Lecture Fourteen: Oestrogen

This lecture aims to understand the role of the oestrogen hormone and its forms in female growth, development, sexual characteristics, menstruation, and pregnancy. To discover the role of estrogen in other organs and how estrogen levels and synthesis vary with age. To review how the estrogen receptor becomes activated upon binding with the estrogen hormone to transduce the signal and ignite a cellular response. The lecture discusses two main oestrogen pathways: genomic and non-genomic signaling. There are two types of oestrogen receptors: alpha and beta. In genomic signaling, the lecture discusses how the activated oestrogen receptor has a dual role in being a transcription factor. It recognizes and binds to the oestrogen response element found in the genome in the nucleus.
In the non-genomic signaling pathway, the activated receptor joins other signaling pathways (MAPK) and secondary messengers (cAMP) in the uterus. The Insulin Growth Factor (IGF-1) promotes the growth of bones and tissues). This leads to crosstalk with the genomic signaling pathway to transcribe target genes involved in growth, proliferation, angiogenesis, and tissue development. Furthermore, the lecture reveals the other side of the oestrogen pathway where abnormally high levels and overexpression of the oestrogen ligand and receptor can cause cancer. For instance, if the alpha oestrogen receptor expresses more than the beta oestrogen receptor. This is commonly seen in type 1 low-grade endometrial tumours. On the other hand, type 2 high-grade endometrial tumours have low expression of oestrogen receptors and additional mutations. Other contributing factors that link the dysregulation of the oestrogen signaling pathway with cancer are the imbalance of oestrogen more than the progesterone hormone, exposure to harmful chemicals, and being overweight.