scholarly journals Heterozygous Orthodenticle Homeobox 2 Mutations Are Associated with Variable Pituitary Phenotype

2010 ◽  
Vol 95 (2) ◽  
pp. 756-764 ◽  
Author(s):  
Sumito Dateki ◽  
Kitaro Kosaka ◽  
Kosei Hasegawa ◽  
Hiroyuki Tanaka ◽  
Noriyuki Azuma ◽  
...  
Keyword(s):  
Target Genes ◽  
Japanese Patients ◽  
Dominant Negative ◽  
Pituitary Function ◽  
Hormone Deficiency ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Positive Role ◽  
Negative Effect ◽  
And Function

Abstract Context: Although recent studies have suggested a positive role of OTX2 in pituitary as well as ocular development and function, detailed pituitary phenotypes in OTX2 mutations and OTX2 target genes for pituitary function other than HESX1 and POU1F1 remain to be determined. Objective: We aimed to examine such unresolved issues. Subjects: We studied 94 Japanese patients with various ocular or pituitary abnormalities. Results: We identified heterozygous p.K74fsX103 in case 1, p.A72fsX86 in case 2, p.G188X in two unrelated cases (3 and 4), and a 2,860,561-bp microdeletion involving OTX2 in case 5. Clinical studies revealed isolated GH deficiency in cases 1 and 5; combined pituitary hormone deficiency in case 3; abnormal pituitary structures in cases 1, 3, and 5; and apparently normal pituitary function in cases 2 and 4, together with ocular anomalies in cases 1–5. The wild-type Orthodenticle homeobox 2 (OTX2) protein transactivated the GNRH1 promoter as well as the HESX1, POU1F1, and IRBP (interstitial retinoid-binding protein) promoters, whereas the p.K74fsX103-OTX2 and p.A72fsX86-OTX2 proteins had no transactivation functions and the p.G188X-OTX2 protein had reduced (∼50%) transactivation functions for the four promoters, with no dominant-negative effect. cDNA screening identified positive OTX2 expression in the hypothalamus. Conclusions: The results imply that OTX2 mutations are associated with variable pituitary phenotype, with no genotype-phenotype correlations, and that OTX2 can transactivate GNRH1 as well as HESX1 and POU1F1.

scholarly journals Heterozygous Orthodenticle Homeobox 2 Mutations Are Associated with Variable Pituitary Phenotype

2010 ◽  
Vol 31 (1) ◽  
pp. 133-133
Author(s):  
Sumito Dateki ◽  
Kitaro Kosaka ◽  
Kosei Hasegawa ◽  
Hiroyuki Tanaka ◽  
Noriyuki Azuma ◽  
...  
Keyword(s):  
Target Genes ◽  
Japanese Patients ◽  
Dominant Negative ◽  
Pituitary Function ◽  
Hormone Deficiency ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Positive Role ◽  
Negative Effect ◽  
And Function

ABSTRACT Context Although recent studies have suggested a positive role of OTX2 in pituitary as well as ocular development and function, detailed pituitary phenotypes in OTX2 mutations and OTX2 target genes for pituitary function other than HESX1 and POU1F1 remain to be determined. Objective We aimed to examine such unresolved issues. Subjects We studied 94 Japanese patients with various ocular or pituitary abnormalities. Results We identified heterozygous p.K74fsX103 in case 1, p.A72fsX86 in case 2, p.G188X in two unrelated cases (3 and 4), and a 2,860,561-bp microdeletion involving OTX2 in case 5. Clinical studies revealed isolated GH deficiency in cases 1 and 5; combined pituitary hormone deficiency in case 3; abnormal pituitary structures in cases 1, 3, and 5; and apparently normal pituitary function in cases 2 and 4, together with ocular anomalies in cases 1-5. The wild-type Orthodenticle homeobox 2 (OTX2) protein transactivated the GNRH1 promoter as well as the HESX1, POU1F1, and IRBP (interstitial retinoid-binding protein) promoters, whereas the p.K74fsX103-OTX2 and p.A72fsX86-OTX2 proteins had no transactivation functions and the p.G188X-OTX2 protein had reduced (∼50%) transactivation functions for the four promoters, with no dominant-negative effect. cDNA screening identified positive OTX2 expression in the hypothalamus. Conclusions The results imply that OTX2 mutations are associated with variable pituitary phenotype, with no genotype-phenotype correlations, and that OTX2 can transactivate GNRH1 as well as HESX1 and POU1F1.

scholarly journals OTX2 Loss of Function Mutation Causes Anophthalmia and Combined Pituitary Hormone Deficiency with a Small Anterior and Ectopic Posterior Pituitary

2009 ◽  
Vol 94 (1) ◽  
pp. 314-319 ◽  
Author(s):  
Toshihiro Tajima ◽  
Akira Ohtake ◽  
Masaya Hoshino ◽  
Shin Amemiya ◽  
Nozomu Sasaki ◽  
...  
Keyword(s):  
Brain Magnetic Resonance Imaging ◽  
Dominant Negative ◽  
Hormone Deficiency ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Posterior Lobe ◽  
Loss Of Function ◽  
Pituitary Hormone Deficiency ◽  
Combined Pituitary Hormone Deficiency ◽  
Negative Effect

Abstract Context: Orthodenticle homeobox 2 (OTX2) is a transcription factor necessary for ocular and forebrain development. In humans, heterozygous mutations of OTX2 cause severe ocular malformations. However, whether mutations of OTX2 cause pituitary structural abnormalities or combined pituitary hormone deficiency (CPHD) has not been clarified. Objectives: We surveyed the functional consequences of a novel OTX2 mutation that was detected in a patient with anophthalmia and CPHD. Patient: We examined a Japanese patient with growth disturbance, anophthalamia, and severe developmental delay. He showed deficiencies in GH, TSH, LH, FSH, and ACTH. Brain magnetic resonance imaging revealed a small anterior pituitary gland, invisible stalk, ectopic posterior lobe, and Chiari malformation. Results: Sequence analysis of OTX2 demonstrated a heterozygous two bases insertion [S136fsX178 (c.576-577insCT)] in exon 3. The mutant Otx2 protein localized to the nucleus, but did not activate the promoter of the HESX1 and POU1F1 gene, indicating a loss of function mutation. No dominant negative effect in the presence of wild-type Otx2 was observed. Conclusion: This case indicates that the OTX2 mutation is a cause of CPHD. Further study of more patients with OTX2 defects is necessary to clarify the clinical phenotypes and endocrine defects caused by OTX2 mutations.

scholarly journals The R271W mutant form of Pit-1 does not act as a dominant inhibitor of Pit-1 action to activate the promoters of GH and prolactin genes

2003 ◽  
pp. 619-625 ◽  
Author(s):  
M Kishimoto ◽  
Y Okimura ◽  
M Fumoto ◽  
G Iguchi ◽  
K Iida ◽  
...  
Keyword(s):  
Reporter Gene ◽  
Dominant Negative ◽  
Hormone Deficiency ◽  
Luciferase Reporter ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Mutant Form ◽  
Wild Type ◽  
Expression Study ◽  
Negative Effect

OBJECTIVE: Genetic abnormalities of the pituitary specific transcription factor, Pit-1, have been reported in several patients with GH, prolactin (PRL) and TSH deficiencies. The most common is a mutation altering an arginine to a tryptophan in codon 271 (R271W) in one allele of the Pit-1 gene. According to the previous in vitro expression study, R271W acted as a dominant negative inhibitor of the wild type to activate the GH promoter. However, healthy carriers with this mutation, who should be affected by the dominant negative effect of R271W, have also been reported. The aim of this study was to clarify in more detail the function of this mutant form of Pit-1. METHODS: Transcriptional activity of R271W for the expression of Pit-1-associated genes was investigated in COS7 cells with the aid of transient transfection assays. The 1.8 kb rat GH, 0.6 kb rat PRL or 1.9 kb rat PRL 5'-flanking regions were inserted upstream of the luciferase reporter gene and were used for functional analysis of R271W. Another reporter gene containing seven Pit-1 responsive elements was also used. The same experiments were also performed using JEG3 and CHO cells. RESULTS: We could not confirm the dominant negative effect of R271W on wild type Pit-1. Furthermore, our expression study revealed that R271W could activate the promoters of GH and PRL genes to levels similar to the wild type. CONCLUSION: Taken together with the evidence that phenotypically normal cases have been reported with this mutation, our results deny the relationship between R271W and combined pituitary hormone deficiency.

scholarly journals The Diagnostic Journey of a Patient with Prader–Willi-Like Syndrome and a Unique Homozygous SNURF-SNRPN Variant; Bio-Molecular Analysis and Review of the Literature

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 875
Author(s):  
Karlijn Pellikaan ◽  
Geeske M. van Woerden ◽  
Lotte Kleinendorst ◽  
Anna G. W. Rosenberg ◽  
Bernhard Horsthemke ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Single Nucleotide Polymorphism Array ◽  
Genetic Defect ◽  
Missense Variant ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Negative Effect

Prader–Willi syndrome (PWS) is a rare genetic condition characterized by hypotonia, intellectual disability, and hypothalamic dysfunction, causing pituitary hormone deficiencies and hyperphagia, ultimately leading to obesity. PWS is most often caused by the loss of expression of a cluster of genes on chromosome 15q11.2-13. Patients with Prader–Willi-like syndrome (PWLS) display features of the PWS phenotype without a classical PWS genetic defect. We describe a 46-year-old patient with PWLS, including hypotonia, intellectual disability, hyperphagia, and pituitary hormone deficiencies. Routine genetic tests for PWS were normal, but a homozygous missense variant NM_003097.3(SNRPN):c.193C>T, p.(Arg65Trp) was identified. Single nucleotide polymorphism array showed several large regions of homozygosity, caused by high-grade consanguinity between the parents. Our functional analysis, the ‘Pipeline for Rapid in silico, in vivo, in vitro Screening of Mutations’ (PRiSM) screen, showed that overexpression of SNRPN-p.Arg65Trp had a dominant negative effect, strongly suggesting pathogenicity. However, it could not be confirmed that the variant was responsible for the phenotype of the patient. In conclusion, we present a unique homozygous missense variant in SNURF-SNRPN in a patient with PWLS. We describe the diagnostic trajectory of this patient and the possible contributors to her phenotype in light of the current literature on the genotype–phenotype relationship in PWS.

scholarly journals Pituitary Morphology and Function in 43 Children with Central Diabetes Insipidus

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Wendong Liu ◽  
Limin Wang ◽  
Minghua Liu ◽  
Guimei Li
Keyword(s):  
Diabetes Insipidus ◽  
Central Diabetes Insipidus ◽  
Pituitary Function ◽  
Pituitary Stalk ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Initial Manifestation ◽  
Stalk Diameter ◽  
And Function

Objective. In pediatric central diabetes insipidus (CDI), etiology diagnosis and pituitary function monitoring are usually delayed. This study aimed to illustrate the importance of regular follow-up and pituitary function monitoring in pediatric CDI.Methods. The clinical, hormonal, and neuroradiological characteristics of children with CDI at diagnosis and during 1.5–2-year follow-up were collected and analyzed.Results. The study included 43 CDI patients. The mean interval between initial manifestation and diagnosis was 22.29 ± 3.67 months (range: 2–108 months). The most common complaint was polyuria/polydipsia. Causes included Langerhans cell histiocytosis, germinoma, and craniopharyngioma in 2, 5, and 4 patients; the remaining were idiopathic. No significant changes were found during the 1.5–2 years after CDI diagnosis. Twenty-three of the 43 cases (53.5%) had ≥1 anterior pituitary hormone deficiency. Isolated growth hormone deficiency was the most frequent abnormality (37.5%) and was not associated with pituitary stalk diameter. Multiple pituitary hormone deficiencies were found in 8 cases with pituitary stalk diameter > 4.5 mm.Conclusion. Diagnosis of CDI is usually delayed. CDI with a pituitary stalk diameter > 4.5 mm carries a higher risk of multiple pituitary hormone deficiencies. Long-term MRI and pituitary function follow-ups are necessary for children with idiopathic CDI.

scholarly journals Yeast formin Bni1p has multiple localization regions that function in polarized growth and spindle orientation

2012 ◽  
Vol 23 (3) ◽  
pp. 412-422 ◽  
Author(s):  
Wenyu Liu ◽  
Felipe H. Santiago-Tirado ◽  
Anthony Bretscher
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Spindle Orientation ◽  
Bud Neck ◽  
Negative Effect ◽  
The Right ◽  
Actin Cables ◽  
And Function

Formins are conserved proteins that assemble unbranched actin filaments in a regulated, localized manner. Budding yeast's two formins, Bni1p and Bnr1p, assemble actin cables necessary for polarized cell growth and organelle segregation. Here we define four regions in Bni1p that contribute to its localization to the bud and at the bud neck. The first (residues 1–333) requires dimerization for its localization and encompasses the Rho-binding domain. The second (residues 334–821) covers the Diaphanous inhibitory–dimerization–coiled coil domains, and the third is the Spa2p-binding domain. The fourth region encompasses the formin homology 1–formin homology 2–COOH region of the protein. These four regions can each localize to the bud cortex and bud neck at the right stage of the cell cycle independent of both F-actin and endogenous Bni1p. The first three regions contribute cumulatively to the proper localization of Bni1p, as revealed by the effects of progressive loss of these regions on the actin cytoskeleton and fidelity of spindle orientation. The fourth region contributes to the localization of Bni1p in tiny budded cells. Expression of mislocalized Bni1p constructs has a dominant-negative effect on both growth and nuclear segregation due to mislocalized actin assembly. These results define an unexpected complexity in the mechanism of formin localization and function.

Both the paired domain and homeodomain are required for in vivo function of Drosophila Paired

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2709-2718 ◽  
Author(s):  
P. Miskiewicz ◽  
D. Morrissey ◽  
Y. Lan ◽  
L. Raj ◽  
S. Kessler ◽  
...  
Keyword(s):  
Dna Binding ◽  
Target Genes ◽  
Ectopic Expression ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Paired Domain ◽  
Mutant Proteins ◽  
Segment Polarity ◽  
Negative Effect

Drosophila paired, a homolog of mammalian Pax-3, is key to the coordinated regulation of segment-polarity genes during embryogenesis. The paired gene and its homologs are unusual in encoding proteins with two DNA-binding domains, a paired domain and a homeodomain. We are using an in vivo assay to dissect the functions of the domains of this type of molecule. In particular, we are interested in determining whether one or both DNA-binding activities are required for individual in vivo functions of Paired. We constructed point mutants in each domain designed to disrupt DNA binding and tested the mutants with ectopic expression assays in Drosophila embryos. Mutations in either domain abolished the normal regulation of the target genes engrailed, hedgehog, gooseberry and even-skipped, suggesting that these in vivo functions of Paired require DNA binding through both domains rather than either domain alone. However, when the two mutant proteins were placed in the same embryo, Paired function was restored, indicating that the two DNA-binding activities need not be present in the same molecule. Quantitation of this effect shows that the paired domain mutant has a dominant-negative effect consistent with the observations that Paired protein can bind DNA as a dimer.

Feed-back mechanisms affecting Notch activation at the dorsoventral boundary in the Drosophila wing

Development ◽  
1997 ◽  
Vol 124 (17) ◽  
pp. 3241-3251 ◽  
Author(s):  
J.F. Celis de ◽  
S. Bray
Keyword(s):  
Positive Feedback ◽  
Target Genes ◽  
Normal Growth ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Drosophila Wing ◽  
Negative Effect ◽  
Dorsoventral Boundary ◽  
Late Stages ◽  
Notch Activation

Notch function is required at the dorsoventral boundary of the developing Drosophila wing for its normal growth and patterning. We find that clones of cells expressing either Notch or its ligands Delta and Serrate in the wing mimic Notch activation at the dorsoventral boundary producing non-autonomous effects on proliferation, and activating expression of the target genes E(spl), wingless and cut. The analysis of these clones reveals several mechanisms important for maintaining and delimiting Notch function at the dorsoventral boundary. First, Notch activation in the wing leads to increased production of Delta and Serrate generating a positive feedback loop that maintains signalling. We propose that during normal development, wingless co-operates with Notch to reinforce this positive feedback and Cut, which is activated by Notch at late stages, acts antagonistically to prevent Delta and Serrate expression. Second, high levels of Delta and Serrate have a dominant negative effect on Notch, so that at late stages Notch can only be activated in cells next to the ligand-producing cells. Thus the combined effects of Notch and its target genes cut and wingless regulate the expression of Notch ligands which restrict Notch activity to the dorsoventral boundary.

scholarly journals Mutant p53 exerts a dominant negative effect by preventing wild-type p53 from binding to the promoter of its target genes

Oncogene ◽  
2004 ◽  
Vol 23 (13) ◽  
pp. 2330-2338 ◽  
Author(s):  
Amy Willis ◽  
Eun Joo Jung ◽  
Therese Wakefield ◽  
Xinbin Chen
Keyword(s):  
Target Genes ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Mutant P53 ◽  
Wild Type ◽  
Negative Effect ◽  
Wild Type P53

scholarly journals Mutant p53 Enhances the Development and Sustained Growth of MYC-Driven Lymphoma and Exerts a Dominant Negative Effect Preferentially Deregulating Pathways for Metabolism and DNA Repair

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1545-1545
Author(s):  
Brandon J Aubrey ◽  
Ana Janic ◽  
Yunshun Chen ◽  
Gordon K Smyth ◽  
Andrew J Kueh ◽  
...  
Keyword(s):  
Dna Damage ◽  
Target Genes ◽  
Human Cancer ◽  
Gene Mutations ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Wild Type ◽  
Over Expression ◽  
Negative Effect ◽  
Induced Apoptosis

Abstract Over-expression of the c-MYC oncogene and Trp53 gene mutations are among the most common genetic alterations in human cancer and, when combined, result in highly aggressive malignant disease. Trp53 gene mutations produce over-expressed mutant TRP53 proteins that drive cancer growth through both loss of wild-type Trp53 tumor suppressor function and gain-of-function oncogenic properties. The Eμ-Myc mouse model provides a setting to study the functional interplay between c-Myc over-expression and mutant TRP53 proteins. Eμ-Myc transgenic mice carry a c-Myc transgene under the control of the immunoglobulin heavy chain gene enhancer (Eμ), recapitulating the chromosomal translocation underlying human Burkitt Lymphoma, and develop aggressive pre-B/B cell lymphoma with a high (~20%) spontaneous rate of Trp53 mutation. The effect of five mouse mutant TRP53 proteins (V170M, I192S, G280, R246Q, R270H) was initially examined in three settings (Trp53-/-, Trp53+/- and Trp53+/+;Eμ-Myc) using a hematopoietic stem and progenitor cell (HSPC) reconstitution model. Each mutant TRP53 protein studied corresponds to a commonly re-occurring Tp53 mutation in human cancer. Retroviral over-expression enabled the comparison of mutant-specific and genotype-specific features for each mutant TRP53 protein. Mutant TRP53 expression did not accelerate lymphoma development in mice receiving Trp53-/- or Trp53+/- HSPCs. However, mice reconstituted with Trp53+/- HSPCs expressing the TRP53 mutants displayed an altered tumor spectrum compared to mice reconstituted with control Trp53+/- HSPCs. In contrast, mutant TRP53 markedly accelerated lymphoma development in mice receiving Trp53+/+;Eμ-Myc HSPCs, highlighting a synergy between c-Myc over-expression and Trp53 mutations in neoplastic transformation. Furthermore, inducible mutant TRP53 expression demonstrated a dependency on sustained expression of mutant TRP53 in established MYC-driven lymphomas. Notably, none of the c-MYC plus mutant TRP53 driven lymphomas exhibited spontaneous endogenous Trp53 mutations. Despite the enhanced tumorigenesis, most established lymphomas from this model displayed sensitivity to TRP53-activating drugs consistent with a weak dominant negative effect over wild-type Trp53-induced apoptosis. Consistent with this finding, pre-malignant Trp53+/+;Eμ-Myc primary B-cells expressing mutant TRP53 were not protected against Trp53-induced apoptosis. Pre-malignant B-cells displayed a small increase in cell cycling and an expansion of the tumor-initiating pre/pro-B cell population. Most significantly, functional assessment of DNA damage in pre-malignant cells, using single cell gel electrophoresis (comet assay) and γ-H2AX staining, revealed increased DNA damage, suggesting an important role for defects in DNA repair during mutant TRP53-driven lymphoma development. To investigate the nature of the dominant negative effect, mutant TRP53 protein was exogenously expressed in mouse Eµ-Myc Trp53+/+ lymphoma cell lines. The impact of mutant TRP53 on the transcriptional function of the endogenous wild-type TRP53 protein was then studied using the TRP53-activating compound, nutlin-3a. Surprisingly, in established lymphoma cell lines, mutant TRP53 impaired nutlin-3a-induced apoptosis despite substantial induction of the critical pro-apoptotic effector, PUMA. To explore this finding further, we globally characterized the dominant negative effect, and assessed for mutant TRP53-specific transcriptional targets, by performing whole transcriptome sequence (RNAseq) analysis after treatment with nutlin-3a. Analysis of known wild-type Trp53 target genes (n=283) demonstrated that the induction of these genes as a group was repressed in the presence of the mutant TRP53 protein (ROAST test, p=6.7e-04). Remarkably, however, mutant TRP53 significantly repressed only 57% of the nutlin-3a-induced Trp53 target genes. Analysis of these strongly repressed genes highlighted the importance of several pathways, including metabolism, DNA damage repair and negative feedback loops in TRP53 signaling. This suggests a previously unrecognized selectivity of the dominant-negative-effect for certain p53 pathways that may be important in cancer initiation. Additional mutant TRP53-specific transcriptional targets were also identified and are under further investigation. Disclosures No relevant conflicts of interest to declare.

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