Stephen G Hillier
The first sex steroid to be crystallized was the vertebrate ovarian hormone, estrone – a less potent metabolite of 17β-estradiol, which in mammals stimulates the female urge to mate (estrus). The gadfly (Greek oistros) lent its name to the process of estrus, as an insect that bites and torments in classical Greek mythology. With the purification and crystallization of a moult-inducing steroid (ecdysone) from insects, an interesting parallel emerged between mating and moulting in lower mammals and arthropods. Ecdysterone (potent ecdysone metabolite) has anabolic effects in mammalian muscle cells that can be blocked by selective estrogen receptor antagonists. Insects utilize ecdysteroids in similar ways that vertebrates use estrogens, including stimulation of oocyte growth and maturation. Ecdysteroids also modify precopulatory insect mating behaviour, further reinforcing the gonad-gadfly/mate-moult analogy.
Stephen G Hillier
The year 1946 was not only the year that the Society for Endocrinology was founded, but also the year that Edward Kendall’s compound E (cortisone) was first synthesised by Louis Sarett. By 1948, sufficient quantities of compound E were available for the rheumatologist Philip Hench to test it successfully for the first time in a patient with rheumatoid arthritis. It was immediately hailed as a ‘wonder drug’ and was shown to be effective in a number of inflammation-associated conditions, most notably rheumatoid arthritis. The subsequent development of endocrinology as a discipline is inextricably linked to the chemistry, biology and medicine of antiinflammatory glucocorticoids. Sixty years after the first chemical synthesis of cortisone, corticosteroids remain among the top ten most commonly used prescription and over the counter drugs. Basic and clinical studies of glucocorticoid biosynthesis, metabolism and action have trail-blazed developments in endocrinology ever since. This article surveys the extraordinary cortisone timeline, from first synthesis until now. The concluding scientific message is that intracrine metabolism of cortisone to cortisol via 11βhydroxysteroid dehydrogenase type 1 likely sustains local amplification of glucocorticoid action at sites of inflammation throughout the body. The broader message is that the discovery of compound E by Kendall (basic scientist), its large-scale synthesis by Sarett (industrial chemist) and its therapeutic application by Hench (rheumatologist) serves as a paradigm for modern translational medicine. It is concluded that endocrinology will remain a force in health and disease if it continues to evolve sans frontières at the basic/applied/clinical science interface. A challenge for the Society for Endocrinology is to ensure this happens.
Stephen G Hillier and Richard Lathe
The year 2019 marks the 80th anniversary of the 1939 Nobel Prize in Chemistry awarded to Leopold Ruzicka (1887–1976) for work on higher terpene molecular structures, including the first chemical synthesis of male sex hormones. Arguably his crowning achievement was the ‘biogenetic isoprene rule’, which helped to unravel the complexities of terpenoid biosynthesis. The rule declares terpenoids to be enzymatically cyclized products of substrate alkene chains containing a characteristic number of linear, head-to-tail condensed, C5 isoprene units. The number of repeat isoprene units dictates the type of terpene produced (i.e., 2, monoterpene; 3, sesquiterpene; 4, diterpene, etc.). In the case of triterpenes, six C5 isoprene units combine into C30 squalene, which is cyclized into one of the signature carbon skeletons from which myriad downstream triterpenoid structures are derived, including sterols and steroids. Ruzicka also had a keen interest in the origin of life, but the pivotal role of terpenoids has generally been overshadowed by nucleobases, amino acids, and sugars. To redress the balance, we provide a historical and evolutionary perspective. We address the potential abiotic generation of isoprene, the crucial role that polyprene terpenoids played in early membranes and cellular life, and emphasize that endocrinology from microbes to plants and vertebrates is firmly grounded on Ruzicka’s pivotal insights into the structure and function of terpenes. A harmonizing feature is that all known lifeforms (including bacteria) biosynthesize triterpenoid substances that are essential for cellular membrane formation and function, from which signaling molecules such as steroid hormones and cognate receptors are likely to have evolved.
Christopher R Harlow, Angela C Bradshaw, Michael T Rae, Kirsty D Shearer and Stephen G Hillier
Ovarian follicular development involves continual remodelling of the extracellular matrix (ECM) forming the basement membrane and intercellular framework that support granulosa cell (GC) growth and differentiation. Insight into the molecular regulation of ovarian ECM remodelling is potentially translatable to tissue remodelling elsewhere in the body. We therefore studied the link between a gene marker of ECM remodelling (connective tissue growth factor (CTGF)) and oestrogen biosynthesis (cytochrome P450aromatase (P450arom)) in rat granulosa cells. To determine if a cause–effect interaction exists, we used semi-quantitative in situ hybridisation to analyse patterns of CTGF and P450arom mRNA expression and immunohistochemistry to detect CTGF protein localisation throughout follicular development, and tested the actions of CTGF on oestrogen biosynthesis and oestradiol on CTGF mRNA expression in isolated GC in vitro. CTGF mRNA levels in GC rose gradually through small preantral (SP) and small antral (SA) stages of development to a maximum (fivefold higher) in large antral (LA) follicles. In preovulatory (PO) follicles, the CTGF mRNA level fell to 30% of that in SP follicles. P450arom mRNA also increased (threefold in LA relative to SP) throughout antral development follicles, but in contrast to CTGF continued to increase (12-fold) in PO follicles. In the cumulus oophorus of PO follicles, the residual GC CTGF mRNA expression increased with proximity to the oocyte, being inversely related to P450arom. Elsewhere in the follicle wall, there was a mural-to-antral gradient of CTGF mRNA expression, again inversely related to P450arom. Immunohistochemistry showed CTGF protein localisation broadly followed mRNA expression during follicular development, although the protein was also present in the theca interna and ovarian surface epithelium. Gradients in CTGF expression across the cumulus oophorus and follicle wall were similar to those observed for mRNA with CTGF protein expression being greatest in proximity to the oocyte. Treatment of isolated GC from preantral and SA follicles with recombinant human CTGF (1–100 ng/ml) did not affect basal or FSH-stimulated GC aromatase activity. However, in the absence of FSH, oestradiol (10−7–10−5 M) stimulated CTGF mRNA expression up to twofold. Conversely, FSH (10 ng/ml) alone reduced CTGF mRNA expression by 40% and combined treatment with FSH and oestradiol further suppressed CTGF to 10% of the control value. The oestrogen receptor (ER) antagonist, ICI 182 780 blocked the stimulatory and inhibitory effects of oestradiol, suggesting a specific ER-mediated mode of action on CTGF. Therefore, CTGF gene expression in GC is under local control by oestrogen whose effect (positive or negative) is modulated by FSH. This helps explain why gene expression of CTGF and P450arom diverge in FSH-induced PO follicles and has implications for oestrogenic regulation of CTGF formation elsewhere in the body.
Georgia Papacleovoulou, Hilary O D Critchley, Stephen G Hillier and J Ian Mason
The human ovarian surface epithelium (hOSE) is a mesothelial layer that surrounds the ovary and undergoes injury and repair cycles after ovulation-associated inflammation. We previously showed that IL4 is a key regulator of progesterone bioavailability during post-ovulatory hOSE repair as it differentially up-regulated 3 β -HSD1 and 3 β -HSD2 mRNA transcripts and total 3β-hydroxysteroid dehydrogenase activity whereas it inhibited androgen receptor (AR) expression. We now show that the pro-inflammatory effect of IL1α on 3 β -HSD1 expression is mediated by nuclear factor-κB (NF-κB), whereas its anti-inflammatory action on 3 β -HSD2 expression is exerted via p38 mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K) and NF-κB signalling pathways. The anti-inflammatory IL4 effects on 3 β -HSD1 and 3 β -HSD2 mRNA expression are mediated through STAT6 and PI3K signalling networks. IL4 effects on AR and 3 β -HSD2 expression involve the p38 MAPK pathway. We also document that IL4 up-regulates lysyl oxidase (LOX) mRNA transcripts, a key gene for extracellular matrix (ECM) deposition and inhibits IL1α-induced expression of cyclooxygenase-2 (COX-2) mRNA, a gene involved in breakdown of ECM, showing a further role in post-ovulatory wound healing. We conclude that IL1α and IL4 actions in the post-ovulatory wound healing of hOSE cells are mediated by different signalling transduction pathways. The p38 MAPK signalling pathway may have possible therapeutic benefit in inflammation-associated disorders of the ovary, including cancer.