Olayiwola Oduwole

Intrahepatic cholestasis of pregnancy levels of sulfated progesterone metabolites inhibit farnesoid X receptor resulting in a cholestatic phenotype

Intrahepatic cholestasis of pregnancy (ICP) is the most prevalent pregnancy‐specific liver disease and is associated with an increased risk of adverse fetal outcomes, including preterm labor and intrauterine death. The endocrine signals that cause cholestasis are not known but 3α‐sulfated progesterone metabolites have been shown to be elevated in ICP, leading us to study the impact of sulfated progesterone metabolites on farnesoid X receptor (FXR)‐mediated bile acid homeostasis pathways. Here we report that the 3β‐sulfated progesterone metabolite epiallopregnanolone sulfate is supraphysiologically raised in the serum of ICP patients. Mice challenged with cholic acid developed hypercholanemia and a hepatic gene expression profile indicative of FXR activation. However, coadministration of epiallopregnanolone sulfate with cholic acid exacerbated the hypercholanemia and resulted in aberrant gene expression profiles for hepatic bile acid‐responsive genes consistent with cholestasis. We demonstrate that levels of epiallopregnanolone sulfate found in ICP can function as a partial agonist for FXR, resulting in the aberrant expression of bile acid homeostasis genes in hepatoma cell lines and primary human hepatocytes. Furthermore, epiallopregnanolone sulfate inhibition of FXR results in reduced FXR‐mediated bile acid efflux and secreted FGF19. Using cofactor recruitment assays, we show that epiallopregnanolone sulfate competitively inhibits bile acid‐mediated recruitment of cofactor motifs to the FXR‐ligand binding domain. Conclusion: Our results reveal a novel molecular interaction between ICP‐associated levels of the 3β‐sulfated progesterone metabolite epiallopregnanolone sulfate and FXR that couples the endocrine component of pregnancy in ICP to abnormal bile acid homeostasis. (HEPATOLOGY 2013;)

The transcriptional co-factor RIP140 regulates mammary gland development by promoting the generation of key mitogenic signals

Nuclear receptor interacting protein (Nrip1), also known as RIP140, is a co-regulator for nuclear receptors that plays an essential role in ovulation by regulating the expression of the epidermal growth factor-like family of growth factors. Although several studies indicate a role for RIP140 in breast cancer, its role in the development of the mammary gland is unclear. By using RIP140-null and RIP140 transgenic mice, we demonstrate that RIP140 is an essential factor for normal mammary gland development and that it functions by mediating oestrogen signalling. RIP140-null mice exhibit minimal ductal elongation with no side-branching, whereas RIP140-overexpressing mice show increased cell proliferation and ductal branching with age. Tissue recombination experiments demonstrate that RIP140 expression is required in both the mammary epithelial and stromal compartments for ductal elongation during puberty and that loss of RIP140 leads to a catastrophic loss of the mammary epithelium, whereas RIP140 overexpression augments the mammary basal cell population and shifts the progenitor/differentiated cell balance within the luminal cell compartment towards the progenitors. For the first time, we present a genome-wide global view of oestrogen receptor-α (ERα) binding events in the developing mammary gland, which unravels 881 ERα binding sites. Unbiased evaluation of several ERα binding sites for RIP140 co-occupancy reveals selectivity and demonstrates that RIP140 acts as a co-regulator with ERα to regulate directly the expression of amphiregulin (Areg), the progesterone receptor (Pgr) and signal transducer and activator of transcription 5a (Stat5a), factors that influence key mitogenic pathways that regulate normal mammary gland development.

Overlapping dose responses of spermatogenic and extragonadal testosterone actions jeopardize the principle of hormonal male contraception

Testosterone (T), alone or in combination with progestin, provides a promising approach to hormonal male contraception. Its principle relies on enhanced negative feedback of exogenous T to suppress gonadotropins, thereby blocking the testicular T production needed for spermatogenesis, while simultaneously maintaining the extragonadal androgen actions, such as potency and libido, to avoid hypogonadism. A serious drawback of the treatment is that a significant proportion of men do not reach azoospermia or severe oligozoospermia, commensurate with contraceptive efficacy. We tested here, using hypogonadal luteinizing hormone/choriongonadotropin receptor (LHCGR) knockout (LHR–/–) mice, the basic principle of the T‐based male contraceptive method, that a specific T dose could maintain extragonadal androgen actions without simultaneously activating spermatogenesis. LHR–/– mice were treated with increasing T doses, and the responses of their spermatogenesis and extragonadal androgen actions (including gonadotropin suppression and sexual behavior) were assessed. Conspicuously, all dose responses to T were practically superimposable, and no dose of T could be defined that would maintain sexual function and suppress gonadotropins without simultaneously activating spermatogenesis. This finding, never addressed in clinical contraceptive trials, is not unexpected in light of the same androgen receptor mediating androgen actions in all organs. When extrapolated to humans, our findings may jeopardize the current approach to hormonal male contraception and call for more effective means of inhibiting intratesticular T production or action, to achieve consistent spermatogenic suppression.—Oduwole, O. O., Vydra, N., Wood, N. E. M., Samanta, L., Owen, L., Keevil, B., Donaldson, M., Naresh, K., Huhtaniemi, I. T. Overlapping dose responses of spermatogenic and extragonadal testosterone actions jeopardize the principle of hormonal male contraception. FASEB J. 28, 2566–2576 (2014). www.fasebj.org

Mouse models of altered gonadotrophin action: insight into male reproductive disorders

The advent of technologies to genetically manipulate the mouse genome has revolutionised research approaches, providing a unique platform to study the causality of reproductive disorders in vivo. With the relative ease of generating genetically modified (GM) mouse models, the last two decades have yielded multiple loss-of-function and gain-of-function mutation mouse models to explore the role of gonadotrophins and their receptors in reproductive pathologies. This work has provided key insights into the molecular mechanisms underlying reproductive disorders with altered gonadotrophin action, revealing the fundamental roles of these pituitary hormones and their receptors in the hypothalamic-pituitary-gonadal axis. This review will describe GM mouse models of gonadotrophins and their receptors with enhanced or diminished actions, specifically focusing on the male. We will discuss the mechanistic insights gained from these models into male reproductive disorders, and the relationship and understanding provided into male human reproductive disorders originating from altered gonadotrophin action.

Constitutively active follicle-stimulating hormone receptor enables androgen-independent spermatogenesis

Spermatogenesis is regulated by the 2 pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This process is considered impossible without the absolute requirement of LH-stimulated testicular testosterone (T) production. The role of FSH remains unclear because men and mice with inactivating FSH receptor (FSHR) mutations are fertile. We revisited the role of FSH in spermatogenesis using transgenic mice expressing a constitutively strongly active FSHR mutant in a LH receptor–null (LHR-null) background. The mutant FSHR reversed the azoospermia and partially restored fertility of Lhr–/– mice. The finding was initially ascribed to the residual Leydig cell T production. However, when T action was completely blocked with the potent antiandrogen flutamide, spermatogenesis persisted. Hence, completely T-independent spermatogenesis is possible through strong FSHR activation, and the dogma of T being a sine qua non for spermatogenesis may need modification. The mechanism for the finding appeared to be that FSHR activation maintained the expression of Sertoli cell genes considered androgen dependent. The translational message of our findings is the possibility of developing a new strategy of high-dose FSH treatment for spermatogenic failure. Our findings also provide an explanation of molecular pathogenesis for Pasqualini syndrome (fertile eunuchs; LH/T deficiency with persistent spermatogenesis) and explain how the hormonal regulation of spermatogenesis has shifted from FSH to T dominance during evolution.

Feasibility of Male Hormonal Contraception: Lessons from Clinical Trials and Animal Experiments

The general interest in the availability of male contraceptives is on the increase across different cultures and ethnic backgrounds, due in part to the fact that men are now willing more than ever, to share the responsibility of family planning. Despite the expression of interest and tremendous advances in research however, a modern male hormonal contraceptive method has remained an elusive goal. Testosterone (T) alone, or in combination with a progestin currently provides the most promising lead to male hormonal contraception. The principle relies on enhanced negative feedback of exogenous T to suppress gonadotropins, thereby blocking the endocrine stimulus for the process of spermatogenesis. A serious drawback is the inconsistent suppression among men of different ethnic backgrounds. This has increased the quest for development to include other nonhormonal methods. In reality many obstacles still have to be overcome before an acceptable method is available. In this review, we highlight recent developments in male hormonal contraceptives methods. Based on our recent findings from animal experiment, we shed light on why the method is not achieving the intended results, and suggest possible ways forward.

Gestational disruptions in metabolic rhythmicity of the liver, muscle, and placenta affect fetal size

Maternal metabolic adaptations are essential for successful pregnancy outcomes. We investigated how metabolic gestational processes are coordinated, whether there is a functional link with internal clocks, and whether disruptions are related to metabolic abnormalities in pregnancy, by studying day/night metabolic pathways in murine models and samples from pregnant women with normally grown and large‐for‐gestational age infants. In early mouse pregnancy, expression of hepatic lipogenic genes was up‐regulated and uncoupled from the hepatic clock. In late mouse pregnancy, rhythmicity of energy metabolism‐related genes in the muscle followed the patterns of internal clock genes in this tissue, and coincided with enhanced lipid transporter expression in the fetoplacental unit. Diurnal triglyceride patterns were disrupted in human placentas from pregnancies with large‐for‐gestational age infants and this overlapped with an increase in BMAL1 expression. Metabolic adaptations in early pregnancy are uncoupled from the circadian clock, whereas in late pregnancy, energy availability is mediated by coordinated muscle‐placenta metabolic adjustments linked to internal clocks. Placental triglyceride oscillations in the third trimester of human pregnancy are lost in large‐for‐gestational age infants and may be regulated by BMAL1. In summary, disruptions in metabolic and circadian rhythmicity are associated with increased fetal size, with implications for the pathogenesis of macrosomia. —Papacleovoulou, G., Nikolova, V., Oduwole, O., Chambers, J., Vazquez‐Lopez, M., Jansen, E., Nicolaides, K., Parker, M., Williamson, C. Gestational disruptions in metabolic rhythmicity of the liver, muscle, and placenta affect fetal size. FASEB J. 31, 1698–1708 (2017) www.fasebj.org