Fundamental aspects of oestrogens: intracellular receptors and gene activation.
The steroid hormones exert their biological responses through a multi-step process involving regulation of gene expression. The hormone passes across the target-cell membrane from the circulation and enters the cytoplasm where it binds to a specific protein designated the receptor. A conformational change in the receptor ensues and the receptor-hormone complex is translocated to the chromatin in the cell nucleus. Interaction of the receptor-hormone complex with specific regions of the DNA and with specific non-histone chromatin proteins leads to initiation of transcription of new molecules of RNA. The primary RNA transcripts are processed to give mature molecules of messenger-RNA which are transported to the cytoplasm where they combine with ribosomes to form polysomes. The messenger-RNA is translated, by the cytoplasmic machinery of protein synthesis, into various new proteins. These proteins then promote the well-established biological responses associated with each particular steroid. Impairment of any of these steps (for example, lack of production of steroid, absence of receptor, a defect in structure of the receptor) results in a disturbance in or loss of the normal biological response.
D001943:Breast Neoplasms / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004247:DNA / Q000502:physiology; D004967:Estrogens / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D008024:Ligands / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011960:Receptors, Estrogen / Q000502:physiology*; D015533:Transcriptional Activation
D002868:Chromosomal Proteins, Non-Histone; D004967:Estrogens; D008024:Ligands; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D004247:DNA