Showing papers by "Ursula B. Kaiser published in 2010"

Mutations of the KISS1 gene in disorders of puberty

Abstract: Context: Kisspeptin, encoded by the KISS1 gene, is a key stimulatory factor of GnRH secretion and puberty onset. Inactivating mutations of its receptor (KISS1R) cause isolated hypogonadotropic hypogonadism (IHH). A unique KISS1R-activating mutation was described in central precocious puberty (CPP). Objective: Our objective was to investigate KISS1 mutations in patients with idiopathic CPP and normosmic IHH. Patients: Eighty-three children with CPP (77 girls) and 61 patients with IHH (40 men) were studied. The control group consisted of 200 individuals with normal pubertal development. Methods: The promoter region and the three exons of KISS1 were amplified and sequenced. Cells expressing KISS1R were stimulated with synthetic human wild-type or mutant kisspeptin-54 (kp54), and inositol phosphate accumulation was measured. In a second set of experiments, kp54 was preincubated in human serum before stimulation of the cells. Results: Two novel KISS1 missense mutations, p.P74S and p.H90D, were identified in th...

TAC3/TACR3 Mutations Reveal Preferential Activation of Gonadotropin-Releasing Hormone Release by Neurokinin B in Neonatal Life Followed by Reversal in Adulthood

Abstract: Context: Mutations in TAC3 and TACR3 (encoding neurokinin B and its receptor) have been identified in Turkish patients with idiopathic hypogonadotropic hypogonadism (IHH), but broader populations have not yet been tested and genotype-phenotype correlations have not been established Objective: A broad cohort of normosmic IHH probands was screened for mutations in TAC3/TACR3 to evaluate the prevalence of such mutations and define the genotype/phenotype relationships Design and Setting: The study consisted of sequencing of TAC3/TACR3, in vitro functional assays, and neuroendocrine phenotyping conducted in tertiary care centers worldwide Patients or Other Participants: 345 probands, 18 family members, and 292 controls were studied Intervention: Reproductive phenotypes throughout reproductive life and before and after therapy were examined Main Outcome Measure: Rare sequence variants in TAC3/TACR3 were detected Results: In TACR3, 19 probands harbored 13 distinct coding sequence rare nucleotide variants [three nonsense mutations, six nonsynonymous, four synonymous (one predicted to affect splicing)] In TAC3, one homozygous single base pair deletion was identified, resulting in complete loss of the neurokinin B decapeptide Phenotypic information was available on 16 males and seven females with coding sequence variants in TACR3/TAC3 Of the 16 males, 15 had microphallus; none of the females had spontaneous thelarche Seven of the 16 males and five of the seven females were assessed after discontinuation of therapy; six of the seven males and four of the five females demonstrated evidence for reversibility of their hypogonadotropism Conclusions: Mutations in the neurokinin B pathway are relatively common as causes of hypogonadism Although the neurokinin B pathway appears essential during early sexual development, its importance in sustaining the integrity of the hypothalamic-pituitary-gonadal axis appears attenuated over time

Human GnRH Deficiency: A Unique Disease Model to Unravel the Ontogeny of GnRH Neurons

Abstract: Evolutionary survival of a species is largely a function of its reproductive fitness. In mammals, a sparsely populated and widely dispersed network of hypothalamic neurons, the gonadotropin-releasing hormone (GnRH) neurons, serve as the pilot light of reproduction via coordinated secretion of GnRH. Since it first description, human GnRH deficiency has been recognized both clinically and genetically as a heterogeneous disease. A spectrum of different reproductive phenotypes comprised of congenital GnRH deficiency with anosmia (Kallmann syndrome), congenital GnRH deficiency with normal olfaction (normosmic idiopathic hypogonadotropic hypogonadism), and adult-onset hypogonadotropic hypogonadism has been described. In the last two decades, several genes and pathways which govern GnRH ontogeny have been discovered by studying humans with GnRH deficiency. More importantly, detailed study of these patients has highlighted the emerging theme of oligogenicity and genotypic synergism, and also expanded the phenotypic diversity with the documentation of reversal of GnRH deficiency later in adulthood in some patients. The underlying genetic defect has also helped understand the associated nonreproductive phenotypes seen in some of these patients. These insights now provide practicing clinicians with targeted genetic diagnostic strategies and also impact on clinical management.

Reproductive hormone-dependent and -independent contributions to developmental changes in kisspeptin in GnRH-deficient hypogonadal mice.

Abstract: Kisspeptin is a potent activator of GnRH-induced gonadotropin secretion and is a proposed central regulator of pubertal onset. In mice, there is a neuroanatomical separation of two discrete kisspeptin neuronal populations, which are sexually dimorphic and are believed to make distinct contributions to reproductive physiology. Within these kisspeptin neuron populations, Kiss1 expression is directly regulated by sex hormones, thereby confounding the roles of sex differences and early activational events that drive the establishment of kisspeptin neurons. In order to better understand sex steroid hormone-dependent and -independent effects on the maturation of kisspeptin neurons, hypogonadal (hpg) mice deficient in GnRH and its downstream effectors were used to determine changes in the developmental kisspeptin expression. In hpg mice, sex differences in Kiss1 mRNA levels and kisspeptin immunoreactivity, typically present at 30 days of age, were absent in the anteroventral periventricular nucleus (AVPV). Although immunoreactive kisspeptin increased from 10 to 30 days of age to levels intermediate between wild type (WT) females and males, corresponding increases in Kiss1 mRNA were not detected. In contrast, the hpg arcuate nucleus (ARC) demonstrated a 10-fold increase in Kiss1 mRNA between 10 and 30 days in both females and males, suggesting that the ARC is a significant center for sex steroid-independent pubertal kisspeptin expression. Interestingly, the normal positive feedback response of AVPV kisspeptin neurons to estrogen observed in WT mice was lost in hpg females, suggesting that exposure to reproductive hormones during development may contribute to the establishment of the ovulatory gonadotropin surge mechanism. Overall, these studies suggest that the onset of pubertal kisspeptin expression is not dependent on reproductive hormones, but that gonadal sex steroids critically shape the hypothalamic kisspeptin neuronal subpopulations to make distinct contributions to the activation and control of the reproductive hormone cascade at the time of puberty.

Frequency-Dependent Regulation of Follicle-Stimulating Hormone β by Pulsatile Gonadotropin-Releasing Hormone Is Mediated by Functional Antagonism of bZIP Transcription Factors

Abstract: Oscillatory synthesis and secretion of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), under the control of pulsatile hypothalamic gonadotropin-releasing hormone (GnRH), is essential for normal reproductive development and fertility. The molecular mechanisms by which various patterns of pulsatile GnRH regulate gonadotrope responsiveness remain poorly understood. In contrast to the alpha and LH beta subunit genes, FSH beta subunit transcription is preferentially stimulated at low rather than high frequencies of pulsatile GnRH. In this study, mutation of a cyclic AMP response element (CRE) within the FSH beta promoter resulted in the loss of preferential GnRH stimulation at low pulse frequencies. We hypothesized that high GnRH pulse frequencies might stimulate a transcriptional repressor(s) to attenuate the action of CRE binding protein (CREB) and show that inducible cAMP early repressor (ICER) fulfills such a role. ICER was not detected under basal conditions, but pulsatile GnRH stimulated ICER to a greater extent at high than at low pulse frequencies. ICER binds to the FSH beta CRE site to reduce CREB occupation and abrogates both maximal GnRH stimulation and GnRH pulse frequency-dependent effects on FSH beta transcription. These data suggest that ICER production antagonizes the stimulatory action of CREB to attenuate FSH beta transcription at high GnRH pulse frequencies, thereby playing a critical role in regulating cyclic reproductive function.

A novel homozygous splice acceptor site mutation of KISS1R in two siblings with normosmic isolated hypogonadotropic hypogonadism

Abstract: Context Loss-of-function mutations of the kisspeptin-1 receptor gene, KISS1R, have been identified in patients with normosmic isolated hypogonadotropic hypogonadism (nIHH). Objective To investigate KISS1R defects in patients with absent or delayed puberty. Patients We investigated KISS1R gene defects in a cohort of 99 Brazilian patients with nIHH or constitutional delay of puberty (CDP). Methods The entire coding region of KISS1R was amplified by PCR followed by automatic sequencing. In addition, screening for KISS1R exonic deletions was performed by multiplex ligation-dependent probe amplification. Results One novel homozygous KISS1R mutation was identified in two siblings with nIHH. This variant was an insertion/deletion (indel) mutation characterized by the deletion of three nucleotides (GCA) at position -2 to -4, and by the insertion of seven nucleotides (ACCGGCT) at the same position, within the 3' splice acceptor site of intron 2 of KISS1R. The brothers who carried this KISS1R mutation had no clinical evidence of pubertal development at the ages of 14 and 20 years. Computational analysis of this indel mutation predicted the generation of an abnormal protein. In addition, a new heterozygous KISS1R variant (p.E252Q) was identified in a male patient with sporadic nIHH. However, in vitro studies of this variant did not demonstrate functional impairment. Only known polymorphisms were identified in patients with CDP. Conclusion Loss-of-function mutations of KISS1R represents a rare cause of nIHH, and was absent in patients with CDP. We have described a novel KISS1R homozygous splice acceptor site mutation in the familial form of nIHH.

Deciphering genetic disease in the genomic era: the model of GnRH deficiency.

Abstract: Isolated gonadotropin-releasing hormone (GnRH) deficiency is a treatable albeit rare form of reproductive failure that has revealed physiological mechanisms controlling human reproduction, but despite substantial progress in discovering pathogenic single-gene defects, most of the genetic basis of GnRH deficiency remains uncharted. Although unbiased genetic investigations of affected families have identified mutations in previously unsuspected genes as causes of this disease in some cases, their application has been severely limited because of the negative effect of GnRH deficiency on fertility; moreover, relatively few of the many candidate genes nominated because of biological plausibility from in vitro or animal model experiments were subsequently validated in patients. With the advent of exciting technological platforms for sequencing, homozygosity mapping, and detection of structural variation at the whole-genome level, human investigations are again assuming the leading role for gene discovery. Using human GnRH deficiency as a paradigm and presenting original data from the screening of numerous candidate genes, we discuss the emerging model of patient-focused clinical genetic research and its complementarities with basic approaches in the near future.

Cushing's Disease and Idiopathic Intracranial Hypertension: Case Report and Review of Underlying Pathophysiological Mechanisms

Abstract: Context: Several studies have reported an association between idiopathic intracranial hypertension (IIH) and deficits of the hypothalamic-pituitary-adrenal (HPA) axis. Case Illustration: A 33-yr-old woman with Cushing’s disease underwent successful surgical resection of a pituitary adenoma and developed IIH 11 months later after inadvertent withdrawal of oral glucocorticoids. Methods: A review of the literature was conducted to identify previous studies pertaining to IIH in association with neuroendocrine disease, focusing on reports related to HPA axis dysfunction. Results: A number of patients developing IIH due to a relative deficiency in glucocorticoids, after surgical or medical management for Cushing’s disease, withdrawal from glucocorticoid replacement, or as an initial presentation of Addison’s disease, have been reported. Hypotheses regarding the underlying pathophysiology of IIH in this context and, in particular, the role of cortisol and its relationship to other neuroendocrine and inflammatory...

The Role of Prokineticins in the Pathogenesis of Hypogonadotropic Hypogonadism

Abstract: The prokineticin system comprises two multifunctional secreted proteins, prokineticin-1 (PROK1) and prokineticin-2 (PROK2), and their cognate G protein-coupled receptors The prokineticins were originally identified as endogenous regulators of gastrointestinal motility Currently, these bioactive peptides are involved in a wide spectrum of biological functions, including angiogenesis, neurogenesis, circadian rhythms, nociception, hematopoiesis and immune response Mice homozygous for null mutations in Prokr2 or Prok2 recapitulate the human phenotype of Kallmann syndrome, exhibiting severe atrophy of the reproductive system and hypoplastic olfactory bulbs Indeed, the evidence from several naturally inactivating mutations in the PROK2 and PROKR2 genes in patients with Kallmann syndrome and normosmic hypogonadotropic hypogonadism also indicate the essential role of PROK2 in olfactory bulb morphogenesis and GnRH secretion in humans

Lymphocytic hypophysitis with diabetes insipidus in a young man

Abstract: Lymphocytic hypophysitis—an inflammatory condition of presumed autoimmune etiology—is characterized by an enlargement of the pituitary gland, resulting in its dysfunction. Although found generally in peripartum women, this Case Study of a 29-year-old man, who was referred to a neurosurgical clinic for evaluation of a suprasellar mass and diabetes insipidus, illustrates the need to consider this disorder in men. Background. A 29-year-old man was referred to a multidisciplinary pituitary clinic with a 3.5-year history of central diabetes insipidus, initially presumed to be idiopathic based on a normal MRI scan of the pituitary gland. Subsequent scanning revealed a suprasellar mass, which demonstrated progressive enlargement on serial imaging. He also developed hypogonadotropic hypogonadism. Investigations. Measurement of levels of serum morning fasting cortisol, adrenocorticotropic hormone, total testosterone, luteinizing hormone, follicle-stimulating hormone, prolactin, insulin-like growth factor 1, TSH and free T4, MRI of the pituitary gland and a transsphenoidal biopsy of a pituitary mass were performed. Diagnosis. Lymphocytic hypophysitis presenting with diabetes insipidus, with development of hypogonadotropic hypogonadism and a suprasellar mass. Management. The patient was treated with intranasal desmopressin and transdermal testosterone. The underlying lymphocytic hypophysitis was initially managed conservatively with serial MRI and visual field testing. No immunosuppressant medication was given and, aside from the diagnostic transsphenoidal biopsy, no surgical intervention was required. He subsequently developed secondary hypothyroidism, secondary adrenal insufficiency and growth hormone deficiency. These disorders were managed with levothyroxine and prednisone.

Infants of Women with Polycystic Ovary Syndrome have Lower Cord Blood Androstenedione and Estradiol Levels

Abstract: Context: Kisspeptin, encoded by the KISS1 gene, is a key stimulatory factor of GnRH secretion and puberty onset. Inactivating mutationsofitsreceptor(KISS1R)causeisolatedhypogonadotropichypogonadism(IHH).AuniqueKISS1Ractivatingmutationwas described in central precocious puberty (CPP). Objective: To investigate KISS1 mutations in patients with idiopathic CPP and normosmic IHH. Patients: Eighty-three children with CPP (77 girls) and 61 patients with IHH (40 men) were studied. The control group consisted of 200 individuals with normal pubertal development. Methods: The promoter region and the 3 exons of KISS1 were amplified and sequenced. Cells expressing KISS1R were stimulated with synthetic human wild-type or mutant kisspeptin-54 (kp54) and inositol phosphate accumulation was measured. In a second set of experiments, kp54 was pre-incubated in human serum prior to stimulation of the cells. Results:Two novelKISS1missense mutations, p.P74S and p.H90D, were identified in three unrelated children with idiopathic CPP. Both mutations were absent in 400 control alleles. The p.P74S mutation was identified in the heterozygous state in a boy who developedCPPat1yrofage.Thep.H90DmutationwasidentifiedinthehomozygousstateintwounrelatedgirlswithCPP.Invitro studies revealed that the capacity of the P74S and H90D mutants to stimulate IP production was similar to the wild-type. After pre-incubation of wild-type and mutant kp54’s in human serum, the capacity to stimulate signal transduction was significantly greater for P74S compared to the wild-type, suggesting that the p.P74S variant is more stable. Only polymorphisms were found in the IHH group. Conclusion:TwoKISS1mutationswereidentifiedinunrelatedpatientswithidiopathicCPP.Thep.P74Svariantwasassociatedwith

A high-throughput small-molecule ligand screen targeted to agonists and antagonists of the G-protein-coupled receptor GPR54.

Abstract: Recent data have shown that the G-protein-coupled receptor GPR54 (also known as KiSS-1 receptor) regulates GnRH release from the hypothalamus. This essential role of GPR54 in controlling the hypothalamic-pituitary-gonadal axis makes it an attractive target for therapeutic intervention in reproductive and cancer medicine. Currently, there are no small-molecule modulators of GPR54 function for experimental or clinical use. To identify small-molecule compounds that modify GPR54 signal transduction, the authors have adapted a cell-based functional assay for high-throughput screening (HTS) using a commercially available homogeneous time-resolved fluorescence assay for inositol phosphate accumulation. They generated stable Chinese hamster ovary cell transfectants that express human GPR54 for use in this assay. After optimization in an automated HTS environment, they screened a library of 110,000 small-molecule compounds using 2 protocols, one to identify agonists and one to identify antagonists. Hits obtained in the primary screen were confirmed to be active in secondary in vitro assays. Compounds identified as agonists or antagonists from HTS and secondary screening will be characterized to identify agents with the potential to be developed as novel orally active agents to treat hormone-dependent disorders such as abnormal puberty, infertility, endometriosis, and sex steroid-dependent tumors.

Stalking the Diagnosis

Abstract: A 58-year-old woman presented to her primary care physician after several days of dizziness, anorexia, dry mouth, increased thirst, and frequent urination. She had also had a fever and reported that food would “get stuck” when she was swallowing. She reported no pain in her abdomen, back, or flank and no cough, shortness of breath, diarrhea, or dysuria.

TAC3/TACR3 Mutations Reveal Preferential Activation of GnRH Release by Neurokinin B in Neonatal Life Followed by Reversal in Adulthood

Abstract: Objective: Diabetes in the context of severe insulin resistance (SIR) presents a major therapeutic challenge because conventional therapies including insulin and insulin sensitizers often fail to achieve adequate metabolic control. Adjunctive therapy with recombinant human IGF-I (rhIGF-I)/recombinant human IGF binding protein-3 (rhIGFBP-3) has been shown to improve insulin sensitivity in both type 1 and type 2 diabetes and may have a role in the treatment of SIR. We report clinical and physiological outcomes after adjunctive therapy with rhIGF-I/rhIGFBP-3 in five subjects with SIR. Research Design and Methods: Five females (median age, 17 yr; range, 5-37) with SIR (two with pathogenic insulin receptor mutations) were treated with 0.5-2.0 mg/kg rhIGF-I/rhIGFBP-3 using a 16-wk dose escalation protocol. Glycosylated hemoglobin was recorded monthly, and at baseline and end of treatment all patients were evaluated using continuous glucose monitoring sensing and admitted for overnight GH profiling and insulin-modified stable-label iv glucose tolerance test. Changes in body composition were assessed using dual-energy x-ray absorptiometry and magnetic resonance imaging. Results: Treatment with rhIGF-I/rhIGFBP-3 was well tolerated, and all subjects reported clinical improvements with reduction in acanthosis nigricans. Glycosylated hemoglobin was reduced (8.5% pretreatment to 7.1%; P 0.03) with a trend toward reduction in mean continuous glucose monitoring sensing glucose (10.7 vs. 8.5 mmol/liter; P 0.08). Effects of treatment on other biochemical measures were variable, but there was a trend toward improved C-peptide responses during the iv glucose tolerance test. Conclusions: rhIGF-I/rhIGFBP-3 is well tolerated and clinically effective in subjects with SIR. TAC3/TACR3 Mutations Reveal Preferential Activation of GnRH Release by Neurokinin B in Neonatal Life Followed by Reversal in Adulthood Elena Gianetti, Cintia Tusset, Sekoni D. Noel, Margaret G. Au, Andrew A. Dwyer, Virginia A. Hughes, Ana Paula Abreu, Jessica Carroll, Ericka Trarbach, Leticia FG Silveira, Elaine MF Costa, Berenice Bilharinho de Mendonca, Margaret de Castro, Adriana Lofrano, Janet E. Hall, Erol Bolu, Metin Ozata, Richard Quinton, John K. Amory, Susan E. Stewart, Wiebke Arlt, Trevor R. Cole, William F. Crowley, Ursula B. Kaiser, Ana Claudia Latronico, and Stephanie B. Seminara (J Clin Endocrinol Metab, 10.1210/jc.2009-2320) ABSTRACT Context: Mutations in TAC3 and TACR3 (encoding neurokinin B and its receptor) have been identified in Turkish patients with hypogonadotropic hypogonadism (IHH), but broader populations have not yet been tested and genotype-phenotype correlations have not been established. Objective: A broad cohort of normosmic IHH probands was screened for mutations in TAC3/TACR3 to evaluate the prevalence of such mutations and define the genotype/phenotype relationships. Design: Sequencing of TAC3/TACR3; in vitro functional assays, neuroendocrine phenotyping. Setting: Tertiary care centers world-wide. Patients or other participants: 345 probands, 18 family members, 292 controls. Intervention: Examination of reproductive phenotypes throughout reproductive life and pre/post therapy. Main Outcome Measure: Rare sequence variants in TAC3/TACR3. T R A N S L A T I O N A L H I G H L I G H T S F R O M T H E E N D O C R I N E S O C I E T Y J O U R N A L SContext: Mutations in TAC3 and TACR3 (encoding neurokinin B and its receptor) have been identified in Turkish patients with hypogonadotropic hypogonadism (IHH), but broader populations have not yet been tested and genotype-phenotype correlations have not been established. Objective: A broad cohort of normosmic IHH probands was screened for mutations in TAC3/TACR3 to evaluate the prevalence of such mutations and define the genotype/phenotype relationships. Design: Sequencing of TAC3/TACR3; in vitro functional assays, neuroendocrine phenotyping. Setting: Tertiary care centers world-wide. Patients or other participants: 345 probands, 18 family members, 292 controls. Intervention: Examination of reproductive phenotypes throughout reproductive life and pre/post therapy. Main Outcome Measure: Rare sequence variants in TAC3/TACR3. T R A N S L A T I O N A L H I G H L I G H T S F R O M T H E E N D O C R I N E S O C I E T Y J O U R N A L S