Hormones are the major signaling molecules that have a complex signaling cascade involving intracellular and intranuclear receptors, coreceptors, and signal transduction pathways. The molecular mechanism of hormonal action is written in a poetic verse to kindle the interest of students and to augment their affinity toward the onerous yet awesome topic. The hormones are secreted from the site of their synthesis and carried by transport binding proteins to exert their action in their target cells at a different site. Cortisol and aldosterone are derived from cholesterol with pregnenolone as an intermediate. Cortisol binds to the Glucocorticoid receptor (GR) in the cytoplasm by displacing the heat shock protein (hsp) already bound to it. The receptor ligand complex then traverses the nuclear membrane and binds to the Glucocorticoid Responsive Element (GRE) in the DNA. Except the orphan receptors, the nuclear receptors of thyroid, retinol (Vitamin A) and calcitriol (Vitamin D) exist as heterodimers and are bound to the DNA by their DNA binding domains. These nuclear receptors exist as heterodimers partnered with RXR (retinoic x receptor). Binding of insulin to its receptor on the target cells results in a cascade of intracellular events that involves activation of various kinases like PDK, mTOR and MAPK. This leads to phosphorylation of signal molecules that mediates the actions of insulin. Somatotropin (Growth hormone) and prolactin acts by JAK‐STAT pathway where the phosphorylated STAT protein dimerises and translocates to the nucleus and binds to Interferon Responsive Element and activates transcription. Somatotropin prevents dwarfism by promoting growth and prolactin promotes synthesis of milk by mammary glands. The communication between the nuclear receptors (FXR, LXR, PPAR‐Gamma) and the basal transcription apparatus is accomplished by protein – protein interaction between the nuclear receptors and the nuclear coregulators like CREB, TRAP and DRIP. These coregulators bind to various coactivators and transcription factors that activate RNA polymerase resulting in the synthesis of Pre‐pri RNA strand. Hence hormones act as first messengers that initiates the expression of genetic message in the codon of genes as protein synthesis by a process of translation.

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基因中激素的节律

激素是主要的信号分子，具有复杂的信号级联反应，涉及细胞内和核内受体、辅助受体和信号转导通路。荷尔蒙作用的分子机制被写成一首诗，以激发学生的兴趣，并增加他们对繁重但令人敬畏的话题的亲和力。激素从它们的合成部位分泌出来，并由转运结合蛋白携带，以在不同部位的靶细胞中发挥作用。皮质醇和醛固酮来源于胆固醇，孕烯醇酮作为中间体。皮质醇通过置换已经与其结合的热休克蛋白 (hsp) 与细胞质中的糖皮质激素受体 (GR) 结合。然后受体配体复合物穿过核膜并与 DNA 中的糖皮质激素反应元件 (GRE) 结合。除孤儿受体外，甲状腺、视黄醇（维生素 A）和骨化三醇（维生素 D）的核受体以异源二聚体形式存在，并通过其 DNA 结合域与 DNA 结合。这些核受体作为与 RXR（视黄酸 x 受体）配对的异二聚体存在。胰岛素与其靶细胞上的受体结合会导致一系列细胞内事件，包括激活各种激酶，如 PDK、mTOR 和 MAPK。这导致介导胰岛素作用的信号分子磷酸化。生长激素（生长激素）和催乳素通过 JAK-STAT 途径起作用，其中磷酸化的 STAT 蛋白二聚化并转移到细胞核，与干扰素反应元件结合并激活转录。生长激素通过促进生长来预防侏儒症，催乳素通过乳腺促进乳汁的合成。核受体（FXR、LXR、PPAR-Gamma）和基础转录装置之间的通讯是通过核受体与核共调节因子（如 CREB、TRAP 和 DRIP）之间的蛋白质 - 蛋白质相互作用来完成的。这些共调节因子与激活 RNA 聚合酶的各种共激活因子和转录因子结合，导致 Pre-pri RNA 链的合成。