Chromosomal instability in women with primary ovarian insufficiency.

Study Question: What is the prevalence of somatic chromosomal instability among women with idiopathic primary ovarian insufficiency (POI)?

Summary Answer: A subset of women with idiopathic POI may have functional impairment in DNA repair leading to chromosomal instability in their soma.

What Is Known Already: The formation and repair of DNA double-strand breaks during meiotic recombination are fundamental processes of gametogenesis. Oocytes with compromised DNA integrity are susceptible to apoptosis which could trigger premature ovarian aging and accelerated wastage of the human follicle reserve.

Association of Concussion With Abnormal Menstrual Patterns in Adolescent and Young Women.

Importance: Brain injury may interrupt menstrual patterns by altering hypothalamic-pituitary-ovarian axis function. Investigators have yet to evaluate the association of concussion with menstrual patterns in young women.

Objective: To compare abnormal menstrual patterns in adolescent and young women after a sport-related concussion with those after sport-related orthopedic injuries to areas other than the head (nonhead).

How Protein Kinase A Activates Canonical Tyrosine Kinase Signaling Pathways To Promote Granulosa Cell Differentiation.

Protein kinase A (PKA) has recently been shown to mimic the actions of follicle-stimulating hormone (FSH) by activating signaling pathways that promote granulosa cell (GC) differentiation, such as phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK). We sought to elucidate the mechanism by which PKA, a Ser/Thr kinase, intersected the PI3K/AKT and MAPK/ERK pathways that are canonically activated by receptor tyrosine kinases (RTKs). Our results show that for both of these pathways, the RTK is active in the absence of FSH yet signaling down the pathways to commence transcriptional responses requires FSH-stimulated PKA activation.

Protein Kinase A: A Master Kinase of Granulosa Cell Differentiation.

Activation of protein kinase A (PKA) by follicle stimulating hormone (FSH) transduces the signal that drives differentiation of ovarian granulosa cells (GCs). An unresolved question is whether PKA is sufficient to initiate the complex program of GC responses to FSH. We compared signaling pathways and gene expression profiles of GCs stimulated with FSH or expressing PKA-CQR, a constitutively active mutant of PKA.

Prohibitin regulates the FSH signaling pathway in rat granulosa cell differentiation.

Published results from our laboratory identified prohibitin (PHB), a gene product expressed in granulosa cells (GCs) that progressively increases during follicle maturation. Our current in vitro studies demonstrate that follicle-stimulating hormone (FSH) stimulates Phb expression in rat primary GCs. The FSH-dependent expression of PHB was primarily localized within mitochondria, and positively correlates with the morphological changes in GCs organelles, and synthesis and secretions of estradiol (E2) and progesterone (P4).

Convergence of 3',5'-cyclic adenosine 5'-monophosphate/protein kinase A and glycogen synthase kinase-3beta/beta-catenin signaling in corpus luteum progesterone synthesis.

Progesterone secretion by the steroidogenic cells of the corpus luteum (CL) is essential for reproduction. Progesterone synthesis is under the control of LH, but the exact mechanism of this regulation is unknown. It is established that LH stimulates the LH receptor/choriogonadotropin receptor, a G-protein coupled receptor, to increase cAMP and activate cAMP-dependent protein kinase A (PKA).

FSH and FOXO1 regulate genes in the sterol/steroid and lipid biosynthetic pathways in granulosa cells.

The forkhead box transcription factor FOXO1 is highly expressed in granulosa cells of growing follicles but is down-regulated by FSH in culture or by LH-induced luteinization in vivo. To analyze the function of FOXO1, we infected rat and mouse granulosa cells with adenoviral vectors expressing two FOXO1 mutants: a gain-of-function mutant FOXOA3 that has two serine residues and one threonine residue mutated to alanines rendering this protein constitutively active and nuclear and FOXOA3-mutant DNA-binding domain (mDBD) in which the DBD is mutated. The infected cells were then treated with vehicle or FSH for specific time intervals.

Constitutively active protein kinase A qualitatively mimics the effects of follicle-stimulating hormone on granulosa cell differentiation.

Activation of the protein kinase A (PKA) signaling system is necessary for FSH-induced granulosa cell differentiation, but it is not known whether activation of PKA is sufficient to account for the complex pattern of gene expression that occurs during this process. We addressed this question by infecting granulosa cells with a lentiviral vector that directs the expression of a constitutively active mutant of PKA (PKA-CQR) and compared the cellular responses to PKA-CQR with cells stimulated by FSH. Expression of PKA-CQR in undifferentiated granulosa cells resulted in the induction of both estrogen and progesterone production in the absence of cAMP.

Inhibition of rat granulosa cell differentiation by overexpression of Galphaq.

Activation of FSH and LH receptors in undifferentiated granulosa cells (i.e., no prior exposure to FSH) results in comparable induction of progesterone production, but activation of the LH receptor is less effective than FSH in inducing aromatase and the native LH receptor.

Comparison of progesterone and glucocorticoid receptor binding and stimulation of gene expression by progesterone, 17-alpha hydroxyprogesterone caproate, and related progestins.

Objective: This study was undertaken to determine whether the reduction in premature birth attributable to 17-alpha hydroxyprogesterone caproate occurs because of a greater affinity for progesterone or glucocorticoid receptors or by enhanced stimulation of progestogen responsive genes when compared with progesterone.

Study Design: We performed competitive steroid hormone receptor binding assays using cytosols expressing either recombinant human progesterone receptor-A or -B or rabbit uterine or thymic cytosols. We used 4 different carcinoma cell lines to assess transactivation of reporter genes or induction of alkaline phosphatase.

Liver receptor homolog-1 and steroidogenic factor-1 have similar actions on rat granulosa cell steroidogenesis.

Granulosa cells express the closely related orphan nuclear receptors steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1). To determine whether SF-1 and LRH-1 have differential effects on steroid production, we compared the effects of overexpressing LRH-1 and SF-1 on estrogen and progesterone production by undifferentiated rat granulosa cells. Adenovirus mediated overexpression of LRH-1 or SF-1 had qualitatively similar effects.

Apoptosis of rat granulosa cells after staurosporine and serum withdrawal is suppressed by adenovirus-directed overexpression of prohibitin.

Prohibitin (Phb1) is a highly conserved mitochondrial protein that is associated with granulosa cell differentiation, atresia, and luteolysis. Although prohibitin has been implicated in the suppression of apoptosis in mammalian cells, its specific role in programmed cell death in granulosa cells is unknown. In the present study, we examined the role of prohibitin in mediating staurosporine (STS) and serum withdrawal induced apoptosis in undifferentiated rat granulosa cells.

Follicle-stimulating hormone/cAMP regulation of aromatase gene expression requires beta-catenin.

Estrogens profoundly influence the physiology and pathology of reproductive and other tissues. Consequently, emphasis has been placed on delineating the mechanisms underlying regulation of estrogen levels. Circulating levels of estradiol in women are controlled by follicle-stimulating hormone (FSH), which regulates transcription of the aromatase gene (CYP19A1) in ovarian granulosa cells.

The physiology of follicle selection.

During the follicular phase of the primate menstrual cycle, a single follicle usually matures to the preovulatory stage and releases its oocyte for fertilization and the potential establishment of pregnancy. In assisted reproductive technology procedures, it is desirable to override the natural process of follicle selection to produce many oocytes that are capable of being fertilized and undergoing normal embryo development. The goal of this chapter is to summarize the current views regarding the natural process of follicle selection in primates and to discuss how this process may be amplified to produce a greater number of oocytes.

Liver receptor homolog-1 stimulates the progesterone biosynthetic pathway during follicle-stimulating hormone-induced granulosa cell differentiation.

FSH-stimulated granulosa cell differentiation is associated with the induction of the LH receptor (LHr) as well as induction of the estrogen and progesterone biosynthetic pathways. Although activation of the cAMP-protein kinase A pathway is sufficient to stimulate progesterone production, additional pathways are required for the induction of the LHr and p450 aromatase. The orphan nuclear receptor, liver receptor homolog-1 (LRH-1), is expressed in granulosa cells and has been shown to synergize with the cAMP signaling system to regulate the gonadal type II aromatase promoter in transient transfection assays.

Administration of dihydrotestosterone to rhesus monkeys inhibits gonadotropin-stimulated ovarian steroidogenesis.

Androgens, in addition to serving as a substrate for estrogen biosynthesis, exert autocrine/paracrine actions on ovarian function. However, much of the information regarding the actions of androgens on the ovary has been obtained using rodents, and the extent to which these results can be extrapolated to higher primates is uncertain. The current study was initiated to determine the effects of dihydrotestosterone (DHT) and testosterone (T) on the responsiveness of the rhesus monkey ovary to exogenous FSH and LH in vivo.

Protein kinase B is obligatory for follicle-stimulating hormone-induced granulosa cell differentiation.

Although FSH receptors are linked to the cAMP second messenger system, additional intracellular signaling pathways appear to be required for the induction of aromatase and the LH receptor during granulosa cell differentiation. We employed adenovirus vectors to modulate specific intracellular signaling systems in undifferentiated granulosa cells to identify the signaling pathway(s) that may be involved in the FSH-mediated induction of aromatase and the LH receptor. Expression of either the constitutively activated human LH receptor D578H or the constitutively active human G(s)alpha Q227L resulted in increased cAMP production without increasing aromatase activity or mRNA levels for the LH receptor.

Administration of insulin-like growth factor I to rhesus monkeys does not augment gonadotropin-stimulated ovarian steroidogenesis.

Although it is well established that IGF-I is able to amplify the actions of FSH and LH on ovarian cells in vitro, little information is available regarding the effects of IGF-I on ovarian function in vivo. To address this question, rhesus monkeys whose spontaneous gonadotropin secretion was interrupted with a GnRH antagonist received continuous iv infusions of saline, IGF-I (240 microg/kg.d), or IGF-I (240 microg/kg.

Regulation of steroidogenesis and the steroidogenic acute regulatory protein by a member of the cAMP response-element binding protein family.

The mitochondrial phosphoprotein, the steroidogenic acute regulatory (StAR) protein, is an essential component in the regulation of steroid biosynthesis in adrenal and gonadal cells through cAMP-dependent pathways. In many cases transcriptional induction by cAMP is mediated through the interaction of a cAMP response-element binding protein (CREB) family member with a consensus cAMP response element (CRE; 5'-TGACGTCA-3') found in the promoter of target genes. The present investigation was carried out to determine whether a CRE-binding protein (CREB) family member [CREB/CRE modulator (CREM) family] was involved in the regulation of steroidogenesis and StAR protein expression.