Kākāpō reproduction: Identification of steroid receptors and oestrogenic activity in native flora

<p>Kākāpō (Strigops habroptilus) are a critically endangered parrot species endemic to New Zealand that exhibit a reproductive strategy linked to “masting” years. Crucial to their survival is increased reproductive success. It has been hypothesised that their pattern of reproduction is synchronised with a steroidal “trigger” present in plants during intensive masting. If this hypothesis is valid, then Kākāpō and other closely related NZ parrots might be receptive to these masting plants in a manner different from that of other avian species. The aims of this study were firstly, to identify whether unique amino acid motifs were present in the ligand binding domains (LBD) for the steroid receptors oestrogen receptor α (ER-α), oestrogen receptor β (ER-β), androgen receptor (AR) and progesterone receptor (PR) for the New Zealand parrots Kākāpō, Kākā, Kākāriki and Kea. These LBD amino acid sequences were compared with those in an Australian parrot, the Cockatiel, as well as in Chicken and Japanese Quail. Moreover, the role of these amino acid changes on the binding of ligands (both the native ligand and other steroidogenic compounds) for ER-α was assessed by in silico modelling by comparing the most favourable binding position of the ligands in the three-dimensional structure of Kākāpō ER-α with that of human ER-α. The second aim was to test extracts of New Zealand native plants known to be a food source for Kākāpō for their seasonal variation in oestrogenic activity and hence possible involvement in the reproductive cycle of Kākāpō. The LBD for ER-β and AR of the parrot species (New Zealand and Australian) displayed 100% identity whilst those for ER-α and PR had variations. When the parrot sequences were compared with those for other avian species and human, there were a number of amino acid differences present, with the greatest disparity present in the LBD of ER-α. From in silico modelling studies, the amino acid substitutions in this receptor were predicted to have an indirect influence on the binding position of both 17β-oestradiol and a number of phytoestrogens through changes in the structure of this region. Consequently, this could have an effect on the binding affinity of certain plant chemicals for ER-α and thus their potency. Plants extracts from the foliage and fruit of native New Zealand species were screened for oestrogenic activity in a yeast bioassay transfected with the human isoform of ER-α. The results from these experiments indicated that all the plants tested (excluding Dacrycarpus dacrydioides) exhibited detectable oestrogenic activity and a number also displayed variable and sometimes seasonal trends in activity. In summary, the results in this study identified ER-α LBD amino acid motifs unique to New Zealand parrots. For the other steroid receptors, the ER-β LBD had a three amino acid combination of M, V and L that was only present in the parrot species whilst both the AR and PR LBD displayed much greater inter-species conservation. These changes, particularly those in the ER-α LBD, may influence the binding of steroidogenic compounds, known to be present in the plants consumed by Kākāpō as demonstrated by in silico modelling. Thus, this research provides evidence that the diet of Kākāpō may influence their reproductive pattern. However, it remains to be determined whether the steroidogenic potency of these plant extracts is modified when interacting with the unique LBD of native NZ parrots.</p>

Kākāpō reproduction: Identification of steroid receptors and oestrogenic activity in native flora

<p>Kākāpō (Strigops habroptilus) are a critically endangered parrot species endemic to New Zealand that exhibit a reproductive strategy linked to “masting” years. Crucial to their survival is increased reproductive success. It has been hypothesised that their pattern of reproduction is synchronised with a steroidal “trigger” present in plants during intensive masting. If this hypothesis is valid, then Kākāpō and other closely related NZ parrots might be receptive to these masting plants in a manner different from that of other avian species. The aims of this study were firstly, to identify whether unique amino acid motifs were present in the ligand binding domains (LBD) for the steroid receptors oestrogen receptor α (ER-α), oestrogen receptor β (ER-β), androgen receptor (AR) and progesterone receptor (PR) for the New Zealand parrots Kākāpō, Kākā, Kākāriki and Kea. These LBD amino acid sequences were compared with those in an Australian parrot, the Cockatiel, as well as in Chicken and Japanese Quail. Moreover, the role of these amino acid changes on the binding of ligands (both the native ligand and other steroidogenic compounds) for ER-α was assessed by in silico modelling by comparing the most favourable binding position of the ligands in the three-dimensional structure of Kākāpō ER-α with that of human ER-α. The second aim was to test extracts of New Zealand native plants known to be a food source for Kākāpō for their seasonal variation in oestrogenic activity and hence possible involvement in the reproductive cycle of Kākāpō. The LBD for ER-β and AR of the parrot species (New Zealand and Australian) displayed 100% identity whilst those for ER-α and PR had variations. When the parrot sequences were compared with those for other avian species and human, there were a number of amino acid differences present, with the greatest disparity present in the LBD of ER-α. From in silico modelling studies, the amino acid substitutions in this receptor were predicted to have an indirect influence on the binding position of both 17β-oestradiol and a number of phytoestrogens through changes in the structure of this region. Consequently, this could have an effect on the binding affinity of certain plant chemicals for ER-α and thus their potency. Plants extracts from the foliage and fruit of native New Zealand species were screened for oestrogenic activity in a yeast bioassay transfected with the human isoform of ER-α. The results from these experiments indicated that all the plants tested (excluding Dacrycarpus dacrydioides) exhibited detectable oestrogenic activity and a number also displayed variable and sometimes seasonal trends in activity. In summary, the results in this study identified ER-α LBD amino acid motifs unique to New Zealand parrots. For the other steroid receptors, the ER-β LBD had a three amino acid combination of M, V and L that was only present in the parrot species whilst both the AR and PR LBD displayed much greater inter-species conservation. These changes, particularly those in the ER-α LBD, may influence the binding of steroidogenic compounds, known to be present in the plants consumed by Kākāpō as demonstrated by in silico modelling. Thus, this research provides evidence that the diet of Kākāpō may influence their reproductive pattern. However, it remains to be determined whether the steroidogenic potency of these plant extracts is modified when interacting with the unique LBD of native NZ parrots.</p>

Molecular Characterization of Membrane Steroid Receptors in Hormone-Sensitive Cancers

Cancer is one of the most common causes of death worldwide, and its development is a result of the complex interaction of genetic factors, environmental cues, and aging. Hormone-sensitive cancers depend on the action of one or more hormones for their development and progression. Sex steroids and corticosteroids can regulate different physiological functions, including metabolism, growth, and proliferation, through their interaction with specific nuclear receptors, that can transcriptionally regulate target genes via their genomic actions. Therefore, interference with hormones’ activities, e.g., deregulation of their production and downstream pathways or the exposition to exogenous hormone-active substances such as endocrine-disrupting chemicals (EDCs), can affect the regulation of their correlated pathways and trigger the neoplastic transformation. Although nuclear receptors account for most hormone-related biologic effects and their slow genomic responses are well-studied, less-known membrane receptors are emerging for their ability to mediate steroid hormones effects through the activation of rapid non-genomic responses also involved in the development of hormone-sensitive cancers. This review aims to collect pre-clinical and clinical data on these extranuclear receptors not only to draw attention to their emerging role in cancer development and progression but also to highlight their dual role as tumor microenvironment players and potential candidate drug targets.

Early preantral follicles of the domestic cat express gonadotropin and sex steroid signalling potential

Key biomolecular processes which regulate primordial ovarian follicle dormancy and early folliculogenesis in mammalian ovaries are not fully understood. The domestic cat is a useful model to study ovarian folliculogenesis and is the most relevant for developing in vitro growth methods to be implemented in wild felid conservation breeding programs. Previously, RNA-sequencing of primordial, primary, and secondary follicle samples from domestic cat implicated ovarian steroidogenesis and steroid reception during follicle development. Here we aimed to identify which sex steroid biosynthesis and metabolism enzymes, gonadotropin receptors, and sex steroid receptors are present and may be potential regulators. Differential gene expression, functional annotation, and enrichment analyses were employed and protein localisation was studied too. Gene transcripts for PGR, PGRMC1, AR (steroid receptors), CYP11A1, CYP17A1, HSD17B1 and HSD17B17 (steroidogenic enzymes), and STS (steroid metabolising enzyme) were significantly differentially expressed (Q values of ≤0.05). Differential gene expression increased in all transcripts during follicle transitions apart from AR which decreased by the secondary stage. Immunohistochemistry localised FSHR and LHCGR to oocytes at each stage. PGRMC1 immunostaining was strongest in granulosa cells whereas AR was strongest in oocytes throughout each stage. Protein signals for steroidogenic enzymes were only detectable in secondary follicles. Products of these significantly differentially expressed genes may regulate domestic cat preantral folliculogenesis. In vitro growth could be optimised as all early follicles express gonadotropin and steroid receptors meaning hormone interaction and response may be possible. Protein expression analyses of early secondary follicles supported its potential for producing sex steroids.

104 Epigenetic Changes Due to Environmental Toxicants: An Animal Health Concern

Endocrine disrupting chemicals (EDCs) mimic natural hormones in the body, but they are not subject to normal homeostatic regulatory mechanisms. One such EDC that is particularly important in animal and human health is bisphenol A (BPA) that is an industrial chemical used to harden plastic, and thus, it is prevalent in many common household items. Notably, BPA, and likely other EDCs, persist in the environment. Besides binding to steroid and non-steroid receptors, BPA and other EDCs may induce epigenetic changes directly or by affecting gut bacteria that can promote such host changes. The objective of current studies was to determine whether developmental exposure to BPA and/or genistein, a phytoestrogen, induce persistent epigenetic and transcriptomic changes in various brain regions and the placenta. Additionally, the ability of these chemicals to alter gut microbiota and gut metabolites that may trigger such epigenetic alterations were investigated. Animal models used to examine for such effects included California mice (Peromyscus californicus), deer mice (Peromyscus maniculatus), laboratory mice (Mus musculus), and eastern painted turtles (Chrysemys picta). To link these ‘omics changes to actual phenotypic modifications, several behavioral domains were assessed in these species following developmental exposure to these compounds. Results across taxa clearly show that BPA and genistein leads to behavioral deficits, including cognitive and social impairments, anxiogenic behaviors, and reduced voluntary physical activity. Correspondingly, both chemicals transformed the epigenome and transcriptome in key brain regions and the placenta. Gut dysbiosis and stimulation of harmful bacterial metabolites ensued following early EDC exposure, and such effects persisted through adulthood. By using a one health medicine approached that evaluated various vertebrate animal species, there is solid evidence that perinatal exposure to BPA and genistein reprograms the epigenome and thereby lead to longstanding health consequences. Such findings have important veterinary and human health ramifications.

Steroid Receptors in Breast Cancer: Understanding of Molecular Function as a Basis for Effective Therapy Development

Breast cancer remains one of the most important health problems worldwide. The family of steroid receptors (SRs), which comprise estrogen (ER), progesterone (PR), androgen (AR), glucocorticoid (GR) and mineralocorticoid (MR) receptors, along with a receptor for a secosteroid—vitamin D, play a crucial role in the pathogenesis of the disease. They function predominantly as nuclear receptors to regulate gene expression, however, their full spectrum of action reaches far beyond this basic mechanism. SRs are involved in a vast variety of interactions with other proteins, including extensive crosstalk with each other. How they affect the biology of a breast cell depends on such factors as post-translational modifications, expression of coregulators, or which SR isoform is predominantly synthesized in a given cellular context. Although ER has been successfully utilized as a breast cancer therapy target for years, research on therapeutic application of other SRs is still ongoing. Designing effective hormone therapies requires thorough understanding of the molecular function of the SRs. Over the past decades, huge amount of data was obtained in multiple studies exploring this field, therefore in this review we attempt to summarize the current knowledge in a comprehensive way.

Maternal sucrose consumption alters behaviour and steroids in adult rat offspring

Maternal diets can have dramatic effects on the physiology, metabolism, and behaviour of offspring that persist into adulthood. However, the effects of maternal sucrose consumption on offspring remain unclear. Here, female rats were fed either a sucrose diet with a human-relevant level of sucrose (25% of kcal) or a macronutrient-matched, isocaloric control diet before, during, and after pregnancy. After weaning, all offspring were fed a standard low-sucrose rodent chow. We measured indicators of metabolism (weight, adipose, glucose tolerance, liver lipids) during development and adulthood (16-24 wk). We also measured food preference and motivation for sugar rewards in adulthood. Finally, in brain regions regulating these behaviours, we measured steroids and transcripts for steroidogenic enzymes, steroid receptors, and dopamine receptors. In male offspring, maternal sucrose intake decreased body mass and visceral adipose, increased preference for high-sucrose and high-fat diets, increased motivation for sugar rewards, and decreased mRNA levels of Cyp17a1 (an androgenic enzyme) in the nucleus accumbens. In female offspring, maternal sucrose intake increased basal corticosterone levels. These data demonstrate the profound, enduring, diverse, and sex-specific effects of maternal sucrose consumption on offspring phenotype.

Effects of Sleep Deprivation by Olfactorily Induced Sexual Arousal Compared to Immobilization Stress and Manual Sleep Deprivation on Neuromessengers and Time Keeping Genes in the Suprachiasmatic Nuclei and Other Cerebral Entities of Syrian Hamsters—An Immunohistochemical Study

We investigated the effects of sexual arousal induced by olfactory stimuli on the expression of neuromodulators, neurotransmitters and sexual steroid receptors in the suprachiasmatic nucleus (SCN, the circadian pacemaker of mammals) and other cerebral entities of Syrian hamsters (Mesocricetus auratus) compared to manual sleep deprivation and immobilization stress. The hamsters kept under a 12:12 hours (h) light:dark cycle were deprived of sleep by sexual stimulation, gentle manual handling or immobilization stress for 1 h at the beginning of the light phase and subsequently sacrificed at zeitgeber time 01:00, respectively; for comparison, hamsters were manually sleep deprived for 6 or 20 h or sacrificed after completing a full sleep phase. As demonstrated by immunohistochemistry, apart from various alterations after manual sleep deprivation, sexual stimulation caused down-regulation of arginine-vasopressin (AVP), vasointestinal peptide (VIP), serotonin (5-HT), substance P (SP), and met-enkephalin (ME) in the SCN. Somatostatin (SOM) was diminished in the medial periventricular nucleus (MPVN). In contrast, an increase in AVP was observed in the PVN, that of oxytocin (OXY) in the supraoptic nucleus (SON), of tyrosine-hydroxylase (TH) in the infundibular nucleus (IN), and dopamine beta-hydroxylase (DBH) in the A7 neuron population of the brain stem (A7), respectively. Testosterone in plasma was increased. The results indicate that sexual arousal extensively influences the neuropeptide systems of the SCN, suggesting an involvement of the SCN in reproductive behavior.