adaptation: Central Role of the Brain', Physiological Reviews, 2007, DOI: 10.1152/physrev.00041.2006
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1152/physrev.00041.2006
#HPA轴 #皮质醇 #应激 #负反馈
为什么肽类激素的受体在细胞膜上，而类固醇激素的受体多在细胞内？
Why are receptors for peptide hormones located on the cell membrane while steroid hormone receptors are mostly intracellular?
肽类激素亲水、分子较大，无法自由穿过磷脂双分子层，只能结合膜受体并通过第二信使把信号转入细胞内，因此起效快但作用短暂。类固醇激素由胆固醇衍生、脂溶性强，可直接扩散进入细胞，与胞质或核内的核受体结合形成转录调控复合物。这决定了类固醇激素起效较慢，但通过改变基因表达产生持续数小时到数天的效应。
Peptide hormones are hydrophilic and relatively large, so they cannot cross the lipid bilayer and must bind surface receptors that relay the signal inward through second messengers, giving fast but short-lived effects. Steroid hormones are cholesterol-derived and lipophilic, so they diffuse into the cell and bind nuclear receptors in the cytosol or nucleus to form transcription-regulating complexes. Consequently steroid signalling is slower in onset but alters gene expression for hours to days.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Evans 与 Mangelsdorf,《Nuclear Receptors, RXR, and the Big Bang》,Cell,2014 (DOI: 10.1016/j.cell.2014.03.012)
Evans & Mangelsdorf, 'Nuclear Receptors, RXR, and the Big Bang', Cell, 2014, DOI: 10.1016/j.cell.2014.03.012
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.cell.2014.03.012
#激素分类 #膜受体 #核受体 #第二信使